相扩散阻挡法制备铁酸钴/改性钛酸铋钠0-3复合多铁性陶瓷

Abstract

通过溶胶−凝胶工艺在CoFe₂O₄(简称CFO)粉体表面包覆二氧化锆陶瓷层来阻挡烧结过程中铁磁相与铁电相之间的离子扩散. 包覆后的CFO 与0.92(Bi₀.₅Na₀.₅)TiO₃-0.02(Bi₀.₅K₀.₅)TO₃-0.06BaTiO₃(简称BNBT) 陶瓷粉体分别按照xCFO/(1−x) BNKLABT (质量分数x = 0.05、0.10、0.15、0.20、0.25、0.30)混合均匀, 并用聚乙烯醇为粘结剂模压成圆片; 再经过1050℃烧结制备了铁磁/铁电0-3 型复合材料. XRD 分析表明: 二氧化锆在高温烧结过程中对离子扩散具有良好的阻挡作用. 复合陶瓷的耐击穿电压大于75kV/cm. 测量结果表明: 复合陶瓷的压电应变常数、机电耦合系数、介电常数和剩余极化随CFO 含量的增加而降低; 磁电耦合系数、介电损耗随CFO 含量的增加而有所增大. φ35mm×1.5mm 的复合陶瓷样品(x=0.05)在谐振频率(90kHz)和199kA/m 偏置磁场下的磁电系数为1.39V/A. The ZrO₂ buffer layer was coated on CoFe₂O₄(CFO) powder via a Sol-Gel method. The coated CFO and 0.92(Bi₀.₅Na₀.₅)TiO₃-0.02(Bi₀.₅K₀.₅)TiO₃-0.06BaTiO₃ (BNBT) ceramic powder were mixed according to the chemical for-mula of xCFO/(1-x) BNBT (weight fraction x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30). Using polyvinyl alcohol (PVA) as binder, the mixture was pressed into disks. After sintered at 1050℃, the xCFO/(1-x) BNBT 0-3 composite ce-ramic disks were prepared. The X-ray diffraction results show that the ZrO₂ layer can buffer the Fe³⁺ and Co²⁺ ions diffusing from CFO to BNBT during the sintering process. The break-down voltage of the co-fired composites is measured to be 75kV/cm. It is found that the piezoelectric con-stant, electromechanical coefficient, remnant polarization and dielectric permittivity decrease as the CFO content increasing. Magnetoelectric coefficient (ME) and dielectric loss increase with the CFO content increasing. For a composite disk with dimension of f35mm×1.5mm, the ME coefficient at resonance frequency of 90 kHz is 1.39V/A under a DC magnetic bias of 199 kA/m.