Thermal properties of high order crystalline dielectric mixtures

Through experiments the heat capacity is determined at constant volume in ternary and quaternary KCl_0.5KBr_0.25RbBr_0.25:Eu²⁺ and KCl_0.25 KBr_0.25RbCl_0.25RbBr_0.25:Eu²⁺ single crystals. The results are compared with calculated values using the low temperature approximation of the Debye Model, in which the Debye temperature is obtained by applying a Kopp-Neumann relation. It is shown that the C_v values obtained by the Debye model are in good agreement with the measured ones which demonstrates that the Kopp-Neumann law used for metals and other solids can also be applied to ternary and quaternary alkali halide crystals, that is also an element that strengthens the diffractogram of the quaternary mixture which shows that the crystal has a single phase, thus being a solid solution.