Open AccessStructural, Thermal behaviour and Vibrational study of a new Cesium- Ammonium Dihydrogen Phosphate–Arsenate: Cs0.55(NH4)0.45H2(PO4)0.39(AsO4)0.61
Author(s) -
Samia CHAUCHENE,
K. Jaouadi,
Tahar Mhiri
Publication year - 2014
Publication title -
journal of advances in chemistry
Language(s) - English
Resource type - Journals
ISSN - 2321-807X
DOI - 10.24297/jac.v10i7.6809
Subject(s) - isostructural , tetragonal crystal system , arsenate , chemistry , crystal structure , crystallography , differential scanning calorimetry , hydrogen bond , ion , differential thermal analysis , ferroelectricity , materials science , molecule , dielectric , diffraction , organic chemistry , physics , arsenic , thermodynamics , optoelectronics , optics
Mixed crystals Cs0.55(NH4)0.45H2(PO4)0.39(AsO4)0.61 (CADPA) of the two antiferroelectric NH4H2PO4 (ADP) and NH4H2AsO4 (ADA) and of the two ferroelectric CsH2PO4 (CDP) and CsH2AsO4 (CDA) have been prepared by slow evaporation from aqueous solution at room temperature. The structural properties of the crystal were characterized by X-ray single analysis (performed at room temperature), which revealed that (CADPA) crystallizes in space group I42d with lattice parameters: a = 7.6473(1) Å, c = 7.6803(1) Å and Z = 4. The title compound is isostructural with the tetragonal phases of (ADP) and (ADA). This structure is characterized by two kinds of disorder: a statical or dynamical disorder of the acidic proton in the O–H…O hydrogen bond and another one which is connected with a reorientational motion of NH4+ ions. Broader peaks in the IR spectrum confirm a structural disorder in this material. Thermal analysis of the (CADPA) were characterized by differential scanning calorimetry (DSC), showed that the title compound undergo two phase transitions at T = 204 K and T = 407 K.