Concentration dependence of the spin gap in solid solutions La1−xGdxCoO3−δ

The temperature dependence of the static magnetization of polycrystalline rare-earth cobaltites La1−xGdxCoO3−δ (x=0.2, 0.5, 1) was measured in a wide temperature range up to 900 K. The contribution from Co3+ ions at high temperatures to the magnetic susceptibility was obtained. The Birch-Murnaghan equation and the magnetic date were used to determine the spin gap ΔS as the difference between the energies of high-spin and low-spin states in these compounds.