UV shielding and transparency of K+-doped Li3VO4 nanostructured superionic conductors

Abstract

A potassium (K)-doped lithium vanadate (Li3VO4) sample was synthesised by using the conventional solid-state reaction technique. X-ray diffraction results showed the polycrystalline behaviour of potassium-doped lithium vanadate. It was also observed that the lithium (Li+) ion did not show its presence in the diffraction pattern, which indicates that potassium (K+) ions were well substituted in the interstitials and did not disturb the planes of the lithium vanadate matrix. The presence of potassium ions in the lithium vanadate matrix was also confirmed through molecular fingerprint (Fourier transform infrared) spectroscopy. The optical absorption study (ultraviolet (UV)–visible) showed that the materials absorbed in the UV region only and remained transparent for the visible region. With an increase in the potassium-ion doping concentration, the absorbance peaks shifted slightly towards higher wavelengths, suggesting an enhancement of the particle size. Furthermore, the emission spectroscopy studies (photoluminescence) showed an increase in the emission intensity towards the blue region of the visible spectrum. From the electrical conductivity study, it was found that the materials exhibited a supersonic phase above 800 K with predominantly ionic conductivity in the range 91.954–6.100 Ω−1 m−1. The ionic conductivity and transparency indicate the feasibility of designing transparent batteries with good UV-shielding properties.