Effects of La2O3 on sintering of MgO-CaO ceramics: Molecular dynamic simulation and experiments

The mechanism of the additive La 2 O 3 on the sintering process of MgO-CaO ceramics was investigated by molecular dynamics simulation, and the interfacial reaction and nanoparticles sintering models were established. The simulations demonstrated that MgO and CaO dissolve into La 2 O 3 crystals, creating O 2- vacancies around Mg 2+ and Ca 2+ . These vacancies significantly increase the diffusion rate of ions. Meanwhile, the La 2 O 3 shifts the sintering driving force from reducing internal energy to increasing entropy, thereby enhancing the sintering degree of nanoparticles. However, excessive La 2 O 3 introduction prolongs solid solution reaction times and impedes particle-particle contact, negatively affecting sintering densification. Experimental results show that the density of MgO-CaO ceramics initially increases with the addition of La 2 O 3 , reaching a peak of 3.43 g/cm³ at 0.3 mol%, before decreasing. This result aligns with the model's predictions regarding the effect of La 2 O 3 addition. Moreover, the established models offer reference for selecting sintering aids in composite ceramics production.