Temperature dependence of lattice constants and thermal expansion coefficient of terbium-yttrium ferrites garnets

Abstract Lattice constants of polycrystalline samples of mixed terbium-yttrium ferrites garnets Tb x Y 3- x Fe 5 O 12 (1; 1.98; 2.5; x = 3) and single crystals Tb 3 Fe 5 O 12 have been measured in the temperature interval 80–300 K by X-ray diffraction, without the presence of magnetic field. The anomalous behavior of lattice constants and expansion coefficients have been found in the vicinity of the compensation point (which changes with the concentration of the terbium ion) of these polycrystals and the single crystal. The single-crystalline TbIG shows a rhombohedral distortion at low temperatures, which can be followed up to the temperatures near the compensation temperature.