Phase transitions and ferroelectric properties in BiScO3-Bi(Zn1∕2Ti1∕2)O3-BaTiO3 solid solutions

Abstract

Ceramics solid solutions within the ternary perovskite system Bi(Zn1/2Ti1/2)O3-BiScO3-BaTiO3 were synthesized via solid-state processing techniques. The crystal structure of sintered ceramics was analyzed by xray diffraction. A stable perovskite phase was obtained for all compositions with a BaTiO3 content greater than 50 mol %. Furthermore, a change in symmetry from pseudocubic to tetragonal was observed as the mole fraction of BaTiO3 increased. Dielectric measurements show a dielectric anomaly associated with a phase transformation over the temperature range of 30 °C-210 °C for all compositions. Examination of the polarization hysteresis behavior revealed weakly nonlinear hysteresis loops. With these data, ferroelectric phase diagrams were derived showing the transition between the pseudocubic relaxor behavior to the tetragonal normal ferroelectric behavior. This transition was also correlated with changes in the diffuseness parameter. KeywordsDielectric oxides, Phase transitions, Ozone, Zinc, Solid solutions, X-ray diffraction, Relaxor ferroelectrics, Sintering, Dielectrics, Ferroelectric phase transitions Disciplines Materials Science and Engineering CommentsThe following article is from Journal of Applied Physics 102 (2007) Ceramics solid solutions within the ternary perovskite system Bi͑Zn 1/2 Ti 1/2 ͒O 3 -BiScO 3 -BaTiO 3 were synthesized via solid-state processing techniques. The crystal structure of sintered ceramics was analyzed by x-ray diffraction. A stable perovskite phase was obtained for all compositions with a BaTiO 3 content greater than 50 mol %. Furthermore, a change in symmetry from pseudocubic to tetragonal was observed as the mole fraction of BaTiO 3 increased. Dielectric measurements show a dielectric anomaly associated with a phase transformation over the temperature range of 30°C -210°C for all compositions. Examination of the polarization hysteresis behavior revealed weakly nonlinear hysteresis loops. With these data, ferroelectric phase diagrams were derived showing the transition between the pseudocubic relaxor behavior to the tetragonal normal ferroelectric behavior. This transition was also correlated with changes in the diffuseness parameter.

Relationship between tolerance factor and temperature coefficient of permittivity of temperature-stable high permittivity BaTiO3–Bi(Me)O3 compounds

“…In this case, the composition with the optimum TC" was 0.50BaTiO 3 -0.25Bi(Zn 1=2 Ti 1=2 ÞO 3 -0.25BiScO 3 with a value of TC" = À182 ppm/ C. It should be noted that this composition was near the solubility limit of this solid solution. Similar behavior was observed in the BaTiO 3 -Bi(Me)O 3 system with different Bi(Me)O 3 endmembers, [12][13][14][15][16] however, TC" values were not reported for these systems. The variation of TC" as a function of tolerance factor of selected BaTiO 3 -Bi(Me)O 3 compositions is shown in Fig.…”

“…An increase in the mole content of Bi(Me)O 3 (with compounds such as Bi(Zn 1=2 Ti 1=2 ÞO 3 , Bi(Mg 1=2 Ti 1=2 ÞO 3 , Bi(Ni 1=2 Ti 1=2 ÞO 3 , BiScO 3 Þ leads to an increase in the temperature stability of the permittivity at high temperatures. [12][13][14][15] In particular, the BaTiO 3 -Bi(Zn 1=2 Ti 1=2 ÞO 3 -BiScO 3 solid solution exhibits a temperature-stable high permittivity with " r greater than 1000 over the temperature range 100-400 C. 16,17 This family of compounds (BaTiO 3 -Bi(Me)O 3 Þ exhibits weak relaxor ferroelectric behavior which governs the low-field and high-field dielectric behavior. 15 The low-field (i.e., E < 10 kV/cm) dielectric response is characterized by a broad and diffuse temperature dependence of the permittivity.…”

Incipient piezoelectrics and electrostriction behavior in Sn-doped Bi1/2(Na0.82K0.18)1/2TiO3 lead-free ceramics

“…Careful observation indicates that undoped BNKT has a peak splitting at $46 , corresponding to the (002)/(200) reflection of a tetragonal phase. 21 Similar to the changes in X-ray diffraction patterns for BNT-BT-KNN, 3 Sn-doped BT, 22 BiScO 3 -Bi(Zn 0.5 Ti 0.5 )O 3 -BaTiO 3 (BS-BZT-BT), 23 BaTiO 3 -BiYbO 3 (BT-BY), 24 and modified BNKT ceramic systems, 4-10 the increase in Sn concentration causes the tetragonal (002)/(200) peaks to gradually merge into a single (200) pc (the subscript "pc" denotes pseudocubic Miller index) reflection at x ¼ 0.08, indicative of the loss of macroscopically conceivable non-cubic distortion. The trend is consistent with the previous results as shown in the BNT-BKT system with other chemical modifiers.…”

High temperature dielectric ceramics: a review of temperature-stable high-permittivity perovskites

“…The BiScO3 end-member has a high Curie temperature (~ 450ºC) but can only be prepared at high pressures and temperatures (~ 6 GPa, ~ 1100ºC) [18,19]. Ogihara et al, Penn State University, demonstrated weakly coupled relaxor behaviour in the binary system (1-x)BaTiO3-xBiScO3 [BT-BS] prepared with 3 mol % excess Bi2O3 [20].…”