Co valence by K-edge X-ray absorption spectroscopy, magnetic properties, and structure of polycrystalline bulk Zn/sub 1-x/Co/sub x/O

We report on magnetic properties and a Co K-edge X-ray absorption spectroscopy (XAS) study of polycrystalline bulk Zn1-xCoxO (x=0.10,0.15,0.17) samples. All samples show paramagnetic behavior and no ferromagnetism was observed. XAS results showed that for all samples the valence of Co is 2+. Spin state assessment derived from Currie-Weiss fitting indicated a possible spin state transition from Co2+ high spin to Co2+ low spin. Calculated μeff values for samples with x=0.10 and 0.15 indicated an orbital contribution to the effective magnetic moment of the Co ion.