X-RAY STUDY OF THE STRUCTURE AND THERMAL-PROPERTIES OF BA1-XKXBIO3 ATDIFFERENT TEMPERATURES

The crystal structure as well as the temperature and composition depen dences of the lattice parameters, the thermal expansion coefficients i n the high-temperature superconducting Ba1-xKxBiO3 system were determi ned by an X-ray powder diffraction method at temperatures between 80 a nd 650 K. The character of variation of intensity, profiles, and line widths of the diffraction lines for different perovskite structures as a function of the content x and temperatures was found. The correlati on between the behaviour of the thermal expansion coefficients and pot assium content was revealed at different temperatures. It is shown tha t the thermal expansion coefficients vary inversely with rising x at a ny temperature in the range from 80 to 400 K.