Cd⁺(5s¹) Centres in Rb₂ZnCl₄ Single Crystals

Abstract

Electron paramagnetic resonance and optical absorption spectra attributed to 5s' trapped electron Cd+(I) and Cd+(II) centres are observed over a broad temperature range in Rb,ZnCI, single crystals doped with cadmium, after X-ray irradiation at 80 K and room temperature, respectively. The low temperature Cd+(I) centre, which seems to be a substitutional Cd' ion in a ZnZf site, transforms into a Cd+(II) centre at 190 K by trapping an anion vacancy, which has become mobile at this temperature, in its nearest-neighbour positions. The suggested structural models of the Cd' centres are supported by the analysis of the spectral data considering covalency effects.Nous avons obtenu, apres I'irradiation avec des rayons X, dans des monocristaux du Rb,ZnCI, dopees avec CdZ +, des spectres de resonance paramagnttique tlectronique et d'absorption optique attribue aux centres Cd+(I) et Cd+(II). Le centre Cd+(I), qui est produit par l'irradiation aux temperatures basses, est forme par la capture d'un electron B un ion du CdZ+ insere pr6firentiellement au site du Zn2+. Le centre Cd+(II) est forme aux temperatures superieures a 190 K, par la capture d'une vacance anionique a un centre Cd+(I).