2010 Volume 59 Issue 2 Pages 127-134
Using neutron and resonant X-ray scattering, crystal structure and charge-ordering pattern in La1.5Ca0.5CoO4 was studied. Taking A2mm and Bm2m with a-b type twin structure into account, Co2+/Co3+ checkerboard charge ordering pattern was suggested in La1.5Ca0.5CoO4 by neutron scattering structure analysis. The charge ordering pattern and the valences of the two Co sites was clarified by a resonant X-ray scattering(RXS)measurement near the Co K-edge. We found a resonant signal at(3,0,0)reflection which corresponds to the charge ordering with a Co2+/Co3+ checkerboard pattern, and the Co valences of charge ordering were fully charge disproportionate.