Crystal structure and thermal expansion properties of new compound La 2Cu 0.8Ge 3

Abstract

A new ternary compound La 2Cu 0.8Ge 3 was synthesized and studied. The crystal structure of La 2Cu 0.8Ge 3 was refined from X-ray powder diffraction data by Rietveld method. The new compound was found to have a tetragonal α-ThSi 2 structure with space group I4 1/ amd (No. 141), and a = 0.42807(2) nm, c = 1.45626(6) nm, Z = 2 and D calc = 6.931 g/cm 3. The thermal expansion properties of La 2Cu 0.8Ge 3 were investigated using high-temperature powder X-ray diffraction technique in the temperature range from 321 K to 753 K. Results show that its unit-cell parameters increase with increasing temperature. The coefficients of average lattice thermal expansion are α ¯ a m = 1.17 × 10 − 5 K − 1 , α ¯ c m = 1.09 × 10 − 5 K − 1 and α ¯ V m = 3.42 × 10 − 5 K − 1 .