(Bi_(0.5)Na_(0.5))_(0.935)Ba_(0.065)TiO_3-xBiScO_3陶瓷储能及应变性能研究

Energy Storage and Strain Property of (Bi_(0.5)Na_(0.5))_(0.935)Ba_(0.065)TiO_3-xBiScO_3 Ceramics

本研究采用BiScO_3组分对固相烧结工艺制备的(1-x)(Bi_(0.5)Na_(0.5))_(0.935)Ba_(0.065)TiO_3-x BiScO_3(BNBT-x BS)无铅陶瓷进行改性,考察了BiScO_3掺杂含量对陶瓷的微观结构、储能、场致应变和介电等性能的影响。结果表明:随着BiScO_3掺杂含量的增加,BNBT-x BS陶瓷的相结构由三方相与四方相共存演变为伪立方相,无杂相形成,且平均晶粒尺寸略有增大;BiScO_3组分的引入破坏了BNBT陶瓷铁电畴的长程有序,表现出弱极化,且伴随有铁电相到弛豫铁电相的相变过程。BiScO_3组分提高了储能和应变性能,在70 kV/cm电场下其最大储能密度为0.46 J/cm^3,电致应变达到0.25%。介电常数随着掺杂含量的增加逐渐降低,其介电行为也表明陶瓷具有弛豫铁电体特征;BNBT-x BS陶瓷表现出负温度系数效应,且在450℃以下具有较好的绝缘性。

(1-x)(Bi 0.5 Na 0.5 ) 0.935 Ba 0.065 TiO 3 -xBiScO 3 (BNBT-xBS) lead-free ceramics were fabricated by conven- tional ceramic sintering process and modified by BiScO 3 . Effects of BiScO 3 content on microstructure, energy storage, field-induced strain and dielectric properties of BNBT-xBS ceramics were investigated. The results indicated that the structure of BNBT-xBS ceramics without impurity phase transferred from the co-existence phase of rhom- bohedral and tetragonal phase to pseudo-cubic phase. Average grain size of BNBT-xBS ceramics grew slightly with increment of doping content. The long-range ferroelectric order of BNBT-xBS ceramics was destroyed by BiScO 3 , which resulted in weak polarization. Meanwhile, the phase transition of BNBT-xBS ceramics was observed from a typical ferroelectric phase to relaxor phase. BiScO 3 dopants improved energy storage and strain performance of ce- ramics as well, whose maximum energy storage density and high strain were 0.46 J/cm 3 and 0.25% at 70 kV/cm. The dielectric constant decreased with doping content increasing. Relaxor ferroelectric characteristics were also verified by temperature-dependence dielectric spectra. The resistance of BNBT-xBS ceramics illustrated a negative temperature coefficient and excellent electrical insulativity below 450℃.