Predicting properties of MgO·nAl₂O₃ by first‐principles calculation combined with bond valence models

Abstract

Spinel‐type oxides have attracted tremendous attentions owing to their wide applications. However, the complicated composition and structure of spinel‐type solid solution brought about challenge to explore the relationship among composition, structure, and properties. A new approach which combined first‐principles calculation with bond valence models was developed to explore the composition dependence of structure and properties for spinel‐type oxide solid solution. The first‐principles calculation was used to simulate the structural parameters of spinel‐type oxide solid solution. The mechanical and thermal properties of Mg1‐xAl2(1+x/3)O4 spinel‐type solid solution were estimated by bond valence models based on the structure which was reconstructed from the structural parameters determined by the first‐principles calculation. Besides, bond valence arguments were also used to assess the reliability of reconstructed structure. The results suggest that the extremely overbonded or underbonded atoms can be avoided in the reconstructed structure, which improves the stability of reconstructed structure. By comparing the results with experimental values, it can be seen that mechanical and thermal properties could be simulated exactly by the new approach and bulk modulus was used as an example to explore the relationship among composition, structure, and properties of Mg1‐xAl2(1+x/3)O4.

Theoretical study on composition‐dependent properties of ZnO·nAl2O3 spinels. Part II: Mechanical and thermophysical

“…The variation of the derived Poisson's ratio is shown in Figure 4B as well. With the rise of n , ZnO· n Al 2 O 3 shows some improvement in elastic moduli ( B , G , and E ), and essentially constant Poisson's ratio, which is similar to MgO· n Al 2 O 3 8,19 …”

“…Hence, results based on the crystal structure parameters determined from LDA, that is, by Equations () and () and those from GGA, that is, by Equations () and () can be seen as the extremes of properties, respectively. The reliability of the reconstructed structure was assessed by the bond valence arguments 19 (Seen in Supporting Information ). In this work, the global instability index ( GII ) for the reconstructed structure of ZnO· n Al 2 O 3 ( n = 1–4) from either LDA or GGA is lower than 0.20 (inset in the bottom left of Figure 2), suggesting the structural stability.…”

“…Now that the rules for cation distribution in ZnO· n Al 2 O 3 are known, the spinel‐type structure can be reconstructed. Our previous investigations 19,20 have elaborated on the feasibility, accuracy, and high efficiency of such an approach; the crystal structure thus obtained was used as the input for the bond valence models, which solves the problem of predicting the mechanical and thermal properties of complex and disordered spinel‐type solid solutions.…”

Elasticity of Nonstoichiometric Alumina-Rich Spinel Determined by Bond Valence Theory and Brillouin Scattering

“…Furthermore, the site preference of disordered species should be fully understood first, because the distribution of cationic vacancies and inversion atoms is not totally random. 39,40 The calculation is relatively time-consuming and inefficient.…”

Composition‐dependent thermal and thermomechanical properties of spinel‐type MgAlON from density functional calculation

“…The results indicated that the thermal expansion of RE 2 Si 2 O 7 is mainly controlled by the interaction between O atoms and surrounding RE atoms, and the vibration of Si–O–Si is significant for the thermal expansion of RE 2 Si 2 O 7 . More recently, a new approach that combines first‐principles calculations and bond valence models (FP‐BVM) was developed for exploring the origin of composition‐dependent properties in complex systems 19–21 . The successful applications of FP‐BVM in complex spinel‐type compounds 19–21 bring enlightenment to MgAlON solid solution.…”