Compound in a ternary system of phosphorus(V) oxide-chromium(III) oxide-magnesium oxide and methods of its preparation

Abstract

The subject of the application is a compound in a three-component oxide system: phosphorus(V) oxide—chromium(III) oxide—magnesium oxide, which has the molecular formula Mg5Cr2P8O28. The subject of the application is also a method for producing a compound in a three-component oxide system, where the three-component system is phosphorus(V) oxide—chromium(III) oxide—magnesium oxide, which consists in mixing ammonium hydrogen orthophosphate(V), chromium(III) oxide, and a magnesium oxide precursor, homogenizing by grinding, and heating the resulting mixtures at a temperature starting from 350°C. The essence of the invention is that 4MgCO3•Mg(OH)2•4H2O is used as a magnesium oxide precursor, and the components are mixed in such a molar ratio that, calculated as the components of the ternary system, the content of phosphorus(V) oxide is 40 mol%, chromium(III) oxide 10 mol%, and magnesium oxide 50 mol%.After homogenization, the reagent mixture is heated at temperatures ranging from 350°C to 1050°C and triturated, yielding a product of the formula Mg5Cr2P8O28. Another method for preparing the compound, according to the invention, involves mixing chromium phosphate and magnesium phosphate, homogenizing, and annealing the resulting mixtures. The essence of the invention is that Cr4P6O21 and Mg2P2O7 are mixed in a molar ratio of 1:5. The resulting reagent mixture, after being homogenized by trituration, is heated at temperatures ranging from 850°C to 1070°C.