Synthesis and optoelectrical properties of ABO2 (A=Li, Na; BY, Yb)

Abstract

The transparent electrically conductive composite materials ABO2 (ALi, Na; BY, Yb) were synthesized under high temperature solid-state reactions from A2O and B2O3. The synthesized compounds have been investigated by Rietveld analysis, giving the crystal (monoclinic, c12/c1, a 611.6 pm) for LiYO2, (monoclinic, p121/c1, a 999 pm) for NaYO2, (trigonal, Rm, a335.2 pm) for NaYbO2, (tetragonal, I41/amd, a 438.6 pm) for LiYbO2. Optical properties of the four compounds were studied by UV-vis spectral measurements, results show each of the compounds has an optical band gap more than 3.3 eV which is the standard for transparent property. Electrical conductivities of the four compounds have been studied by two probe direct current electrical conductivity measurements. The results show with increasing heating temperature, an obvious increase in electrical conductivity was observed for each compound. Also, the crystal energy band structure of each compound has been studied by using density functional theory code CASTEP. The results show the solid-state compounds of NaYO2, NaYbO2 and LiYbO2 are semiconductors with direct band gaps, LiYO2 is a semiconductor with an indirect band gap. © Published under licence by IOP Publishing Ltd.