Evolution of Cr4+, Cr3+ and Cr2+ contents in Cr:Mg2SiO4 single crystals during their prolonged high-temperature oxidizing annealing

• Published in: Journal of crystal growth Vol. 468; pp. 718 - 723
• Main Authors: Subbotin, K.A., Slavkina, V.V., Lis, D.A., Lis, O.N., Zharikov, E.V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.06.2017
• Subjects: Czochralski method; Impurities; Oxides; Point defects; Solid state lasers; Czochralski method; Oxides; Point defects; Impurities; Solid state lasers
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2016.10.043

The evolution dynamics of Cr4+, Cr3+ and Cr2+ contents in chromium doped forsterite (Cr: Mg2SiO4) laser crystals during their prolonged high-temperature multi-stage oxidizing annealing have been investigated for the samples grown by Czochralski in ‘standard’ slightly oxidizing atmosphere (Ar +2,2vol%O2), as well as in inert atmosphere (argon, the residual O2 content is 0,01vol%). The contents of Cr4+ increase by factor of 1,5–3 during the first 800–1000h of the annealing and then do not change substantially. Cr2+ practically disappears from the crystals within 800–900h of the annealing. The content of Cr3+ passes through a maximum during the annealing. Therefore, this content is determined by two parallel reactions: Cr2+→Cr3+ and Cr3+→Cr4+. •Oxidizing annealing of Cr: Mg2SiO4 crystals allows to delete the parasitic Cr2+ absorption.•Oxidizing annealing of Cr: Mg2SiO4 crystals allows to raise substantially the Cr4+ content.•Lack of Si4+ vacancies, possibly, limits the increase of Cr4+ content at annealing of Cr: Mg2SiO4 crystals.