Absorption and ionic conductivity of oxygen‐containing SrF₂ crystals

An absorption band at 3644 cm −1 is caused by isolated OH − ions. O − ions cause an absorption band at 213 nm the oscillator strength of which is 0.020. Charge‐compensation of O − ions is effected by F − ion vacancies (F ). As for CaF 2 crystals there occur monomers and dimers of [O − – F ] complexes. The mass action constants of association of F with oxygen centres are K AD = ⅓ exp (4.28 – 0.82 eV/ kT ) for [O − – F ], K AT = 4 exp (17.4 – 1.25 eV/ kT ) for [2 O − – F ] and K AQ = exp (4.2 – 0.89 eV/ kT ) for [2 O − – 2 F ].