X-RAY-DIFFRACTION MEASUREMENT OF THE EFFECT OF LAYER THICKNESS ON THEFERROELECTRIC TRANSITION IN EPITAXIAL KTAO3 KNBO3 MULTILAYERS/

KTaO3/KNbO3 strained-layer superlattices of variable periodicity were grown by pulsed laser deposition on KTaO3 substrates. The KNbO3 layers were found to be strained in plane to match the substrate lattice par ameter. Therefore, the applied strain is independent of the layer thic kness. High-temperature x-ray diffraction was used to measure the ferr oelectric-paraelectric phase transition temperature T-c. For superlatt ice periodicity Lambda less than or equal to 5.1 nm, T-c = 475 K, inde pendent of Lambda. For Lambda > 5.1 nm, T-c increases to 825 K at Lamb da = 33.8 nm.