ESR of Free Radicals in Ferroelectric and Antiferroelectric Arsenate Single Crystals

摘要

The electron spin resonance of gamma irradiated single crystals of KH2AsO4, KD2AsO4, NH4H2AsO4, and ND4D2AsO4has been investigated. New paramagnetic centers present in several varieties and which exhibit a strong coupling with one75As atom have been described. At room temperature, theirgtensor is nearly isotropic and their hyperfine couplings are axially symmetric. The annealing of these centers is examined and their behavior upon cooling down belowTcis described. All these centers which seem to belong to the same family have been identified asAsO32minus;species. Their different varieties must be ascribed to different environments coming either from various proton environments or from several associations with varied impurities.