Luminescence properties of CsI crystals grown from the melt treated by metals-getters

• Published in: Journal of crystal growth 2013-10, Vol.380, p.143-147
• Main Authors: Cherginets, V.L., Rebrova, T.P., Datsko, Yu.N., Kosinov, N.N., Shevchenko, E.E., Pedash, V.Yu
• Format: Article
• Language: English
• Subjects: A1. Impurities; A1. Purification; A2. Bridgman technique; B1. Halides; B2. Scintillation materials; Band spectra; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Crystals; Exact sciences and technology; Growth from melts; zone melting and refining; Luminescence; Materials science; Melts; Melts (crystal growth); Methods of crystal growth; physics of crystal growth; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics; Tantalum; Titanium; Zirconium
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2013.06.013

The processes of purification of CsI melt from admixtures by metals-getters (Ti, Ta, and Zr) are studied through two ways: investigation of change in concentration of oxide-ion entering from the getter into the melt and investigation of luminescence properties of CsI single crystals grown from the treated melt. The treatment by Ti does not lead to the removal of oxide-ions; however the growth melt is polluted by Ti species (Ti2O3). This causes drastic changes in the luminescence properties of CsI crystals. Their radioluminescence spectra do not contain the band caused by fast 7 and 30ns components (maximum at 308nm) and there arises a band (maximum 418nm) corresponding to slow microsecond component. The enterance of Ta leads to removal of oxide ions, but the interaction products (Ta2O5 or CsTaO3) are partially dissolved in CsI melt that leads to appearance in the radioluminescence spectrum of the intense band (maximum 416nm) caused by the slow component together with less intense band (maximum at 305nm) due to the fast components. Only treatment by Zr allows to suppression of the slow component completely. The radioluminescence spectrum of CsI crystals grown from the Zr-treated melt includes only one band (maximum at 306nm), whereas the luminescence at wavelengths more than 410nm is absent. For this crystal two parameters describing its performance are determined. The effective time of luminosity of the fast components is equal to 14ns and the ‘Fast/Total’ ratio is 0.88. So, the treatment of CsI melt by Zr allows obtaining an extremely fast scintillation material. •Getters forming refractory oxides (mp>2700K) can be used for deep purification of halide melts.•The use of Zr allows performing deep purification of alkali metal halide melts.•Ta and Ti are not appropriate due to pollution of the melts by interaction products.•Getters forming oxides with mp>2700K can be used for purification of halide melts.•Zr-treated CsI single crystals demonstrate high performance.