A second polymorph of technetium dichloride, β-TcCl2, has been synthesized from the reaction of Tc metal and chlorine in a sealed tube at 450 C. The crystallographic structure and physical properties of β-TcCl2 have been investigated. The structure of β-TcCl2 consists of infinite chains of face sharing [Tc 2Cl8] units; within a chain, the Tc-Tc vectors of two adjacent [Tc2Cl8] units are ordered in the long-range where perpendicular and/or parallel arrangement of Tc-Tc vectors yields a modulated structure. Resistivity and Seebeck measurements performed on a β-TcCl2 single crystal indicate the compound to be a p-type semiconductor while a magnetic susceptibility measurement shows technetium dichloride to be diamagnetic. A band gap of 0.12(2) eV was determined by reflectance spectroscopy measurements. Theoretical calculations at the density functional level were utilized for the investigation of other possible stable forms of TcCl2.
ASJC Scopus subject areas
- Colloid and Surface Chemistry