Electronic Structures and Physical Properties of Transition Metal Tetraphosphides Tmp4 (Tm = V, Cr, Mo)

Abstract

Transition metal phosphides have promising applications in catalysis, sensors, environmental remediation, and energy storage due to their diverse crystal structures and physicochemical properties. In this study, using first principles calculations, we investigate the structural, electronic, mechanical, optical, and thermally conductive properties of transition metal tetraphosphides, TMP4 (TM = V, Cr, Mo). The mechanic properties and phonon spectra prove that TMP4 (TM = V, Cr, Mo) are mechanically and thermodynamically stable. The electronic structures calculated by HSE06 reveal that VP4 is metallic, while CrP4 and MoP4 are direct bandgap semiconductors with bandgaps of 0.646 and 0.142 eV, respectively. Both CrP4 and MoP4 have very low carrier effective masses and much high carrier mobilities in the [[EQUATION]] direction. The optical properties of CrP4 and MoP4 are mainly dominated significantly by the electronic transition from the valence band of P-2p orbital to the conduction band of M-d orbital. Moreover, our results also indicate that CrP4 and MoP4 exhibit relatively high absorption coefficients in order of 104 in the visible range and 105 in the UV region. Besides, the thermal conductivity properties indicate that both CrP4 and MoP4 possess high lattice thermal conductivities due to their large Gruneisen coefficients and long phonon lifetimes. Therefore, CrP4 and MoP4 have the potential to be used as high-temperature solar-light-absorbing materials.

Keywords: Transition Metal Phosphides, Mechanical Properties, Electronic Structures, Optical Properties, Thermal Conductivity Properties