Investigation on the synthesis and the mechanical and thermal expansion properties of ZrMgMo3O12 ceramic bodies

Abstract ZrMgMo3O12 ceramics were synthesized via primary sintering at 700–750 °C for 5 h and second sintering at 700 °C for various times. The crystal structure and lattice parameters of ZrMgMo3O12 were confirmed by structural refinement. The microstructure, mechanical and thermal expansion properties of the as-synthesized ZrMgMo3O12 specimens were evaluated via XRD, XPS, SEM, TEM, Vickers hardness and coefficient of thermal expansion (CTE) analyses. The results show that single-phase ZrMgMo3O12 ceramics were synthesized via primary sintering at 700–750 °C for 5 h. Second sintering at 700 °C for various times improved the compactness, density and grain bonding of ZrMgMo3O12. The optimal synthesis process is primary sintering for 5 h at 700 °C and then second sintering for 72 h at 700 °C. Structural refinement revealed that each of the as-synthesized ZrMgMo3O12 ceramics had an orthorhombic crystal structure with a Pna21 space group and lattice parameters of a = 13.1886 A, b = 9.49382 A and c = 9.57818 A. Second sintering increased the mechanical properties and decreased the CTEs of the as-synthesized ZrMgMo3O12 ceramics. The ZrMgMo3O12 ceramics synthesized with the optimal synthesis process had hardness values of 205 HV, elastic moduli of 49.45 GPa and CTEs of 0.038 × 10−6 °C−1. Although the hardness was lower than those of traditional ceramics, the near zero CTE of the ZrMgMo3O12 ceramic demonstrated that it is a potential candidate for high dimensional stability materials.