SYMMETRY FACTOR FOR ELECTRONIC CONFIGURATION IN Ca3Co4O9 SYSTEM

This study deals with the electronic configuration of Co ions in misfit Ca3Co4O9 system at high temperature. The magnetic behaviour of this system shows an anomaly around 700 K. It is believed that this anomaly is caused by spin state transitions of Co2+, Co3+ and Co4+ ions in the system. A detailed study of the symmetry properties of the wave functions of Co ions in an octahedral environment indicates that Co4+ ion prefers high spin configuration earlier than Co3+ ions. On the other hand the ligand field splitting of d orbitals in an octahedral environment shows that high spin configuration of Co3+ ions should be populated earlier than the high spin state of Co4+ ions.