Processing and purification techniques of heavy metal fluoride glass (HMFG)

Robinson, M.

doi:10.1016/0022-0248(86)90240-x

Cited by 33 publications

(8 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The reaction chamber was flushed with ultra pure nitrogen (o0.5 ppm O 2 ) and heated up to 3501C for more than 12 h to remove water. Then, the temperature was raised to 5501C and SF 6 was flowed through the reaction chamber for half an hour to remove traces of oxygen [16]. Again under N 2 , the sample was heated above the melting temperature.…”

Section: Methodsmentioning

confidence: 99%

Site selective 4f5d spectroscopy of CaF2:Pr3+

Oskam

Houtepen

Meijerink

2002

Journal of Luminescence

View full text Add to dashboard Cite

Spectroscopic investigations were performed on a single crystal of CaF 2 doped with 0.05% Pr 3+ . Three different Pr 3+ sites with different luminescent properties were identified. The 4f 2 -4f 1 5d 1 excitation spectrum of the first site has a sharp maximum at 221.3 nm. Excitation in the 4f5d bands of this site yields strong 4f5d emissions in the UV/VIS part of the spectrum and also weaker intraconfigurational 4f 2 emissions. By comparing the intraconfigurational 4f emissions and their decay times with data from the literature, these 4f5d bands are assigned to transitions on Pr 3+ ions on a site with C 4V symmetry. The fd excitation spectrum of the second site has a zero phonon line at 223.3 nm. Upon selective excitation in this band, only 4f5d emission is observed. Probably, these 4f5d bands correspond to Pr 3+ ions on a O h site. The third set of 4f5d bands has a 4f5d onset at 208 nm. By comparison of the luminescence spectra of the intraconfigurational 4f 2 transitions with literature data, these transitions are assigned to Pr 3+ on an L site. Excitation in these 4f5d band yields 1 S 0 emission followed by emission from the 3 P 0 state. The present results clarify some contradictions reported in the literature. r

show abstract

Section: Methodsmentioning

confidence: 99%

Site selective 4f5d spectroscopy of CaF2:Pr3+

Oskam

Houtepen

Meijerink

2002

Journal of Luminescence

View full text Add to dashboard Cite

show abstract

“…Flushing with SF 6 as a reactive agent during heating was used to eliminate oxygen in the samples [16]. Slow cooling from the melt (1 to 5 days) resulted in oxygen-free, transparent single crystals for Er 3þ in LiYF 4 and LaF 3 , which were polished before the spectroscopic measurements.…”

Section: Methodsmentioning

confidence: 99%

Luminescence spectroscopy of high-energy 4f¹¹levels of Er³⁺in fluorides

et al. 2003

View full text Add to dashboard Cite

The 4 f 11 energy levels of Er 3þ in LiYF 4 in the spectral region 39 000-65 000 cm À1 have been studied. The agreement between experimental energy levels, obtained from luminescence excitation spectra, and calculated energy levels is good. Luminescence originating from high-lying energy levels has been investigated. in LiYF 4 , where it lies in between the two lowest 4 f 10 5d states. IntroductionThe need for luminescent materials for excitation in the vacuum ultraviolet spectral region (VUV; E > 50 000 cm À1 , < 200 nm) has triggered an increase in research on the VUV spectroscopy of lanthanides. These materials (VUV phosphors) are required for application in mercury-free fluorescent lamps and in plasma display panels [1]. In these devices the VUV radiation generated by a noble gas discharge (e.g. Xe) has to be converted into visible light. In theory, the high energy of VUV photons is sufficient to generate two visible photons for each VUV photon absorbed by a phosphor. In other words, it is theoretically possible to obtain visible quantum efficiencies higher than 100%, which is called quantum cutting. In contrast, the quantum efficiencies of (UV) phosphors used in mercury discharge fluorescent tubes cannot exceed 100% due to the lower energy of the exciting photons. The use of VUV phosphors with quantum efficiencies above 100% can compensate for the lower number of photons generated per watt by the noble gas discharge relative to the mercury discharge.Because of their sharp-line emissions, trivalent lanthanide ions are optical centres for which quantum cutting, or photon-cascade emission, can possibly be obtained. Indeed, quantum cutting has been demonstrated for

show abstract

“…Participation of OH − groups in the process of defect formation is also indicated by observation, that samples heated in Ar + (10%) SF 6 atmosphere remain white in the whole investigated temperature range. SF 6 was proved to be an effective agent for removing of water, OH − and other oxy-type impurities, and works efficiently already at temperatures below 500 • C [13]. Indeed, comparison of IR spectra obtained for samples heated for 5 h at 450 • C proves, that the water content is lower for powders treated in Ar + (10%) SF 6 than in pure Ar atmosphere, and that this effect is more pronounced for Eu:KGF(I) sample.…”

Section: Infrared Spectramentioning

confidence: 99%