(NH4)2Te2WO8:: A new polar oxide with second-harmonic generating, ferroelectric, and pyroelectric properties
(NH4)2Te2WO8:: A new polar oxide with second-harmonic generating, ferroelectric, and pyroelectric properties
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DOI：
10.1021/cm7019334
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发表时间：
2007-11-13
影响因子：
8.6
通讯作者：
Halasyamani, P. Shiv
中科院分区：
文献类型：
--
作者：
Kim, Jun-Ho;Baek, Jaewook;Halasyamani, P. Shiv
合成了一种新的极性铵钨亚碲酸盐（NH_4）（_2）Te_2WO_8，并对其结构进行了表征。该材料是水热合成的，使用NH 4 OH，WO 3，和TeO 2作为试剂，并通过单晶X射线衍射的结构表征。（NH 4）2 Te 2 WO 8晶体属非中心对称（NCS）极性单斜空间群P2（1）（No.4），a = 6.9716（9）A，B = 7.0279（9）A，c = 9.4593（13）A，β = 99.188（2）度。该材料呈现由WO 6八面体连接TeO 4多面体组成的二维结构。W 6+和Te 4+离子都处于不对称的配位环境中，这归因于二阶Jahn-Teller（SOJT）效应。（NH 4）2 Te 2 WO 8是NCS;因此进行二次谐波产生（SHG）测量。使用1064 nm辐射的SHG实验显示出约250 x（α-SiO2.由于（NH_4）_2Te_2WO_8也是极性的，因此进行了铁电和热释电测量。观察到铁电电滞回线（极化与电场），表明（NH_4）_2Te_2WO_8中的偶极矩是可切换的。测得的自发极化（P-s）为0.19 μ C/cm（2）。此外，热释电系数（总效应）p在50 ℃下被确定为-0.22 μ C/m（2）中心点K。
A new polar ammonium tungsten tellurite, (NH4)(2)Te2WO8, has been synthesized and structurally characterized. The material was synthesized hydrothermally, using NH4OH, WO3, and TeO2 as reagents, and structurally characterized by single-crystal X-ray diffraction. (NH4)2Te2WO8 crystallizes in the noncentrosymmetric (NCS) polar monoclinic space group P2(1) (No. 4) with a = 6.9716(9) A, b = 7.0279(9) A, c = 9.4593(13) A, and beta = 99.188(2)degrees. The material exhibits a two-dimensional structure consisting Of WO6 octahedra connected to TeO4 polyhedra. Both the W6+ and the Te4+ cations are in asymmetric coordination environments attributable to second-order Jahn-Teller (SOJT) effects. (NH4)2Te2WO8 is NCS; thus second-harmonic generation (SHG) measurements were performed. SHG experiments, using 1064 mn radiation, revealed an efficiency of approximately 250 x (alpha-SiO2. As (NH4)2Te2WO8 is also polar, ferroelectric and pyroelectric measurements were performed. A ferroelectric hysteresis loop (polarization vs electric field) was observed, indicating the dipole moment in (NH4)2Te2WO8 is switchable". A spontaneous polarization (P-s) of 0.19 mu C/cm(2) was measured. In addition, the pyroelectric coefficient (total effect), p, was determined to be -0.22 mu C/m(2)center dot K at 50 degrees C.