Sc- and W-substitution and tuning of phase transition in the Al2Mo3O12

Al2Mo3O12 is a typical negative thermal expansion (NTE) material, whose thermal expansion behavior depends on its crystal phase. The thermal shock caused by temperature-induced phase transition limits its wide application. The two series of Al2. xScxMo3O12 (0 < x < 1) and Al2Mo3-xWxO12 (0 < x < 2.5) solid solutions with controllable phase transition temperature were synthesized via single cation substitution at the A or B position. The problem of thermal shock caused by the change of temperature is effectively solved in the synthesized Al1.6Sc0.4Mo3O12 and Al2Mo0.5W2.5O12, showing stable NTE performance above room temperature, and the coefficients of thermal expansion of which are -2.19 x 10-6 degrees C-1 in 100-550 degrees C and -4.25 x 10-6 degrees C-1 in 85-500 degrees C, respectively. A-site cation substitution is a more effective way to tune the thermal expansion properties of Al2Mo3O12, which is attributed to the fact that the bond strength of A-O is weaker than that of B-O in the compound.

Automated summary

Al2Mo3O12 is a typical negative thermal expansion material, and its thermal expansion behavior depends on crystal phase, with thermal shock caused by temperature-induced phase transition being a limiting factor. A-site cation substitution is found to be a more effective way to tune the thermal expansion properties of Al2Mo3O12.