First-principles study of elastic and thermodynamic properties of UO2, γ-UO3 and α-U3O8

•The elastic moduli as well as Poisson's ratio and the Debye temperature of UO2, γ-UO3, and α-U3O8 polymorphs were calculated.•The anisotropic indexes of above polymorphs were calculated to describe their elastic anisotropy.•The thermodynamic properties of UO2, γ-UO3, and α-U3O8 compounds were predicted up to 2000 K.•Both PBE+U and LDA+U methodologies were used to better describe the physical properties of these uranium oxides.