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Abstract Single crystal scintillators of RE 2 O 3 :Eu (RE = Lu, Y, Sc) with high (8%) and low (1%) Eu doping concentration were grown by the optical floating zone method. The luminescence and scintillation properties have been investigated and compared thoroughly. Correlated measurements of afterglow curves, photoluminescence excitation and photoluminescence, photoluminescence decay curves and X-ray excitation curves were performed. Lu 2 O 3 :Eu and Y 2 O 3 :Eu present significant afterglow intensity decreasing after high Eu concentration doping. While for the Sc 2 O 3 :Eu, its afterglow intensity even increases slightly. The luminescence efficiencies of high doping concentration samples are weaker than that of the low concentration ones due to the concentration quenching. The integrated X-ray excitation luminescence reveals the scintillation luminescence efficiencies of samples with the high concentration or the low ones both have the following sequence:Lu 2 O 3 :Eu＞Y 2 O 3 :Eu＞Sc 2 O 3 :Eu. Highlights • RE 2 O 3 :Eu (RE = Lu,Y,Sc) single crystal scintillators are grown by optical FZ method. • Sc 2 O 3 :Eu present different afterglow behavior comparing with Lu 2 O 3 :Eu and Y 2 O 3 :Eu. • The relationship between afterglow and Eu(S 6).→Eu(C 2) energy transfer is discussed. [ABSTRACT FROM AUTHOR]

Colquiriite-type Eu-doped LiCaAlF6 and LiSrAlF6 (Eu:LiCAF and Eu:LiSAF) scintillator single crystals were grown using Al metal as a starting material to improve the Eu dopant segregation. All Eu:LiCAF and Eu:LiSAF single crystals using Al metal (Eu,AlM:LiCAF and Eu,AlM:LiSAF) indicated high transparency and effective segregation coefficients (keff) of Eu2%,AlM1%:LiCAF and Eu2%,AlM1%:LiSAF single crystals were significantly improved to the value of 0.40 and 0.99, respectively. EuF3 starting material reacted with Al metal before colquiriite-type phase was generated. As a result, Eu3+ ion in EuF3 was changed to Eu2+ ion which could be incorporated into Ca2+ and Sr2+ sites easily. [ABSTRACT FROM AUTHOR]

Inorganic phosphors based on rare earth elements are commonly used as scintillation materials due to their high chemical and radiation resistance. In this work, we study gadolinium oxyselenide as a new phosphor material. The work describes a facile synthesis method for Gd 2 O 2 Se. Single crystal structure of this compound was determined for the first time: sp.gr. P ¯3 m 1 with a ​= ​3.8911(4) Å and c ​= ​6.8829(8) Å. Gd 2 O 2 Se is stable in the inert atmosphere and melts at 2075 ​± ​20 ​°C. This material is also stable when heated in air up to 720 ​°C. with the following oxidation and weight increase. This mass increase can be explained by the oxidation of Se2− to Se4+. Further temperature increase above 952°С leads to a sharp mass loss and the final mass of sample corresponds to full oxidation of Gd 2 O 2 Se to gadolinium oxide. The band gap of the material was estimated to be 3.6 ​eV. Photoluminescence spectrum for Gd 2 O 2 Se:Tb3+ shows the characteristic transitions in Tb3+ ion with the most intense green emission that corresponds 5D 4 → 7F J transitions. [Display omitted] • A powder of Gd 2 O 2 Se was obtained and the single crystal structure was determined: sp.gr. P ¯3 m 1, a ​= ​3.89Å, c ​= ​6.88 Å. • The melting point was found to be 2075 ​± ​20 ​°C. High air stability for this compound was demonstrated up to 720 ​°C. • The estimated value of the band gap is 3.6 ​eV. The photoluminescence of the Tb3+ doped sample was investigated. [ABSTRACT FROM AUTHOR]