ELECTRON-PARAMAGNETIC-RESONANCE OF MN4+ IN PBTIO3

The electron paramagnetic resonance spectrum of Mn4+ in single-crystal lead titanate has been studied at 9.8 and 33.8 GHz. An axial sextet with g(perpendicular to)(eff) = 3.7742(1) to g(parallel to)(eff) approximate to 2.00 was measured at 9.8 GHz and with g(perpendicular to)(eff) = 2.7048(15) at 33.8 GHz; a second sextet was observed at high held at 9.8 GHz. The spectrum was fitted using spin Hamiltonian parameters S = 3/2, I =5/2, g(parallel to) = 1.99, g(perpendicular to) = 1.987, A(parallel to) = 79.46 x 10(-4) cm(-1), A(perpendicular to) = 71.05 x 10(-4) cm(-1) and \D\ = 0.3166 cm(-1). The electronic spin value and the magnitude of the hyperfine constant, \A\ = 73.9 cm(-1), confirm the Mn4+ assignment. A superposition model analysis using available (b) over bar(2)(R) functions for 3d(3) configuration ions in oxide hosts was unable to reproduce the observed axial crystal field magnitude, \D\.