Divalent impurity ions in potassium tantalate studied by EPR

EPR results of potassium tantalate single crystals eloped by Co2+ ions as well as new results of our continuous studies of KTaO3. Cu single crystal have been submitted. Divalent impurity ions substitute for Ta5+ in the octahedron position in the KTO3 crystal and oxygen vacancies are required to compensate the extra charge of Ta5+. The Cu2+ ions associated with oxygen vacancies form only axial centres (included exchange coupled pair centre), the symmetry axes being along cubic directions. New axial centre of Co2+ in the crystal of KTaO3: Co have been studied.