Crystalline phases have been coprecipitated from Al/Cr mixed-nitrate aqueous solutions with ammonium carbonate. These phases have been characte rized as probably layered hydroxycarbonates with the likely composition (NH4)2(Al,Cr)6(OH)14(CO3)3·H2O, using XRD, FTIR and TG–DTA analyses. The calcination of these materials gives rise to amorphous mixed oxides where Cr is partly in the hexavalent state, while further calcination at 1173 K gives rise to polyphasic materials. Samples with Al: Cr atom ratio between 551 and 151 give rise to four phase materials with three corundum-type phases and a spinel-type phase. All these phases contain both Al and Cr.

Characterization of coprecipitated aluminium–chromium mixed hydroxides and of the products of their calcination

CRISTIANI, CINZIA;
1997

Abstract

Crystalline phases have been coprecipitated from Al/Cr mixed-nitrate aqueous solutions with ammonium carbonate. These phases have been characte rized as probably layered hydroxycarbonates with the likely composition (NH4)2(Al,Cr)6(OH)14(CO3)3·H2O, using XRD, FTIR and TG–DTA analyses. The calcination of these materials gives rise to amorphous mixed oxides where Cr is partly in the hexavalent state, while further calcination at 1173 K gives rise to polyphasic materials. Samples with Al: Cr atom ratio between 551 and 151 give rise to four phase materials with three corundum-type phases and a spinel-type phase. All these phases contain both Al and Cr.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/657109
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