Synthesis, characterization of imidazole-based copper complex mixtures and study of their thermal behaviour

Herein, the synthesis, characterization and thermal behaviour of imidazole-based two copper-phosphate mixtures, A = Cu-2(PO4)(OH)center dot Cu(HPO4)(H2O)center dot(C3H4N2)(2).3.25 H2O and B = Cu-3(PO4)(2)H2O center dot(C3H4N2)(3) (H2O)center dot 0.1(C3H4N2).3.25 H2O are reported. The characterization was done by adopting various electro-analytical techniques such as elemental analysis, X-ray Powder Diffraction (XRD), Thermogravimetric Analysis (TGA) and Derivative Thermogravimetry (DTG), Fourier Transform Infrared (FT-IR) Spectrometry, Absorption Spectrophotometry and Ultraviolet-Visible and near Infrared (UV-Vis-NIR). Differential Scanning Calorimetry performed with the heating rate 10 K/min from 297.96 to 770.46 K in normal atmosphere for both mixtures. DSC data indicated that both mixtures A and B are exhibiting exothermic property by their net specific heat capacities (C-p) -11.11 and -2.83 J/g K, respectively. Therefore, these complex mixtures can be utilized as heat dissipation materials. Both mixtures A and B undergo phase change in terms of hydrated phase to dehydrated phase up to 356 and 392 K, respectively. The specific heat capacity of Mixture A during hydration, C-p = 2.54 J/g K, is higher than the tin, lead, stainless steel, glass and aluminium at their respective melting points. This mixture is also found better than the commercial product based on lithium ion battery in terms of specific heat capacity. From UV-Vis-NIR analysis, it is found that the mixtures A and B are showing semiconducting behaviour with band gaps 1.66 and 1.68 eV, respectively. The average crystallite sizes of these nano-complex mixtures are 35.29 and 30.94 nm and these were calculated using the Debye-Scherrer equation and Williamson-Hall method.