High-pressure effects on the optical-absorption edge of CdIn2S4, MgIn2S4, and MnIn2S4 thiospinels

TL;DR

This study investigates how high pressure affects the optical absorption edges and band-gap behaviors of CdIn2S4, MgIn2S4, and MnIn2S4 thiospinels, revealing linear and non-linear shifts and abrupt changes linked to structural transitions.

Contribution

It provides new insights into the pressure-dependent optical properties and electronic structure changes of these thiospinels up to 20 GPa.

Findings

CdIn2S4 and MgIn2S4 exhibit linear blue-shift of band-gap with pressure.

MnIn2S4 shows a non-linear band-gap shift under pressure.

Abrupt decreases in band-gap occur at specific pressures for each compound.

Abstract

The effect of pressure on the optical-absorption edge of CdIn2S4, MgIn2S4, and MnIn2S4 thiospinels at room temperature is investigated up to 20 GPa. The pressure dependence of their band-gaps has been analyzed using the Urbach rule. We have found that, within the pressure-range of stability of the low-pressure spinel phase, the band-gap of CdIn2S4 and MgIn2S4 exhibits a linear blue-shift with pressure, whereas the band-gap of MnIn2S4 exhibits a pronounced non-linear shift. In addition, an abrupt decrease of the band-gap energies occurs in the three compounds at pressures of 10 GPa, 8.5 GPa, and 7.2 GPa, respectively. Beyond these pressures, the optical-absorption edge red-shifts upon compression for the three studied thiospinels. All these results are discussed in terms of the electronic structure of each compound and their reported structural changes.