Syntheses And Characterization Of Iron Phosphates And Lithium Borophosphates

In the past decade, much attention has been paid on the applications of iron phosphates, as molecular sieves, catalyst and ion exchangers. Although a considerable literature available reported on the compounds of Lipscombite-Barbosalite-Giniite (LBG for short), a series of basic ferrous and ferric phosphates, most of them was mainly limited for the syntheses and characterizations of LBG compounds via powder samples. To date, few articles were devoted to the completed structural investigation by X-ray single crystal diffraction. Here we present the characterization of the LBG compounds by XRD, SEM, IR, Ultra-vis etc. on single crystal samples. Our work also extended to lithium borophosphates due to phosphates and borates are two kinds of important Non-linear optical (NLO) candidate materials and more expectation has been focused on the potential application of borophosphates.In the ferrous and ferric iron systems of basic phosphates, a series of LBG crystals with different colors were successfully hydrothermally synthesized and characterized. This study showed that the crystals with colors changed from pink to dark green are all in the same space group I4₁/amd and there are no regular, significant changes found in the unit cell sizes. Their structures are formed by infinite columns of ferrous-ferric octahedra via face-sharing with a variable number of Fe along [010] and [100]. While the crystals with black color were detected with three different space group, B22₁2, P2₁/n and F2₁, respectively. Each FeO₆ octahedron shares face along[100] and [1-10].The ferrous-ferric iron of the LBG crystals can be easily replaced by other divalent ions. So Mn²⁺, Co²⁺ and Ni²⁺ were introduced into the structure. A series of crystals with different colors were successfully hydrothermally synthesized. Composition analyses showed that the ferrous-ferric iron of the crystals with different colors is partially substituted by Mn²⁺, Co²⁺ and Ni²⁺ ions. The X-ray single crystal diffraction analyses indicated that all the crystals have the same structure in the tetragonal space group I4₁/amd. However, no regular, significant changes in the unit cell sizes were detected yet in the crystals with different colors.In this paper, particular crystal morphology, leaf-like shape was reported firstly in the crystals of LBG compounds. Aggregated crystal morphology exhibited beautiful, attractive, various performs.In the lithium catena-borodiphosphate system, four new compounds namely LiM/(H₂O)₂[BP₂O₈]·H₂O(M=Mn, Co, Mg, Ni) were hydrothermally synthesized and characterized by XRD, X-ray single crystal diffraction, IR, SEM and Ultra-vis etc. It showed that the crystal structure of above four new compounds crystallized in the hexagonal system is built up of an open framework of helical borophosphate ribbons(?) along 6₁ or 6₅ screw axes interconnected by MO₄(H₂O)₂ octahedra,forming one-dimensional channels along [001] occupied by Li⁺ cations and disordered H₂O molecules (site occupancy 0.5). The Li cations reside in two partially occupied sites near the helices.