Spin transition in Co3+ by optical absorption and time-resolved spectroscopy under pressure: An appraisal of the different spin states

Marta N. Sanz-Ortiz (1) , Fernando Rodríguez (1) , Gérard Demazeau (2)

1 Universidad de Cantabria [Santander]
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

This work investigates the electronic structure of CoF3 by optical absorption and its relationship with the ground-state spin and the Jahn-Teller (JT) effect exhibited by Co3+(d6) in octahedral coordination (CoF6)3-. The results are compared with other Co3+ fluorides and oxides, where Co3+ is high spin (HS) and low spin (LS), respectively. In CoF3 we detect an absorption band with a doublet structure at 1.89eV (657nm) and 1.45eV (855nm) at 2.5GPa, which is associated with the T e JT effect on the 5T2 HS ground state. Absorption measurements under pressure have been carried out around the HS-LS (5T2 1A1) spin crossover transition in the 0-20 GPa range. We show that the JT effect is stable in a wide pressure range. No sign of intermediate spin (3T1, 2 states) is observed in the explored pressure range.

Mots clés: Cobalt; CoF3; Intermediate spin; Jahn-Teller effect; Spin crossover

Domaines: Chimie inorganique; Chimie théorique et/ou physique

Marta N. Sanz-Ortiz, Fernando Rodríguez, Gérard Demazeau. Spin transition in Co3+ by optical absorption and time-resolved spectroscopy under pressure: An appraisal of the different spin states. High Pressure Research, 2008, PROCEEDINGS OF THE XLVI TH EUROPEAN HIGH PRESSURE RESEARCH GROUP (EHPRG 46) MEETING, VALENCIA (SPAIN), 7–12 SEPTEMBER 2008, 28 (4), pp.571-576. ⟨10.1080/08957950802552119⟩. ⟨hal-00352991⟩