Negative Thermal Expansion of Gd2Fe16.5Cr0.5 Compound with Th2Ni17-Type Structure
The thermal expansion and the Curie temperature of Gd2Fe16.5Cr0.5 compound have been investigated by means of x-ray diffraction and magnetization measurements. The result shows that the Gd2Fe16.5Cr0.5 compound annealed at 1243°C has a hexagonal Th2Ni17-type structure. Cr atom substituting for Fe atom can increase the Curie temperature obviously. In magnetic state, an anisotropic anomolous thermal expansion was observed. Along the c-axis, the average linear thermal expansion coefficient αc=-2.79×10-6/K in the temperature range 294-472K, and αc =-3.09×10-5/K in 472-592K. Along the a-axis, the average linear thermal expansion coefficient αa =9.22×10-6/K in 294-552K, and αa =-1.41×10-5/K in 552-592K. In the temperature range 472-592K, the average volume thermal expansion coefficient αv =-2.14×10-5/K. The mechanism of the thermal expansion anomaly of Gd2Fe16.5Cr0.5 compound was discussed in this paper.
Jianzhong Wang and Jingang Qi
Y. M. Hao et al., "Negative Thermal Expansion of Gd2Fe16.5Cr0.5 Compound with Th2Ni17-Type Structure", Advanced Materials Research, Vols. 299-300, pp. 47-50, 2011