Spectral analysis of transition metal-doped MgO “matched emitters” for thermophotovoltaic energy conversion

Abstract

A new, thermally excited Co/Ni-doped MgO ceramic emitter for TPV energy conversion is described in this work, and termed the “matched emitter” because its emissive power spectrum is very efficiently matched with the portion of the electromagnetic spectrum that can be converted directly into electrical energy by infrared responding GaSb photovoltaic cells. Ligand Field Theory calculations are used to estimate the crystal field splitting energies at high temperatures for Co and Ni-doped MgO matched emitters. Experimental measurements of the high temperature (1300–1400°C) emissive power spectrums for Co and Ni-doped MgO emitters are compared with predictions obtained from ligand field calculations for what is believed to be the first time. It was found that crystal field splitting energies of 10 Dq = 9070 cm⁻¹ represented the “best fit” for the Co-doped MgO high temperature emissive power spectrum, and 10 Dq = 7950 cm⁻¹ for the Ni-doped MgO spectrum. These values are only slightly lower than values reported for corresponding single crystal, transition metal doped laser materials that were measured at or well below room temperature.