Volume combustion and mechanochemical syntheses of LaB₆

Abstract

LaB6 powder was produced by volume combustion synthesis (VCS) and mechanochemical synthesis (MCS) methods, through magnesiothermic reduction of La2O3 and B2O3 powders. VCS was achieved by rapid heating of the reactant mixture in argon, whereas MCS was performed via high energy ball milling. All the products were subjected to XRD, SEM, gravimetric and particle size distribution analyses. MCS resulted in the expected products LaB6 and MgO. In addition to these, VCS products contained LaBO3 and Mg3B2O6. In order to obtain pure LaB6, 30 min leach in 1 M HCl was found to be enough for MCS products, whereas Mg3B2O6 could not be removed from the VCS products even after 15 h leach. Wet milling of VCS products before leach facilitated obtaining of pure LaB6. Average particle sizes of the LaB6 powder produced by VCS and MCS were 290 and 180 nm, respectively.