Department of Chemistry, Chung-Ang University, 221 Heukseok-dong, Dongjak-gu, Seoul 156-756, Republic of Korea.
Inorg Chem. 2012 Oct 1;51(19):10402-7. doi: 10.1021/ic301615f. Epub 2012 Sep 17.
Solid solutions of the noncentrosymmetric (NCS) Aurivillius phases, Bi(4-x)La(x)Ti(3)O(12) (x = 0, 0.25, 0.50, 0.75), have been synthesized through standard solid-state reactions and structurally characterized by powder X-ray and neutron diffractions. These materials crystallize in the orthorhombic space group B2cb (No. 41) and exhibit layered perovskite structures with both (Bi(2)O(2))(2+) fluorite-like units and A(n-1)B(n)O(3n+1) (n = 3) blocks. As the amount of La(3+) cations increases, the polarization arising from the Bi(3+) positions, especially the A sites of the perovskite units, continuously decreases in the reported materials. Powder second-harmonic generation (SHG) measurements on Bi(4-x)La(x)Ti(3)O(12) using 1064 nm radiation revealed frequency-doubling efficiencies ranging from 200 to 50 times that of α-SiO(2). Converse piezoelectric measurements resulted in d(33) values of 19 and 13 pm V(-1) for Bi(4)Ti(3)O(12) and Bi(3.5)La(0.5)Ti(3)O(12), respectively. The magnitudes of the SHG efficiency and piezoelectric response are strongly dependent on the asymmetric coordination environment attributable to the lone pairs on Bi(3+). Structure-property relationships along with the influence of the doped foreign cation on the associated NCS properties are discussed.
固溶体的非中心对称（NCS）Aurivillius 相，Bi（4-x）La（x）Ti（3）O（12）（x = 0，0.25，0.50，0.75），已经通过标准的固态反应合成，并通过粉末 X 射线和中子衍射进行了结构表征。这些材料结晶在正交晶系 B2cb（No.41）空间群中，并表现出层状钙钛矿结构，同时具有（Bi（2）O（2））（2+）萤石类似单元和[A（n-1）B（n）O（3n+1）]（2-）（n = 3）块。随着 La（3+）阳离子数量的增加，报道的材料中来自 Bi（3+）位置的极化，特别是钙钛矿单元的 A 位，连续降低。使用 1064nm 辐射对 Bi（4-x）La（x）Ti（3）O（12）进行的粉末二次谐波产生（SHG）测量显示，倍频效率范围从 200 到 50 倍于α-SiO（2）。逆压电测量结果表明，Bi（4）Ti（3）O（12）和 Bi（3.5）La（0.5）Ti（3）O（12）的 d（33）值分别为 19 和 13pm V（-1）。SHG 效率和压电响应的大小强烈依赖于归因于 Bi（3+）的孤对电子的不对称配位环境。讨论了结构-性能关系以及掺杂的外来阳离子对相关 NCS 性能的影响。
