Single-Crystalline cooperite (PtS): Crystal-Chemical characterization, ESR spectroscopy, and 195Pt NMR spectroscopy

Abstract

Single-crystalline cooperite (PtS) with a nearly stoichiometric composition was characterized in detail by X-ray diffraction, electron-probe X-ray microanalysis, and high-resolution scanning electron microscopy. For the first time it was demonstrated that 195Pt static and MAS NMR spectroscopy can be used for studying natural platinum minerals. The 195Pt chemical-shift tensor of cooperite was found to be consistent with the axial symmetry and is characterized by the following principal values: δ xx = −5920 ppm, δ yy = −3734 ppm, δ zz = +4023 ppm, and δiso = −1850 ppm. According to the ESR data, the samples of cooperite contain copper(II), which is adsorbed on the surface during the layer-by-layer crystal growth and is not involved in the crystal lattice.