Chen's Peak Shape Method Research Articles

Investigations of thermoluminescence characteristics of SrAlBO4 :Eu3+ phosphors irradiated with gamma rays and carbon ion beam.

A series of SrAlBO4 :Eu phosphors doped with different concentrations of Eu (0.1, 0.3, 0.5, 0.7, 1.0mol%) was synthesized using a solid-state diffusion method, and their thermoluminescence (TL) properties were analyzed for gamma and carbon ion irradiation. The phase purity, morphological properties, vibrational features, and thermal stability of the prepared sample were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric/differential thermal analyzer (TG/DTA) techniques, respectively. The TL properties of the proposed materials showed broad dosimetric bands, peaking at 202°C for 0.12 kGy gamma irradiation. The highest TL intensity was obtained for a 0.7mol% concentration of Eu ions under gamma irradiation. Furthermore, the glow curve of the proposed materials showed a broad emission band, centred at 148°C under carbon ion beam irradiation and exhibited the highest emission intensity for a 0.1mol% Eu concentration. In addition, the dosimetric trapping parameters of the prepared samples such as symmetry factor, order of kinetics, activation energy, and frequency factor, were analyzed using various methods such as Chen's peak shape method, initial growth method, and the Ilich method. The obtained results of the samples showed the potential for dosimetric application.

Synthesis, characterization and thermoluminescence properties of LiCaPO4 phosphor for ionizing radiation dosimetry

Many minerals and compounds show thermoluminescence (TL) properties but only a few of them can meet the requirements of an ideal dosimeter. Several phosphate materials have been studied for low-dose dosimetryin recent times. Among the various phosphates, ABPO4-type material shows interesting TL properties. In this study, an ABPO4-type (A = Lithium, B=Calcium) phosphor is synthesized using a modified solid-state diffusion method. Temperature is maintained below 800 °C in every step of phosphor preparation to obtain the pure phase of Lithium calcium phosphate (LiCaPO4). The purpose of this work is to synthesize LiCaPO4 using a simple method, examine its structural and luminescence properties in order to gain a deeper understanding of its TL characteristics. The general TL properties, such as TL glow curve, dose linearity, sensitivity, and fading, are investigated. Additionally, this study aims to determine various kinetic parameters through Glow Curve Deconvolution (GCD) method using the Origin Lab software together with the Chen model. XRD analysis confirmed the phase purity of the phosphor with a rhombohedral structure. Lattice parameters, unit cell volume, grain size, dislocated density, and microstrain were also calculated from XRD data. Raman analysis and Fourier Transform Infrared analysis were used to collect information about molecular bonds, vibrations, identity, and structure of the phosphor. To investigate TL properties and associated kinetic parameters, the phosphor was irradiated with 6.0 MV (photon energy) and 6.0 MeV (electron energy) from a linear accelerator for doses ranging from 0.5 Gy to 6.0 Gy. For both photon and electron energy, TL glow curves have two identical peaks near 200 °C and 240 °C.The TL glow curves for 0.5 Gy–6 Gy are deconvoluted, then fitted with the appropriate model and then calculated the kinetic parameters. Kinetic parameters such as geometric factor (μg), order of kinetics, activation energy (E), and frequency factor (s) are obtained from Chen's peak shape method. The dose against the TL intensity curve shows that the response is almost linear in the investigated dose range. For photon and electron energy, the phosphor is found to be the most sensitive at 2.0 Gy and 4.0 Gy, respectively. The phosphor shows a low fading and after 28 days of exposure, it shows a signal loss of better than 3%. The studied TL properties suggest the suitability of LiCaPO4 in radiation dosimetry and associated fields.

Al5BO9:Tb3+: Synthesis, structural characterization and thermoluminescence dosimetry studies for high intensity thermal neutron beams

In this manuscript, gel-combustion synthesis of Al5BO9:xTb3+ (x = 0.0%, 0.05%, 0.1%, 0.2% and 1.5%) phosphor along with the detailed structural characterizations using a host of techniques such as XRD, SEM, EDS, IR, EXAFS and PL etc. has been reported. XRD analysis confirmed the phase pure formation and also the nanocrystalline nature of the materials. Detailed EXAFS analysis explained the oxidation state and the coordination behaviour of Tb3+ ion in the Al5BO9 matrix. PL study showed that the material can be a potential green light emitting phosphor. Thermoluminescence (TL) study revealed the presence of a wide shoulder peak and a broad dosimetry peak situating at 551 K. Net TL response from 10B and 11B enriched Al5BO9:0.1%Tb3+ thin pellets showed prolonged linearity within the thermal neutron fluence range of 3.2 × 1010 to 1.6 × 1011 n/cm2. Also, the maximum fading of the TL signal is only 9% during the storage period of 112 days. These indicates that the developed material can be a potential candidate for dosimetry applications involving high intensity slow neutron beams. The TL glow curve was deconvoluted which revealed the presence of five individual peaks whose kinetic parameters viz. activation energy (E), order of kinetics (b) and frequency factor (s) were evaluated using both glow curve deconvolution and Chen's peak shape method and the results were found to be in good agreement.

Photoluminescence and thermoluminescence kinetic features of Eu3+ doped Sr2YVO6 double perovskite phosphor

Through traditional high-temperature combustion synthesis, a series of luminescent orange-red emitting Sr2YVO6:Eu3+ double perovskite phosphors were prepared, and their luminescence properties were examined. Through X-ray diffraction (XRD) and Rietveld analysis, the monoclinic crystal structure of all prepared Sr2YVO6:Eu3+ phosphors were confirmed. Scanning electron microscopy (SEM) was used to analyse the morphology of the phosphor. Under 320 nm excitation, Eu3+ doped Sr2YVO6 phosphors exhibit very strong red photoluminescence (PL) emission bands at 595 nm, 616 nm and 620 nm as well as distinct red emission bands at 653 nm and 699 nm, which are originated due to the 5D0-7FJ (J = 1,2,3,4) transition of Eu3+. A series of phosphor also exhibit orange-red emission at 595 nm, 612 nm, 616 nm and 620 nm under the excitation wavelength of 396 nm. High color purity of the phosphors is revealed by calculated color purity and excellent chromaticity coordinates, which also confirms the presence of far-red luminescence emission. After the irradiation of the phosphors at various beta doses via 90Sr/90Y beta source, the thermoluminescence (TL) studies of Eu3+ activated Sr2YVO6 phosphors was conducted. Exposer of beta irradiation revises a prominent TL glow curve at 124 °C with a small hump at around 290 °C, indicating the development of different trap centres in the phosphor. As the dose of beta radiation increased, a linear dose response was observed in TL intensity. Computerised Glow Curve Deconvolution (CGCD) method and Chen's Peak Shape Method (PSM) were used to determine the activation energies and trapping parameters of TL glow curves. According to CGCD fitting of TL glow curves, it is found that all glow curves consist of five deconvoluted peaks, which follows general order kinetics. Activation energies calculated through different methods were comparable and significant.

Luminescence investigation of CaY2 Al4 SiO12 :Dy3+ phosphor synthesized by sol-gel method.

Dy3+ -doped CaY2 Al4 SiO12 phosphors were prepared using the sol-gel method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive spectroscopy analyses (EDS) were used to analyse the crystal structure, morphology, and elemental composition of the prepared samples. The luminescence behaviour of the sample was investigated using photoluminescence (PL) and thermoluminescence (TL) techniques. The prepared CaY2 Al4 SiO12 :xDy3+ phosphor showed a characteristic blue and yellow emission at ~480 and 583 nm, respectively, with an excitation wavelength of 350 nm. The most intense PL emission was found for a 4mol% doping concentration of Dy3+ ions. The CIE diagram of the phosphor showed bluish-white colour emission. For TL studies, the prepared phosphors were irradiated with a 60 Co γ (gamma) source and the TL glow curve of the CaY2 Al4 SiO12 :0.04Dy3+ phosphor showed three overlapped peaks. For the Gaussian peaks, Chen's peak shape method was applied to determine the kinetic parameters of the samples.

Europium doped Sr2 YNbO6 double perovskite phosphor for photoluminescence and thermoluminescence properties.

A luminescent double perovskite phosphor Sr2 YNbO6 doped with Eu3+ crystallized to the monoclinic phase and was synthesized successfully via a conventional high-temperature combustion method. The formation of the crystal structure, phase purity, and surface morphology were studied using X-ray diffraction patterns and scanning electron microscopy. The characteristic vibrations between the atoms of the functional groups present in phosphor were studied using Fourier transform infrared spectra analysis. The luminescence properties of the prepared phosphors were investigated in terms of photoluminescence (PL) and thermoluminescence (TL). PL excitation spectra exhibited charge transfer bands and the characteristic 4f6 transitions of Eu3+ . A prominent PL emission was obtained for the phosphor doped with 4 mol% Eu3+ under the 396 nm excitation wavelength. PL emission quenching was observed for the higher doping concentrations due to a multipole-multipole interaction. A highly intense PL emission arose due to the hypersensitive 5 D0 -7 F2 electric dipole transition of Eu3+ that dominated the emission spectra. The thermal stability of the phosphor was examined through temperature-dependent PL. The TL properties of the Sr2 YNbO6 double perovskites irradiated with a 90 Sr beta source at different doses were measured. The double perovskite phosphors under study showed a linear dose-response with increasing beta dose, ranging from 1 Gy to 10 Gy. Trapping parameters of the TL glow curves were determined using Chen's peak shape method and computerized glow curve deconvolution (CGCD). CGCD fitting of the TL glow curves revealed that it was consisted of three major peaks and followed second-order kinetics. The estimated activation energies were determined using different methods and were comparable and significant.

Thermoluminescent studies of GdAlO3 powders

The increasing use of thermoluminescence (TL) materials as radiation detectors with application in different areas of ionizing radiation has motivated research on new materials with adequate luminescent characteristics. In this work, experimental results gadolinium aluminate (GdAlO3) analyzed by thermoluminescent phenomenon under beta irradiation effect are studied. To prepare GdAlO3 powders the coprecipitation method was used. TL glow curve and other luminescent characteristics were analyzed using an automatic Lexsig Smart TL/OSL luminescent reader. TL glow curve showed four peaks with three prominent and well-defined peaks centered at 140, 230, and 270 °C. TL response as a function of beta radiation dose was linearity in the range from 1.1 up to 44 Gy. Kinetic parameters such as activation energy (E), frequency factor (s), and order of kinetics after the deconvolution of the TL glow curve were also determined using Chen's peak shape method. Experimental results show GdAlO3 as a potential luminescent host material for TL studies.

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.

Investigation of thermoluminescence and photoluminescence properties of Tb3+, Eu3+, and Dy3+ doped NaYF4 phosphors for dosimetric applications.

Hexagonal phase sodium yttrium fluoride activated with lanthanide ions; Tb3+, Eu3+ and Dy3+ doped NaYF4 phosphors were synthesized using a simplistic hydrothermal method. The photoluminescence studies demonstrated green, red and blue emission lines corresponding to 5D4 → 7FJ (J = 6, 5, 4, 3), 5D0 → 7FJ (J = 1, 2 and 4) and 4F9/2 to 6HJ (J = 15/2 and 13/2) transitions, which are characteristic of Tb3+, Eu3+ and Dy3+ ions, respectively. The as-synthesized samples were subjected to annealing at varying temperatures from 500 °C to 800 °C primarily for the optimization of the thermoluminescence glow curve. Meanwhile, we studied the influence of thermal annealing treatment on the crystal phase, morphological features, and photoluminescence properties of the phosphors. The spherical-like morphology of NaYF4:Tb3+ phosphor changed to micro block-like structures and the hexagonal phase of NaYF4 transforms into a cubic phase at a higher annealing temperature of ∼800 °C. The photoluminescence emission intensity also varied at different annealing temperatures. The systematic study using different dopants and annealing temperatures was carried out to accomplish efficient thermoluminescence (TL) properties. The most suitable TL dosimetric glow peak was attained for NaYF4:0.5%Tb3+ phosphor, which was annealed at a temperature of 800 °C, located at 194 °C. The NaYF4:Tb3+ phosphor exhibited TL response fairly linear in the dose range from 1 kGy to 25 kGy of gamma radiation. The phosphor showed TL response at higher doses, which stipulates that the NaYF4:Tb3+ is reasonably well suitable for high dose measurements and respective applications. The phosphor exhibited negligible fading and good reproducibility features. Trap-level analysis and experimental determination of activation energy were performed using the Tm-Tstop technique and initial rise method (IRM). The trapping parameters of the TL glow curve, such as activation energy (E), order of kinetics (b), and frequency factor (s) were estimated by Chen's glow peak shape (PS) method and glow curve deconvolution (GCD) method. The trapping parameters obtained using the IRM, PS and GCD methods are in good accordance with each other. Henceforth, along with efficient photoluminescence properties, the NaYF4:Tb3+ phosphor exhibited favorable thermoluminescence dosimetric properties. Consequently, this study provides new opportunities for utilizing these phosphors in the area of radiation dosimetry applications such as environmental and food monitoring, space dosimetry etc.

Thermoluminescence Glow Curve Analysis with Variable Concentration of Erbium‐Doped Y2O3 Phosphor

AbstractA series of Y2O3:Er3+ phosphors have been synthesized via combustion synthesis method using urea as a fuel. The prepared samples are characterized by X‐ray diffractometer (XRD) and Fourier transforms infrared spectroscopy (FTIR) techniques. TL glow curves are recorded for Y2O3:Er3+ doped phosphors to study dose dependence, UV response, and heating rate effect. The trapping parameters (μ, E, s) are calculated from Chen's glow peak shape method. TL glow curve is fitted in computerized glow curve deconvolution (CGCD) techniques and are discussed in detail for their possible usage in dosimetry applications.

Characterizing and comparing the kinetic parameters of Gd3+ doped hafnium oxide nanoparticles in clinical photon and neutron beam

Thermoluminescence (TL) properties of Gd3+(0,1,3,5 &7 mol%): HfO2 NPs were synthesized by precipitation and co-precipitation method. The synthesized materials were irradiated in gamma, 6 MV, 10 MV, 15 MV and Am–Be neutron source. The glow curve were deconvoluted and analyzed by curve fitting with good values of FOM. The kinetic parameters such as order of kinetics (b), activation energy (Ea) and frequency factor (s) were determined by chen's peak shape method. The result shows that the intrinsic HfO2 has higher number of traps compared to extrinsic HfO2 due to the enrichment of oxygen vacancies. The TL glow curve achieved the higher TL counts in Gd (5 mol%) and above these concentration TL counts decreases due to concentration quenching. High energy beams such as 10 MV and 15 MV also shows similar result and verified with photon dose-linearity for the dose range in 5 cGy–100 cGy. Finally, the study concludes that the effect of doping material such as Gd3+ has the influence of their relative concentration in the host material to provide the information about pure HfO2 NPs suitable for gamma rays and X-rays(6 MV) and for neutron detection Gd(5 mol%) doped HfO2 can be used.

Tailoring of thermoluminescent properties and assessment of trapping parameters of natural fluorite samples from Dogargaon fluorite mines, India.

Mineral fluorite or fluorspar (CaF2 ) can host significant quantities of trivalent REE3+ (rare earth element) by substitution with divalent Ca2+ . The fluorites associated with carbonatites are often REE-rich compared to those derived from sedimentary, hydrothermal, or Mississippi Valley-type (MVT) fluorites. The naturally occurring fluorites have several industrial applications one of which is for luminescence. Whether or not REE enriched, the fluorite makes an ideal host for REEs, which are very important phosphors. The naturally occurring fluorites are available in sufficient quantities to cater to the industrial demand. Investigations have been carried out on the fluorites from active fluorite mines at Dongargaon in central India. Thermoluminescence behavior of a natural fluorite sample was investigated using a Nucleonix TL 1009I thermoluminescence reader. Multiple traps formed in the broad thermoluminescent (TL) glow curve were found by TL anal deconvolution software. Trapping parameters for all multiple traps formed on deconvoluting broad TL glow curve were found by different methods like Initial rise method, Chen's Peak shape method and Ilich method.

Photonic crystal fibre as a potential medium for radiotherapy dosimetry

Present study concerns the key thermoluminescence (TL) properties of photonic crystal fibres (PCFs), seeking development of alternatively structured TL materials that are able to offer a advantages over existing passive dosimeters. In terms of their internal structure and light guiding properties the PCFs, collapsed and structured, differ significantly from that of conventional optical fibres. To investigate the dosimetric parameters of the PCFs use was made of a linear accelerator producing a 6 MV photon beam, delivering doses ranging from 0.5 Gy to 8 Gy. The parameters studied included TL response, linearity index, glow curves, relative sensitivity and TL signal fading, the results being compared against those obtained using TLD-100 chips. At 4 Gy photon dose the Ge-doped collapsed PCFs were found to provide a response 27 × that of structured PCF, also giving a TL yield similar to that of standard TLD-100 chips. Over post-irradiation periods of 15 and 30 days collapsed PCF TL signal fading were 8% and 17% respectively, with corresponding values of 37% and 64% for the structured PCF. Trapping parameters including the order of kinetics (b), activation energy (E) and frequency factor (s-1) were assessed with Chen's peak shape method. Lifetime of trapping centre was found to be (2.36 E+03) s and (9.03 E +01) s regarding the collapsed and structured PCF respectively with 6 Gy of photon beam. For the Ge-doped collapsed PCF, the high TL yield, sensitivity and low fading provide the basis of a highly promising system of TLD for radiotherapy applications.

Luminescence Properties of Rare Earth–Doped Cubic Double Perovskite Tungstate Ba2(1−x)(Na,RE)xZnWO6 (RE = Ce3+, Eu3+ and Dy3+) Phosphors

Herein, the photoluminescence (PL) and thermoluminescence (TL) properties of rare earth doped cubic double perovskite tungstate Ba2(1−x)(Na,RE)xZnWO6 (RE = Ce3+, Eu3+ and Dy3+) phosphors synthesized by the solid‐state reaction method are presented. The self‐luminescence of pure Ba2ZnWO6 material in the blue‐green region is enhanced by Ce3+ doping with its most effective concentration of 3 mol%. The dominant emission in orange (of Eu3+ at 597 nm) and blue (of Dy3+ at 485 nm) region in the emission spectra of Ba2(1−x)(Na,Eu)xZnWO6 and Ba2(1−x)(Na,Dy)xZnWO6 phosphor, respectively, shows highest intensity for 3 mol% of Eu3+ and 2 mol% of Dy3+ ion in the host lattice. The broad excitation band of Ce3+ and Dy3+ doped phosphor in the near UV region claims its candidature for solid‐state lighting. TL studies are also performed using γ‐radiation. Pure host material shows a simple glow curve while the rare earth ion doped phosphor shows a complex glow curve with enhanced intensity. Phosphor shows the fairly linear response up to 1 kGy radiation. Glow curves are deconvoluted and the trap parameters are calculated by Chen's peak shape method.

THERMOLUMINESCENCE AND KINETIC PARAMETERS OF MICRO-NANO MATRIX OF LITHIUM TRIBORATE AND ZINC OXIDE NANOPARTICLE.

This study presents the first report on the kinetic parameters of micro-nano interaction of lithium triborate microparticles doped with zinc oxide nanoparticles (LBZ) in 0.1 to 0.4% dopant concentrations. The parent-dopant mix was synthesized using high-temperature solid-state method. The materials were subjected to X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and differential thermal analysis (DTA) to ascertain their structural, physical properties as well as gamma irradiation and thermoluminescence (TL) analysis for their dosimetric properties. XRD and DTA confirmed the formation of polycrystalline lithium triborate compounds, while SEM and EDS showed the presence of the dopant. TL analysis presented a simple glow curve structure with the main temperature peak for different dopant concentrations varying from 243 to 327°C. The activation energy (E) and frequency factor (s) were calculated for each peak shape parameter τ (low temperature half width), δ (high temperature half-width) and ω (total half width) using Chen's peak shape (PS) method and the order of kinetics was deduced from the symmetry factor (μg) and gamma dose-response curves. The activation energy and frequency factor with respect to the peak shape parameters Eτ, Eδ, Eω and sτ, sδ, sω across the dopant concentrations were in the range of 1.14 to 2.2eV and 3.92 × 1010 to 7.71 × 1022s-1, respectively. Comparing the methods for the determination of the order of kinetics, LBZ 0.2% agrees with the conditions of first-order kinetics, while second-order kinetics is assigned to LBZ 0.1, 0.3 and 0.4%. The results present simple glow curve structure which relates to stability, high-temperature peaks and E values which correspond to deep trap states.

Investigation of thermoluminescence response and trapping parameters of natural barite samples from Dongargaon mine, India.

Dosimetry is a technique that quantitatively measures the ionizing radiation absorbed by matter. The present study was conducted on the barites from a mine at Dongargaon in Central India. Morphological and structural analysis of proposed sample was carried out using X-ray diffraction and standard error of the mean. Thermal analysis and chemical composition of the proposed sample were carried out using thermogravimetric analysis and differential thermal analysis, and electron probe microanalysis. Thermoluminescence (TL) studies on a natural barite sample were performed using a Nucleonix TL1009I TL reader following sample irradiation with γ-rays generated from a 60 Co irradiation source. A broad TL glow curve was observed after TL study that was then deconvoluted using TLanal deconvolution software. Trapping parameters from the sample such as activation energy (E), order of kinetics (b), and frequency factor (s) were calculated using Chen's peak shape method, the initial rise method, and Ilich's method. The results indicated that the natural barite sample could be used in high-dose TL dosimetric applications in various fields.

Thermoluminescence study of sodium aluminosilicate phosphors

Sodium aluminosilicates NaAlSi2O6: Dy and Na6Al6Si10O32: Eu has been synthesized using Combustion method. The formation of Na6Al6Si10O32: Eu phosphor was confirmed by XRD, SEM and FTIR analysis. Thermoluminescence properties of NaAlSi2O6: Dy and Na6Al6Si10O32: Eu after irradiating with 75 MeV O6+ ion beam have been studied and are found to be similar. Both the phosphors show single TL glow peak that is desirable for good dosimeter. Further both NaAlSi2O6: Dy and Na6Al6Si10O32: Eu shows linear TL response for fluence range 1 × 1011 ions/cm2 to 1 × 1012 ions/cm2. The trapping parameters for both the samples were studied using Chen's peak shape method, Initial rise method and Ilich method and found to have good agreement with each other. So, Sodium aluminosilicates NaAlSi2O6: Dy and Na6Al6Si10O32: Eu can be useful in this particular range for their applications in radiation dosimetry.

Thermoluminescence study and evaluation of trapping parameters CaTiO3: RE (RE=Eu3+, Dy3+) phosphor for TLD applications

Thermoluminescence study of RE3+ (RE3+= Eu3+ and Dy3+) activated CaTiO3 phosphors and determination of trapping parameters are the main focus of this work. Here, CaTiO3: X mol % RE3+ phosphors were synthesized by low temperature solution combustion method at 500 ± 20 OC using citric acid as a fuel. Structure, bonding between each element of the sample and morphology of the sample were analyzed using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), which showed that the samples were crystallized in a well known structure. Both the samples were irradiated with 60Co- γ (gamma) source and thermoluminescence studies of both samples were done by Nucleonix TL 1009I thermoluminescence (TL) reader. Chen's peak shape method, Initial rise method and Ilich method are used to determine trapping parameters of both samples like activation energy (E), order of kinetics (b) and frequency factor (s). This all results indicate that both the phosphors are potential candidate for the thermoluminescence dosimetry.

Sub kGy photon irradiation alterations in graphite

Present work concerns polymer pencil-lead graphite (PPLG) and the potential use of these in elucidating irradiation-driven structural alterations. The study provides detailed analysis of radiation-induced structural interaction changes and the associated luminescence that originates from the energy absorption. Thermally stimulated emission from the different occupied defect energy levels reflects the received radiation dose, different for the different diameter PPLGs. The PPLG samples have been exposed to photon irradiation, specifically x-ray doses ranging from 1 to 10 Gy, extended to 30–200 Gy through use of a60Co gamma-ray source. Trapping parameters such as order of kinetics, activation energy and frequency factor are estimated using Chen's peak-shape method for a fixed-dose of 30 Gy. X-ray diffractometry was used to characterize the crystal structure of the PPLG, the aim being to identify the degree of structural order, atomic spacing and lattice constants of the various irradiated PPLG samples. The mean atomic spacing and degree of structural order for the different diameter PPLG are found to be 0.3332 nm and 26.6° respectively. Photoluminescence spectra from PPLG arising from diode laser excitation at 532 nm consist of two adjacent peaks, 602 nm (absorption) and 1074 nm (emission), with mean energy band gap values within the range 1.113–1.133 eV.

Effect of Flux Boric Acid (H3BO3) on Yttrium Silicate Y2SiO5:Dy3+ (9 mol%) Nanophosphors Its Characterization and Luminescence Studies

Flux Boric acid (H3BO3) doped on Y2SiO5:Dy3+ phosphors were synthesized by auto ignition based low temperature Solution Combustion Synthesis (SCS) using Oxalic acid dihydrate (ODH) as fuel. Powder X-ray diffraction (PXRD) patterns confirm the nano sized particles corresponding to JCPDS card 36-1476. The crystallite size of the samples estimated from Scherer's formula and Williamson-Hall (W-H) plots was found to be in the range ˜21 nm and 26 nm respectively. Scanning electron Microscope (SEM) micrographs infer addition of flux gives the enhanced grain growth and it attains smooth surface improves the crystallinity and particle morphology of the sample. Fourier transform Infrared (FTIR) data reveals the presence of M–O bonds and Y–O bonds and also the bands at 642 cm–1, 655 cm–1, 668 cm–1, 697 cm–1, 719 cm–1 are ascribed due to the B–O–B linkage in the borate network. Addition of flux on Thermoluminescence (TL) glow curves from 0.5 KGy–4 KGy acts as a sensitizer and the peak appearing at 185 °C is quite stable and can be named as "dosimetric peak" to use in TL phosphor. The kinetic parameters estimated by Chen's peak shape method was found to be second order with activation energy 0.82.