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Exploring the Relationship between Crystalline Structure and Intrinsic Properties for MgGa₂O₄ Transparent Ceramic with the Bond Valence Method

Shiqiao Li, Hao Wang, Bin Wang, Bingtian Tu, Weimin Wang, Zhengyi Fu

Journal of Ceramic Science and Technology, Vol. 12, No. 2 (2021), pp. 87-96

DOI: 10.4416/JCST2020-00027

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Abstract

In this work, a novel spinel MgGa2O4 transparent ceramic was firstly prepared by means of air-presintering combined with hot isostatic pressing sintering. In contrast to the nearly normal spinel MgAl2O4, the MgGa2O4 was confirmed as the approximately inverse spinel with X-ray Rietveld refinement. Meanwhile, the polyhedral bond properties such as bond valence, bond length and bond force constant, which were obtained from the crystal structure parameters by means of the bond valence method, can aid understanding of the relationship between the crystal structure and properties. It was found that the MgGa2O4 with smaller anion position parameter (u) and larger lattice parameter (a) has the shorter tetrahedral bond and longer octahedral bond, compared with MgAl2O4, since there is a larger cation inversion parameter (i) in MgGa2O4. Furthermore, the tetrahedral bond in MgGa2O4 is much stronger than that in MgAl2O4 while the octahedral bond in MgGa2O4 is weaker than that in MgAl2O4. From the bulk modulus, Vickers hardness to the thermal expansion coefficient, the influence of tetrahedral bonds on these properties is gradually decreased while the influence of octahedral bonds on them is progressively increased. Thus, MgGa2O4 has a slightly larger bulk modulus than MgAl2O4. The hardness and thermal expansion coefficient of MgGa2O4 are lower and higher than that of MgAl2O4, respectively.

Keywords

MgGa2O4 transparent ceramic, crystal structure, properties, bond valence method

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