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

• Published in: High pressure research Vol. 28; no. 4; pp. 571 - 576
• Main Authors: Sanz-Ortiz, Marta N., Rodríguez, Fernando, Demazeau, Gérard
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 01.12.2008
• Series: PROCEEDINGS OF THE XLVI TH EUROPEAN HIGH PRESSURE RESEARCH GROUP (EHPRG 46) MEETING, VALENCIA (SPAIN), 7–12 SEPTEMBER 2008
• Subjects: Chemical Sciences; CoF; Inorganic chemistry; intermediate spin; Jahn-Teller; or physical chemistry; spin crossover; Theoretical and; CoF3; Intermediate spin; Cobalt; Jahn-Teller effect; Spin crossover
• ISSN: 0895-7959; 1477-2299
• DOI: 10.1080/08957950802552119

This work investigates the electronic structure of CoF 3 by optical absorption and its relationship with the ground-state spin and the Jahn-Teller (JT) effect exhibited by Co 3+ (d 6 ) in octahedral coordination (CoF 6 ) 3− . The results are compared with other Co 3+ fluorides and oxides, where Co 3+ is high spin (HS) and low spin (LS), respectively. In CoF 3 we detect an absorption band with a doublet structure at 1.89 eV (657 nm) and 1.45 eV (855 nm) at 2.5 GPa, which is associated with the T ⊗ e JT effect on the 5 T 2 HS ground state. Absorption measurements under pressure have been carried out around the HS-LS ( 5 T 2 ↔ 1 A 1 ) 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 ( 3 T 1, 2 states) is observed in the explored pressure range.