KNa0.78Eu0.27In3.80B12S12: a novel hexanary thioborate featuring a B12S12 cluster and diverse InSx (x = 4, 5, 6) units

Abstract

Thioborates combine the advantages of sulfides and borates, and are a new type of multifunctional inorganic material with versatile structural features. Here, a thioborate KNa_0.78Eu_0.27In_3.80B₁₂S₁₂ crystallizing with a new type of compound was synthesized by a high-temperature flux method. Its structure features a rarely discovered B₁₂S₁₂ cluster and diverse InS_x (x = 4, 5, 6) units built in a three-dimensional {[In_3.80B₁₂S₁₂]^2.6−}_∞ polyanionic framework. The structural complexity and novelty are well elaborated. Its optical band gap was determined to be 2.28 eV, and a theoretical calculation of its electronic structure was also performed. This work not only enriches the structural chemistry of chalcogenoborates but also provides a new potential RE–B–Q family (RE = rare-earth metal; Q = S, Se). The latter may produce some interesting functionals.