spin-state transition

https://doi.org/10.1351/goldbook.S05877
An electronic transition from a @LT06788@ state to a @LT07067@, or vice versa. Example: With an increase in temperature Co3+ ions in LaCoO3 transform from a @LT07067@ (\(\text{t}_{\text{2g}}^{6}\text{e}_{\text{g}}^{0}\)) to the @LT06788@ state (\(\text{t}_{\text{2g}}^{4}\text{e}_{\text{g}}^{2}\)).
Source:
PAC, 1994, 66, 577. (Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)) on page 591 [Terms] [Paper]