Prominent Glow Peak Research Articles

An attempt to enhance the afterglow luminescence of NIR light emitting long persistent phosphor Zn3Ga2Ge2O10:Cr3+ by Pr3+ co-doping

In this study we have focused on the improvement of luminescence intensity and the long afterglow luminescence of Cr3+ doped Zn3Ga2Ge2O10 long persistent phosphor by adding an appropriate amount of Pr3+ ions in proportion with Ga concentration. We have successfully developed a series of long persistent Zn3Ga(2-x-y)CrxPryGe2O10 (where x = 0, 0.04 and y = 0, 0.01, 0.02, 0.03, 0.04) phosphors by high temperature solid state reaction method. The structural properties of the developed phosphors were characterized by X-ray diffraction method. The diffuse reflectance spectra were recorded at room temperature and it shows three strong absorbance bands at the wavelength of 256, 412 and 570 nm due to the transitions of 4A2g→4T1g (4P), 4A2g→4T1g (4F) and 4A2g→4T2g (4F) of Cr+3 ions which are also confirmed from the photoluminescence (PL) excitation spectra. PL emission analysis revealed that developed phosphors have a strong narrow luminescence around 698 nm and significantly enhanced with the Pr3+ content upto its optimum value (0.02). Afterglow NIR light emission from the developed phosphors was captured by night vision monocular and it is found that the phosphors have long persistent luminescence for more than 24 h. Thermoluminescence (TL) measurement was also carried out for better understanding the kinetic mechanism and luminescence process in these materials. This will enable to calculate the trapping parameters associated with prominent glow peaks.

Samarium doped Ca3Y2B4O12 phosphor prepared by combustion method: Anomalous heating rate effect, dosimetric features, and TL kinetic analyses

The structural and thermoluminescence characteristics of samarium doped Ca3Y2B4O12 samples at various concentrations are presented. The samples were synthesized via the combustion method. The thermoluminescence (TL) glow curves for Ca3Y2B4O12:Sm3+ depict strong peaks at 97 and 410 °C. Ca3Y2B4O12:Sm3+ exhibited completely opposite behavior, contrary to expectations, in that the luminescence intensity of both the total and individual glow peaks increased with the heating rate throughout the TL experiments. This unusual TL glow peak pattern was discussed via the Mandowski model of semi-localized transitions. The kinetic characteristics of both prominent glow peaks were established using various analysis techniques, including variable heating rate, initial rise (IR) by using the TM-Tstop method and the fractional glow technique (FGT), and computerized glow curve deconvolution (GCD). The dose response of the high temperature peak at 410 °C is linear between 0.1 and 5 Gy, and then sublinear at higher doses. In addition, the repeatability and fading results of 410 °C TL peak also yielded very favorable results. These findings suggest that Ca3Y2B4O12:Sm3+ has great potential in the development of high temperature dosimetric materials for beta irradiation.

Thermoluminescence of aquamarine: A preliminary study

Thermoluminescence of aquamarine, the cyan variety of beryl (Be3Al2(SiO3)6), is reported. Samples were irradiated at room temperature using a 90Sr/90Y β source at a rate of 0.10 Gys–1. Measurements made at 1 °C/s after irradiation to 10 Gy show a prominent glow peak at 75 °C and three secondary peaks at 113, 188 and 306 °C. Kinetic analysis of the main peak performed using the initial rise, whole glow peak and curve fitting methods show that the peak follows first order kinetics, that its activation energy is of the order of 1 eV and that it has a frequency factor of ∼1012 s−1. Reproducibility analysis shows that the material reproduces its response under identical experimental conditions with a maximum uncertainty of 2.0%.

Investigations of thermoluminescence characteristics of CaSiO3:Yb phosphor irradiated with gamma rays and carbon ion beam

In the present work, the thermoluminescence (TL) properties of Yb doped CaSiO3 phosphor exposed to gamma rays and carbon (C) ion beam have been reported. The phosphor has been synthesized using solid-state reaction method. The formation and surface morphology of the phosphor have been studied using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) respectively. The optical band gap of the phosphor is determined using UV–Visible spectroscopy. TL properties on Yb doped CaSiO3 phosphor irradiated with carbon ion beam has been reported first time. Different TL properties like TL glow curve, dose response, fading etc. have been investigated in detail. The TL glow curve of CaSiO3:Yb phosphor consists of two prominent glow peaks. Under gamma irradiation, the main dosimetric peak is centered at 141 °C and other peak is centered at 265 °C. The dose response behaviour has been studied in the range 10 Gy–1000 Gy. However, C ion beam irradiated phosphor also consists similar TL glow curve structure with glow peaks shifted towards high temperature side (approx. 50 °C). The dose response behaviour of C ion beam irradiated phosphor has been examined in the ion fluence range varying from 5 × 109–5 × 1012 ions/cm2. A track interaction model is used to explain the sublinearity at higher fluences of carbon ion beam. Different ion beam parameters have been analyzed using Monte-Carlo simulation-based SRIM code. A comparative TL study of the phosphor irradiated with gamma rays and carbon ion beam suggests that gamma irradiated phosphor has shown better TL properties such as high TL sensitivity, good linear dose response (10 Gy–500 Gy), stable TL glow curve structure and low fading. Various TL trapping parameters i.e. order of kinetics, activation energy and frequency factor have been calculated using Chen's peak shape method to analyze the nature of TL traps responsible for showing different behaviour of the phosphor towards both the radiations. Good TL properties of CaSiO3:Yb phosphor supports its possible use in gamma dosimetry.

Structural, thermal and thermoluminescence response of transition and alkaline earth metals activated on aluminium borate [Al2(B4O7)3:Mn, Mg

Aluminium borate doped with manganese (Mn) and magnesium (Mg) at different concentrations are studied. The samples were synthesized by solid state sintering. The structure, morphology and crystallite size of the aluminium borate are affected by the dopants used. The crystallite size values calculated for different concentrations of manganese and magnesium used in doping of aluminium borate are within a range of 32.5–35.1 nm and 21.3–28.7 nm respectively. The particle size obtained using a scanning electron spectroscopy for Mn and Mg-doped aluminium borate are in the range of 30–40 nm and 20–30 nm respectively. A loss in weight from the thermal analysis performed for Mn and Mg-doped aluminium borate are observed to be 10.43% and 20.06%. The thermoluminescence glow peaks from all the samples measured at 1 °C.s−1 following irradiation to 50 Gy showed a prominent glow peak at 96 °C with minor peak observed at higher temperature (178 °C) region of the glow curve. The activation energy for Mn and Mg-doped aluminium borate were determined to be approximately 0.78 ± 0.30 eV and 0.76 ± 0.25 eV by using the initial rise, glow curve deconvolution and variable heating rate method. The dose responses were considered from 1 to 300 Gy for Mn (0.4%) and Mg (0.3%) doped aluminium borate and were further studied by using the g(D) and f(D) functions.

Thermoluminescence behavior of gamma irradiated Y2O3:Sm3+ nanophosphor

Thermoluminescence (TL) properties of 60Co gamma irradiated Sm3+ doped Y2O3 nanophosphors were investigated for possible application for high dose gamma radiation dosimetry. Sm3+ doped Y2O3 nanophosphors were synthesized by the solution combustion method. The crystalline phase was analyzed with X-ray diffraction and an average crystallite size was found to be ~20–33 nm. TL glow curves of gamma irradiated Sm3+ doped Y2O3 nanophosphors were recorded. The TL glow curves showed a prominent glow peak at ~400 K, a smaller intensity peak at 510 K and a very weak intensity glow peak at ~640 K. These glow peaks were ascribed to host defects and Sm3+ characteristic emission. The effect of Sm3+ concentration on the TL was explored and the optimum Sm3+ concentration was found to be 0.1 mol%. The number of overlapping TL glow peaks were identified from the broad TL glow curve by the thermal cleaning method. The kinetic parameters were obtained by the glow curve deconvolutions method using the general order kinetics expression. The variation of the TL intensity with dose, the effect of heating rates, repeatability and the fading effects of gamma irradiated Sm3+ doped Y2O3 nanophosphors were also studied. TL emission showed a strong green (545 nm) emission at ~400 K and a characteristic Sm3+ emission was observed at a high dopant concentration. The results obtained were favorable for the application of high dose gamma radiation dosimetry.

Properties optimization of temperature dependence of nanophosphor KCl:Sm3+ for radiation dosimetry

Present study reports the temperature dependent optically stimulated luminescence (TA-OSL) properties of KCl:Sm in the range of 40–310 °C. KCl:Sm was synthesized by high-temperature solid-state reaction method with optimized dopant concentration of Sm (0.45%). The morphological and structural properties of KCl:Sm are carried out using SEM, and XRD. KCl:Sm is found to be polycrystalline in nature with average crystallite size 30–70 nm as confirmed by XRD. SEM images of KCl:Sm showed the uniform morphology within the range of 0.1 μm. The KCl:Sm exhibits good TA-OSL intensity at 100 °C (at a fixed dose of 10 Gy of gamma photons) as well as the linear response. The optimized elevated temperature for KCl:Sm is found to be 100 °C because of the maximum TA-OSL intensity on this temperature due to the depletion of its filled traps. The Arrhenius analysis estimated the activation energy of Ea, is 0.2 ± 0.05 eV. In this work, we also report thermally stimulated luminescent (TSL) characteristics till 500 °C. Intense and broad TSL peaks are obtained at 265 °C, 310 °C & 340 °C when irradiated to the low energy HCPs protons and carbon beams of 250 keV. In this analysis, the prominent glow peak temperature shifts towards lower temperature region. The trapping kinetic parameters are estimated (for knowing the trap structure) and glow curves are analyzed though de-convolution techniques. The temperature dependence characteristics of KCl:Sm with respect to low LET gamma photons and high LET HCPs have been discussed with reference to medical as well as high radiation dosimetry.

Optical, electrical and luminescent studies of CuO/MgO nanocomposites synthesized via sonochemical method

CuO/MgO nanocomposites (NCs) were synthesized by energy efficient sonochemical method using glucose as surfactant. The structural properties were carried out by means of Powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Diffused Reflectance Spectra (DRS). In addition to this, Photoluminescence (PL), Electrical conductivity and Thermoluminescence (TL) properties were also discussed in detail. The diffraction peaks indicates the coexistence of CuO/MgO composite. PXRD studies revealed CuO and MgO exhibit monoclinic and cubic phases respectively. PL studies of the composites showed peaks at 478, 538, 593 and 714 nm upon excited at 431 nm wavelength. Among the composites, the highest PL intensity was recorded for 70:30 ratio of CuO/MgO. The CIE chromaticity coordinates and Correlated Color Temperature (CCT) results clearly evident that the optimized composites were quite useful for display applications. Enhanced electrical conductivity and dielectric properties were observed for 90:10 CuO/MgO NCs. The TL results clearly indicate, single prominent glow peak of composites recorded in the range of 114–120 °C along with shouldered peak at ∼150 °C. The Kinetics parameters (τ, S, b) and dosimetric properties of the composites were thoroughly investigated. A good conformity was obtained between the results obtained from various analysing methods. The present results addresses that CuO/MgO nanocomposite is a promising candidate for use as a radiation dosimeter.

Structural, photoluminescence and thermoluminescence study of novel Li+ co-activated lanthanum oxide activated with Dy3+ and Eu3+ obtained by microwave-assisted solution combustion synthesis

Stimulated luminescence of novel La2O3 nanophosphors doped with Dy3+ and Eu3+ and co-activated with Li+, prepared by microwave-assisted solution combustion synthesis, was investigated for the very first time. X-ray diffraction results indicated hexagonal La2O3 crystalline phase. Lanthanide and Li+ doping did not affect the La2O3 crystal structure. Scanning electron microscopy images showed nanoparticle morphologies such as plates, rods and irregular shapes. Photoluminescence spectra of La2O3:Dy3+, Li+ exhibited blue and green emission bands due to Dy3+ transitions. For La2O3:Eu3+, Li+, sharp emission lines, corresponding to the optical transitions of Eu3+ were observed. Thermoluminescence glow curve of La2O3:Dy3+, Li+ previously exposed to beta radiation exhibited a prominent glow peak located at ∼46 °C, possibly useful for after-glow or persistent luminescence applications, whereas La2O3:Eu3+, Li+ curve, displayed three intense peaks at ∼50, ∼110 and ∼150 °C. Thermoluminescent signal repeatability and decay curve asymptotic behaviour could place La2O3:Eu3+, Li+ as suitable for medium and high-dose radiation dosimetry applications.

Annealing effect on the structural, optical and thermoluminescent properties of ZnAl2O4:Cr3+

The nanocrystalline phosphor of ZnAl2O4:Cr3+ has been prepared by the hydrothermal method which utilizes the adjournment of cationic precursors in a urea aqueous solution. The as-prepared sample was annealed at different temperatures and the effect of thermal annealing with Cr3+ impurity ions on the structural, optical and thermoluminescence properties of the obtained samples was investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM), UV–Vis spectroscopy, Photoluminescence (PL), Fourier transform infra-red spectroscopy (FTIR) and Thermo luminescence (TL) were used for the characterizations of the materials. From the XRD analysis, it is found that with increasing temperature, the crystallite size and lattice constants of the samples are increased. The morphological changes have been also observed by TEM. The variation in the optical properties showed that the PL emission peaks observed which corresponds to Cr3+ ions. The FTIR spectrum exhibits the transmission band of Al-O octahedral groups. The change in thermoluminescence (TL) glow curves characteristics of all the phosphors samples was also studied. A prominent glow peak at 428K was observed in the TSL of γ-irradiated Cr3+-doped ZnAl2O4 phosphors. Thus, the crystal structure, particle size and morphology were found to depend on the precursors, method of synthesis and annealing temperature.

Variation of trap depth by dopant/codopant and heating rate in CaWO4 phosphors

This paper deals with comparative investigation on the thermoluminescence (TL) properties as well as trapping parameters of undoped, Dy3+ doped and K+ codoped CaWO4 phosphors. The glow curves of phosphors were recorded after exposure to γ-rays in the dose range 1–5 kGy at a heating rate of 5 °C/s. The glow curves of undoped, doped and codoped phosphors show single prominent glow peak at 100, 135 and 130 °C respectively. In order to investigate the effect of heating rate, TL glow curves were also recorded by varying the heating rates to 3 and 7 °C/s. The TL glow curves were analyzed in order to get the trapping parameters such as trap depth (E), order of kinetics (b) and frequency factor (s). The obtained trapping parameters confirm the presence of second order kinetics. The codoped phosphor show better linear TL response compared to other phosphors indicating their suitability in radiation dosimetry.

Thermoluminescence characteristics of NaCl from Different Origins

In radiological emergencies, table salt can be considered an established method for the retrospective dosimetry of past exposures and the dosimetry of potentially exposed people, where it is a material that can be expected to be easily available in accident locations and it can easily be sampled collection. The characteristics of thermoluminescence (TL) have been studied for four different commercial salt samples (NaCl) obtained from different sources. Indian salt (supplied by oxford lab) is used for comparison, not for measuring doses, Egyptian table salt (SAL), Saudi Arabian table salt (MASA) and British table salt (Cook’s), are the three nominated types of salt to procedure in this work. Samples were irradiated with Gamma source using Cs-137. TL analysis of the samples were done using Harshaw Model 4500 TLD Reader, with WinREMS (Windows Radiation Evaluation and Management System) at heating rate 5 oC /sec with final temperature set to 350 oC. One prominent glow peak is observed in the glow curve at around 216 - 222 oC of the commercial salt samples. For all salt samples, the TL intensity of the glow curve is direct proportional to the grain size. By comparison the highest TL intensity for each salt sample, it is found that, Cook’s salt is the most sensitive and preferable one to complete the study. The results show also that, TL intensity of the chosen salt (Cook’s salt) has a linear response with the dose for a broad range from 250 mGy to 20 Gy. The post-irradiated fading rates are investigated and show stability after 8 days. The fading at room temperature was monitoring during 24 days. Cook’s salt may be candidate for using as a Gamma ray retrospective dosimeter.

Luminescence analysis of SrGa2 Si2 O8 : RE3+ (RE=Dy, Tm) phosphors.

This article reports on the luminescence properties of rare earth (Dy3+ and Tm3+ )ions doped SrGa2 Si2 O8 phosphor were studied. SrGa2 Si2 O8 phosphors weresynthesizedby employing solid state reaction method.From the measured X-ray diffraction (XRD) pattern of the samplemonoclinic phase structure has been observed. Thermoluminescenceand Mechanoluminescence properties of the γ-ray irradiated samples have been studied. Photoluminescence spectra of Dy3+ activated SrGa2 Si2 O8 phosphor has been measured with an excitation wavelength at 348nm,and it shows two emission bands at 483 and 574nm due to 4 F9/2 →6 H15/2 and 4 F9/2 →6 H13/2 transitions respectively. Whereas the photoluminescence spectra of Tm3+ activated SrGa2 Si2 O8 phosphor has been measured with an excitation wavelength at 359nm and it exhibits two emission bands at 454 and 472nm due to 1 D2 →3 F4 and1 G4 →3 H6 transitions respectively. In thermoluminescence study, γ-irradiatedthermoluminescence glow curve of SrGa2 Si2 O8 :Dy3+ phosphor shows two well defined peaks at 293°C (peak1)and 170°C (peak2) whereas thermoluminescence glow curve of SrGa2 Si2 O8 :Tm3+ phosphor shows peaks at 292°C (peak1) and 184°C (peak2) indicating that two sets of traps are being activated within the particular temperature range and the trapping parameters associated with the prominent glow peaks of SrGa2 Si2 O8 :Dy3+ and SrGa2 Si2 O8 :Tm3+ are calculated using Chen's peak shape and initial rise method.From the Mechanoluminescence study, only one glow peak has been observed. Copyright © 2016 John Wiley & Sons, Ltd.

Thermoluminescence study of Mn doped lithium tetraborate powder and pellet samples synthesized by solution combustion synthesis

In this paper, the thermoluminescence (TL) dosimetric characteristics under beta-ray, x-ray and gamma-ray excitations of powder and pellet Mn-doped lithium tetraborates (LTB) which were produced by solution combustion synthesis technique were investigated, and the results were compared with that of TLD-100 chips. The chemical composition and morphologies of the obtained LTB and Mn-doped LTB (LTB:Mn) were confirmed by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and scanning electron microscopy (SEM) with EDX. LTB:Mn was studied using luminescence spectroscopy. In addition, the effects of sintering and annealing temperatures and times on the thermoluminescence (TL) properties of LTB:Mn were investigated. The glow curves of powder samples as well as pellet samples exposed to different beta doses exhibited a low temperature peak at about 100°C followed by an intense principal high temperature peak at about 260°C. The kinetic parameters (E, b, s) associated with the prominent glow peaks were estimated using Tm–Tstop, initial rise (IR) and computerized glow curve deconvolution (CGCD) methods. The TL response of integral TL output increased linearly with increasing the dose in the range of 0.1–10Gy and was followed by a superlinearity up to 100Gy both for powder and pellet samples using beta-rays. Powder and pellet LTB:Mn were irradiated to a known dose by a linear accelerator with 6 and 18MV photon beams, 6–15MeV electron beams and a traceable 137Cs beam to investigate energy response. Further, TL sensitivity, fading properties and recycling effects related with beta exposure of LTB:Mn phosphor were evaluated and its relative energy response was also compared with that of TLD-100 chips. The comparison of the results showed that the obtained phosphors have good TL dose response with adequate sensitivity and linearity for the measurement of medical doses.

Determination of the kinetic parameters of BeO using isothermal decay method

Most of the existing methods for obtaining the frequency factors make use of the trap depth (activation energy) making some assumptions about the order of the kinetics. This causes inconsistencies in the reported values of trapping parameters due that the values of the activation energy obtained by different methods differ appreciably among them. Then, it is necessary to use a method independent of the trap depth making use of the isothermal luminescence decay (ILD) method.The trapping parameters associated with the prominent glow peak of BeO (280°C) are reported using ILD method. As a check, the trap parameters are also calculated by glow curve shape (Chen's) method after isolating the prominent glow peak by thermal cleaning technique. Our results show a very good agreement between the trapping parameters calculated by the two methods. ILD method was used for determining the trapping parameters of BeO. Results obtained applying this method are in good agreement with those obtained using other methods, except in the value of the frequency factor.

Thermoluminescence properties of Al2O3:Tb nanoparticles irradiated by gamma rays and 85 MeV C6+ ion beam

Carbon ions beam is recently recognized as an ideal cancer treatment modality, because of its excellent local tumor control. These ions have a high relative biological effectiveness resulting from high linear energy transfer (LET) and their sharp Bragg peak. However, the dose of those energetic ions needs to be measured with great precision using a proper dosimeter. Aluminum Oxide (Al2O3) is a highly luminescent phosphor widely used for radiation dosimetry using thermoluminesence (TL) technique. In this work nanoparticles of this material activated by different elements like Eu, Tb, Dy, Cu and Ag were evaluated for their TL response to gamma rays irradiation. Tb doped sample is found to be the most sensitive sample, which could be selected for exposure to 85MeV C6+ ion beam in the fluence range 109–1013ions/cm2. The obtained result shows that C ion beam irradiated sample has a simple glow curve structure with a prominent glow peak at around 230°C. This glow curve has a dosimetric peak better than those induced by gamma rays. This glow peak exhibits a linear response in the range 109–1011ions/cm2, corresponding to the equivalent absorbed doses 0.285–28.5kGy. The absorbed doses, penetration depths and main energy loss were calculated using TRIM code based on the Monte Carlo simulation. The wide linear response of Al2O3:Tb nanoparticles along with the low fading makes this low cost nanomaterial a good candidate for C ion beam dosimetry.

Influence of Li+ and Dy3+ on structural and thermoluminescence studies of sodium sulfate

Na2SO4, Na2SO4: Dy3+, LiNaSO4 and LiNaSO4: Dy3+ nanoparticles successfully synthesized by slow evaporation technique followed by calcination at 400 oC. The resultant products were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared and UV–Vis spectroscopy. The average crystallite size was calculated using Debye–Scherrer’s formula and Williamson–Hall’s (W–H) plots. The optical energy band gap (E g) was estimated from Wood and Tauc’s relation, which varies from 3.70 to 4.45 eV. The variation in band gap values attributed to large degree of structural defects. Thermoluminescence studies were investigated using γ-irradiation in the dose range 0.5–5 kGy at a heating rate of 5 K s−1. The samples Na2SO4 and LiNaSO4 showed a well-resolved glow peak at ~180 and ~170 °C, respectively. The prominent glow peak at ~175 °C along with shouldered peak at ~60 °C was observed for Na2SO4: Dy3+. LiNaSO4: Dy3+ showed prominent glow peak at ~100 °C and a small shoulder peak at ~180 °C. The addition of isovalent (Li+) quenches the TL intensity, whereas the hypervalent (Dy3+) increases the intensity of Na2SO4. The variations of TL intensity for all the phosphors follow linear behavior up to 5 kGy and were useful in radiation dosimetry. The kinetic parameters (E, b and s) were estimated from the glow peak shape method.

Thermoluminesence of gamma rays irradiated CaSO4 nanorods doped with different elements

Nanorods of calcium sulfate (CaSO4) activated by Ag, Cu, Dy, Eu and Tb were synthesized by the co-precipitation technique. They were irradiated by γ-rays in a wide range of exposures and studied for their thermoluminesence (TL) properties. The as-synthesized samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) emission spectra. SEM images show that the samples doped with rare earths elements (i.e. Dy, Eu and Tb) have thinner nanorods than the other samples, while XRD pattern shows a complete crystalline structures in a monoclinic phase. The TL glow curves of these samples show two components. The first one include low temperature glow peaks at around 125°C, while the second component shows high temperature peaks in the range 230–270°C. These glow peaks diver from sample to sample by their TL intensity. The TL results are promising, particularly that of Tb and Eu. Tb doped sample is found to be a highly TL sensitive with a prominent glow peak at around 270°C, while Eu has created very active, high dense electron traps. The later shows quite linear response in the whole studied exposures i.e. 10Gy–10kGy. These results show that Eu or Tb doped CaSO4 nanorods might be proper candidates as dosimeters for high doses of ionizing radiations used in irradiation of foods and seeds.

TLD Instrumentation: A Case Study of PC Controlled TL Reader

Thermoluminescence reader is an important tool and a requisite for a researcher to study and characterize Thermoluminescence (TL) materials in different forms. Requirement for a versatile PC Controlled TL Reader has been felt for quite some time globally. Nucleonix Systems, Hyderabad, India, have developed a PC Controlled TL Reader by integrating complete electronics hardware circuits (comprising of Power Electronics, Low/High voltage Supplies, Temperature Controller, Micro Controller based data acquisition circuits having serial counter, ADC, DAC, EEPROM, PMT, PMT housing, sample heating system, drawer assembly, etc.) in a single enclosure. The system also integrated with software to calculate the activation energy (E), frequency factor (S) and order of kinetics ‘1’ for the prominent glow peaks using different equations.This Integral TL Reader unit gets connected to the Personal Computer System through serial port RS232C/USB port. The user interface to the system is through front–end VB software defined Graphics User Interface (GUI). The system also contains some of the software features like glow curve acquisition, analysis, filing, printing, plotting, overlapping, maker data reporting, etc. Additionally, system facilitates single/two/three plateau heating with variable heating rates.The primary objective of this development is to bring out versatile TL instrumentation system and also to make it affordable to many of the researchers in the Universities and other areas, including Radio-therapist, Medical Physicists in Cancer Hospitals. This system has been evaluated for its performance with CaSO4: Dy discs, powder, as well as with LiF: Mg, Ti chips. Linearity and reproducibility have been found to be quite satisfactory also within +2%. This system is quite useful to study the TL of phosphor, minerals and characterization of various solid semiconducting materials, and also can be used in personal dosimetry measurements and research studies in medical dosimetry, environmental radiation monitoring, and host of other applications in R&D Labs., etc.

Low temperature synthesis, structural and dosimetric characterization of ZnAl2O4:Ce3+ nanophosphor

Dosimetric properties of γ-irradiated ZnAl2O4:Ce3+ (1–9mol%) nanophosphors were studied and reported for the first time. The phosphor prepared by solution combustion route was well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. PXRD patterns of calcined phosphor show pure cubic phase of ZnAl2O4:Ce3+. Flake type morphology was observed from SEM studies. The particle size estimated by Scherrer’s and Williamson Hall (W–H) plots and found to be in the range 11–17nm. From photoluminescence (PL) studies two characteristic emission peaks at 363 and 480nm were observed due to 5d–4f transitions of Ce3+ ions. The thermoluminescence (TL) glow curves of ZnAl2O4:Ce3+ (1–9mol%) nanophosphor recorded two glow peaks 145 and 215°C at a warming rate of 2.5°Cs−1. The optimized TL intensity was observed for ∼5mol% Ce3+ concentration. The two TL glow peaks in the γ-irradiated (0.1–6kGy) ZnAl2O4:Ce3+ (5mol%) nanophosphor indicates that two set of traps were activated within the temperature range 145 and 215°C. The kinetic parameters (E,b,s) associated with the prominent glow peaks were estimated using Chen’s glow peak shape method. The intensity of the TL glow peak (145°C) increases linearly with increase of γ-dose upto 1kGy above which it follows sub-linear behavior. Track interaction model (TIM) was used to explain the linearity/sub linearity/saturation behavior of TL intensity. The TL glow curves show simple glow peak structure, good reusability, low fading and wide range of linearity. Hence, the optimized ZnAl2O4:Ce3+ (5mol%) nanophosphor was quite useful for radiation dosimetry and display applications.