Dissymmetrization in X-irradiated RbTiOPO4 crystal

Abstract

Electron paramagnetic resonance has been used to study the hole and electron paramagnetic centers formed in X-irradiated RbTiOPO4, the crystals of the KTP family. X-irradiation of RbTiOPO4 crystals at 77 K produced an oxygen hole center and four different trivalent titanium electron centers I" II, III and IV. The g-tensors, their principal values and axes for the defects were calculated and compared with those for KTiOPO4 centers. X-irradiation at 300 K produced another two oxygen hole centers and three electron centers I" 1 2 and II. EPR spectra of the center II revealed dissymmetrization, i.e., irregular distribution of growth defects, between the physically equivalent sites lowering the point group symmetry of the local environment of paramagnetic centers Ti'+

Hyperfine structure associated with the dominant radiation‐induced trapped hole center in RbTiOPO4 crystals

“…Thus, we agree with Laruhin et al [18] that the dominant trapped hole center formed in RTP by exposure to ionizing radiation at 77 K is associated with a rubidium vacancy, but we significantly modify the initial interpretation of the hyperfine structure that they offer.…”

“…In the present paper, we describe the results of an EPR and ENDOR study of the dominant trapped hole center initially reported by Laruhin et al [18] in RTP crystals. This defect is produced in RTP by © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim irradiating at 77 K with X-rays.…”

“…Irradiating an undoped RTP crystal at 77 K with X-rays produces one intense holelike center and a set of distinct Ti 3+ electron centers [18]. These defects are easily observed with EPR.…”

“…Its g matrix is slightly anisotropic with small positive g shifts, and its EPR spectra exhibit complex hyperfine patterns. Laruhin et al [18] indicate that the observed hyperfine structure in the EPR spectra of this hole center in RTP is most likely due to several of its phosphorus neighbors ( 31 P has I = 1/2 and is 100% abundant). These investigators note that this interpretation of the hyperfine requires principal hyperfine matrix values that differ significantly from the phosphorus values reported for the analogous trapped-hole center in KTP [15,16].…”

“…The g matrix and the hyperfine matrices obtained from the resulting electron paramagnetic resonance (EPR) and electronnuclear double resonance (ENDOR) spectra then verify the existence of an alkali vacancy next to the unpaired spin. Trapped holes located next to potassium vacancies have been observed in KTP crystals [15][16][17], and Laruhin et al [18] have suggested that similar hole centers associated with rubidium vacancies are produced in RTP crystals.…”