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Phase Transition of Rubidium Lead Tetrathiophosphate RbPbPS 4
Author(s) -
Belkyal Imane,
El Azhari Mohamed,
Wu Yuandong,
Bensch Wolfgang,
Depmeier Wulf
Publication year - 2009
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200801178
Subject(s) - orthorhombic crystal system , crystallography , phase transition , rubidium , differential scanning calorimetry , phase (matter) , ion , crystal structure , materials science , chemistry , space group , stoichiometry , x ray crystallography , diffraction , condensed matter physics , physics , optics , thermodynamics , potassium , organic chemistry , metallurgy
The single crystal structure of RbPbPS 4 was determined at 293 K. The compound crystallizes in the orthorhombic space group Pnma (No. 62) with a = 17.486(1) Å, b = 6.7127(5) Å, c = 6.4191(5) Å, V = 753.5(1) Å 3 , Z = 4. Differential scanning calorimetry shows a reversible structural phase transition at 182 K on cooling and at 184 K on heating. The phase transition is attributed to the displacement of the lead atoms which are located on the mirror planes at room temperature. In the low temperature modification, the Pb 2+ ions are moved away from the mirror plane thus changing the coordination number from seven at low temperature to six at room temperature. The low temperature phase of RbPbPS 4 is non‐centrosymmetric with space group P 2 1 2 1 2 1 , which is a maximal translationengleiche subgroup index 2 ( t 2) of Pnma . The analysis demonstrates that the phase transition is of second order, or at least nearly so.