Relationship between combustion temperature of carbon in tight contact with (Bi2O3)0.942(MOx)0.058 (M: metal elements) ceramic powder and the Mn+ ionic radius and the enthalpy of formation of M-O

In this study, the Bi2O3 powder, which was heat-treated at 700 °C and then finely ground, was placed in tight contact with carbon in a weight ratio of 98/2. In this case, the combustion temperature of carbon alone was lowered from 660 °C to 414 °C. 39 types of metal elements M, consisting of 17 rare earth elements and Ca, Sr, Ba, Ni, Cu, Zn, Al, Cr, Mn, Fe, Co, Ga, In, Si, Ge, Ti, Zr, Hf, Sn, Nb, Ta, Mo, and W, were dissolved in the Bi2O3 to prepare (Bi2O3)0.942(MOx)0.058. The carbon combustion temperature was measured when the finely ground (Bi2O3)0.942(MOx)0.058 ceramic powder was with carbon in a weight ratio of 98/2 in tight contact. The carbon combustion temperature was lower for all (Bi2O3)0.942(MOx)0.058 compared to Bi2O3 alone, with the lowest carbon combustion temperature of 354 °C observed for Co. Except for Sr and, Ba, the carbon combustion temperature tended to decrease as the ionic radius of Mn+ increased. In addition, the carbon combustion temperature tended to decrease as the enthalpy of formation per oxygen atom increased.