The effect of magnesium compounds (MgO and MgAl2O4) on the synthesis of Lanthanum magnesium hexaaluminate (LaMgAl11O19) by solid-state reaction method

In the present study, the lanthanum magnesium hexaaluminate (LaMgAl11O19)(LaMA) powder was synthesized by the solid-state reaction method using two types of magnesium compounds, including magnesium oxide (MgO) and magnesium aluminate (MgAl2O4) spinel (MAS). The effect of substitution of magnesium oxide with MAS on the synthesis temperature, intermediate compounds and morphology of synthesized powders were investigated. The microstructural results showed that the intermediate compounds of lanthanum aluminate (LaAlO3), aluminum oxide and MAS were formed in the presence of magnesium oxide, whereas in the latter case, the LaAlO3 intermediate phase was not observed and La4Al2MgO10 was formed at about 810 °C. Also in both cases, a single LaMA phase with the platelet-like morphology was formed. The thickness of the LaMA platelets decreased from 300 nm to 125 nm and the synthesis temperature increased from 1330 °C to 1355 °C, by replacing MgO with MAS.