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-...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 areα-phase on the left,β-phase on the right,andγ-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.展开更多
文摘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 areα-phase on the left,β-phase on the right,andγ-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.
