Thermal diffusivity and conductivity of Pr, Eu and Ho zirconates

Abstract

The article presents the thermal diffusivity and conductivity value of rare earth elements (Pr, Eu, Ho) zirconates as a function of the temperature. All analysed systems were synthesised using the polymerized-complex method (PCM) with Zr(NO₃)₄ as a precursor. The rare earth cations RE³⁺ were introduced as nitrate compounds. The products of the primary stage of synthesis were calcinated and milled. As a final product, the monophasic pyrochlore zirconates of Eu, Pr and fluorite zirconate of Ho were obtained, confirmed by XRD analysis of phase constituents. The theoretical density and the specific heat were calculated (Neumann–Kopp rule). Based on these data and thermal diffusivity measurement (laser-flash method), the thermal conductivity was calculated for all considered compounds. Obtained data were used to determine the thermal conductivity value in the function of porosity. Based on the approximation procedure, the thermal conductivity of pores-free compounds was calculated. It can be assumed that the presented research revealed the thermal properties of Pr and Ho zirconates, which are very narrowly presented in the literature. It should also be noted that thermal conductivity’s tendency to decrease correlates with the cation size of rare earth elements used in zirconate compounds (except the Pr zirconate). Moreover, the relatively low influence of temperature on thermal conductivity thermal course suggests the strong influence of the phonon scattering mechanism.