Electron Spin Resonance of Gd 3+ in Reduced BaTiO 3

Electron spin resonance (ESR) of trivalent gadolinium in reduced barium titanate has been observed at room temperature and 163°C with an X-band spectrometer. According to this temperature rise, the amount of Gd 3+ ions substituting Ti 4+ remarkably increased in BaTiO 3 reduced at 1300°C, while those substituting Ba 2+ decreased. The local symmetry of the crystalline field acting on Gd 3+ at the Ti 4+ site is cubic. Hence the observed spectrum was analyzed using a spin Hamiltonian {aligned} H{=}g⃗{·}S⃗+{b₄}⁰[{Y₄}⁰+{√70}{14}({Y₄}⁴+{Y₄}⁻⁴)]+{b₆}⁰[{Y₆}⁰-{√14}{2}({Y₆}⁴+{Y₆}⁻⁴)] {aligned} where g , b 4 0 and b 6 0 are 1.992, 26±1 and -4±3 gauss, respectively, at room temperature and 1.992, 25.0±0.5 and -1.9±0.5 gauss at 163°C (above Curie temperature).