Cathodoluminescence from mixed KTaO3-KNbO3 crystals

Cathodoluminescence spectra are shown for a sequence of mixed crystals of KTaO3:KNbO3. The luminescence emission bands are broadly similar across the spectrum from 250 to 850 nm, although their relative strengths are sensitive to composition and temperature. A UV band near 330 nm is only well resolved in some compositions and a broad line near 700 nm may arise from Cr ions. The presence of low temperature phase transitions within the crystals is evidenced by intensity steps and spectral changes of the cathodoluminescence. Hysteresis is seen, as are domain effects and electric field shifts of the transition temperatures. The cathodoluminescence of the surface material reveals more transitions than are reported from earlier bulk studies. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.