Thermoluminescence Light Output Research Articles

Influence of Nd3+ ions on TL characteristics of Li2O-MO-B2O3 (MO = ZnO, CaO, CdO) glass system

Thermoluminescence (TL) characteristics of X-ray irradiated pure and doped with Nd3+ ions glasses have been studied in the temperature range 303–573 K; all the pure glasses have exhibited single TL peak at 382, 424 and 466 K, respectively. When these glasses are doped with Nd3+ ions no additional peaks are observed but the glow peak temperature of the existing glow peak shifted gradually towards higher temperatures with gain in intensity of TL light output. The area under the glow curve is found to be maximum for Nd3+-doped glasses mixed with cadmium oxide as modifier. The trap depth parameters associated with the observed TL peaks have been evaluated using Chen’s formulae. The possible use of these glasses in radiation dosimetry has been described. The result clearly showed that neodymium (Nd)-doped cadmium borate glass has a potential to be considered as the thermoluminescence dosimeter.

Luminescence properties of Pr3+ doped Li2O–MO–B2O3 glasses

Lithium borate glasses of composition 30Li2O–10MO–59B2O3:1Pr2O3 (MO=ZnO, CaO and CdO) were prepared by a conventional melt quenching method. The amorphous nature of these glasses was confirmed by X-ray diffraction. Characterization of these glasses was carried out by differential scanning calorimetry and infrared spectra. Optical absorption and photoluminescence spectra of these glasses were investigated. Judd–Ofelt intensity parameters Ωλ (λ=2, 4, and 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. From this theory various radiative properties like transition probability A, branching ratio βr, the radiative lifetime τR, and the stimulated emission cross-section σP for various emission levels of these glasses have been determined and reported. The relationship between the structural modifications and luminescence efficiencies of all the three glasses is explained. After X-ray irradiation on these glasses, the thermoluminescence emission properties were also studied. The thermoluminescence studies indicate that CdO modified glass gives out the maximum thermoluminescence light output among the three glasses studied.

Thermal Luminescence of Ho2O3‐PbO‐Al2O3‐SiO2 Glasses Exposed to Gamma Radiation

Thermoluminescence (TL) characteristics of PbO‐Al2O3‐SiO2: Ho3+ glass system mixed with different concentrations of Al2O3 were studied in the temperature range 0–300°C. The samples were exposed to γ‐rays in the dose range of 0–5 kGy. The glow curves of the samples exposed >1.0 kGy, exhibited a dosimetric peak at about 209°C. With the increase of the dose up to 5 kGy, the TL light output increased considerably, and the peak was shifted towards higher temperature. A linear dose‐dependent enhancement of the TL emission was also found for the glasses mixed with 5 and 8 mol% Al2O3. However, the glass mixed with 10 mol% Al2O3 exhibited supralinearity beyond 3 kGy. The mechanisms responsible for TL emission and enhancement of TL output were discussed in view of the results obtained from optical absorption, IR, and Raman spectral studies. The results suggested that both e− and h+ trapped centers were generated at the deeper trap levels and gave TL emission at higher temperatures. In the dose range of 2–5 kGy, the dose–response was found to be linear and could be useful for dosimetry in commercial radiation processing of perishable food commodities.

Dosimetric and kinetic parameters of lithium cadmium borate glasses doped with rare earth ions

Thermoluminescence (TL) characteristics of X-ray irradiated pure and doped with four different rare earth ions (viz., Pr3+, Nd3+, Sm3+ and Eu3+) Li2O–Cdo–B2O3 glasses have been studied in the temperature range 303–573 K; the pure glass has exhibited single TL peak at 466 K. When this glass is doped with different rare earth ions no additional peaks are observed but the glow peak temperature of the existing glow peak shifted gradually towards higher temperatures with gain in intensity of TL light output. The area under the glow curve is found to be maximum for Eu3+ doped glasses. The trap depth parameters associated with the observed TL peaks have been evaluated using Chen's formulae. The possible use of these glasses in radiation dosimetry has been described. The result clearly showed that europium doped cadmium borate glass has a potential to be considered as the thermoluminescence dosimeter.

Influence of induced structural changes on thermoluminescence characteristics of γ-ray irradiated PbO–Al2O3–SiO2: Dy3+ glasses

Thermoluminescence (TL) studies on PbO–Al2O3–SiO2: Dy3+ glasses mixed with varying concentrations (5–10mol%) of Al2O3 exposed to γ-rays of dose, 0–5.0kGy, have been carried out. The glow curves of these glasses have exhibited a dosimetric peak at about 180°C and a high temperature peak at about 300°C. The TL light output has been observed to increase with increasing Al2O3 and also with the γ-ray dose. Results of these studies (coupled with data on optical absorption, and IR spectroscopy) have been analyzed within a framework of induced structural changes in the glass network. Probable mechanisms responsible for TL emission have been identified and discussed. The dose response of these glass samples exhibited linear behavior within the dose range of 1.0–3.0kGy and beyond that it exhibited near saturation.

Influence of copper ions on thermoluminescence characteristics of CaF2–B2O3–P2O5 glass system

Thermoluminescence (TL) characteristics of γ−ray irradiated calcium fluoro borophosphate glasses doped with different concentrations of CuO (0.2–1mol%) have been studied in the temperature range 30–300°C. The γ−ray dose is varied from 0.25kGy to 10kGy. The glow curves of these glasses have exhibited a dosimetric peak at about 200°C and a high temperature peak at about 300°C. The glasses doped with 0.2mol% of CuO have exhibited maximum TL light output. The increase of dopant concentration beyond 0.2mol% caused the inhibition of TL emission drastically with shifting of peak positions towards higher temperatures. The probable mechanism responsible for quenching of TL emission in these glasses has been explained based on the variations in the valence state of copper ions with the aid of optical absorption spectra. The dose response of 0.2mol% CuO doped borophosphate glass samples showed linear behavior within the dose range of 0.25 to 4kGy. Samples containing higher concentrations of CuO (>0.2mol%) were found to be not suitable for radiation dosimetry within 10kGy dose.

Spectroscopic studies of lead arsenate glasses doped with nickel oxide

Lead arsenate glasses containing different concentrations of NiO ranging from 0 to 1 mol% (in steps of 0.2 mol%) were prepared. The samples were characterized by X-ray diffraction and differential thermal analysis. A number of studies viz., optical absorption, thermoluminescence, magnetic susceptibilities and IR spectra, have been carried out on these glasses. The bands observed in the optical absorption spectra of the glasses have been analyzed using Tanabe–Sugano diagrams for d 8 ion; the analysis indicates the presence of Ni 2+ ions in both tetrahedral and octahedral positions. The increase in the concentration of NiO in the glass matrix shows a gradual transformation of nickel ions from tetrahedral positions to octahedral positions in the glass network. The thermoluminescence light output of the X-ray irradiated glasses has exhibited a glow peak at 353 K (with increasing intensity with an increase in the concentration of NiO) in addition to the conventional peak due to the recombination of electron–hole centers; this glow peak is identified due to 3T 2 → 3A 2 emission transition of octahedral Ni 2+ ions. The value of the magnetic moment evaluated from the measured magnetic susceptibility show a decreasing trend from 3.84 to 3.10 μ B with the increase in the concentration of NiO. All these studies indicate an increasing presence of octahedral (lasing) Ni 2+ ions in these glasses with the increase in the concentration of NiO.

Thermoluminescence studies on PbO–Sb 2O 3–As 2O 3 glasses doped with iron ions

Thermoluminescence (TL) studies on PbO–Sb 2O 3–As 2O 3 glasses doped with different concentrations (0–1.0 mol%) of Fe 2O 3 have been carried out. The TL light output has been observed to decrease with increase in the concentration of Fe 2O 3 up to 0.6 mol%. For further increase in the content of Fe 2O 3, the TL light output has been observed to increase. Results of these studies (coupled with data on optical absorption, ESR and magnetic susceptibility measurements) have been analyzed in the light of different oxidation states of iron ions.

Optical absorption, fluorescence and thermoluminescence properties of ZnF2–MO–TeO2 (MO=ZnO, CdO and PbO) glasses doped with Er3+ ions

ZnF2–TeO2 glasses mixed with the three different modifier oxides, viz. ZnO CdO and PbO doped with Er2O3 were prepared. Optical absorption and photoluminescence spectra of these glasses have been studied. From the measured intensities of various absorption bands of these glasses, the Judd–Ofelt parameters Ω2, Ω4 and Ω6 have been evaluated and compared with those of other reported glass systems. Various radiative properties like transition probability A, branching ratio βr, radiative lifetime τr, and emission cross-section σE for various emission levels of these glasses have been determined and reported. The studies on these glasses are also extended for the thermoluminescence (TL) emission of these glasses after X-ray irradiation. The analyses of TL data indicate PbO modifier glass to be a better candidate for giving out maximum TL light output among the three glasses studied.

Optical absorption, fluorescence and thermoluminescence properties of ZnF 2–MO– [formula omitted], CdO and PbO) glasses doped with Er 3+ ions

ZnF 2–TeO 2 glasses mixed with the three different modifier oxides, viz. ZnO CdO and PbO doped with Er 2O 3 were prepared. Optical absorption and photoluminescence spectra of these glasses have been studied. From the measured intensities of various absorption bands of these glasses, the Judd–Ofelt parameters Ω 2 , Ω 4 and Ω 6 have been evaluated and compared with those of other reported glass systems. Various radiative properties like transition probability A, branching ratio β r, radiative lifetime τ r, and emission cross-section σ E for various emission levels of these glasses have been determined and reported. The studies on these glasses are also extended for the thermoluminescence (TL) emission of these glasses after X-ray irradiation. The analyses of TL data indicate PbO modifier glass to be a better candidate for giving out maximum TL light output among the three glasses studied.

Spectroscopic investigations on ZnF 2–MO–TeO 2 (MO=ZnO, CdO and PbO) glasses doped with chromium ions

Differential scanning calorimetric studies, spectroscopic studies (viz., optical absorption, ESR, infrared spectra) and thermoluminescence studies of ZnF 2–MO–TeO 2 (MO=ZnO, CdO and PbO) glasses doped with different concentrations of chromium ions have been investigated. Results have been analyzed in the light of different oxidation states of chromium ion. The analysis indicates chromium ions mostly exist in Cr 3+ state in ZT, CT and PT glasses when Cr 2O 3 is present upto 0.1%, 0.2% and 0.3%, respectively; these ions seems to be present in Cr 6+ state that take part network forming positions with CrO 4 2− structural groups in all the three glasses when the concentration of Cr 2O 3 is greater than the above quantities. Quenching of thermoluminescence light output of the glasses has been observed with increase in Cr 2O 3 concentration upto 0.1%, 0.2% and 0.3%, respectively in ZT, CT and PT glasses. This has been identified due to the killing effect of Cr 3+ ions. Further it has also been concluded that ZnF 2–PbO–TeO 2 is more favourable glass network for the presence of large concentration of laser-emitting Cr 3+ ions, among the three glass series studied.

Luminescence quenching by manganese ions in MO–CaF2–B2O3 glasses

Abstract Thermoluminescence (TL) characteristics of X-ray irradiated calcium fluoro borate glasses mixed with three different alkali oxide modifiers viz., Li2O, Na2O and K2O have been studied in the temperature range 303–600 K; all the glasses have exhibited single TL peak at 485, 541 and 497 K respectively. The glasses containing Na2O as modifier has exhibited the maximum TL light output. The doping of manganese oxide by a small concentration (0.2 mol%) in all these glasses has been observed to inhibit TL light output drastically with shifting of peak positions towards lower temperatures. The trap depth parameters associated with the observed TL peaks have been evaluated using Chen’s formulae. The probable mechanism responsible for quenching of TL emission by manganese ions in these glasses has been suggested with the aid of optical absorption, IR spectra and differential scanning calorimetric studies.

Thermoluminescence studies on Li 2O–CaF 2–B 2O 3 glasses doped with manganese ions

Thermoluminescence studies on X-ray irradiated Li 2O–CaF 2–B 2O 3 glasses doped with different concentrations (0–0.4 mol%) of MnO have been carried out. The thermoluminescence light output has been observed to decrease with increase in MnO concentration. Results of these studies (coupled with the data on optical absorption and infrared spectra) are analyzed in the light of different oxidation states of Mn ions.

Electron traps and transfer efficiency of cerium-doped aluminate scintillators

Comparative measurements of thermoluminescence and scintillation light outputs of gamma-ray irradiated Ce;LuAlO 3 (LuAP) and Ce:YAlO 3 (YAP) reveal that electron trapping significantly depresses transfer efficiency in these scintillator materials, but fails to explain fully either their performance differential or their departures from ideal efficiency. In the limit of short radiation times, the ratio of integrated thermoluminescence light output to integrated scintillation light output is 0.14 in LuAP and 0.02 in YAP.

Effect of High AC Electric Field on the F-Band Absorption and Thermoluminescence of X-Ray Irradiated NaCl and KCl Single Crystals

The F-band absorption and thermoluminescence (TL) light output in the two peaks of as-cleaved NaCl and KCl single crystals after X-ray irradiation and later subjecting the irradiated crystals to high AC fields, have been studied. The F-centre concentration at room temperature is considerably reduced (in both materials) with the AC field and this is true whether the X-ray irradiation is done for 15 min. or 1 hr. Similar behaviour is reflected in the TL light output, namely, the light output in the two TL peaks of these crystals decreases appreciably with the AC field. These results indicate that a large part of the F-centres formed in these crystals with X-ray irradiation can be destroyed even at room temperature when the samples are later subjected to high AC fields. An attempt has been made to understand the results.

Influence of high alternating electric-field treatment on X-ray-induced colouration in potassium-bromide single crystals

The effect of high alternating electric-field treatment (AC-field treatment) on the optical absorption and thermoluminescence of potassium-bromide single crystals upon X-ray irradiation has been investigated. A substantial enhancement both in F-centre concentration as well as in thermoluminescence light output has been observed in AC-field treated crystals upon X-ray irradiation at room temperature (30°C). The influence of AC-field treatment on F-centre growth has been studied. The dielectric properties of AC-field treated KBr crystals has also been reported. The observed results are discussed in terms of defects which are generated during AC-field treatment, and some useful conclusions are drawn thereby.

Radiation-induced coloration in KBr crystals subjected to AC electric fields

Optical absorption and thermoluminescence (TL) output measurements were made on KBr single crystals treated in a high alternating (50 Hz) electric field and irradiated with X-rays at room temperature. A substantial enhancement of both the F-centre concentration and the thermoluminescence light output was observed in AC field treated samples upon X-irradiation. The effect of AC field treatment on the F-centre growth curves is also reported.

Colour centres and thermal bleaching of sodium chloride and lithium fluoride

The thermoluminescence light output at different stages of thermal bleaching and the corresponding changes in colour centres, have been investigated in the case of sodium chloride and lithium flouride crystals, coloured at room temperature by X-rays. It has been observed that, during the early stages of thermoluminescence, the F centers are partly transformed into other centres responsible for the long wavelength colour bands: thermal release of lattice vacancies in excess of the stable concentration at any temperature makes it possible for the lattice imperfections to be mobile at comparatively low temperatures. In the case of coloured sodium chloride, during the first stage of thermal bleaching upto about 100°C, the F band decreases in intensity giving thermoluminescence and also producing another band at 580 mμ. This band seems to be due to aggregates of F centres and is found to be responsible for the thermoluminescence emission at temperatures above 200°C. The thermal bleaching of coloured lithium flouride is found to occur roughly in three stages. The thermoluminescence light output given out by the coloured crystal when heated to 180°C is due to the partial destruction of F-, colloid-, R1 and R2 bands. In the region from 180°C to 340°C the largest light output is observed and it is mostly due to the bleaching of M and F centres. In the final stage of bleaching from 340°C to 380°C, a large amount of light has been given out due to destruction of the F band and colloid centres. The results of the present investigation suggest that the emission bands at 519 mμ and 416 mμ observed in the thermoluminescence of sodium chloride are due to radiative recombination of holes with the electrons trapped at F and aggregate centres respectively. The present measurements on lithium fluoride crystals indicate that four different colour centres are involved in the emission process; thus the variation in the spectral composition of the emission during thermoluminescence is likely to be due to the corresponding emission bands.