부산대학교 도서관

Abstract In this paper we report about the in-situ experiments on cobalt titanate (CoTiO 3), in which were investigated the compressibility at high pressures up to 24.6 GPa, at room temperature, using synchrotron X-ray diffraction (SXRD) and also the thermal expansion at high temperatures, from 298 to 723 K, using a conventional diffractometer at atmospheric pressure. The diffraction patterns were analyzed using the Rietveld method. The obtained lattice parameters were used to determine thermodynamic data of the CoTiO 3 in its ilmenite phase: the bulk modulus, compressibility, and thermal expansion coefficients. It was observed that increasing pressure, the volume of the unit cell decreased from 306.16 Å3 to 266.01 Å3. The third-order Birch-Murnaghan equation of state was fitted to determine the bulk modulus, B 0 , and its pressure derivative, B 0 ' along with the compressibility of the a - and c -crystallographic axis. In contrast, increasing temperature caused a volumetric expansion of the unit cell from 306.16 Å3 to 309.92 Å3. In both cases, changes in the c-axis dominate the expansion or contraction of the unit cell. Within the pressure and temperature ranges investigated in this paper, no structural phase transition was observed. Graphical abstract Image 1 Highlights • The crystal structure of CoTiO 3 is studied at high-pressures and high-temperatures. • All data reduction is done by Rietveld refinement. • The bulk modulus, compressibility and the thermal expansion coefficients are determined. [ABSTRACT FROM AUTHOR]