Structure study of superconducting Li2Pd3B system by neutron powder diffraction

The crystal structure of the superconducting boride Li2Pd3B has been refined by Rietveld analysis of time-of-flight neutron powder diffraction data at room temperature. This compound exhibits superconductivity at 8 K, and X-ray diffraction study shows that this compound has a cubic structure with the distorted BPd6 octahedron. The neutron powder diffraction study revealed that there was no deficiency and no anomaly in the atomic displacement parameters of the Li and B sites. The Li partial structure is rigid, and the distorted BPd6 octahedron exists at the clearance gap of the Li partial structure. The Li2Pt3B compound substituted of Pt for Pd has larger distortion of the BPt6 octahedron than that of the BPd6 octahedron, which affects the decrease of the superconducting transition temperature.