Search results for "Uvarovite"
showing 4 items of 4 documents
A rietveld study of the cation substitution between uvarovite and yttrium-aluminum synthetic garnets, obtained by sol-gel method
1994
A series of synthetic garnets solid solutions with compositions between Y 3 Al 2 Al 3 O 12 (Y-Al garnet) (YAG) and Ca 3 Cr 2 Si 3 O 12 (uvarovite) was synthesized using the sol-gel method. The expected general formula is (Ca x Y 1-x ) 3 (Cr x Al 1-x ) 2 (Si x Al 1-x ) 3 O 12 where x=0 to x=1. The cation distribution in dodecahedral, octahedral and tetrahedral sites and bond distances in these synthetic garnets were determined using the Rietveld method. It shows the incomplete substitution in small sites. The smaller site the smaller substitution there is
Synthesis of Uvarovite Garnet
1989
A garnet with interesting optical properties is synthesized by means of the ceramic method and the formation of gels. Colloidal silica or tetraethoxysilane (TEOS) is used as a starting reagent in the latter method of synthesis, together with nitrate and chloride salts of the remaining components. Use is made of ultraviolet-visible and infrared spectroscopy techniques and X-ray diffraction in studying the evolution of the system. Formation of the garnet phase at lower temperatures is observed when using the gel methods, as well as the absence of chromates during the process in the samples which contained chlorides.
ChemInform Abstract: Synthesis of Uvarovite Garnet.
1989
A garnet with interesting optical properties is synthesized by means of the ceramic method and the formation of gels. Colloidal silica or tetraethoxysilane (TEOS) is used as a starting reagent in the latter method of synthesis, together with nitrate and chloride salts of the remaining components. Use is made of ultraviolet-visible and infrared spectroscopy techniques and X-ray diffraction in studying the evolution of the system. Formation of the garnet phase at lower temperatures is observed when using the gel methods, as well as the absence of chromates during the process in the samples which contained chlorides.
The preparation and thermal evolution of polymeric gels with garnet stoichiometry in the CaOAl2O3SiO2 and CaOCr2O3SiO2 systems
1990
Abstract The synthesis of gels with garnet stoichiometry in the CaOAl 2 O 3 SiO 2 and CaOCr 2 O 3 SiO 2 systems and their evolution in thermal processing have been studied. Dried gels with the stoichiometry 3CaO.Al 2 O 3 .3SiO 2 show a homogeneous aspect without detectable crystalline phase. The thermal evolution of these gels indicates no formation of grossularite at temperatures up to 1000°C after 12 h. In the uvarovite garnet samples, 3CaO.Cr 2 O 3 .3SiO 2 , a small amount of crystalline phase was detected in the dried gels. The homogeneity of the gels was checked by scanning electron microscropy. The infrared study of these polymeric gels confirmed the presence of SiOMe (MeCr 3+ …