NEW METHOD OF MICROPHASE AND CHEMICAL-ANALYSIS AS APPLIED TO THE YBACUO THIN-FILMS

A new chemical method, differential dissolution, has been used to char acterize thin (0.05-1 mu m) YBCO films. By this technique the qualitat ive and quantitative phase composition of the films was determined. Ne w information on the film inhomogeneity was obtained. Chemical inhomog eneity was defined as second-phase precipitates at a content below 10( -6) g and as local deviations from 123 stoichiometry of the main phase throughout the thickness of the film. Not only the total quantity but also the interphase distribution of Al in poly- and single-crystal fi lms with the sapphire substrate temperature were established. Occurren ce of amorphous or disorder forms of the 123 phase together with the c rystalline one, as an effect of the substrate temperature was detected and quantities of the forms were correctly determined. The obtained i nformation is considered in combination with structural parameters and transport properties of the films. The technique as an important tool for analyzing thin films and its application to growing the single-cr ystal YBCO films by laser deposition are discussed.