Alignment of acentric MoO3F3-3 anions in a polar material:: (Ag3MoOT3F3(Ag3MoO4)Cl
Alignment of acentric MoO3F3-3 anions in a polar material:: (Ag3MoOT3F3(Ag3MoO4)Cl
复制标题
DOI：
10.1016/s0022-4596(03)00090-2
复制
发表时间：
2003-10-01
影响因子：
3.3
通讯作者：
Poeppelmeier, KR
中科院分区：
文献类型：
--
作者：
Maggard, PA;Nault, TS;Poeppelmeier, KR
采用水热（溶剂热）法合成了（Ag 3 MoO 3F 3）（Ag 3 MoO 4）Cl晶体，并对其进行了X射线单晶衍射（P3 m1，No.156，Z = 1，a = 7.4488（6）Angstrom，c = 5.9190（7）Angstrom）。透明无色晶体由扭曲的fac-MoO 3F 33-八面体和MoO 42-四面体阴离子的链组成，如式（AgMoO 3F 3）-Mo-3和Ag 3 MoO 4+所示，并且通过Ag+阳离子以沿着c轴的极性排列连接。每个分子式单元有一个Cl-阴离子作为电荷平衡，以交错的方式连接两种类型的链，偏移量约为1/2 x c。在MoO 42-中，Mo原子向单个氧化物顶点位移，而在MoO 3F 33-中，Mo向三个氧化物配体位移。MoO 3F 33-阴离子上的有序氧化物-氟化物配体对于防止局部反转中心是重要的，而极性组织由Cl-阴离子和链间偶极-偶极相互作用指导。MoO 3F 33-和MoO 42-的偶极矩沿负c轴方向排列。给出一个极性结构，而不消除各个时刻。MoO_3F_（33）-和MoO_（42）-的偶极矩的方向和大小由键价分析计算，分别为6.1和1.9德拜（10（-18）esu cm），而LiNbO_3中的极性NbO_6八面体为4.4德拜，KTiO_4（KTP）中的极性TiO_6八面体为4.5德拜。(C)2003 Elsevier Science（美国）。All rights reserved.
(Ag3MoO3F3)(Ag3MoO4)Cl was synthesized by hydro(solvato)thermal methods and characterized by single-crystal X-ray diffraction (P3m1, No. 156, Z = 1, a = 7.4488(6) Angstrom, c = 5.9190(7) Angstrom). The transparent colorless crystals are comprised of chains of distorted fac-MoO3F33- octahedra and MoO42- tetrahedra anions, as suggested by the formulas (AgMoO3F3)-Mo-3 and Ag3MoO4+, and are connected through Ag+ cations in a polar alignment along the c-axis. One Cl- anion per formula unit serves as a charge balance and connects the two types of chains in a staggered fashion, offset by similar to1/2 x c. In MoO42- the Mo atom displaces towards a single oxide vertex, and in MoO3F33- the Mo displaces towards the three oxide ligands. The ordered oxide-flouride ligands on the MoO3F33- anion is important to prevent local inversion centers, while the polar organization is directed by the Cl- anion and interchain dipole-dipole interactions. The dipole moments of MoO3F33- and MoO42- align in the negative c-axis direction. to give a polar structure with no cancellation of the individual moments. The direction and magnitude of the dipole moments for MoO3F33- and MoO42- were calculated from bond valence analyses and are 6.1 and 1.9 debye (10(-18)esu cm) respectively, compared to 4.4 debye for polar NbO6 octahedra in LiNbO3, and 4.5 debye for polar TiO6 octahedra in KTiOPO4 (KTP). (C) 2003 Elsevier Science (USA). All rights reserved.