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The X‐, Q‐band field‐sweep electron spin echo (FS ESE) study of n‐type 6H‐SiC wafers shows besides the well known hyperfine (hf) triplet lines of 14N on two quasi‐cubic (Nc1, Nc2) and hexagonal (Nh) sites additional triplet lines (Nx) of comparatively low intensity with a g ‐tensor of about the average value of the Nc2 and Nh spectrum at 4.2 K. The Nx triplet has half of the hf splitting with respect to the nitrogen residing at cubic sites Nc2. Pulsed electron nuclear double resonance (ENDOR) measurements performed on the Nx EPR triplet line demonstrate that there is an efficient spin‐coupling between Nh and Nx nitrogen related centers. The Nx triplet lines were attributed to distant donor Nc–Nh pairs between nitrogen atoms residing at quasi‐cubic and hexagonal sites having a total electron spin S = 1, which were found before in n‐type 4H‐SiC. Based on Q‐band FS ESE and X‐band pulsed ENDOR measurements the values of the hf interaction for Nc1, Nc2 were reassigned with respect to the assignment accepted hitherto.The super hyperfine (shf) interaction with neighboring atoms of nitrogen on the quasi‐cubic lattice sites was studied by FS ESE and pulsed ENDOR. The new shf lines due to 29Si and 13C atoms with large shf interaction which were not observed previously were found in nitrogen FS ESE and ENDOR spectra. One of them, with the largest shf splitting (23.12 MHz), were attributed to the 29Si atoms along the c‐axis in nearest‐neighbor positions of nitrogen on the quasi‐cubic sites which unambiguously confirms that nitrogen substitute carbon lattice site in 6H‐SiC. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The processes of hole localization in double-doped PbWO 4 :Mo,La and PbWO 4 :Mo,Y single crystals have been studied by continuous wave and pulse electron spin resonance (ESR) and thermally stimulated luminescence (TSL) methods. We show that the holes created by the UV irradiation are preferably trapped at lattice oxygen ions in the vicinity of perturbing defects such as lead vacancies, impurity ions (La, Y, Mo), and other lattice imperfections. This leads to a variety of Ocenters, which differ both by thermal stability (from about 170 K up to 240 K) and ESR parameters. The hole centers of this type were not observed neither in PbWO 4 :Mo nor in PbWO 4 :La(Y) crystals. The recombination processes of thermally released holes with electrons stored at different traps, including Pb + -WO 3 and (MoO 4 ) 3centers, are systematically studied by TSL. Thermal stability parameters are defined by ESR and TSL techniques for different Otype defects.180 202