Composition-Driven Phase Transition and Electrical Performances of 0.74BiFe1-xGaxO3-0.26BaTi O3 High Temperature Lead-Free Piezoceramics

作者：Yi Wenbin; Lu Zhenya^*; Liu Xingyue; Huang Du; Jia Zhi; Chen Zhiwu; Wang Xin; Zhu Huixiang

来源：RARE METAL MATERIALS AND ENGINEERING, 2022, 51(2): 374-377.

• piezoelectric materials
• electrical performances
• phase transition
• BiFeO3-BaTiO3
• lead-free

Morphotropic phase boundary (MPB) is very important for enhancing piezoelectric properties of piezoceramics. In general, the MPB of BiFeO3-BaTiO3 system ceramics locates near the composition of 0.70BiFeO(3)-0.30BaTiO(3). However, higher content of BaTiO3 will lead to lower Curie temperature of BiFeO3-BaTiO3 ceramics. Therefore, constructing an MPB for BiFeO3-BaTiO3 ceramics with lower BaTiO3 content is a reasonable strategy to obtain both the good piezoelectric property and high Curie temperature. 0.74BiFe(1-x)Ga(x)O(3)-0.26BaTiO(3) (x=0-0.05) lead-free piezoceramics were fabricated by traditional sintering methods, and effect of Ga content on the structures and electrical performances was investigated. Results show that a composition-driven phase transition from rhombohedral (R) to pseudocubic (pC) is identified as x increases from 0 to 0.05. The ceramics show symmetries of R at x <= 0.01 and pC at 0.04 <= x <= 0.05, and the MPB with R-pC coexistence is detected in the composition range of 0.02 <= x <= 0.03. The Curie temperature of the piezoceramics decreases slightly owing to increased tolerance factor t with the increment of Ga content. In particular, the high Curie temperature similar to 515 degrees C and improved piezoelectric property of piezoelectric coefficient d(33) of similar to 127 pC/N are obtained in the ceramics near MPB.