SYNTHESIS OF CRXTI1-2XNBXO2 -LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.5 RUTILE SOLID-SOLUTIONS FROM ALKOXIDES

In this study, CrxTi1-2xNbxO2 (0 less-than-or-equal-to x less-than-or- equal-to 0.5) rutile solid solutions have been synthesized from gels b uilt from hydrolysis-condensation of Cr (111) acetylacetonate, NbCl5 a nd Ti (IV) isopropoxide mixture (polymeric gel). Characterization of t hese solid solutions was carried out by X-ray diffraction, ultraviolet -visible and infrared spectroscopy, differential thermal and thermogra vimetric analysis and CIELAB (Commission Internationale del'Eclairage La*b*) parameter measurements, The results obtained by the polymeric gel method were compared with those obtained by traditional ceramic sy nthesis. This comparison reveals some differences with regard to synth esis temperatures and reaction mechanisms. The formation of CrxTi1-2xN bxO2 (0 less-than-or-equal-to X less-than-or-equal-to 0.5) rutile soli d solutions by the ceramic method requires temperatures of about 1200- degrees-C and soaking times of several days. These solid solutions are synthesized at 1 000-degrees-C in 24 h by the polymeric gel method. I n ceramic synthesis, the CrNbO4 compound with rutile structure appears as an intermediate compound in the formation of rutile solid solution s. ln polymeric gel synthesis, however, the CrNbO4 rutile compound was not detected in the samples.