Document Type


Publication Date



Electron paramagnetic resonance (EPR) is used to identify the singly ionized charge state of the Sn vacancy (VSn) in single crystals of Sn2P2S6 (often referred to as SPS). These vacancies, acting as a hole trap, are expected to be important participants in the photorefractive effect observed in undoped SPS crystals. In as-grown crystals, the Sn vacancies are doubly ionized (V2−Sn) with no unpaired spins. They are then converted to a stable EPR-active state when an electron is removed (i.e., a hole is trapped) during an illumination below 100 K with 633 nm laser light. The resulting EPR spectrum has g-matrix principal values of 2.0079, 2.0231, and 1.9717. There are resolved hyperfine interactions with two P neighbors and one Sn neighbor. The isotropic portions of these hyperfine matrices are 167 and 79 MHz for the two 31P neighbors and 8504 MHz for the one Sn neighbor (this latter value is the average for 117Sn and 119Sn). These VSn vacancies are shallow acceptors with the hole occupying a diffuse wave function that overlaps the neighboring Sn2+ ion and (P2S6)4− anionic unit. Using a general-order kinetics approach, an analysis of isothermal decay curves of the VSn EPR spectrum in the 107–115 K region gives an activation energy of 283 meV.


A 12-month embargo was observed before posting, in accordance with AIP policy. Sourced from the version of record as cited below.

© 2016 Authors. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Applied Physics, 120, 133101 (2016) and may be found at



Source Publication

Journal of Applied Physics