EPR of a non-Kramers iron ion in KTaO3

The EPR spectrum of the non-Kramers iron ion Fe4+ (S = 2) in a KTaO3:Fe cry stal appearing after illumination of the sample in the visible has been det ected and studied. Because of the large initial splitting (\D\ = 4.15 cm(-1 )), only transitions within the \+/- 1 > and \+/- 2 > doublets are seen exp erimentally. Superhyperfine structure in the spectrum of a non-Kramers ion in perovskites has been detected for the first time. A structure is propose d for the center responsible for the new EPR spectrum, which represents a c omplex of a Fe4+ ion substituting for Ta with an oxygen vacancy at the near est anion site. (C) 1999 American Institute of Physics. [S1063-7834(99)0150 8-7].