Structural, thermal behavior, vibrational study and superprotonic behavior of a new rubidium dihydrogen phosphate-arsenate: RbH2(PO4)0.65(AsO4)0.35
详细信息 查看全文
- 作者：Samia Chouchene ; Khaled Jaouadi ; Tahar Mhiri ; Nabil Zouari
- 关键词：Tetrahedral arrangement ; Phase transitions ; Protonic conduction
- 刊名：Solid State Ionics
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：300
- 期：Complete
- 页码：205-211
- 全文大小：1350 K
- 卷排序：300
文摘
The structural characteristics of the crystals (RbH2(PO4)0.65(AsO4)0.35) were analyzed by means of X-ray diffraction, which revealed that the new title compound is nearly isomorphous with the tetragonal phase of RbH2AsO4 (RDA). The following results have been obtained: space group I− 42d, a = 7.6837 (8) Å, c = 7.3824 (19) Å, V = 435.85(13) Å3 and Z = 4. The phosphorus and the arsenic atom as well as the rubidium ions lie on points with site symmetry S4, the oxygen atoms lie in general positions about the phosphorus–arsenic atoms, in a tetrahedral arrangement. The (P/As)O4 tetrahedra are connected by OH…O hydrogen bonds laying essentially in the a,b plane. Differential scanning calorimetric traces show three phase transitions at 229, 390 and 580 K in this material. Moreover, protonic conduction of the mixed compound determined by impedance and modulus spectroscopy has been studied in the temperature range 150–450 K in order to determine the nature of the phase transition.