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采用弛豫铁电体(Sr_(0.7)Bi_(0.2))TiO_3与铁电体(Bi_(0.5)Na_(0.5))TiO_3构建了的新型二元系BNT基无铅陶瓷材料:(1-x)(Bi_(0.5)Na_(0.5))TiO_3-x(Sr_(0.7)Bi_(0.2))TiO_3(记为BNT-xSBT,x=10mol%、20mol%、30mol%和40mol%)。通过传统固相法进行制备,研究了(Sr_(0.7)Bi_(0.2))TiO_3取代对其结构、相变、铁电性能和储能特性的影响。结果表明,室温所测BNTxSBT陶瓷为准立方结构;介温和铁电性则证实其为极性三方和非极性四方共存相结构。A位复合占位的BNTxSBT陶瓷是典型的弛豫铁电体,其T_m随x的增大而减小。低温(T_d)处的介电反常源于结构(三方和四方)起伏所引起的缓慢转变过程。(Sr_(0.7)Bi_(0.2))TiO_3取代量增大时,其Td降低,四方相增多,并伴随非极性微区增长;并导致BNT-xSBT陶瓷的铁电性减弱和电滞回线变形。x=30mol%时,BNT-xSBT陶瓷具有大的P_(max)=26.8μC/cm~2、小的Pr=1.4μC/cm~2,和较好的储能特性:W=0.74 J/cm~3,η=68.5%(@70 kV/cm)。
A novel binary BNT-based lead-free ceramic material has been fabricated by using a relaxed ferroelectric (Sr 0.7 Bi 0.2) TiO 3 and a ferroelectric (Bi 0.5 Na 0.5) TiO 3: (1-x (Bi_ (0.5) Na_ (0.5) TiO_3-x (Sr_ (0.7) Bi_ (0.2)) TiO_3 (denoted as BNT-xSBT, x = 10mol%, 20mol%, 30mol% and 40mol%). The effects of (Sr 0.7 Bi 0.2) TiO 3 substitution on its structure, phase transition, ferroelectric properties and energy storage properties were investigated by the conventional solid-state method. The results show that the BNTxSBT ceramic measured at room temperature is a quasi-cubic structure and the moderately ferroelectricity is confirmed as a tripartite and non-polar tetragonal coexisting phase structure. A-bit composite BSTxSBT ceramic is a typical relaxation of ferroelectrics, T_m decreases with increasing x. Dielectric anomalies at low temperatures (T_d) originate from the slow transitions caused by structural (tripartite and tetragonal) fluctuations. (Sr 0.7 Bi 0.2) TiO 3 substitution, the Td decreases, the tetragonal phase increases, accompanied by the growth of non-polar micro-regions, and leads to the decrease of ferroelectricity and hysteresis loop of BNT-xSBT ceramics Deformation. The BNT-xSBT ceramic has a large P max of 26.8 μC / cm 2 and a small Pr of 1.4 μC / cm 2 at x = 30 mol%, and a good energy storage property of W = 0.74 J / cm ~ 3, η = 68.5% (@ 70 kV / cm).