钇掺杂调控铌酸银反铁电性与第一性原理研究

Research on the Antiferroelectricity and First Principles of Yttrium Doping Modulating AgNbO_3

基于铌酸银(AgNbO_(3))陶瓷材料存在的铁电与反铁电相界,可通过离子掺杂的手段对其进行调控。本文通过水热法制备了A位Y掺杂的Ag_(1-3x)Y_(x)NbO_(3)(AN-xY,x=0~0.05)反铁电陶瓷,对微结构、介电,以及阻抗性能进行测试,并基于密度泛函理论的第一性原理计算,探究了AN-xY禁带宽度变化的机理。结果表明,随着Y^(3+)掺杂量的增加,AN-xY陶瓷的M_(1)-M_(2)相向低温移动,反铁电稳定性增加,阻抗值减小。Y^(3+)掺杂所产生的施主能级使电子更容易从价带激发至导带,禁带宽度由1.959 eV减小至1.746 eV。A位Y^(3+)的掺杂可以对AgNbO_(3)的电性能进行目的性调控,对当前AgNbO_(3)基无铅反铁电陶瓷的研究与微观机理分析具有重要的参考价值。

Based on the existence of ferroelectric and antiferroelectric phase boundaries in AgNbO_(3) ceramic materials,they can be modulated by means of ionic doping.In this paper,A-site Y-doped Ag_(1-3x)Y_xNbO_3(AN-xY,x=0~0.05) antiferroelectric ceramics were prepared by hydrothermal method,and the microstructure,dielectric as well as impedance properties were tested,and the mechanism of AN-xY forbidden band width variation was investigated based on the first principles calculation of density generalized theory.The results show that with the increase of Y^(3+) doping,the M_(1)-M_(2) phase of AN-xY ceramics shifts to low temperature,the antiferroelectric stability increases,and the impedance value decreases.The doping of Y^(3+) at the A-position can purposely modulate the electrical properties of AgNbO_3,which is an important reference for the current research and micromechanical analysis of AgNbO_3-based lead-free antiferroelectric ceramics.