The temperature dependence of the electron paramagnetic resonance spectra of Cu3Ba2Sm0.5Y0.5O6 tetragonal-phase ceramics was investigated at 3.22 to 32K. The complicated electron paramagnetic resonance spectra were attributed to various paramagnetic centers such as isolated divalent Cu ions, exchange-coupled Cu pairs of ions, and molecular O ions. The line-width of the electron paramagnetic resonance spectrum of exchange-coupled Cu ions reached a minimum at 7.5K, whereas the g-factor decreased with increasing temperature. The intensity of the electron paramagnetic resonance spectra of molecular O ions exhibited a critical behavior at 3.60K, where the intensity appreciably increased. The observed temperature dependences were explained in terms of a model for the collective motion of magnetic moments in a marked bottleneck. The other electron paramagnetic resonance spectra were attributed to molecular O ions and isolated divalent Cu ions.

N.Guskos, V.Likodimos, J.Typek, M.Wabia, H.Fuks: Materials Science Forum, 1997, 239-241, 77-80