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The Specific Heat of Tetramethylammonium Salts |
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| Authors: | Ruiz-Larrea I Fraile-Rodríguez A Arnáiz A López-Echarri A |
| Institution: | (1) Departamento de Física Aplicada II, Ciencias, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain;(2) Departamento de Física de la Materia Condensada, Ciencias, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain;(3) Departamento de Química Inorgánica, Facultad de Ciencias, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain |
| Abstract: | New measurements of the (N(CH3 )4 )2 MnBr4 specific heat by adiabatic calorimetry around the ferro- paraelastic phase transition shown by the crystal around 276 K are compared with previous calorimetric studies on similar tetramethylammonium bromide compounds. The thermodynamic behaviour of the tribromides and tetrabromides derivatives together with the influence on the phase transition parameters of the cation and halogen molecular substitutions are examined. The thermal relaxation experiments permit to study the behaviour of the crystals thermal conduction as a function of the temperature. Finally, the Landau theory for second order phase transitions is used to describe the thermodynamic behaviour of some of these crystals. This revised version was published online in July 2006 with corrections to the Cover Date. |
| Keywords: | adiabatic calorimetry specific heat tetramethylammonium salts |
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