PARAMAGNETIC CENTERS IN ND2-XSRXNIOY - AN EPR STUDY

We present an EPR study on the Nd2-xSrxNiOy system with 0 less than or equal to x less than or equal to 0.6 at 100 less than or equal to T(K ) less than or equal to 500. Samples were prepared by the ceramic meth od and reduced in a thermogravimetric balance. Three series were studi ed: (a) air-prepared samples containing Ni2+ and Ni3+, (b) reduced sam ples in which Ni2+ and Ni1+ coexist, and (c) reduced single valence Ni 2+ samples. No EPR signal was observed in the oxidized samples. For th e reduced samples, a correlation between the EPR intensity and the oxy gen content was found.