Investigating Se atom position and dimerization in new visible band gap semiconductor material YBi2O4Se

We have recently synthesized the new semiconductor (band gap = 1.2 eV) YBi2O4Se, which has Se in a formal oxidation state of -1 on a 2D square net. Density functional theory calculations demonstrate that Se(-1) dimerisation is required to open a band gap in the compound. Neither ordered or disordered dimerisation is observed using X-Ray diffraction, likely due to Se having 8 Bi nearest neighbours. Here we propose measuring the diffraction pattern as a function of temperature from base to room temperature to elucidate the Se(-1) position and dynamics in this new family of visible gap semiconductors.