Integral Scintillation Efficiency Research Articles

Superdense Tb3+‐activated borogermanate‐tellurite scintillating glasses

AbstractNovel Tb3+‐activated borogermanate‐tellurite scintillating glasses with a maximum density of 7.15 g/cm3 aimed at detection of high‐energy rays were prepared by a melt‐quenching method for the first time. The concentration‐dependent optical properties including transmittance, photoluminescence, luminescence dynamic behaviors, and X‐ray excited luminescence in the as‐prepared Tb3+‐activated borogermanate‐tellurite glasses were studied. The optimal content of Tb2O3 in the superdense borogermanate‐tellurite glasses is revealed to be 7 mol% under both 275 nm ultraviolet light and X‐ray excitation. The integral scintillation efficiency of Tb3+‐activated borogermanate‐tellurite scintillating glass is about 33.71% of the standard Bi4Ge3O12 (BGO) scintillating crystal.

Spectroscopic properties of Eu3+-doped gadolinium calcium phosphate and fluorophosphates glasses

The 1 mol% of Eu3+-doped gadolinium calcium phosphate and fluorophosphates glasses were prepared by melt quenching technique and study on spectroscopic properties: absorption, emission spectra and decay time. The Judd-Ofelt parameters (Ωλ, λ = 2, 4 and 6) were estimated by absorption results. All glasses show same trend of Ω2 > Ω4 > Ω6. The predicted radiative transition probabilities (AR), branching ratio (βR) and emission cross-section (σem(λ)) for the 5D0 → 7F2 transition have been obtained which were used to estimate the red laser performance. The decay time of the 5D0 level of Eu3+-doped glasses promote single exponential. Besides, the radioluminescence spectrum was investigated on integral scintillation efficiency by comparing with Bi4Ge3O12 (BGO). It shows the integral scintillation efficiency is 62% of BGO and could be used as a good scintillator.

Energy transfer based emission analysis of Eu3+ doped Gd2O3-CaO-SiO2-B2O3 glasses for laser and X-rays detection material applications

The Eu3+-doped CaO-Gd2O3-SiO2-B2O3 glasses were prepared to study photoluminescence, lasing potential and scintillation properties. Glasses absorb photons in ultraviolet, visible light and near infrared regions and are assigned to the energy transitions of Gd3+ and Eu3+. Ultraviolet with 275nm can generate the strong red emission with 614nm via energy transfer form Gd3+ to Eu3+. X-ray scintillation study exhibits strong emission pattern due to Gd-Eu energy transfer. The optimum concentrations of Eu3+ ion in this glass is 0.30mol% as it results maximum emission intensity. The fluorescence lifetime of the 5D0 level decreases from 1.763 to 1.726ms when concentration increased from 0.05 to 0.40mol%. From Judd-Ofelt analysis, this glass exhibit high potential for using as laser medium for red laser device with high lasing power and energy extraction ratio. Moreover, this glass performs the integral scintillation efficiency as 13% compared with BGO.

Luminescence, scintillation, and energy transfer in SiO2 -Al2 O3 -B2 O3 -Gd2 O3 :Ce3+ ,Pr3+ glasses

Ce3+,Pr3+-codoped SiO2–Al2O3–B2O3–Gd2O3 glasses (SABG:Ce,Pr) were prepared by melt quenching under a CO reducing atmosphere. Luminescence properties were investigated under UV and X-ray excitations. A dominant emission band at 430 nm belonging to the Ce3+:5d1 → 4f transition was observed in the photo- and radio-luminescence spectra. The energy transfer occurs from this Ce3+ band toward the 3PJ levels of Pr3+ with an efficiency of up to 24%, followed by the reduction of integrated luminescence intensity with an increasing Pr3+ concentration. This result is attributed to the increase in the reabsorption of Ce3+ luminescence and the non-radiative energy transfer toward the 3PJ levels of Pr3+. The cross-relaxation process within the Pr3+ pairs can further diminish the total luminescence yield at high Pr3+ concentrations. The integral scintillation efficiency and light yield measurements were carried out and compared to the reference Bi4Ge3O12 (BGO) crystal.

Development of Dy3+-doped Gd2MoB2O9 phosphor and their luminescence behavior

ABSTRACTIn this work, the Gd2MoB2O9 and Gd2MoB2O9:Dy3+ phosphors have been prepared by solid state reaction and their structural and luminescence properties have been studied. The Gd2O3, MoO3, H3BO3 and Dy2O3 were used as starting materials and homogeneously mixed with appropriate ratio. The mixed materials were pressed at 20 tons and sintered at 800, 850, 900, 950, 1000, 1050 and 1100°C. The Gd2MoB2O9 phase was confirmed by X-ray diffractometer (XRD). The photoluminescence spectra measured by 257 nm excitation show one emission peak at 310 nm corresponding to 6P7/2→8S7/2 of Gd3+, and four emission peaks of Dy3+ at 478, 575, 663 and 754 nm corresponding to 4F9/2 → 6H15/2, 6H13/2, 6H11/2 and 6H9/2 transitions, respectively. The chromaticity coordinates under excitation of λex = 352 nm are (0.48, 0.42), which lies in the white region of CIE 1931 chromaticity diagram. The radioluminescence property was studied by 50 kV, 30 mA X-ray irradiation and compared with commercial BGO crystal. It was found that the integral scintillation efficiency showed 76% of BGO. This result suggests that the developed phosphor may be used in W-LEDs and X-rays imaging applications.

Energy transfer from Gd3+ to Sm3+ and luminescence characteristics of CaO–Gd2O3–SiO2–B2O3 scintillating glasses

In this work, density, optical, photoluminescence and x-ray scintillation properties of calcium gadolinium silicoborate glass (CaO:Gd2O3:SiO2:B2O3) have been investigated. Glasses were prepared by the conventional melt quenching technique. The results show that the density of glass increased with increasing of Sm2O3. The optical spectra of glass shows eleven discrete absorption bands at 360, 373, 403, 475, 944, 1077, 1225, 1368, 1468, 1520 and 1586nm which are due to the transitions of 6H5/2 to 4D3/2, 6P7/2, 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2, respectively. The emission spectra were observed and assigned to 312, 563, 600, 646 and 703nm by excitation at 275nm. The emission intensity of Sm3+ increased with increasing of Sm2O3 concentration until 0.25mol%, while decay time decrease with increasing of Sm2O3 content. For results of the radioluminescence (RL), they perform four emission peaks with the strongest emission at 598nm. Glass doped with 0.35mol% Sm2O3 show the highest RL emission. The integral scintillation efficiency of 0.35mol% Sm2O3 doped glass was determined as 25% of commercial BGO scintillator crystal.

Luminescence characteristics of Dy3+ doped Gd2O3-CaO-SiO2-B2O3 scintillating glasses

Glasses were prepared from the compositions of 25Gd2O3-10CaO-10SiO2-(55–x)B2O3-xDy2O3 (where x is 0.0 mol.%–1.0 mol.%) by the conventional melt-quenching technique at 1400 °C. The results demonstrated the increase in the glass density with respect to the increase in the doping concentrations of Dy2O3. Nine absorption bands were observed. The emission spectra of the developed glass showed two strong peaks at 577 nm (4F9/2→6H13/2) and 482 nm (4F9/2→6H15/2). The highest emission intensity was observed from the developed glass prepared at 0.4 mol.% of Dy2O3, as the efficient energy transfer took place from Gd3+ to Dy3+. From the X-ray induced optical luminescence, the emission spectra were identical to those from PL measurements, but with the highest intensity observed from the glass quenched at 0.45 mol.% of Dy2O3. Finally, the integral scintillation efficiency of the developed glass was determined at 27% of that of the commercially available BGO crystal.

Effects of Ce3 + sensitizer on the luminescent properties of Tb3 +-activated silicate oxyfluoride scintillating glass under UV and X-ray excitation

Novel Tb3+ or Ce3+ doped and Tb3+/Ce3+ codoped silicate oxyfluoride scintillating glasses were synthesized by melt-quenching method. The luminescent properties were studied by transmission spectra, photoluminescence excitation (PLE) and photoluminescence (PL) spectra, X-ray excited luminescence (XEL) spectra and luminescence decay curves in order to reveal the roles of Ce3+ sensitizer in the luminescence process of Tb3+-activated silicate oxyfluoride scintillating glass under UV and X-ray excitation. As for Tb3+/Ce3+ codoped scintillating glasses, the Ce3+ ions strongly sensitized the luminescence of the Tb3+ ions by energy transfer process from Ce3+ to Tb3+ ions under UV excitation. The optimal doping concentration of Ce2O3 in Tb3+/Ce3+ codoped scintillating glasses can be determined to be 0.6mol%. But under X-ray excitation, the enhancement of Tb3+ ions emission intensity caused by Ce3+ codoping is not as obvious as that under UV excitation, which is mainly due to the low energy transfer efficiency from host glass to Ce3+ ions. Under X-ray excitation, the intensity of 544nm emission in Tb3+/Ce3+ codoped scintillating glasses with 0.6mol% of Ce2O3 was 6 times than that of 500nm emission in the commercial Bi4Ge3O12 (BGO) crystals. The integral scintillation efficiency was about 83% of the BGO crystals. These results imply that the developed silicate oxyfluoride scintillating glasses in our case can be potential candidate for high-resolution medical X-ray imaging.

Radioluminescence and optical studies of gadolinium calcium phosphate oxyfluoride glasses doped with Sm3+

Sm3+-doped gadolinium calcium phosphate oxyfluoride glasses have been synthesized and investigated their optical, photo and radioluminescence properties. The glasses were prepared by melt quenching technique at 1400°C. The characteristic absorption bands of Sm3+ ions originating from the 6H5/2 ground state and occurring absorbed photon in visible light (VIS) and near-infrared (NIR) region with clearly observed from absorption spectra. From the photoluminescence (PL), the glasses showed the emission at 561 (4G5/2→6H5/2), 598 (4G5/2→6H7/2), 644 (4G5/2→6H9/2) and 705nm (4G5/2→6H11/2). The radioluminescence (RL), emission spectra were corresponding to those from PL measurements. From RL measurement, the integral scintillation efficiency of developed glass was determined at 43% when compared with BGO crystal.

Luminescence and Scintillation Response of Ce<sup>3+</sup>-Doped Oxide Glasses with High Gd<sub>2</sub>O<sub>3</sub> Content

This report presents the luminescence and scintillation response of Ce3+-doped oxide glasses with high Gd2O3 (30 mol%) content. The characteristic emission of Ce3+ 5d → 4f transition peaking around 380 nm was observed in its luminescence spectra under UV and X-ray excitation. Photoluminescence decay kinetics was governed by a few tens of nanoseconds decay time. The integral scintillation efficiency of about 22% of that of the Bi4Ge3O12 scintillator was obtained under X-ray irradiation. The light yield and its dependence on the integration time were measured and compared with that of the Bi4Ge3O12 crystal. The total mass attenuation coefficient at 662 keV γ-rays was also determined and compared with the theoretical one calculated using the WinXCom program.

Photo‐ and radioluminescence of Dy3+‐doped oxide glass with high‐Gd2O3 content

Dy3+‐doped oxide glass with 30 mol.% Gd2O3 content in the glass host was prepared by melt quenching under CO reducing atmosphere. The luminescence properties were investigated under UV and X‐ray excitation. The 4F9/2→6HJ (J = 15/2, 13/2, 11/2, and 9/2) luminescence was observed with intense blue (484 nm; 4F9/2→6H15/2) and yellow (576 nm; 4F9/2→6H13/2) emissions. Energy transfer from Gd3+ to Dy3+ ions was confirmed by photoluminescence excitation and emission spectra as well as photoluminescence decay measurements. The integral scintillation efficiency of 11% of Bi4Ge3O12 scintillator was obtained.

Tunable luminescence and energy transfer from Gd3 + to Tb3 + ions in silicate oxyfluoride scintillating glasses via varying Tb3 + concentration

Silicate oxyfluoride scintillating glasses doped Tb3+ with different concentrations were prepared by a melt-quenching method. The detailed analyses of photoluminescence spectra and luminescence decay curve testified that the Gd3+ indeed transfers their energy to Tb3+ via phonon assistant electric dipole–dipole interaction. The evaluated energy transfer efficiency from Gd3+ to Tb3+ increases gradually with increasing the Tb2O3 content and reaches 99% when the content of Tb2O3 exceeds 5mol%. Due to the more efficient energy transfer from Gd3+ to Tb3+ and higher doping concentration of Tb3+, the intensity of green emission originated from 5D4→7FJ reaching the maximum when the content of Tb2O3 is 6mol%. Meanwhile, a strong 5D3 luminescence quenching happens due to the cross-relaxation process. Under X-ray excitation, the intensity of 542nm emission in our glass doped with 6mol% of Tb2O3 shows 5.2 times stronger than that of 500nm emission in the commercial Bi4Ge3O12 (BGO) crystal, the integral scintillation efficiency is about 68% of the BGO crystal, which is much useful for reducing radiative dose to obtain high-resolution X-ray imaging.

Luminescence, energy transfer properties of Tb3+/Gd3+-coactivated oxyfluoride borogermanate scintillating glasses

Gd3+-, Tb3+/Gd3+-coactivated oxyfluoride borogermanate scintillating glasses with the density of about 6.35–6.61g/cm3 were prepared by a melt-quenching method. The luminescent and energy transfer properties were studied by transmittance, photoluminescence and X-ray excited luminescence (XEL) spectra. The total content of rare-earth oxide and fluoride is as high as 49mol% in oxyfluoride borogermanate glasses, which are necessary to ensure their density up to 6.61g/cm3. Energy transfer efficiency and mechanism from Gd3+ to Tb3+ were determined, and the corresponding critical distances for both Gd3+–Tb3+ and Tb3+–Tb3+ ion pairs were calculated, respectively. The optimal concentration of Tb3+ ions in dense oxyfluoride borogermanate glasses excited by both ultraviolet light and X-ray excitation were also determined. The integral scintillation efficiency of Tb3+-activated borogermanate scintillating glass was found to be about 26.9% of the standard Bi4Ge3O12 (BGO) scintillating crystal.

Luminescence properties of Gd3+-doped borosilicate scintillating glass

Gd3+-doped borosilicate glasses are prepared in different melting atmosphere. Absorption spectra, decay time, luminescence spectra under UV and X-ray excitation are investigated. With melting atmosphere changing from air to CO, the luminescence intensities of Gd3+ at 313nm under the excitation of UV and X-ray are both enhanced. This mainly results from the reduction of Gd3+, which is validated by electron paramagnetic resonance (EPR). The optimal Gd2O3 content for the glasses prepared under CO atmosphere is 7.5mol%, whose integral scintillation efficiency is 20% compared with Bi4Ge3O12.

Photo- and Radioluminescence of Ce<sup>3+</sup>-Doped Dense Oxide Glass

Photo-and radioluminescence characteristics of Ce3+-doped dense oxide glass (SiO2-B2O3-Al2O3-Gd2O3) are presented. The Gd3+→ Ce3+ energy transfer was evidenced by photoluminescence excitation spectra of Ce3+ emission. Photoluminescence decay kinetics was governed by a few tens of nanoseconds decay time. The integral scintillation efficiency of about 22% of that of the Bi4Ge3O12 scintillator was obtained under X-ray irradiation. Scintillation light yield under alpha particle excitation was measured and compared with that of the Bi4Ge3O12 crystal.

Investigation on the luminescent properties of Eu3 +-activated dense oxyfluoride borogermanate scintillating glasses

Eu3+-activated dense B2O3-GeO2-BaF2-10LaF3-(37-x)Gd2O3-xEu2O3 (0≤x≤12.5) scintillating glasses were synthesized by melt-quenching method. Their optical properties were characterized by transmittance, excitation and emission spectra, and X-ray excited luminescence (XEL) spectra in detail. The total content of Gd2O3 and LaF3 rare-earth agents is as high as 47mol% in borogermanate glass, which ensures glass density exceed 6.0g/cm3. Energy transfer from Gd3+ to Eu3+ ions is verified by excitation and emission spectra. High efficiency of this transfer process is confirmed by both Gd3+ emission intensity and the average distances for Gd3+–Eu3+ ion pairs. The degree of Eu–O covalency and the local environment of Eu3+ ions are evaluated by the value of Ωt parameters from the Judd–Ofelt analysis. It is found that the covalency of EuO bond increases with increasing Eu3+ concentration. The optimal concentration of Eu3+-activated borogermanate scintillating glass under both ultraviolet and X-ray excitation is determined. It reveals that the integral scintillation efficiency is about 4% of the standard Bi4Ge3O12 (BGO) scintillating crystal.

Luminescent properties of Tb3 +-activated B2O3–GeO2–Gd2O3 scintillating glasses

Tb3+-activated 25B2O3–40GeO2–(35−x)Gd2O3–xTb2O3 scintillating glasses were prepared by melt-quenching method. Their structure and luminescent properties were characterized by transmittance, Raman, photoluminescence and X-ray excited luminescence (XEL) spectra in details. A high Gd2O3 content is necessary to ensure borogermanate glass with density up to 5.7g/cm3. Energy transfer efficiency from Gd3+ to Tb3+ ions, and critical distances for both Gd3+-Tb3+ and Tb3+-Tb3+ ion pairs were calculated, respectively. The optimal concentration of Tb3+-activated borogermanate scintillating glass under both ultraviolet and X-ray excitation is determined. It reveals that the integral scintillation efficiency is about 30% of the standard Bi4Ge3O12 (BGO) scintillating crystal.

Luminescence of Tb3+-doped high silica glass under UV and X-ray excitation

Tb3+-doped silica glass was prepared as a luminescent material by impregnation of 0.1M TbCl3 solution into a porous silica glass followed by high temperature sintering in a CO reducing atmosphere. Under the 225nm UV and X-ray excitations the intense violet-blue Tb3+ luminescence from 5D3 level is observed, comparable in intensity to the green emission starting from the 5D4 level. Luminescence decay times of 1.18 and 2.18ms are obtained, respectively, for the emission transitions starting from 5D3 and 5D4 levels. Relative concentration of Tb ions participating in cross-relaxation process is estimated. The integral scintillation efficiency obtained for this Tb3+-doped silica glass under X-ray excitation is of about 104% of that of the reference Bi4Ge3O12 scintillation crystal.

Luminescence of Tb3+‐doped oxide glasses with high Gd2O3 concentration under UV and X‐ray excitation

AbstractThis report presents the luminescence properties of Tb3+‐doped oxide glasses with high Gd2O3 (25 mol%) concentration under UV and X‐ray excitation. The intense green 5D4 → 7FJ luminescence is observed with strong luminescence quenching of the 5D3 level due to cross‐relaxation process. Energy transfer from Gd3+ to Tb3+ ions is confirmed by both luminescence spectra and decay measurements. The integral scintillation efficiency obtained for the 0.5 wt% Tb3+‐doped glass under X‐ray excitation is of about 40% of that of the reference Bi4Ge3O12 crystal.

Luminescence and scintillation of Ce3+-doped high silica glass

Ce3+-doped high silica glass was prepared by impregnation of Ce ions into a porous silica glass followed by high temperature sintering in a CO reducing atmosphere. The characteristic emission of Ce3+ 5d→4f transition peaking around 375nm is observed in its luminescence spectra under UV and X-ray excitation. Its photoluminescence decay is governed by several tens of nanoseconds decay time. Its integral scintillation efficiency is comparable to that of a Bi4Ge3O12 (BGO) crystal under X-ray excitation. Scintillation light yield under gamma and alpha excitation was measured and compared with that of BGO.