Crystallographic and optical study of LiNb1†-†xTaxO3.

Powders of lithium niobate-tantalate across the full compositional range have been made and crystals grown using a lithium vanadate flux growth technique. The Li-content of a lithium tantalate crystal has been determined using the zero-birefringence temperature and Curie measurements, confirming the Li content is between that of congruent and stoichiometric crystals. X-ray diffraction measurements show the Nb/Ta displacement and octahedral tilt both decrease as the Ta content is increased. This also results in a decrease in the lattice parameters from lithium niobate to lithium tantalate. Birefringence measurements on the crystals as a function of temperature have been used to determine the point that the crystals become zero-birefringent, and by comparison with the structural studies have confirmed that it is not related to a phase transition and the structures remain polar through the zero-birefringence points.

Raman study of CeO2 texture as a buffer layer in the CeO2/La2Zr2O7/Ni architecture for coated conductors.

The CeO(2)/La(2)Zr(2)O(7)/Ni piled-up structure is a very promising architecture for YBa(2)Cu(3)O(7) (YBCO) coated conductors. We have grown YBCO/CeO(2)/LZO/Ni epitaxial structures by metalorganic decomposition (MOD) and metalorganic chemical vapor deposition (MOCVD) methods. The crystallographic quality of the CeO(2) layer is not well determined by conventional X-ray diffraction (XRD) due to the superposition of LZO and CeO(2) reflections. An alternative simple Raman spectroscopy analysis of the crystalline quality of the CeO(2) films is proposed. The F(2g) Raman mode of CeO(2) can be quantified either by using two polarization configurations (crossed or parallel) or at two different rotation angles around the normal axis (0 degrees and 45 degrees ) to obtain information about the sample texture. The sample texture can be determined via a quality factor (referred to as the Raman intensity ratio, RIR) consisting of calculating the ratio of the integrated intensity of the CeO(2) F(2g) mode at 0 degrees and 45 degrees in parallel polarization. This factor correlates with superconducting performance and the technique can be used as an on-line nondestructive characterization method.