Neutron diffraction and observation of superconductivity for tungsten borides, WB and W2B4

Abstract

Tungsten borides are known to be very hard and metallic materials. Tungsten monoboride, WB, becomes superconducting at Tc = 4.3 K in the tetragonal modification and Tc = 2.8 K in the orthorhombic modification. The structures of the two WB modifications were revised based on X-ray and neutron powder diffraction. W2B4, formerly known as W2B5, also shows a superconducting transition at 5.4 K, which is suppressed for small grain samples.