RUTILE-TYPE ESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1(XO4 PHASES, 0)3, SYNTHESIZED BY THE SOL-GEL TECHNIQUE/

The sol-gel method has been used to synthesise Mn1-xSb1+xO4 compounds, 0 less than or equal to x less than or equal to 1/3, with the rutile- type structure. Xero-gels containing Mn and Sb were prepared with Mn(O Ac)(2).4H(2)O and Sb(OnBu)(3) as precursors. The gels were heated to 3 70 degrees C for 10 min, and these X-ray-amorphous Mn-Sb oxide mixture s were then heat treated at 740 degrees C for 14 h in air. The cell di mensions of the rutile phases are a=4.671(4), c=3.060(4) Angstrom, V=6 6.75 Angstrom(3) for MnSbO4 (x=0) and a=4.709(1), c=3.126(1) Angstrom, V=69.328 Angstrom(3) for Mn Sb O, (x=1/3). The structure of Mn2/3Sb4/ 3 O-4 was refined by the Rietveld method, using X-ray diffractometer d ata, to R(F)=4.9%. The Mn1-xSb1+xO4 rutile phases decompose on prolong ed heating at 800 degrees C, with the formation of trigonal gamma-MnSb 2O6. A partially ordered tri-rutile phase is observed in decomposed sa mples for x greater than or equal to 0.27.