Evidence of ferroelectric behaviour in CaCu3Ti4O12 thin films deposited by RF-sputtering


The origin of abnormal ferroelectric and unusual piezoelectricity in the polycrystalline CaCu3Ti4O12 (CCTO) thin films deposited by RF-sputtering on Pt/Ti/SiO2/Si (100) substrates was explored. The CCTO thin films, deposited at room temperature followed by annealing at 600 °C for 2 h in a conventional furnace, have a cubic structure with lattice parameter a = 7.379 ± 0.001 Å and without any secondary phases. No polarization loss up to 1010 switching cycles, with a switched polarization ∆P of 30 µC/cm2 measured at 400 kV/cm was evidenced. The piezoelectric coefficient investigated by piezoresponse force microscopy (PFM) was approximately 9.0 pm/V. This may be the very first example of exploring the origin of ferroelectric behaviour for a material that possesses space charge polarization with highly resistive grain boundaries in the polycrystalline state.



Calcium copper titanate, CCTO, Ferroelectricity, RF-sputtering, Thin films

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Processing and Application of Ceramics, v. 13, n. 3, p. 219-228, 2019.