Bouraima Adam, Makani Thomas, Assani Abderrazzak, Saadi Mohamed, El Ammari Lahcen
Laboratoire de Chimie du Solide Appliquée, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Battouta, BP 1014, Rabat, Morocco.
Département de Chimie, Faculté des Sciences, Université des Sciences et Techniques de Masuku, BP 943, Franceville, Gabon.
Acta Crystallogr E Crystallogr Commun. 2017 May 26;73(Pt 6):890-892. doi: 10.1107/S205698901700740X. eCollection 2017 Jun 1.
The new silver-, cobalt- and iron-based phosphate, silver cobalt iron tris(ortho-phosphate), AgCoFe(PO), was synthesized by solid-state reactions. Its structure is isotypic to that of NaCoFe(PO), and belongs to the alluaudite family, with a partial cationic disorder, the Ag atoms being located on an inversion centre and twofold rotation axis sites (Wyckoff positions 4 and 4), with partial occupancies of 0.885 (2) and 0.7688 (19), respectively. One of the two P atoms in the asymmetric unit completely fills one 4 site while the Co and Fe atoms fill another 4 site, with partial occupancies of 0.86 (5) and 0.14 (5), respectively. The remaining Co and Fe cations are distributed on a general position, 8, in a 0.39 (4):0.61 (4) ratio. All O atoms and the other P atoms are in general positions. The structure is built up from zigzag chains of edge-sharing [O] ( = Fe/Co) octa-hedra stacked parallel to [101]. These chains are linked together through PO tetra-hedra, forming polyhedral sheets perpendicular to [010]. The resulting framework displays two types of channels running along [001], in which the Ag atoms (coordination number eight) are located.
通过固态反应合成了新型银基、钴基和铁基磷酸盐——三（正磷酸）银钴铁，AgCoFe(PO₄)₃。其结构与NaCoFe(PO₄)₃同型，属于阿硫砷铜矿族，存在部分阳离子无序，Ag原子位于对称中心和二重旋转轴位置（Wyckoff位置4b和4e），占有率分别为0.885(2)和0.7688(19)。不对称单元中的两个P原子之一完全占据一个4b位置，而Co和Fe原子占据另一个4e位置，占有率分别为0.86(5)和0.14(5)。其余的Co和Fe阳离子分布在一般位置8f，比例为0.39(4):0.61(4)。所有O原子和另一个P原子都处于一般位置。该结构由平行于[101]堆叠的共边[O]（=Fe/Co）八面体的锯齿链构成。这些链通过PO₄四面体连接在一起，形成垂直于[010]的多面体片层。所得骨架展示了两种沿[001]方向的通道，Ag原子（配位数为8）位于其中。
