A NEW FURNACE DESIGN FOR USE IN COMBINED X-RAY-ABSORPTION AND DIFFRACTION OF CATALYSIS AND CERAMICS STUDIES - FORMATION FROM CARBONATE PRECURSORS OF CU, CO, MN SPINELS FOR THE OXIDATION OF CO AND THE FORMATIONOF PLZT, A PIEZOELECTRIC CERAMIC

In order to measure combined X-ray absorption fine structure, XAFS and X-ray diffraction, XRD in-situ on a sample, which is being heated in a furnace, there are a number of constraints on the furnace design due to the geometry of the detectors around the sample. We present a new furnace design which is based on a tube furnace: primarily for ceramic s or catalysis research where the sample is heated in air, but at temp eratures of up to 1200 degrees C. The design and specifications of thi s furnace are presented. To demonstrate the use of the high temperatur e furnace we have chosen a system which contains three elements, Mn, C o and Cu, whose XAFS and XRD have been measured. The sample was heated in air to 600 degrees C and the initial collapse of the crystalline c arbonates was followed by the formation of the final spinel phase. Fur thermore, the structural changes also accompany changes in the oxidati on states, especially of Cu and Mn. The Cu and Mn in the final product is present as a mixture of Cu 1+ and 2+ and Mn as 3+ and 4+ oxidation states. The XAFS analysis of the data also yielded information about the local coordination changes during the transformation of the precur sor carbonates to the final spinel product. We also show some prelimin ary data from the kinetics of formation of PLZT [Pb0.92La0.08(Zr0.65Ti 0.35)(0.98)O-3], from an amorphous gel to a crystalline phase material (ABO(3)).