AN EASY METHOD FOR THE DETERMINATION OF DEBYE TEMPERATURE FROM THERMAL-EXPANSION ANALYSES

A combination of the early approaches of the Debye model for specific heat and the Gruneisen theory of the thermal expansion of solids is us ed to interpolate the thermal variation of lattice parameters. From th is analysis, relevant parameters such as the Debye temperature and the value of lattice parameters extrapolated at 0 K are deduced. This met hod and its Limitations are reported. A program has been developed whi ch can be readily used with any computer. Practical applications are g iven as an illustration. The method is first applied to an ideal cubic compound Na2Ca3Al2F14, which we propose as a standard for thermal exp ansion calibrations. Then, magnetoelastic phenomena, which occur at ve ry low temperature, are displayed in cubic rare earth garnets by compa rison of experimental and extrapolated data. The model is extended to an anisotropic hexagonal system, where the values of lattice parameter s extrapolated at 0 K are determined within 10(-5). Debye temperatures are estimated within a relative error of 10% and are in good agreemen t with those calculated from specific heat data; they prove the releva nce of this easy method.