Sol–Gel Synthesis of Magnesium Aluminate Spinel as Influenced by Y2O3 and Eu2O3 Additions
Abstract
Magnesium aluminate spinel has been prepared by sol–gel synthesis. We have studied the effect of europium and yttrium oxides on the synthesis of magnesium aluminate spinel and kinetics of spinel formation during heat treatment in the temperature range 500–1000°C. According to X-ray diffraction and chemical analysis data, the formation of magnesium aluminate spinel from a dried xerogel prepared from a mixture of the Al(NO3)3 and Mg(NO3)2 compounds in the ratio 2 : 1, respectively, occurred at a temperature of 1000°C and a firing time of 240 min. The resultant material contained free MgO as an impurity phase. The addition of 1.5 wt % Eu2O3 relative to the total weight of the starting mixture reduced the peak spinel formation temperature to 900°C at a firing time of 240 min. In the case of Y2O3, the addition of 3 wt % was needed to maximize spinel formation at this temperature.