EPR studies of some f n and d n electronic impurities in KTaO3 single crystals

Single crystals of the cubic perovskite host, potassium tantalate (KTaO3), doped with iron group, lanthanide, and actinide impurities have been investigated using the technique of electron paramagnetic resonance (EPR). The EPR spectra of Yb3+ and U5+ have been observed for the first time in potassium tantalate by employing crystals co-doped with both impurities. Multiple doping of the material during the crystal growth process avoided the production of semiconducting KTaO3 and resulted in the incorporation of adequate concentrations of the trivalent lanthanide ion Yb3+. The EPR results indicate that Yb3+ occupies a site in which the local symmetry is axial as a result of nearby charge compensation. Pentavalent uranium is found to occupy a substitutional cubic symmetry site. EPR investigations of Cu2+, Co2+, Mn2+, Ni3+, and Fe3+ were also carried out.