An experimental and theoretical study of the structural, optical, electrical, and dielectric properties of PrAsO4

Abstract

This study reports the synthesis (by the co-precipitation method) and characterization of the PrAsO 4 polycrystals. The crystal structure has been determined using the Rietveld method. Two validation methods were used to confirm the structural model: the bond valence sum (BVS) and the charge distribution (CHARDI). A constructive description of the structure was made, starting with the connection modes of the coordination polyhedron. The electronic structure of the compound, determined by the DFT method, shows a direct band gap semiconductor material with a calculated energy of 2.21 eV. This compares favorably with the experimental band gap energy value of about 2.52 eV. The microstructural study showed grain and crystalline sizes of about 500 and 17 nm, respectively. TGA analysis was used to study the thermal stability of the compound, which showed a plateau in the 550 − 650 °C range due to the oxidation of Pr 3+ to Pr 4+ . This oxidation was confirmed by the emission spectra of Pr 3+ obtained from the photoluminescence study. The electrical study in the 440–600 °C temperature range shows that the PrAsO 4 is a bad ionic conductor with a value of about 10 −8 Scm −1 . The dielectric study showed a value of 1400 for the dielectric constant ε, and the dipolar polarization dominated the polarization phenomenon. About 10 −6 s was obtained for the relaxation time (τ r ) • The crystal structure of PrAsO4 was determined Rietveld refinement and confirmed by two validation models (BVS) and CHARDI. • The electronic structure was determined by DFT method which shows a direct band gap with energy of 2.21 eV. • The experimental band gap energy is of about 2.52 eV. • The thermal analysis shows the oxidation of Pr3 + to P4 + in the 550–650 °C temperature range. • The electrical measurement shows that PrAsO4 has a conductivity of about 10 −8 Scm −1