Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (7): 1260-1264.doi: 10.3866/PKU.WHXB201504163


Preparation and Thermal Performances of 1-Alkylammonium Tetrachlorocobaltate Eutectoid Mixtures as Phase Change Materials

WU Ke-Zhong, SUN Xiao-Long, CHEN Lei, RUAN Bei   

  1. Key Laboratory of Inorganic Nano-materials of Hebei Province, Department of Chemistry and Material Science, Hebei Normal University, Shijiazhuang 050024, P. R. China
  • Received:2015-02-12 Revised:2015-04-15 Published:2015-07-08
  • Contact: WU Ke-Zhong
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21473048, 21246006) and Natural Science Foundation of Hebei Province, China (B2012205034).


The thermotropic phase-transition compounds 1-alkylammonium tetrachlorocobaltate (1-CnH2n+1NH3)2CoCl4 (n=10, 18) and a series of their binary mixtures were prepared by solution reflux at 353 K in ethanol solutions. Binary-mixture (1-C10H21NH3)2CoCl4-(1-C18H37NH3)2CoCl4 systems were characterized over the entire composition range using differential scanning calorimetry and X-ray diffraction. The phase diagram constructed from the experiments indicated one stable intermediate phase, (1-C10H21NH3)-(1-C18H37NH3)CoCl4, at a mass fraction wC10Co=52.51%, two invariant three-phase equilibria, and two eutectoid temperatures, which are assigned to e1 at (347±1) K, for the eutectoid point with wC10Co=38.50%, and e2 at (343±1) K, for the eutectoid point with wC10Co=69.86%. These three clear solid-solution ranges are α-phase on the left, β-phase on the right, and γ-phase in the middle of the phase diagram. The (1-CnH2n+1NH3)2CoCl4 and their binary-mixture systems as phase change materials have phase-transition temperatures in the range 340-370 K, and transition enthalpies in the range 2.13 and 141.12 J·g-1, between two polymorphic crystal forms.

Key words: Bis(1-alkyammonium) tetrahelometallate, Phase change materials, Differential scanning calorimetry, Eutectoid temperature, Phase diagram