H. Erdem Çamurlu

Mechanochemical and combustion synthesis of CeB6

Abstract CeB6 powder was prepared via combustion synthesis (CS) and mechanochemical processing (MCP) methods starting from CeO2, B2O3 and Mg powder mixtures. In CS, reactant mixtures were ignited in a preheated pot furnace under argon atmosphere. Products contained CeB6, MgO and Mg3B2O6, as revealed by X-ray diffraction analysis. After leaching in 1 M HCl for 15 h, MgO was removed but Mg3B2O6 could not be removed from the products. Ball milling of products in ethanol prior to leaching made the removal of Mg3B2O6 possible by leaching. Yield of CeB6 was 68.6 % in CS. MCP was performed in a stainless steel vial with a planetary ball mill at 300 rpm for 30 h. MCP products contained CeB6, MgO and small amount of Fe. Leaching in 1 M HCl for 30 min was sufficient to remove MgO. Yield of CeB6 was 84.4 % in MCP. According to scanning electron microscopy examinations, particles of CeB6 prepared by CS and MCP had submicrometer size. Average particle sizes were determined as 290 nm and 240 nm, respectively.

Volume combustion and mechanochemical syntheses of LaB 6

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.