Synthesis of single-phase layered oxychalcogenide La2CdO2Se2: crystal structure, optical and electrical properties

Abstract

A single-phase La₂CdO₂Se₂ powder was successfully synthesized and its optical and electrical properties were examined. Single-phase La₂CdO₂Se₂ was obtained by preserving the stoichiometric composition of the initial ingredients, especially Cd and Se, during the sintering process. Exhibiting a yellowish white color, the synthesized sample has a large optical bandgap of ∼3.3 eV. The crystal structure, refined by a Rietveld method taking into account the site occupancies and isotropic thermal vibration parameters of Cd and Se, indicates that La₂CdO₂Se₂ belongs to space group P4₂/nmc. Instability against Cd or Se vacancy formation makes it difficult to generate carriers through vacancies or allo-valent ions doping, leading to electrical insulating properties both in as-prepared and intentionally doped La₂CdO₂Se₂ form.