Ceramics International 42 (2016) 10913–10921 Contents lists available at ScienceDirect Ceramics International http://d 0272-88 n Corr E-m journal homepage: www.elsevier.com/locate/ceramint Synthesis and morphological transformation of BaWO4 crystals: Experimental and theoretical insights Marisa Carvalho Oliveira a,b, Lourdes Gracia a, Içamira Costa Nogueira c, Maria Fernanda do Carmo Gurgel d, Jose Manuel Rivas Mercury c, Elson Longo e, Juan Andrés a,n a Department of Analytical and Physical Chemistry, University Jaume I (UJI), Castelló E-12071, Spain b CDMF-UFSCar, Universidade Federal de São Carlos, PO Box 676, 13565-905 São Carlos, SP, Brazil c PPGEM-IFMA, Instituto Federal do Maranhão, CEP 65030-005 São Luís, MA, Brazil d Department of Chemistry, Universidade Federal de Goiás, Regional Catalão, Av.Dr.Lamartine Pinto de Avelar, 75704-020 Catalão, GO, Brazil e CDMF-UNESP, Universidade Estadual Paulista, PO Box 355, CEP 14801-907 Araraquara, SP, Brazil a r t i c l e i n f o Article history: Received 16 February 2016 Received in revised form 18 March 2016 Accepted 29 March 2016 Available online 30 March 2016 Keywords: BaWO4 crystals Co-precipitation method Morphology DFT calculations Surface energies x.doi.org/10.1016/j.ceramint.2016.03.225 42/& 2016 Elsevier Ltd and Techna Group S.r esponding author. ail address: andres@uji.es (J. Andrés). a b s t r a c t BaWO4 crystals have been obtained by a co-precipitation method, and their structures were character- ized by X-ray diffraction and Rietveld refinement techniques, while field emission scanning electron microscopy was utilized to investigate the morphology of the as-synthesized aggregates. Geometries, bulk electronic properties, surface energies, and surface tension of the obtained BaWO4 crystals were evaluated using first-principles quantum mechanical calculations. A theoretical model based on the Wulff construction was introduced to explain possible crystal morphologies by tuning their surface chemistry, which is related to the relative stability of the faceted crystals. Both the experimental and theoretical data revealed the presence of (112), (001), and (100) facets with low values of surface energy in the BaWO4 crystals. The experimental morphologies of the as-synthesized samples are similar to the theoretically obtained shapes when surface energy values for the (001) and (100) surfaces are increased simultaneously. & 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved. 1. Introduction Barium tungstate (BaWO4) crystals have attracted significant interest from many research groups due to their potential appli- cations in scintillation devices, batteries, capacitors, photo- catalysts, and, in particular, photoluminescent materials [1–6]. In recent years, various synthetic methods have been used to pro- duce BaWO4 crystals, such as co-precipitation (CP), sol–gel, mod- ified Pechini, solid state reaction, solution route, Czochralski, so- nochemical, and hydrothermal techniques [7–24]. BaWO4 is a semiconductor that belongs to the family of scheelites with crystallized tetragonal structures having the space group I41/a and symmetry C4h 6 , in which Ba atoms are coordinated to eight O atoms, while W atoms have tetragonal coordination of O atoms; thus, the building blocks of the BaWO4 crystal are delta- hedral [BaO8] and tetrahedral [WO4] clusters [14,25–30]. Distor- tions of these clusters caused by the deformations of W–O and Ba– O bond distances as well as by tilting of O–W–O and O–Ba–O bond .l. All rights reserved. angles have a significant effect on their geometry, surface struc- ture, and related properties [14]. Various theoretical studies have been published on the geometry as well as electronic and optical properties of BaWO4 [19,31–33]. Surface properties of materials strongly depend on their mor- phology that is characterized by types and relative areas of various crystal facets, which usually can be tuned by tailoring their facets with different surface atomic arrangements and coordination. In general, the most stable surfaces control the crystal growth process, while less stable crystal facets contain large numbers of kink atoms in high-index planes [34]. Thus, studying the morphology of micro- and nanomaterials is an essential step in understanding their phy- sical and chemical properties, while controlled synthesis of specific morphologies is critical for enhancing their performance in practical applications [35,36]. In particular, morphology-controlled syntheses of BaWO4 have been performed by various research groups [37–40]. Nevertheless, these methods are far from being optimized, and their experimental aspects are still debated. In this context, experimental surface energies cannot be readily attained, and computer modeling and simulations are necessary to obtain surface characteristics of BaWO4, which are powerful tools for exploring morphological mechanisms at the atomistic/molecular level. www.sciencedirect.com/science/journal/02728842 www.elsevier.com/locate/ceramint http://dx.doi.org/10.1016/j.ceramint.2016.03.225 http://dx.doi.org/10.1016/j.ceramint.2016.03.225 http://dx.doi.org/10.1016/j.ceramint.2016.03.225 http://crossmark.crossref.org/dialog/?doi=10.1016/j.ceramint.2016.03.225&domain=pdf http://crossmark.crossref.org/dialog/?doi=10.1016/j.ceramint.2016.03.225&domain=pdf http://crossmark.crossref.org/dialog/?doi=10.1016/j.ceramint.2016.03.225&domain=pdf mailto:andres@uji.es http://dx.doi.org/10.1016/j.ceramint.2016.03.225 Fig. 1. A polyhedral representation of the BaWO4 unit cell. The local coordination corresponding to the deltahedral [BaO8] and tetrahedral [WO4] clusters is depicted for both Ba and W atoms, respectively. M.C. Oliveira et al. / Ceramics International 42 (2016) 10913–1092110914 Using a specific methodology, which has been applied to study morphologies of various metal oxides such as SnO2 [41], PbMoO4 [42], and CaWO4 [43], we developed a combination of experi- mental studies with first-principles calculations to deeper in- vestigate electronic, structural, and energetic properties control- ling the morphology and related transformation mechanisms of various metals and metal oxides such as Ag, anatase TiO2, BaZrO3, and α-Ag2WO4 [44] as well as Co3O4, Fe2O3, and In2O3 [45]. Based on the obtained results, we were able to explore facet-dependent photocatalytic and antibacterial properties of α-Ag2WO4 crystals [46] as well as the relationship between the photoluminescence and photocatalytic properties of Ag3PO4 microcrystals [47] and then identify and rationalize morphological, structural, and optical properties of β-Ag2MoO4 microcrystals [48]. These cited papers contain a description of the method of calculating surface en- ergies, which were used to characterize the corresponding surface morphologies. The main goal of this article is to investigate the morphology of the as-synthesized BaWO4 crystals characterized by X-ray dif- fraction and Rietveld refinement and field emission scanning electron microscopy techniques, as well as to simulate the crystal shape possibilities using first-principles quantum mechanical cal- culations based on the Wulff construction. 2. Experimental 2.1. Synthesis of BaWO4 crystals BaWO4 crystals were synthesized by a CP method at 353 K in aqueous solutions. A typical synthesis procedure for the BaWO4 crystals can be described as follows: 1�10�3 mol of sodium tungstate dihydrate (Na2WO4 �2H2O) (99.5% purity, Stream Che- mical) and 1�10�3 mol of barium nitrate [Ba(NO3)2] (99% purity, Sigma-Aldrich) salts were dissolved in two separate beakers con- taining 50 mL of deionized water under constant stirring until it reaches 353 K. Next, the barium nitrate solution was added to the sodium tungstate dihydrate solution and maintained under agi- tation at 353 K for 20 min. As a result, a white precipitate was rapidly formed, which was washed with deionized water several times. Finally, the obtained white precipitates were collected and dried in a conventional furnace at 323 K for 8 h. 2.2. Characterization BaWO4 crystals were structurally characterized by X-ray diffraction (XRD) using a DMax/2500PC diffractometer (Rigaku, Japan) with Cu Kα radiation (λ¼1.5406 Å) in a 2θ range from 10° to 110° with an angular step of 0.02° min�1. Rietveld refinement [49] of the obtained XRD patterns was performed by using a general structure analysis (GSAS) program [50]. The diffraction peak profiles were adjusted by utilizing Thompson-Cox-Hastings pseudo-Voigt (pV-TCH) and asymmetry functions as described by Finger et al. [51] Strain anisotropy broadening was corrected by applying a phenomenological model described by Stephens [52]. Morphologies of the synthesized BaWO4 crystals were studied with a field-emission scanning electron microscope (FE–SEM) (model Inspect F50, FEI Company, Hillsboro, OR) operated at 15 kV. 2.3. Computational methods and modeling First-principles calculations were conducted within the fra- mework of the density functional theory (DFT) using the CRYS- TAL14 software package [53]. The gradient-corrected correlation functional by Lee et al. [54] combined with the Becke's exchange functional (B3LYP) [55] was used for all calculations. This method has been successfully employed in various studies of bulk and surface electronic and structural properties of perovskite [56,57], tungstate [42,58,59], and molybdate-based materials [60]. Diag- onalization of the Fock matrix was performed at adequate k-points grids (Pack–Monkhorst 1976) in the reciprocal space. The thresholds controlling the accuracy of the Coulomb and ex- change integral calculations were set to 10�8 (ITOL1 to ITOL4) and 10�14 (ITOL5), respectively, whereas the percentage of Fock/ Kohn–Sham matrices mixing was set to 30 (IPMIX¼30) [61]. The W atoms were described by large-core effective core potentials derived by Hay and Wadt and modified by Cora et al. [62], while the O [63] and Ba [64] atoms were represented by the 6-31G* basis set. The surface energy, Esurf [43,45], was calculated by using the equation (Eslab�nEbulk)/½A, where nEbulk is the number of surface molecular units multiplied by the energy of the bulk, Eslab is the total energy of the surface slab per molecular unit, and A is the surface area. The equilibrium shape of a crystal can be calculated by utilizing Wulff constructions that minimize the total surface free energy at a fixed volume, providing a simple relationship between the surface energy, Esurf, of a (hkl) plane and its distance from the center of the crystallite in the normal direction [65]. The Visualization for Electronic and Structural Analysis (VESTA) pro- gram [66] has been utilized to obtain morphologies of the BaWO4 crystals. Band structures were calculated for 80 k-points along the appropriate high-symmetry paths of the adequate Brillouin zone. Fig. 2. Schematic representations of the (001), (101), (110), (100), (111), and (112) surfaces. The values of Ba–O and W–O bond distances are listed for the superficial Ba and W atoms, respectively. M.C. Oliveira et al. / Ceramics International 42 (2016) 10913–10921 10915 Fig. 3. Rietveld refinements for the BaWO4 crystals. Table 1 Calculated and experimental values of the lattice parameters (a and c) and atomic coordinates of the Ox, Oy, and Oz. Data Cell parameters Oxygen coordinates a (Å) c (Å) Ox Oy Oz Theo. (this work) 5.5927 12.4055 0.2245 0.1219 0.04635 Exp. (this work) 5.6149 12.7326 0.2295 0.1294 0.05024 Exp. [5] 5.6102 12.7100 – – – Exp. [2] 5.6063 12.7107 0.76731 0.14013 0.08188 Exp. [6] 5.615 (2) 12.722 (4) 0.2422 (2) 0.1403 (3) 0.0369 (9) Exp. [10] 5.612 1 2.706 – – – Exp. [14] 5.5682 12.7702 – – – Exp/theo. [19] 5.611 12.6885 0.2415 0.0086 0.2126 Theo [32,33] 5.61 12.71 – – – Exp. [77] 5.6034 12.6937 0.2336 (4) 0.0976 (6) 0.0499 (6) M.C. Oliveira et al. / Ceramics International 42 (2016) 10913–1092110916 The density of state (DOS) was obtained to analyze the corre- sponding electronic structures. Based on the theoretical and experimental results, seven models were constructed using a single conventional 1�1�1 cell as a repeating unit to represent bulk and surface structures. First, structural and electronic properties were calculated for a perfect bulk BaWO4 lattice (Fig. 1). The representation of the BaWO4 bulk structure is shown in Fig. 1. The W atoms are coordinated to four O atoms, producing tetrahedral [WO4] clusters (with 4 vertices, 4 faces, and 6 edges). Correspondingly, the Ba atoms are coordinated to eight O atoms, resulting in a formation of [BaO8] clusters (with 8 vertices, 12 fa- ces, and 18 edges) [67]. In the second step, different surfaces were modeled by using unreconstructed (truncated bulk) [68] slab models with calculated equilibrium geometries. The (001), (101), (110), (100), (111), and (112) surfaces of BaWO4 were simulated considering symmetrical slabs (with respect to the mirror plane). All surfaces were termi- nated with O planes; and after the corresponding optimization process and thickness convergence tests, the resulting slab models consisted of four molecular units containing 24 atoms, as shown in Fig. 2. Note that the (101), (111), and (112) surfaces are terminated with W and O atoms, while the other listed surfaces are Ba–O terminated. The W surface atoms are coordinated to three or four O atoms, forming [WO3] or [WO4] clusters, respectively, while the Ba surface atoms are coordinated to three, five, or six O atoms, forming [BaO3], [BaO5] or [BaO6] clusters, respectively. Present equilibrium morphology models are derived from cal- culated surface energies [65,69,70] using the assumption that crystal faces with lowest surface energies control the crystal morphology [71–73]. Since surface stability depends on atomic configurations of exposed facets [74], the local coordination of both the W and Ba atoms controls the crystal morphology of BaWO4 and corresponding behavior of each surface (as shown in Fig. 2). Another important aspect that should be considered when studying solid materials is a distinction between the surface en- ergy, Esurf, and the surface tension, s. The surface tension is a “surface stress” represented by a work force per unit area in the surface layer [75,76]. The surface tension can be obtained using the thermodynamic stability model described by the equation s¼∂Etot/∂A, where Etot is the total energy with contributions from the particle bulk and surfaces. To calculate Etot, uniform dilation with an area, ΔA (corresponding to a constant ratio between the in-plane lattice parameters x:y) of the structure must be per- formed while optimizing only the internal parameters (without optimization of the in-plane cell parameters). Thus, Etot can be calculated as ½(Eslab�nEbulk) for optimized structures and surfaces after dilation. Therefore, by applying two-dimensional dilation to a slab in the surface plane and calculating the total energy as pre- viously described, a change in total energy (ΔEtot) after dilation could be obtained for a given dilation area value. 3. Results and discussion 3.1. X-ray diffraction measurements and Rietveld refinements The crystal structure, the lattice parameters and the atomic positions were obtained by using the Rietveld refinement method (Fig. 3). The calculated values for the BaWO4 structure are col- lected in Table 1 and compared with experimental ones, as well as with previous theoretical and experimental results [19,32,33]. The Rietveld refinement results indicate that the obtained dif- fraction patterns for the BaWO4 crystals match the corresponding spectra in the Inorganic Crystal Structure Database (ICSD, card N° 250487) [77], as shown in Fig. 3, which compares the observed patterns with the calculated ones. Low deviation values for the statistical parameters Rwp, Rp, RBragg, and χ2 (14.73%, 9.32%, 5.45% and 1.29%, respectively) were found, which indicate good quality of the structural refinements. The lattice parameters (a, b¼5.6149 Å, c¼12.7326 Å and α¼β¼γ¼90°) estimated from the refinements correspond to a tetragonal structure with space group I41/a (N° 88) and four molecular formula units per unit cell (Z¼4), which confirms the applicability of the CP method to the synthesis of BaWO4 crystals. As can be observed in Table 1, the agreement of our calcula- tions with the experiments is reasonably good, being the unit-cell volume underestimated by 3.3% and the axial ratio c/a agrees within 2.2%. In addition, our structural data are according to pre- viously reported theoretical and experimental results. 3.2. Band structure and density of states The band structures and projected DOS for atoms and orbitals in the bulk BaWO4 and (001), (101), (110), (100), (111), and (112) surfaces are presented in Fig. 4. The analysis of the principal components of atomic orbitals (AOs) for selected bands shows that the BaWO4 valence band (VB) mostly consists of 2px, 2py, and 2pz orbitals of the O atoms, with the most important contribution coming from the 2px orbitals. The Fig. 4. Calculated band structures and DOS for the (a) bulk BaWO4 and (b) (001), (c) (101), (d) (110), (e) (100), (f) (111), and (g) (112) surfaces. M.C. Oliveira et al. / Ceramics International 42 (2016) 10913–10921 10917 lowest part of the conduction band (CB) is composed of the 5dz 2, 5dxz, 5dyz, 5dx2�y2, and 5dxy AOs of the W atoms, with the 5dz2 orbitals being the most important components for the bulk BaWO4. The band structure and DOS projected for the (001), (101), (110), (100), (111), and (112) surfaces are shown in Fig. 4(b–g). The gap energy, Egap, obtained for these surfaces is very similar to that for the bulk crystal (see Table 2). However, the bands contributing to the lowest part of the CB have different arrangements for each studied surface, which affect the contribution of the W 5d orbitals depending on the selected surface. It should be noted that the (111) surface exhibits conducting behavior. Table 2 Calculated values of the surface energy, surface tension, gap energy, and change in total energy (ΔEtot) for a given value of dilation area (ΔA) for each surface. Surface Esuf (J/m2) ΔEtot (Hartree) ΔA (Å2) r (J/m2) Egap(eV) (112) 0.92 0.034 2.350 0.73 6.60 (001) 1.02 0.034 1.263 0.57 6.52 (110) 1.10 0.034 1.982 0.85 6.45 (100) 1.22 0.039 2.803 1.09 6.47 (101) 1.31 0.039 1.537 0.91 6.17 (111) 2.06 0.020 4.161 2.58 Conductor M.C. Oliveira et al. / Ceramics International 42 (2016) 10913–1092110918 3.3. FE-SEM analyses and morphologies of the BaWO4 crystals The morphologies of the BaWO4 crystals obtained by FE–SEM are depicted in Fig. 5. As shown by the obtained experimental micrographs (Fig. 5) [15], crystal morphologies can be modified by tuning surface en- ergy values for various facets using the Wulff theorem and the related construction method [65]. Taking into account the (001), (101), (110), (100), (111), and (112) facets, various crystal morphologies for BaWO4 are displayed in Fig. 6. Fig. 5. FE–SEM images of Fig. 2 shows the local coordination (clusters) for both the Ba and W atoms of the (001), (101), (110), (100), (111), and (112) surfaces. One of the most pronounced differences between the bulk and surface structural properties is that due to the reduced coordination of the O atoms in the top layers, the resulting va- cancies produce spacing between the adjacent layers, thus pro- viding a change in the values of the surface energy, i.e. modifying the stability of the surfaces to generate the corresponding mor- phology [78]. This observation can be confirmed by the detailed analysis of the results presented in Fig. 4, indicating small changes in the CB for each studied surface as compared to the bulk. The Egap surface values follow the order of stability for the BaWO4 surfaces ob- tained from the results of theoretical calculations, which is (112)4 (001)4(110)4(100)4(101)4(111). Recent works of Gao et al. [78,79] revealed that the morphology of scheelite crystals present predominantly the exposed (112), (001), and (100) surfaces, being the (112) surface the most stable. This result agrees with our present data and previous results reported in the literature [80,81]. Table 2 lists the corresponding values of the surface en- ergy and tension. The analysis of the obtained results reveals a similar trend for the given values except for the most stable the BaWO4 crystals. Fig. 6. Crystallographic structures and morphology map for the BaWO4 crystals (the surface energy units are given in J/m2). The experimental FE–SEM images (inset) are included for comparison. M.C. Oliveira et al. / Ceramics International 42 (2016) 10913–10921 10919 surface, (112), which exhibits a higher value of surface tension than that for (001). This phenomenon can be explained by noticing that the (112) surface termination contains a large number of undercoordinated atoms (relative to the bulk coordination) with only three O atoms coordinated to each Ba atom. In addition, the (101) surface is characterized by a low value of surface tension, consistent with high stability due to six-coordinated Ba atoms, which is observed only for the (001) and (101) surfaces. The analysis of the theoretical results indicates that the most stable surfaces are the (112), (001), and (100) facets [�7879], which can form a truncated octahedron corresponding to the ideal morphology (shown in the central part of Fig. 6). When the re- lative stability of the facets changes (increases or decreases), more than one facet type appears in the resulting morphology, produ- cing morphology variations. A truncated cube can be obtained if the surface energy of (112) is increased to 1.20 J/m2, while a edge- truncated octahedron can be produced when the surface energy of (101) is decreased to 0.80 J/m2 (see Fig. 6). Central part of some FE- SEM images (shown in Fig. 5) is included in the left inset of Fig. 6, which is the best well-faceted sighting to compare. A good agreement between the experimental and theoretical morpholo- gies is obtained when the values of surface energy for the (001) and (100) facets increase simultaneously (see Fig. 6). Thus, varia- tions in the ratio between values of surface energy affect the re- lated morphologies and thus can be used to obtain correlations with experimental results. 4. Conclusions Crystal morphology is an important parameter for obtaining high-quality crystals with excellent properties. BaWO4 crystals have been synthesized as representative members of scheelite- based materials by using the CP method. XRD and Rietveld re- finement were utilized to structurally characterize the obtained samples, while FE–SEM was used to investigate the morphologies of the as-synthesized structures. The geometry, electronic prop- erties of the bulk, surface energies, and surface tension of the BaWO4 crystals were evaluated using first-principles quantum mechanical calculations. As a result of this work, the following conclusions were ob- tained: i) By using the Wulff's theorem, a simple model was pro- posed to determine surface energies of BaWO4 crystals at atomic- level resolution. ii) The proposed computational technique was utilized to calculate equilibrium crystal morphologies. Using this model, we were able to evaluate possible morphologies and morphological transformations in BaWO4 by controlling the ratio between surface energy values of each facet. iii) The stability order of the BaWO4 surfaces obtained from the theoretical calculations can be expressed as (112)4(001)4(110)4(100)4(101)4(111). Our work indicates that the morphology of scheelite crystals have (112), (001), and (100) as predominantly exposed surfaces, with the (112) facet being the commonly exposed surface. iv) A trun- cated octahedron corresponds to the ideal morphology predicted for the BaWO4 crystals by theoretical calculations. However, a truncated cube or edge-truncated octahedron can be obtained due to the destabilization of the (112) surface or stabilization of the (101) surface, respectively. v) The obtained experimental and theoretical morphologies are similar when the values of surface energy for the (001) and (100) facets increase simultaneously. Modulations of the BaWO4 crystal morphologies resulting from the theoretical simulations have been applied to explain the changes observed at experimental conditions and clarify how the knowledge of surface-specific properties can be utilized to design crystal morphologies that exhibit improved performance in var- ious applications. Using this knowledge, such modeling type can M.C. Oliveira et al. / Ceramics International 42 (2016) 10913–1092110920 serve as a predictive tool to modify and ultimately control crystal morphologies. Therefore, computational techniques combined with experimental methods can be utilized to study morphologies of materials that can profoundly affect their physical and chemical properties as well as to improve the related performance of ma- terials and innovate the material design. Acknowledgments This work was financially supported by the following Spanish research funding institutions: CTQ2012-36253-C03-02 project (Ministerio de Economia y Competitividad), PrometeoII/2014/022 and ACOMP/2014/270 projects (Generalitat Valenciana), Brazilian Research Funding Institutions: CNPq (INCTMN 573636/2008-7), FAPESP-CDMF (2013/07296-2), CAPES/PNPD 1268069, CAPES (pro- cess A104/2013 and 99999.002998/2014-09), and Programa de Co- operación Científica con Iberoamerica (Brasil) of Ministerio de Educación (PHBP14-00020). J.A. acknowledges to Ministerio de Economia y Competitividad, “Salvador Madariaga” program, PRX15/ 00261. L.G. acknowledges Banco Santander (Becas Iberoamérica: Jóvenes profesores e investigadores). M.C. acknowledges Generalitat Valenciana for Santiago Grisolia Program 2015/033. References [1] M. Kobayashi, M. Ishiib, K. Haradab, Y. Uski, H. Okuno, H. Shimizu, T. Yazawab, Scintillation and phosphorescence of PbWO4 crystals, Nucl. Instrum. Methods A 373 (1996) 333–346. [2] L.S. Cavalcante, J.C. Sczancoski, J.W.M. Espinosa, J.A. Varela, P.S. Pizani, E. Longo, Photoluminescent behavior of BaWO4 powders processed in mi- crowave-hydrotherm, J. Alloy. Compd. 474 (2009) 195–200. [3] R. Dhilip Kumar, S. Karuppuchamy, Microwave-assisted synthesis of copper tungstate nanopowder for supercapacitor applications, Ceram. Int. 40 (2014) 12397–12402. [4] J. Zhang, J. Pan, L. Shao, J. Shu, M. Zhou, J. Pan, Micro-sized cadmium tungstate as a high-performance anode material for lithium-ion batteries, J. Alloy. Compd. 614 (2014) 249–252. [5] C. Anil Kumar, D. Pamu, Dielectric and electrical properties of BaWO4 film capacitors deposited by RF magnetron sputtering, Ceram. Int. 41 (2015) S296–S302. [6] C. Shivakumara, R. Saraf, S. Behera, N. Dhananjaya, H. Nagabhushana, Schee- lite-type MWO4 (M¼Ca, Sr, and Ba) nanophosphors: facile synthesis, struc- tural characterization, photoluminescence, and photocatalytic properties, Mater. Res. Bull. 61 (2015) 422–432. [7] F.M. Pontes, M.A.M.A. Maurera, A.G. Souza, E. Longo, E.R. Leite, R. Magnani, M. A.C. Machado, P.S. Pizani, J.A. Varela, Preparation, structural and optical char- acterization of BaWO4 and PbWO4 thin films prepared by a chemical route, J. Eur. Ceram. Soc. 2 (2003) 3001–3007. [8] D. Rangappa, T. Fujiwara, M. Yoshimura, Synthesis of highly crystallized BaWO4 film by chemical reaction method at room temperature, Solid State Sci. 8 (2006) 1074–1078. [9] M.A.P. Almeida, L.S. Cavalcante, M. Siu Li, J.A. Varela, E. Longo, Structural re- finement and photoluminescence properties of MnWO4 nanorods obtained by microwave-hydrothermal synthesis, J. Inorg. Organomet. Polym. Mater. 22 (2011) 264–271. [10] Y. Shen, W. Li, T. Li, Microwave-assisted synthesis of BaWO4 nanoparticles and its photoluminescence properties, Mater. Lett. 65 (2011) 2956–2958. [11] P.F.S. Pereira, I.C. Nogueira, E. Longo, E.J. Nassar, I.L.V. Rosa, L.S. Cavalcante, Rietveld refinement and optical properties of SrWO4: Eu3þ powders prepared by the non-hydrolytic sol–gel method, J. Rare Earth 33 (2015) 113–128. [12] I.M. Pinatti, I.C. Nogueira, W.S. Pereira, P.F. Pereira, R.F. Goncalves, J.A. Varela, E. Longo, I.L. Rosa, Structural and photoluminescence properties of Eu(3þ ) doped alpha-Ag2WO4 synthesized by the green coprecipitation methodology, Dalton Trans. 44 (2015) 17673–17685. [13] J.C. Rendón-Angeles, Z. Matamoros-Veloza, J. López-Cuevas, I.A. Gonzalez, K. L. Montoya-Cisneros, K. Yanagisawa, J. Willis-Richards, J. Diaz-Algara, Rapid synthesis of scheelite SrWO4 particles using a natural SrSO4 ore under alkaline hydrothermal conditions, Hydrometallurgy 157 (2015) 116–126. [14] A. Phuruangrat, T. Thongtem, S. Thongtem, Precipitate synthesis of BaMoO4 and BaWO4 nanoparticles at room temperature and their photoluminescence properties, Superlattice Microstruct. 52 (2012) 78–83. [15] M. Li, Y. Guan, Y. Yin, X. Cui, S. Rong, G. Jin, Y. Hao, Q. Wu, Controllable synthesis of 3D BaXO4 (X¼W, Mo) microstructures by adjusting nucleation stage and their photoluminescence properties, Superlattice Microstruct. 80 (2015) 222–228. [16] F.J. Manjón, D. Errandonea, N. Garro, J. Pellicer-Porres, P. Rodríguez-Hernán- dez, S. Radescu, J. López-Solano, A. Mujica, A. Muñoz, Lattice dynamics study of scheelite tungstates under high pressure I. BaWO4, Phys. Rev. B 74 (2006) 144111. [17] B. Sun, Y. Liu, W. Zhao, J. Wu, P. Chen, Hydrothermal preparation and white- light-controlled resistive switching behavior of BaWO4 nanospheres, Nano- Micro Lett. 7 (2015) 80–85. [18] L.S. Cavalcante, F.M.C. Batista, M.A.P. Almeida, A.C. Rabelo, I.C. Nogueira, N. C. Batista, J.A. Varela, M.R.M.C. Santos, E. Longo, M. Siu Li, Structural refine- ment, growth process, photoluminescence and photocatalytic properties of (Ba1�xPr2x/3)WO4 crystals synthesized by the coprecipitation method, RSC Adv. 2 (2012) 6438–6454. [19] M. Tyagi, S.G. Singh, A.K. Chauhan, S.C. Gadkari, First principles calculation of optical properties of BaWO4: a study by full potential method, Phys. B 405 (2010) 4530–4535. [20] D. Ran, H. Xia, S. Sun, P. Zhao, F. Liu, Z. Ling, W. Ge, H. Zhang, J. Wang, Optical phonon modes and transmissivity in BaWO4 single crystal, Cryst. Res. Technol. 41 (2006) 1189–1193. [21] C. Kavitha, C. Narayana, B.E. Ramachandran, N. Garg, S.M. Sharma, Acoustic phonon behavior of PbWO4 and BaWO4 probed by low temperature Brillouin spectroscopy, Solid State Commun. 202 (2015) 78–84. [22] H.W. Eng, P.W. Barnes, B.M. Auer, P.M. Woodward, Investigations of the electronic structure of d0 transition metal oxides belonging to the perovskite family, J. Solid State Chem. 175 (2003) 94–109. [23] P. Parhi, T.N. Karthik, V. Manivannan, Synthesis and characterization of metal tungstates by novel solid-state metathetic approach, J. Alloy. Compd. 465 (2008) 380–386. [24] Y. Mi, Z. Huang, F. Hu, X. Li, Room temperature reverse-microemulsion synthesis and photoluminescence properties of uniform BaMoO4 submicro- octahedra, Mater. Lett. 63 (2009) 742–744. [25] Z. Luo, H. Li, J. Xia, W. Zhu, J. Guo, B. Zhang, Controlled synthesis of different morphologies of BaWO4 crystals via a surfactant-assisted method, J. Cryst. Growth 300 (2007) 523–529. [26] X. Wu, J. Du, H. Li, M. Zhang, B. Xi, H. Fan, Y. Zhu, Y. Qian, Aqueous miner- alization process to synthesize uniform shuttle-like BaMoO4 microcrystals at room temperature, J. Solid State Chem. 180 (2007) 3288–3295. [27] J.C. Sczancoski, L.S. Cavalcante, N.L. Marana, R.O.D. Silva, R.L. Tranquilin, M. R. Joya, P.S. Pizani, J.A. Varela, J.R. Sambrano, M.S. Li, E. Longo, J. Andrés, Electronic structure and optical properties of BaMoO4 powders, Curr. Appl. Phys. 10 (2010) 614–624. [28] J.H. Ryu, J.W. Yoon, K.B. Shim, Microwave-assisted synthesis of BaMoO4 na- nocrystallites by a citrate complex method and their anisotropic aggregation, J. Alloy. Compd. 413 (2006) 144–149. [29] A. Phuruangrat, T. Thongtem, S. Thongtem, Barium molybdate and barium tungstate nanocrystals synthesized by a cyclic microwave irradiation, J. Phys. Chem. Solids 70 (2009) 955–959. [30] M. Anicete-Santos, F.C. Picon, C. Nahum Alves, P.S. Pizani, J.A. Varela, E. Longo, The role of short-range disorder in BaWO4 crystals in the intense green photoluminescence, J. Phys. Chem. C 115 (2011) 12180–12186. [31] O. Gomis, J.A. Sanz, R. Lacomba-Perales, D. Errandonea, Y. Meng, J.C. Chervin, A. Polian, Complex high-pressure polymorphism of barium tungstate, Phys. Rev. B 86 (2012) 054121. [32] H. Zhang, T. Liu, Q. Zhang, Xi’en Wang, J. Yin, M. Song, X. Guo, First-principles study on electronic structures of BaWO4 crystals containing F-type color centers, J. Phys. Chem. Solids 69 (2008) 1815–1819. [33] H. Zhang, T. Liu, Q. Zhang, Xi’en Wang, X. Guo, M. Song, J. Yin, First-principles study on electronic structures and absorption spectra for BaWO4 crystal containing barium vacancy, Nucl. Instrum. Methods B 267 (2009) 1056–1060. [34] G. Dhanaraj, K. Byrappa, V. Prasad, M. Dudley, Provides the Reader with the Most Complete State-of-the-Art Presentation on the Basics and Realization of Crystal Growth, Springer Handbook of Crystal Growth, Springer-Verlag Berlin Heidelberg, 2010, ISBN: 978-3-540-74761-1. [35] Q. Kuang, X. Wang, Z. Jiang, Z. Xie, L. Zheng, High-energy-surface engineered metal oxide micro- and nanocrystallites and their applications, Acc. Chem. Res. 47 (2014) 308–318. [36] K. Huang, L. Yuan, S. Feng, Crystal facet tailoring arts in perovskite oxides, Inorg. Chem. Front. 2 (2015) 965–981. [37] G. Zhou, M. Lü, F. Gu, S. Wang, Z. Xiu, Morphology-controlled synthesis of BaWO4 nanocrystals via a surfactant-assisted method, Mater. Lett. 59 (2005) 2706–2709. [38] L.S. Cavalcante, J.C. Sczancoski, L.F. Lima Jr., J.W.M. Espinosa, P.S. Pizani, J. A. Varela, E. Longo, Synthesis, characterization, anisotropic growth and pho- toluminescence of BaWO4, Cryst. Growth Des. 9 (2009) 1002–1012. [39] Y. Yin, F. Yang, Y. Yang, Z. Gan, Z. Qin, S. Gao, B. Zhou, X. Li, Controlled synthesis of BaWO4 hierarchical nanostructures by exploiting oriented attachment in the solution of H2O and C2H5OH, Superlattice Microstruct. 49 (2011) 599–607. [40] C. Cui, J. Bi, D. Gao, K. Zhao, Morphology and crystal phase control in pre- paration of highly crystallized BaWO4 film via galvanic cell method, J. Alloy. Compd. 462 (2008) L16–L19. [41] D.G. Stroppa, L.A. Montoro, A. Campello, L. Gracia, A. Beltrán, J. Andrés, E. R. Leite, A.J. Ramirez, Prediction of dopant atom distribution on nanocrystals using thermodynamic arguments, Phys. Chem. Chem. Phys. 16 (2014) 1089–1094. [42] M.R.D. Bomio, R.L. Tranquilin, F.V. Motta, C.A. Paskocimas, R.M. Nascimento, L. Gracia, J. Andres, E. Longo, Toward understanding the photocatalytic activity of PbMoO4 powders with predominant (111), (100), (011), and (110) facets. A http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref1 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref1 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref1 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref1 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref1 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref1 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref2 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref2 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref2 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref2 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref2 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref2 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref3 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref3 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref3 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref3 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref4 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http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref14 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref15 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref15 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref15 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref15 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref15 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref15 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref15 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref15 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref15 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref15 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref16 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref16 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref16 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref16 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref16 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref16 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref17 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref17 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref17 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref17 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref17 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref17 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref18 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http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref27 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref27 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref27 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref27 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref27 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref27 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref28 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref28 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref28 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref28 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref28 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref28 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref29 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref29 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref29 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref29 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref30 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref30 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref30 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref30 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref30 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref30 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref31 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref31 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref31 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref32 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref32 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref32 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref32 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref32 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref32 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref33 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref33 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref33 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref33 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref33 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref33 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref34 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref34 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref34 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref34 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref35 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref35 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref35 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref35 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref36 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref36 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref36 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref37 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref37 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref37 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http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref39 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref39 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref39 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref39 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref40 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref40 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref40 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref40 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref40 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref40 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref41 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref41 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref41 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref41 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref41 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref42 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref42 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref42 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref42 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref42 M.C. Oliveira et al. / Ceramics International 42 (2016) 10913–10921 10921 combined experimental and theoretical study, J. Phys. Chem. C 117 (2013) 21382–21385. [43] V.M. Longo, L. Gracia, D.G. Stroppa, L.S. Cavalcante, M. Orlandi, A.J. Ramirez, E. R. Leite, J. Andrés, A. Beltrán, J.A. Varela, E. Longo, A joint experimental and theoretical study on the nanomorphology of CaWO4 crystals, J. Phys. Chem. C 115 (2011) (2011) 3–20119. [44] J. Andrés, L. Gracia, L., A.F. Gouveia, M.M. Ferrer, E. Longo, Effects of surface stability on the morphological transformation of metals and metal oxides as investigated by first principles calculations, Nanotechnology 26 (2015) 405703. [45] M.M. Ferrer, A.F. Gouveia, L. Gracia, E. Longo, J. Andrés, A 3D platform for the morphology modulation of materials: first principles calculations on the thermodynamic stability and surface structure of metal oxides: Co3O4, α- Fe2O3, and In2O3, Model. Simul. Mater. Sci. Eng. 24 (2016) 025007. [46] R.A. Roca, J.C. Sczancoski, I.C. Nogueira, M.T. Fabbro, H.C. Alves, L. Gracia, L.P. S. Santos, C.P. de Sousa, J. Andrés, G.E. Luz, E. Longo, L.S. Cavalcante, Facet- dependent photocatalytic and antibacterial properties of α-Ag2WO4 crystals: combining experimental data and theoretical insights, Catal. Sci. Technol. 5 (2015) 4091–4107. [47] G. Botelho, J. Andres, L. Gracia, L.S. Matos, E. Longo, Photoluminescence and photocatalytic properties of Ag3PO4 microcrystals: an experimental and the- oretical investigation, ChemPlusChem 81 (2016) 202–212. [48] M.T. Fabbro, C. Saliby, L.R. Rios, F.A. La Porta, L. Gracia, M.S. Li, J. Andrés, L.P. S. Santos, E. Longo, Identifying and rationalizing the morphological, structural, and optical properties of β-Ag2MoO4 microcrystals, and the formation process of Ag nanoparticles on their surfaces: combining experimental data and first- principles calculations, Sci. Technol. Adv. Mater. 16 (2015) 065002. [49] H.M. Rietveld, A profile refinement method for nuclear and magnetic struc- tures, J. Appl. Cryst. 2 (1969) 65–71. [50] A.C. Larson, R.B.V. Dreele, General Structure Analysis System (GSAS), Los Alamos National Laboratory, New Mexico, USA, 2004, Report LAUR. [51] L.W. Finger, D.E. Cox, A.P. Jephcoat, A correction for power diffraction peak asymmetry due to axial divergence, J. Appl. Cryst. 27 (1994) 892–900. [52] P.W. Stephens, Phenomenological model of anisotropic peak broadening in power diffraction, J. Appl. Cryst. 32 (1999) 281–289. [53] R. Dovesi, V.R.S., C. Roetti, R. Orlando, C.M. Zicovich-Wilson, F. Pascale, B. Civalleri, K. Doll, N.M. Harrison, I.J. Bush, P.H. D’Arco, M. Llunell, M. Causa, Y. Noël, CRYSTAL14 User's Manual, University of Torino, Torino, 2014. [54] A.D. Becke, Perspective on density functional thermochemistry. III. The role of exact exchange, J. Chem. Phys. 98 (1993) 5648–5652. [55] C.T. Lee, W.T. Yang, R.G. Parr, Development of the Colle–Salvetti correlation- energy formula into a functional of the electron density, Phys. Rev. B: Con- dens. Matter 37 (1988) 785–789. [56] M.L. Moreira, J. Andres, L. Gracia, A. Beltrán, L.A. Montoro, J.A. Varela, E. Longo, Quantum mechanical modeling of excited electronic states and their re- lationship to cathodoluminescence of BaZrO3, J. Appl. Phys. 114 (2013) 043714. [57] L. Gracia, V.M. Longo, L.S. Cavalcante, A. Beltran, W. Avansi, M.S. Li, V. R. Mastelaro, J.A. Varela, E. Longo, J. Andres, Presence of excited electronic state in CaWO4 crystals provoked by a tetrahedral distortion: an experimental and theoretical investigation, J. Appl. Phys. 110 (2011) 043501. [58] E. Longo, D.P. Volanti, V.M. Longo, L. Gracia, I.C. Nogueira, M.A.P. Almeida, A. N. Pinheiro, M.M. Ferrer, L.S. Cavalcante, J. Andrés, Toward an understanding of the growth of Ag filaments on α-Ag2WO4 and their photoluminescent properties: a combined experimental and theoretical study, J. Phys. Chem. C 118 (2014) 1229–1239. [59] F.M.C. Batista, F.A. La Porta, L. Gracia, E. Cerdeiras, L. Mestres, M. Siu Li, N. C. Batista, J. Andrés, E. Longo, L.S. Cavalcante, A joint experimental and theo- retical study on the electronic structure and photoluminescence properties of Al2(WO4)3 powders, J. Mol. Struct. 1081 (2015) 381–388. [60] A. Beltrán, L. Gracia, E. Longo, J. Andrés, First-principles study of pressure- induced phase transitions and electronic properties of Ag2MoO4, J. Phys. Chem. C 118 (2014) 3724–3732. [61] H.J. Monkhorst, J.D. Pack,, Special points for Brillouin-x. One integrations, Phys. Rev. B: Condens. Matter 13 (1976) 5188–5192. [62] F. Cora, A. Patel, N.M. Harrison, R. Dovesi, C.R.A. Catlow, An ab initio Hartree– Fock study of the cubic and tetragonal phases of bulk tungsten trioxide, J. Am. Chem. Soc. 118 (1996) 12174–12182. [63] CRYSTAL Basis set. 〈http://www.crystal.unito.it/Basis_Sets/Ptable.html〉, 2016 (accessed 10.02.16). [64] Basis set. 〈http://www.tcm.phy.cam.ac.uk/�mdt26/basis_sets/Ba_basis.txt〉, 2016 (accessed 10.02.16). [65] G. Wulff, Zur Frage der Geschwindigkeit Des Wachstums und Der Auflosung der Krystallflachen, Krist. Miner. 34 (1901) 449–530. [66] K. Momma, F. Izumi, VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data, J. Appl. Cryst. 44 (2011) 1272–1276. [67] A. Kuzmin, J. Purans, Local atomic and electronic structure of tungsten ions in AWO4 crystals of scheelite and wolframite types, Radiat. Meas. 33 (2001) 583–586. [68] F. Toa, Z. Wang, L. Yao, W. Cai, X. Li, Shape-controlled synthesis and char- acterization of YF3 truncated octahedral nanocrystals, Cryst. Growth Des. 7 (2007) 854–858. [69] C. Herring, Some theorems on the free energies of crystal surfaces, Phys. Rev. 82 (1981) 87–93. [70] J.W. Gibbs, A.W. Smith, On the equilibrium of heterogeneous substances, Trans. Conn. Acad. Arts Sci. 3 (1875) 108–248. [71] X. Wang, H. Xu, H. Wang, H. Yan, Morphology-controlled BaWO4 powders via a template-free precipitation technique, J. Cryst. Growth 284 (2005) 254–261. [72] Y. Liu, Y. Chu, Surfactant-assisted synthesis of single crystal BaWO4 octahedral microparticles, Mater. Chem. Phys. 92 (2005) 59–63. [73] B. Xie, Y. Wu, Y. Jiang, F. Li, J. Wu, S. Yuan, W. Yu, Y. Qian, Shape-controlled synthesis of BaWO4 crystals under different surfactants, J. Cryst. Growth 235 (2002) 283–286. [74] L.D. Marks, Modified wulff constructions for twinned particles, J. Cryst. Growth 61 (1983) 556–566. [75] A.S. Barnard, P. Zapol, Effects of particle morphology and surface hydrogena- tion on the phase stability of TiO2, Phys. Rev. B 70 (2004) 235403. [76] L. Li, F. Abild-Pedersen, J. Greeley, J.K. Nørskov, Surface tension effects on the reactivity of metal nanoparticles, J. Phys. Chem. Lett. 6 (2015) 3797–3801. [77] D. Errandonea, J. Pellicer-Porres, F.J. Manjón, A. Segura, Ch Ferrer-Roca, R. S. Kumar, O. Tschauner, J. López-Solano, P. Rodríguez-Hernández, S. Radescu, A. Mujica, A. Muñoz, G. Aquilanti, Determination of the high-pressure crystal structure of BaWO4 and PbWO4, Phys. Rev. B 73 (2006) 224103. [78] Y. Hu, Z. Gao, W. Sun, X. Liu, Anisotropic surface energies and adsorption behaviors of scheelite crystal, Colloids Surf. A 415 (2012) 439–448. [79] Z.Y. Gao, W. Sun, Y.H. Hu, X.-W. Liu, Surface energies and appearances of commonly exposed surfaces of scheelite crystal, Trans. Nonferr. Met. Soc. 23 (2013) 2147–2152. [80] T.G. Cooper, N.H. de Leeuw, A combined ab initio and atomistic simulation study of the surface and interfacial structures and energies of hydrated scheelite: introducing a CaWO4 potential model, Surf. Sci. 531 (2003) 159–176. [81] H.-Y. Jung, Y.-D. Huh, A two-dimensional four-fold symmetric SrMoO4 den- drite, CrystEngComm 17 (2015) 1398. http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref42 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref42 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref42 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref43 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref43 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref43 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref43 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref43 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref43 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref43 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref44 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref44 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref44 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref44 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref45 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref46 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref47 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref47 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref47 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref47 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref47 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http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref78 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref78 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref78 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref78 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref78 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref79 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref79 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref79 http://refhub.elsevier.com/S0272-8842(16)30367-4/sbref79 Synthesis and morphological transformation of BaWO4 crystals: Experimental and theoretical insights Introduction Experimental Synthesis of BaWO4 crystals Characterization Computational methods and modeling Results and discussion X-ray diffraction measurements and Rietveld refinements Band structure and density of states FE-SEM analyses and morphologies of the BaWO4 crystals Conclusions Acknowledgments References