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Na--alumina with MgO stabilized was produced through solid state reaction. High purity starting material, -Al2O3, -Al2O3, Na2CO3 and MgO were used. The desired amount of starting materials corresponding to the nominal formula Na(1+x)MgxAl(11-x)O17 were mixed and calcined at temperature 1200 for 10 h under atmospheric pressure. The effect of Al2O3 source on phase formation and averaged crystallite size of Na--alumina were investigated via X-ray diffraction (XRD), SEM and TGA/DTA. The XRD result show that formation of Na--alumina with high purity is obtained when -Al2O3 was used. The larger crystallite size is found for sample prepared form -Al2O3. For SEM study the Na--alumina microstructure is seen as randomly packing of several sheets. Calculated crystallite size of sample prepared from -Al2O3 show the larger value compared to that one prepared from -Al2O3.

0 ≤ x ≤ 0.05) Delafossite-Type Transition Oxide. -The title compounds are prepared by solid state reaction of stoichiometric mixtures of CuO, Fe2O3, and PtCl2 (1050°C, 15-25 h) and characterized by powder XRD, SEM, and thermoelectric measurements between 300 and 960 K. Small Pt substitution in CuFeO2 improves the thermoelectric properties and enhances the good semiconducting behavior. The highest figure of merit is 0.05 for x = 0.05 at 960 K. The materials may be invented in thermoelectric devices for covering heat losses at high temperature. -(RUTTANAPUN*, C.; WICHAINCHAI, A.; PRACHAMON, W.; YANGTHAISONG, A.; CHAROENPHAKDEE, A.; SEETAWAN, T.; J. Alloys Compd. 509 (2011) 13, 4588-4594, http://dx.