Radiation defects in CaF 2 and SrF 2 crystals doped with cadmium or zinc

2014

Phys. Status Solidi B

Abstract. Radiation defects in barium fluoride single crystals doped with cadmium have been investigated by luminescence and absorption spectroscopy, as well as by electron spin resonance spectroscopy. Three types of Cd + centers differing by the local environment with the point symmetries O h , C 3v and C 2v have been identified although in the crystals only the cubic centers are usually formed. We believe that these features may arise from the difference in the spacial distribution of the impurities in the crystals.

^{+}

_{3 v}

) centers having in its composition anionic vacancy decreases from CaF

_{2}

to SrF

_{2}

and in BaF

_{2}

^{+}

_{h}

) centers in cubic environment.…”

Section: Discussionmentioning

confidence: 78%

“…In our previous papers , three types of Cd

^{+}

or Zn

^{+}

centers differing by the local environment with the point symmetries O

_{h}

, C

_{3 v}

, and C

_{2 v}

have been identified in CaF

_{2}

and SrF

_{2}

crystals. The formation of the last two is the result of the interaction between the reduced impurity centers and anion vacancies.…”

Section: Discussionmentioning

confidence: 99%

“…The crystals of BaF

_{2}

^{+}

Section: Experimental Techniquementioning

confidence: 99%

“…The onset of the motion of anion vacancies in CaF

_{2}

α

–I(F

_{i}^{-}

) defects by their electric fields. The formation of F

_{2 A}^{+}

in CaF

_{2}

–Na , Cd

^{+}

_{3 v}

) in CaF

_{2}

and SrF

_{2}

and Mn/F‐centers in CaF

_{2}

–Mn is apparently connected with the motion of anion vacancies.…”

Section: Introductionmentioning

confidence: 99%

_{3 v}

and C

_{2 v}

, respectively . Usually in crystals of barium fluoride Cd

^{+}

centers only in a cubic environment are created.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Radiation defects in BaF2-Cd

2014

Phys. Status Solidi B

Configurational instability at the excited impurity ions in alkaline earth fluorites

Journal of Physics and Chemistry of Solids

Sizova

2013

The formation of intrinsic defects by ionizing radiation in some ionic crystals in the anion sublattice is only associated with the instability of the self-trapped exciton up to now. In this paper we propose a new mechanism for the formation of the defects in the anion sublattice associated with the Janh-Teller instability occurring near the cation impurities in the excited state. The instability occurs when the degenerate excited state of the impurity ion is localized in the conduction band. We believe that the configuration interaction between the discrete impurity level and host continuum (effect Fano) plays an important role in this process.

Instability of some divalent rare earth ions and photochromic effect

Journal of Physics and Chemistry of Solids

Sizova

Shendrik

et al. 2016

Abstract. It was shown that the divalent rare earth ions (La, Ce, Gd, Tb, Lu, and Y) in cubic sites in alkaline earth fluorides are unstable with respect to electron autodetachment since its d1 (e g ) ground state is located in the conduction band which is consistent with the general tendency of these ions in various compounds. The localization of doubly degenerate d 1 (e g ) level in the conduction band creates a configuration instability around the divalent rare earth ion that leading to the formation of anion vacancy in the nearest neighborhood, as was reported in the previous paper [Journal of Physics and Chemistry of Solids 74 (2013) 530-534]. Thus, the formation of the stable divalent ions as La, Ce, Gd, Tb, Lu, and Y (PC + centers) in CaF 2 and SrF 2 crystals during x-ray irradiation occurs via the formation of charged anion vacancies near divalent ions (Re 2+ v a ), which lower the ground state of the divalent ion relative to the conductivity band. Photochromic effect occurs under thermally or optically stimulated electron transition from the divalent rare earth ion to the neighboring anion vacancy and reverse under ultraviolet light irradiation.