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Amphoteric oxides (Al 2 O 3 and B 2 O 3) represent opposite effects on the structure and properties of silicate melts in different conditions, while the understanding about the transition from acidity to basicity is far from complete. Molecular dynamics simulation was adopted in the present study to investigate the performance and acidity-basicity transformation of Al 2 O 3 and B 2 O 3 in the SiO 2 –CaO–Al 2 O 3 –B 2 O 3 system. The results showed that, different from Ca2+ ions, excessive Al3+ or B3+ ions tend to destroy the bridge oxygen structures, showing the function of basic oxide. This is similar to the behavior of Ca2+ ions and other basicity ions. It was found that, on the one hand, B3+ ions tend to form [BO 3 ]3- planar triangular structures with the increase of B3+ ions contents, on the other hand, B3+ ions could reduce the stability of Si–O bonds. Therefore, B3+ ions could make the system structure less stable, which is the reason why the B 2 O 3 is a kind of active agent. In addition, because of the significant differences in lattice energy and atomic structure between Al 2 O 3 and B 2 O 3 , the effects of Al 2 O 3 and B 2 O 3 on the thermodynamic properties of silicate melts are quite different. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microstructure evolution mechanism of graphene oxide deflagration phenomenon. • Functional group desorption process of GO pyrolysis at high temperature. • Hybridization statistics and graphitization degree analysis of C atoms in GO. • C-O bond length statistics and structural analysis in graphene oxide. • The release process and quantity statistics of gas molecular of GO pyrolysis. An in-depth understanding of the structural evolution of graphene oxide (GO) at high temperatures is of crucial importance for tuning the properties of GO and synthesizing graphene-related materials from GO, which still has many unknown structural changes at the atomic scale. In this work, the overall structural change process and the local structural evolution mechanism during the high-temperature pyrolysis of GO were investigated by the ReaxFF molecular dynamics simulation method. The detonation process of GO was explored for the first time at the atomic simulation level, and the detonation point of GO was found to be positively correlated with the C/O ratio, which is highly consistent with previous experimental results. The bonding pattern between C-O in GO was sorted out, and the desorption mechanism of functional groups during pyrolysis was explained in detail by analyzing the ratio of sp2 and sp3 hybridized C atoms. In addition, the effects of temperature, C/O ratio and functional group type on the small molecule pyrolysis products were also investigated. The present study provides strategies to tune GO structure by pyrolysis at high temperature. [ABSTRACT FROM AUTHOR]