An EPR study of an S = 3/2 defect in CaWO 4

After n‐irradiation of CaWO 4 up to a dose of 3 × 10 19 nvt a spectrum consisting of 12 narrow lines is observed. The angular variation of the spectrum shows that a centre with S = 3/2 located at four magnetically inequivalent sites in the structure is involved. The data are consistent with a spin Hamiltonian ℋ = β S · g · B + S · D. · S , where g and D are noncoincident with principal values g z = 2.048, g y = 2.007, g x = 2.004, D 1 = 4.32 × 10 −4 cm −1 , D 2 = 0.31 × 10 −4 cm −1 and D 3 = −4.63 × 10 −4 cm −1 . Possible intrinsic lattice defects which might account for this spectrum are discussed.