Crystal structure and phase transition in the perovskite-type layer molecular composite NH3(CH2)4NH3PbCl4

Autor: N. B. Chanh, C. Courseille, Abdelaziz Daoud, Th. Maris, M. Laguerre, Y. Abid
Rok vydání: 1994
Předmět:
Zdroj: Physica Status Solidi (a). 143:203-214
ISSN: 1521-396X
0031-8965
DOI: 10.1002/pssa.2211430202
Popis: The crystal structure of NH3(CH2)4NH3PbCl4 at room temperature (RT phase) is determined by X-ray diffraction. The structural arrangement is of two-dimensional type, with ammonium alkylene chains located in between corner-sharing PbCl6 octahedra layers. The connection between the inorganic and organic parts of the structure is assumed by hydrogen bonds of N–H…Cl type. The crystallographic data are: monoclinic, space group P21/c, Z = 4, a = 0.7944(2) nm, b = 0.7772(5) nm, c = 1.9761(8) nm, β = 94.84(3)°. The organic chain is not centrosymmetrical and shows a left-hand conformation at one extremity. The presence of a phase transition is evidenced at T = 323.8 K by calorimetric and diffraction methods. The crystallographic data of the high-temperature phase (HT form) are obtained from single and powder crystal investigations: monoclinic, space group P21/a, Z = 2, a = 0.7963(5) nm, b = 0.7735(6) nm, c = 1.1011(1) nm, β = 102.22(9)°. La structure cristalline de la phase stable a la temperature ambiante (RT phase) de NH3(CH2)4NH3PbCl4 est determinee par diffraction des rayons X. L'arrangement est de type bidimensionnel avec des couches alternees de plans mineraux constitues d'octaedres PbCl6 lies par leurs sommets equatoriaux et de phases organiques constituees de molecules NH3–(CH2)4–NH3. La liaison entre les deux parties inorganique et organique de la structure est assuree par des liaisons hydrogene de type N–H … Cl. Les donnees cristallographiques de la phase sont: monoclinique, Z = 4, a = 0,7944(2) nm, b = 0,7772(5) nm, c = 1,9761(8) nm, β = 94,84(3)°, groupe P21/c. La chaǐne organique est assymetrique et presente une conformation gauche a l'une de ses extremites. Une transition de phase est mise en evidence a T = 323,8 K par methodes calorimetrique et diffractometrique. Les donnees cristallographiques de la phase haute temperature (HT phase) sont determinees a partir des experiences sur poudre et sur monocristaux: monoclinique, Z = 2, a = 0,7963(5) nm, b = 0,7735(6) nm, c = 1,1011(1) nm, β = 102,22(9)°, groupe P21/a.
Databáze: OpenAIRE
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