A new crystal: Layer-structured rhombohedral In₃Se₄

A new layer-structured rhombohedral In₃Se₄ crystal was synthesized by a facile and mild solvothermal method. Detailed structural and chemical characterizations using transmission electron microscopy, coupled with synchrotron X-ray diffraction analysis and Rietveld refinement, indicate that In₃Se₄ crystallizes in a layered rhombohedral structure with lattice parameters of a = 3.964 ± 0.002 Å and c = 39.59 ± 0.02 Å, a space group of R3m, and with a layer composition of Se-In-Se-In-Se-In-Se. The theoretical modeling and experimental measurements indicate that the In₃Se₄ is a self-doped n-type semiconductor. This study not only enriches the understanding on crystallography of indium selenide crystals, but also paves a way in the search for new semiconducting compounds.