Solid - Solid interaction in pure and Li[2]O-doped Cr[2]O[3]/CuO System

ABSTRACT

Cr[2]O[3]/CuO systems having the formulae 0.2 Cr[2]O[3]/CuO and 0.5, Cr[2]O[3]/CuO were prepared by mixing the calculated amounts of copper nitrate trihydrate with CrO[3] dissolved in the least amount of distilled water sufficient to make pastes. The obtained pastes were dried at 100°C then calcined at 500, 700 and 900°C. The solid-solid interactions between chromium and copper oxides were investigated by using DTA and XRD techniques. The effects of Li[2]O-doping [1.5 and 4.5 mol%] of the systems investigated on solid-solid interactions taking place between Cr[2]O[3] and CuO have been also investigated. The results revealed that the investigated mixed solids [copper nitrate and CrO[3] underwent thermal decomposition at about 370°C yielding CuO and Cr[2]O[3-] Chromium oxide interacted readily with CuO producing copper chromate [CuCr[2]O[4]] at temperatures starting from 500°C. The produced phase remained thermally stable by heating at 700°C then converted into CuCrO[2] by heating at 900°C. Li[2]O-doping of the investigated system enhanced the chromate formation and hindered the reduction of some of cupric into cuprous oxides