Phase structure and electrical properties of Sn and Zr modified BaTiO₃ lead-free ceramics

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• 作者：Ning Wang ; Bo-Ping Zhang ; ^{bpzhang@ustb.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Jian Ma ; Lei Zhao ; Jun Pei
• 关键词：Ba(Ti ; Sn ; Zr)O3 ; Phase transition temperature ; Piezoelectric properties ; Ferroelectric properties
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：43
• 期：1
• 页码：641-649
• 全文大小：1728 K

文摘

In this study, a comprehensive analysis on the coupling role of co-doping Zr⁴⁺ and Sn⁴⁺ in BaTiO₃ ceramics on the phase transition between rhombohedral (R), orthorhombic (O), tetragonal (T) and cubic (C) phases was performed on a simple composition Ba(Ti_0.94Sn_0.06-xZr_x)O₃ (0.00≤x≤0.06) (BTSZ_x). Optimizing the Zr content (x) and sintering temperature (Ts) enabled all samples, except for x=0.06, to exhibit the coexistence of O- and T-symmetries with different fractions (C_O and C_T) at room temperature. Enhanced piezoelectric properties with d₃₃=402 pC/N and k_p=39% were attained with x=0.01 at Ts=1550 °C because the C_T/C_O ratio was close to unity along with a proper average grain size, homogeneous grains and high relative density ρ_r. The degree of hybridization with O²⁻ and different phase transition energies (ΔE) derived by adding Zr⁴⁺ and Sn⁴⁺ in B-sites essentially dominated the varying trend of the phase transition temperatures (T_R-O, T_O-T, T_C). Larger ΔE_R-O, ΔE_O-T and ΔE_C-T in BaZrO₃ than in BaSnO₃ contributed to higher T_R-O, T_O-T and T_C in BTZ_x than in BTS_x when the same amount of Sn⁴⁺ or Zr⁴⁺ was added. Meanwhile, a faster T_C decline in BTS_x than in BTZ_x can be ascribed to a stronger hybridization between Zr⁴⁺ and O²⁻ than between Sn⁴⁺ and O²⁻. Our result indicated that the forecast of phase diagrams for hybrid multi-component systems, such as BTSZ, via each end-member composition is a feasible and convenient strategy.