Crystallization, phase evolution and ferroelectric properties of sol–gel-synthesized Ba(Ti_0.8Zr_0.2)O₃–x(Ba_0.7Ca_0.3)TiO₃thin films

Abstract

A lead-free piezoelectric material with ultra-high properties, Ba(Ti0.8Zr0.2)O3-x(Ba0.7Ca0.3)TiO3(BZTxBCT) nanocrystals was synthesized via a sol-gel method, and the corresponding thin films were also deposited on Pt/Ti/SiO2/Si substrates by a spin-coating approach. The BZT-xBCT thin film exhibited a high remnant polarization of 22.15 mC cm2 with a large coercive field of 68.06 kV cm1. The resultant gel is calcined at various elevated temperatures and studied with FTIR/XRD/Raman/DSC-TGA/AFM/SEM techniques for gel composition, crystallization, phase transition, thermochemistry and the morphology of the film. Although the room temperature crystal structure of the BZT-xBCT nanocrystals appears to be a standard perovskite structure by conventional X-ray diffraction (XRD), Raman spectroscopy demonstrates the presence of non-centrosymmetric regions arising from the off-centering of the titanium (zirconium) atoms.The Raman spectra findings demonstrate the degree by which the tetragonal phase grows with the increase of calcining temperature in BZT-0.5BCT, and the characteristic ferroelectric-ferroelectric phase transition in BZT-xBCT while going through the MPB process. The structural and constituent evolution for the conversion process from gel to ceramic, as well as the formation mechanism of the BZT-0.5BCT crystallite, were also elucidated.Keywords gel, synthesized, ba, ti0, 8zr0, 2, crystallization, o3, ferroelectric, x, ba0, 7ca0, 3, tio3, thin, films, evolution, phase, properties, sol Disciplines Engineering | Physical Sciences and Mathematics Publication DetailsWang, Z., Zhao, K., Guo, X., Sun, W., Jiang, H., Han, X., Tao, X., Cheng, Z., Zhao, H., Kimura, H., Yuan, G., Yin, J. & Liu, Z. (2013). Crystallization, phase evolution and ferroelectric properties of sol-gel-synthesized Ba(Ti0.8Zr0.2)O3-x(Ba0.7Ca0.3)TiO3 thin films. Journal of Materials Chemistry C, 1 522-530. AuthorsZeng-mei Wang, Kuan Zhao, Xin-li Guo, Wei Sun, Hua-long Jiang, Xue-qin Han, Xu-tang Tao, Zhen-xiang Cheng, Hong-yang Zhao, Hideo Kimura, Guo-liang Yuan, Jiang Yin, and Zhi-guo Liu nanocrystals was synthesized via a sol-gel method, and the corresponding thin films were also deposited on Pt/Ti/SiO 2 /Si substrates by a spin-coating approach. The BZT-xBCT thin film exhibited a high remnant polarization of 22.15 mC cm À2 with a large coercive field of 68.06 kV cm À1 . The resultant gel is calcined at various elevated temperatures and studied with FTIR/XRD/Raman/DSC-TGA/AFM/SEM techniques for gel composition, crystallization, phase transition, thermochemistry and the morphology of the film. Although the room temperature crystal structure of the BZT-xBCT nanocrystals appears to be a standard perovskite structure by conventional X-ray diffraction (XRD), Raman spectroscopy demonstrates the presence of non-centrosymmetric regions arising from the off-centering of the titanium (zirconium) atoms. The Raman spectra findings demonstrate the degree by which the tetragonal phase grows with the increase of calcining temperature in BZT-0.5BCT, and the...

Composition dependence of ferroelectric and piezoelectric properties of epitaxial (1−x)Ba(Zr0.2Ti0.8)O3–x(Ba0.7Ca0.3)TiO3 thin films prepared by pulsed laser deposition

“…Broadening of (0 0 2) peaks with compositions x ≥ 0.5 indicates the splitting of the peak into (0 0 2) and (2 0 0) peaks, which is a signature of tetragonal phase. A phase transformation from rhombohedral to tetragonal phase thus can be inferred starting from x = 0.5 [12]. The in-plane growth relationship between the film and the substrate was also confirmed by the XRD off-axis scan of the (2 0 2) peak.…”

“…These factors are processing and technique dependent and may lead to diverse properties of the thin films. Kang et al [11] found the best ferroelectric characteristic lied at x = 0.45 with a remnant polarization P r of 15.8 C/cm 2 in CSD-produced BZT-xBCT thin films while P r reached 22.15 C/cm 2 when x = 0.5 with spin-coating approach [12]. Lin et al [13] employed sol-gel method and the largest tunability up to 65% at 400 kV/cm at 100 kHz was achieved in BZT-0.55BCT film.…”

“…Various techniques such as chemical solution deposition (CSD), RF magnetron sputtering, pulsed laser deposition (PLD) etc. were employed to achieve high quality BZT-xBCT thin films [11][12][13][14][15][16]. However, due to the lack of composition-dependence study in BZT-xBCT thin film, the optimal composition in thin film form and the origins of their excellent piezoelectric properties still remain in question.…”

In-situ observation of nanomechanical behavior arising from critical-temperature-induced phase transformation in Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 thin film

“…The remnant polarization (P r ) values and the coercive field (V c ) were 10 lC/cm 2 and 5 V, respectively, which were slightly lower than our previous results. 24 The hardness and elastic modulus of the BZT-0.5BCT film were measured using a Micro Materials NanoTest with a Berkovich diamond indenter at different temperatures, room temperature (RT), and 60, 95, and 120 C. Nanoindentation has been proven to be a powerful technique for characterization of the mechanical response of nanoscale materials. The surface and substrate effects are negligible if the nanoindentation tests are performed at certain penetration depths less than one tenth of the film thickness.…”

“…The BZT-0.5BCT film was prepared via a sol-gel method on Pt(111)/Ti/SiO 2 /Si(100) substrate by annealing at 850 C according to a previously described procedure, 24 and the film thickness was $1 lm. The phase structure of the BZT-xBCT thin film was characterized by using XRD in a Bruker AXS D8 DISCOVER with Cu K a radiation (k ¼ 1.5405 Å ).…”