R8CoAl3 (R = Y, La - Ho)以及RNiAl3 (R = Y, Sm - Ho) 三元稀土化合物之物性研究

Abstract

The crystal structure, electrical, and magnetic properties of the series of rare earth ternary intermetallic compounds R8CoAl3 (R = Y, La-Ho) and RNiAl3 (R = Y, Sm-Ho) have been investigated using powder X-ray diffraction, electrical resistivity, and magnetic susceptibility measurements. X-ray diffraction patterns reveals that R8CoAl3 compounds crystallizes in Pr8CoGa3 type structure with space group P63mc. Whereas RNiAl3 compounds crystallizes in YNiAl3 type structure with space group Pnma. The temperature dependent both magnetic susceptibility χ(T) and resistivity ρ(T) curves of La8CoAl3 shows a superconducting transition at 6 K. The Ce8CoAl3 compound shows a sudden upturn which may due to the spin density behavior. The resistivity behavior of other R8CoAl¬3 compounds shows quite different with each other. The Nd8CoAl3 and Sm8CoAl3 both show two changes of slopes in the ρ(T) curve. While, ρ(T) curves for Gd8CoAl3 and Dy8CoAl3 are exhibits show Kondo-like behavior at low temperature. The RNiAl3 compounds, the resistivity and magnetic susceptibility measurement suggest that the magnetic transitions are quite complicated. The χ(T) curve for GdNiAl3 shows multiple transition at ~ 175 and 75 K, where ρ(T) curve shows a slope change and sharp drop, respectively. The χ(T) curve for HoNiAl3 shows a deviation of ZFC and FC around 27 K. Furthermore, there is a maximum around 23 K and a slope change around 16 K in the ZFC curve. But the YNiAl3 compound is nonmagnetic.