PREPARATION OF KTA0.65NB0.35O3 THIN-FILMS BY A SOL-GEL PROCESS

Crack-free and transparent potassium tantalate niobate (KTN) KTa0.65Nb0.35O3 thin films of perovskite structure were prepared through spin-coating using a sol-gel process. A homogeneous and stable precursor solution was obtained from K(OC2H5), Ta(OC2H5)(5) and Nb(OC2H5)(5) in absolute ethanol without any additives. Infrared absorption spectra indicate the existence of a complex reaction resulting in the formation of double metal alkoxides KNb(OC2H5)(6) and KTa(OC2H5)(6) in solution. The precursor powder crystallized to pyrochlore at 600 degrees C, and then completely transformed to perovskite at 750 degrees C. Highly oriented KTN films possessing a perovskite structure were successfully prepared on R-plane sapphire substrates at 750 degrees C and on SrTiO3(100) substrates at 650 degrees C. The chemical composition of the KTN films is in good agreement with the atomic ratio of the starting materials.