Abstract
Cesium magnesium orthophosphate CsMgPO4 has been reported as a promising candidate for medical applications and as a nuclear waste containment material. In this research paper, we report for the first time the optical and electrical results of this compound, synthesized by the solid-state method. It crystallizes at room temperature in the orthorhombic system with the Pnma space group. The average grain size is around 5 mu m. The vibrational study (IR, Raman) at room temperature confirmed the existence of the PO4 functional group with the absence of H2O due to the hygroscopic nature of this compound. The optical and electrical properties were thoroughly investigated using UV-Vis-NIR diffuse reflectance and impedance spectroscopy. The optical bandgap is approximately 1.54 +/- 0.03 eV for direct transition and 2.79 +/- 0.03 eV for indirect transition, determined using the absorption spectrum. The latter reveals the semiconductor characteristic of this compound. The Nyquist plots revealed the contribution of grains and grain boundaries in the electrical study, confirming the existence of a non-Debye type relaxation. The temperature dependence of these contributions is described in terms of Arrhenius law, with activation energies E-a (G) = 0.82 +/- 0.02 eV and E-a (GB) = 0.66 +/- 0.04 eV, respectively. Alternating current conductivity (sigma(AC)) is processed to reveal the responsible conduction mechanism through the exponent s in the studied temperature and frequency range. The latter confirmed that the conduction is insured by the Overlapping Large Polaron Tunneling (OLPT) model, which has been studied in depth.