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Photoacoustic spectroscopy (PAS) has been utilized for the determination of U(IV). Initial experiments were carried out for determination of U(IV) in uranium tetra fluoride, and were further extended to the determination of U(IV) in uranium oxide samples having various O/M ratios like UO 2.00 , UO 2.17 , U 3 O 8 , and U 3 O 7 . All these oxides, since dark gray/black in color, were having featureless spectra in the visible region, hence solid state reaction of uranium oxide with ammonium bi-fluoride was utilized for the formation of U(IV) and U(VI) oxyfluorides, having narrow well resolved spectra, prior to estimation by Photoacoustic spectroscopy technique. The strong absorption for U(IV) complex at 630 nm was monitored using a He–Ne laser resulting in good sensitivity for determination of U(IV). It was observed that fluorinated uranium dioxide (UO 2 ) is having spectra similar to U(IV); fluorinated uranium trioxide (UO 3 ) is having spectra of uranyl only whereas Triuranium octoxide (U 3 O 8 ) spectra consist of both U(IV) and uranyl component. This was further supported by photoluminescence studies.

A glove box adaptation of a high resolution atomic emission spectrometer (AES) is reported employing sequential radial viewing of an inductively coupled plasma (ICP) source for determination of trace metallic elements in plutonium bearing samples. The original compact ICP-AES unit was converted into separate units. All electronic and optical components were placed outside radioactive containment. The entire assembly of the ICP torch, radiofrequency coil, nebulizer, spray chamber, peristaltic pump, and drainage system were placed inside the glove box for the analysis of radioactive samples. All these modifications were achieved without any compromise on the analytical performance of the spectrometer. Operational experience of the instrument for analysis as well as additional information for the upkeep and maintenance of the same is described. Proper optical alignment of the ICP source and detection system was performed.

The luminescence of uranium in strontium borate (SrB4O7, SBO) matrix was investigated by time resolved photoluminescence, thermoluminescence (TSL) and electron spin resonance techniques (ESR). The samples were synthesized using solid state fusion reaction route and characterized by X-ray diffraction. Photoluminescence excitation and emission data suggested the stabilization of uranium as uranate ( UO 6 6 - ) in the matrix. Luminescence decay time data suggested the stabilization of uranium at two different sites in the matrix. By giving suitable delay times and choosing proper gate widths, the two emission spectra due to the two uranate species could be obtained. Thermoluminescence investigation on the gamma-rays irradiated sample showed a strong glow peak at ∼415 K and a weak glow peak at 505 K. The dose response behavior, the trap parameters along with the order of kinetics for the strong glow peak were determined. To pinpoint the exact chemical nature of the defect centers responsible for the observed glow peaks, electron spin resonance technique was employed. Based on the ESR-TSL correlation data and the observed photoluminescence results, a plausible mechanism for the origin of the luminescence in the system was proposed.

Sm3+-doped ZnAl2O4 phosphor was synthesized by citrate sol-gel method and characterized using X-ray diffraction and scanning electron microscopy to identify the crystalline phase and determine the particle size. Photoluminescence (PL) studies on the sample showed emission peaks at 563, 601, 646 and 707 nm with λ ex = 230 nm corresponding to the 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2 and 4G5/2 → 6H11/2 transitions, respectively, due to Sm3+ ions. PL lifetime decay studies confirmed that Sm3+ ions partly entered into the lattice by replacing Al3+ ions and remaining located at the surface of ZnAl2O4 host matrix. Thermally stimulated luminescence (TSL) studies of γ-irradiated Sm3+-doped ZnAl2O4 sample showed two glow peaks at 440 and 495 K, the former being most intense than the latter. The trap parameters were determined using different heating rate methods. Spectral characteristics of the TSL glow showed emission around 565, 599 and 641 nm, indicating the role of Sm3+ ion as the luminescent centre. A probable mechanism for the prominent TSL glow peak, observed at 440 K, was proposed. CIE chromaticity coordinates for the system was evaluated, which suggested that Sm3+-doped ZnAl2O4 could be employed as a potential orange red-emitting phosphor.

ThO2:Eu3+ nanoparticles were synthesized at 300°C by combustion route using urea as a fuel and characterized by thermogravimetric/differential thermal analysis, X-ray diffraction, transmission electron microscopy, and photoluminescence techniques. To investigate the effect of annealing temperature, as synthesized powder were heated further at 500°C, 700°C, and 900°C. It was observed that extent of asymmetry around Eu3+ at 700°C/900°C is very high as compared to as-prepared or 500°C annealed sample. Based on the time resolved emission spectroscopic investigations, it was inferred that two different types of Eu3+ ions were present in the ThO2 nanoparticles. In ThO2 structure, Eu3+ ions occupy two sites; cubic (Oh) and noncubic (

Present work deals with the distribution study of naturally occurring radioactive materials in drinking water samples around Orissa sands complex, Odisha, India and assessment of the comprehensive ingestion dose to members of the public. The mean total effective dose to member of public is found to be 67.1 µSv/y with a range of 13.2–198.5 µSv/y. The average effective dose is below the reference level of 100 µSv/y and also comparable with the range of global annual ingestion dose value reported worldwide. The activity concentration in drinking water reported here is due to natural distribution of radioanuclides.

To probe the speciation and local structure around the uranium atom in strontium pyrophosphate, time resolved emission and Sr K edge EXAFS study was done. From the photoluminescence data it was observed that uranium was present as uranyl at two different sites. By performing time resolved luminescence, the two uranyl species could be identified. From the EXAFS data it was observed that on doping with uranium, the average Sr–O and Sr–P bond lengths increased. The correlation between the EXAFS and luminescence data confirmed the incorporation of the actinide ion at regular lattice positions of Sr ion in the pyrophosphate matrix.

Undoped and Sr 0.995 Gd 0.005 ZrO 3 were prepared by “the gel-combustion route” using citric acid as fuel. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), photoluminescence (PL) and electron paramagnetic resonance (EPR) spectroscopy. Upon UV light excitation (274 nm), the phosphor exhibits a strong and sharp UV emission at 313 nm, which is ascribed to 6 P 7/2 → 8 S 7/2 transition of Gd 3+ ions. Life time spectroscopy showed the presence of two types of Gd 3+ ions. The EPR spectrum of Gd 3+ doped SrZrO 3 exhibits typical U-shape with resonance signals having effective g values at g = 2.0, 2.8, 4.8 and 6.0. The g values at 2.8, 4.8 and 6.0 are due to presence of Gd 3+ ion at Sr 2+ site having high coordination number (C.N = 8) whereas relatively sharp signal at g = 2.0 is attributed to isolated Gd 3+ ion in polycrystalline region.

Time resolved photoluminescence spectroscopic (TRPLS) technique was used to investigate the speciation of Eu ion in alkali barium borosilicate glasses prepared via sol–gel method. The metal ion concentration and the annealing temperature were optimized for best signal intensity. It was observed that the presence of OH groups in the samples reduced the luminescence decay time values. Upon heating the system at higher temperature, the number of OH groups reduced and the lifetime as well as the intensity increased. At elevated temperatures, it was found that Eu was stabilized in two different asymmetric environments having large site distribution. The overall symmetry around the two metal ion sites was estimated to be C 2 . Judd—Ofelt intensity parameters for the metal ion were evaluated in all the samples adopting standard procedure. It was observed that, for all the samples, Ω 2 > Ω 4 . This indicated the existence of a fair degree of covalency in the metal and ligand bonding.

U6+ doped BaSO4 samples were synthesized by precipitation route. PL, TL and EPR investigations of γ and self α irradiated samples were carried out. PL spectra of these samples give structured broad band peaking around 518 nm with five vibronic bands centred around 498·4, 516·0, 533·7, 554·0 and 575·1 nm, respectively and the average frequency of symmetric stretching of O=U=O in the ground electronic state was found to be 674 cm−1. Trap level spectroscopic studies of U doped BaSO4 give glow peaks at 411, 488 and 512 K, respectively and their spectral characteristics are typical of UO $_{2}^{2+}$ emission. EPR studies of γ-irradiated U6+:BaSO4 sample have shown the presence of sulphoxy centred radicals like SO $_{4}^{-}$ and SO $_{3}^{-}$ in addition to OH•, O $_{3}^{-}$ and SH2−. TSL peaks at 411 and 488 K were correlated with thermal destruction of SO $_{4}^{-}$ and SO $_{3}^{-}$ radicals.

This article describes a glove box adaptation of an atomic absorption spectrometer with a graphite furnace as the atomization source. Unlike flame atomic absorption, in which the ground state atoms quickly diffuse out of the atom cell, graphite furnace atomic absorption, being a total consumption technique, offers the ability to de-solvate and atomize the entire sample solution in a more controlled environment. This significantly improves the sensitivity and provides superior detection limits with microliter sample volumes. An atomic absorption instrument was converted into separate modular units consisting of the source, atomizer, and detection system. In addition, these units were modified to enable their use in the glove box, allowing the analysis of nuclear samples. Proper optical alignment of the source, atomizer, and detector system was performed to allow the analysis of toxic samples.

Bastnasite ore obtained from Indian Rare Earth (IRE) was investigated for its possible use as a phosphor material. The material was characterized by X-ray diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), photoacoustic spectroscopy (PAS), photoluminescence (PL) and electron paramagnetic resonance spectroscopy (EPR) techniques. XRD studies revealed the semi processed ore to be consisting of single phase CeO 2 with no other impurities. EDXRF studies revealed the presence of ‘Th’ and traces of ‘Sm’ along with ‘Ce’ in the sample. PAS studies revealed the presence of strong charge transfer from oxygen to cerium in the system. PL studies confirmed the presence of at least four trivalent rare earths, viz. Sm, Eu, Dy and Tb in the system in trace quantities. The emission spectrum and decay time data were evaluated. It was observed that the rare earth ions are situated at distorted sites in the system surrounded by defect centers. EPR studies confirmed the presence of Ce 3+ in the system along with electron trapped in oxygen ion vacancies. CIE indices for the ore sample were evaluated and it was seen that the overall emission from the system was in the ‘magenta’ region of the visible spectrum. The emission intensities were also compared with that of commercial samples.

Graphical abstract: - Highlights: • ThO{sub 2}:Sm{sup 3+} nanoparticles have been synthesized using cationic surfactant assisted reverse micellar route. • HRTEM shows the formation of thoria nanorods. • Photoluminescence investigation shows host as well as samarium ion emission. • Time resolved fluorescence spectroscopy shows the presence of two types of samarium ion in thoria host. - Abstract: Sm{sup 3+} activated thorium oxide nanorods were synthesized by cationic surfactant assisted reverse micellar route. Phase purity, morphological and luminescent properties were investigated by X-ray diffraction, high resolution transmission electron microscopy and photoluminescence spectroscopy. Upon UV light excitation (245 nm), ThO{sub 2}:Sm{sup 3+} exhibited host emission at 447 nm, along with characteristic emission lines of Sm{sup 3+} at 569, 609, 662 and 716 nm. Lifetime spectroscopy shows the presence of two types of Sm{sup 3+} (τ = 1.1 ms and 4.9 ms) with different asymmetric ratios.

White light emitting Sr2SiO4:Eu2+ nanoparticles were prepared using reverse micellar route using Tergitol as a surfactant. The systems were characterised by X-ray diffraction, scanning electron microscopy (SEM), photoluminescence, thermoluminescence (TL), and electron paramagnetic resonance (EPR) spectroscopy. SEM shows the formation of silicate nanorods. Two emission bands of bluish-green at 490 nm (S(I)) and of orange-red at 605 nm (S(II)) were observed. The two emission bands are assigned to the 4f–5d transition of Eu2+ ions in two different cation sites in α′-Sr2SiO4 orthorhombic lattices. Gamma-irradiated Sr2SiO4:Eu showed the presence of three TL glow peaks at 437, 487 K and weak peak at 540 K; however, no glow was observed in the undoped sample. Reduction of Eu3+ to Eu2+ is confirmed by EPR spectroscopy.

Zn1.98Mn0.02P2O7 was synthesized by the wet chemical route. The purity of the phase and the oxidation state of manganese ion were investigated by x-ray diffraction (XRD) and electron paramagnetic resonance (EPR). Structural phase transition in α-Zn2P2O7 was investigated by high-temperature XRD (HTXRD), differential scanning calorimetry (DSC), and EPR studies. There is a distinct signature of phase transitions between 390 and 400 K in our powder sample by EPR and HTXRD. There was a sharp reduction in the volume of unit cell, while going from alpha to beta phase; with discontinuity in 405 K, which confirmed the transition to be of first order. Similarly, the effect of temperature on zero-field splitting parameter (D) also showed that there is a sudden jump (discontinuity) in the value at around 400 K (phase transition temperature) confirming the transition to be of first order. DSC studies corroborated these findings.

UREX process has been proposed for selective extraction of U(VI) and Tc(VII) from nitric acid medium (∼1M HNO3) using tri-n-butyl phosphate (TBP) as extractant and retaining Pu, Np and fission products in the aqueous phase. The feasibility of the use of luminescence spectroscopy as a technique to understand the complexation of trivalent f-elements cations viz. Eu(III) and Tb(III) with acetohydroxamic acid (AHA) in nitric acid medium has been examined. The luminescence lifetimes for the 1×10(-3)M Eu(III) and AHA complex system decreased with increased AHA concentration from 116±0.2μs (no AHA) to 1.6±0.1μs (0.1M AHA) which was attributed to dynamic quenching. The corrected fluorescence intensities were used to calculate the stability constant (log K) for the formation of 1:1 Eu(3+)-AHA complex as 1.42±0.64 under the conditions of this study. By contrast, the Tb(III)-AHA system at pH 3 (HNO3) did not show any significant variation in the life times of the excited state (364±9μs) suggesting the absence of dynamic quenching. The spectral changes in Tb(III)-AHA system showed the formation of 1:1 complex (log K: 1.72±0.21). These studies suggest that the extent of AHA complexation with the rare earth elements will be insignificant as compared to tetravalent metal ions Pu(IV) and Np(IV) under UREX process conditions.

Undoped and ThO2:Ln3+ (Ln = Nd, Ho, and Er) were synthesized by wet chemical route and characterized using X-ray diffraction (XRD). PAS was used to investigate electronic absorption of Nd3+, Ho3+ and Er3+ in thorium dioxide as well as of pure rare earth oxide powder Ln2O3 (Ln = Nd, Ho, and Er). PA spectra were also obtained for aqueous solution of lanthanides for evaluating various covalency parameters. Various covalency parameters like nephelauxetic ratio (β), covalency factor (b1/2) and Sinha parameter (δ) were evaluated for pure oxide powder and for rare earth doped thoria for all these system from their individual PA spectra.

To study the batch sorption of Eu(III) by different phases of titania viz. amorphous, anatase and rutile, amorphous titania was synthesized by organic route, followed by annealation to prepare anatase and rutile. Characterization of these phases was done by zeta potential measurement and potentiometric titration. Eu(III) sorption by titania phases increases with pH, pH50 (pH corresponding to 50% sorption) being lower in case of rutile than other two. Sorption edges for anatase and amorphous titania overlap on normalizing the data with specific surface area of particles. Surface complexation modelling of sorption data reveals the formation of higher hydrolysed Eu(III) surface species (TiEu(OH)2) on rutile compared to other two phases (TiOEu(OH)+). Consideration of bidentate surface complex for anatase and rutile gave equally good fit. Time resolved fluorescence spectroscopy showed higher lifetime for Eu sorbed on rutile, suggesting higher binding for Eu(III) in the surface complex. Keeping in view the regular arrangement of Ti octahedron on rutile surface, rutile surface can have more bidentate surface complex in comparison to other two phases. These results indicate the simultaneous existence of monodentate and bidentate surface complexes of Eu(III) on titania surfaces, with rutile having higher proportion of bidentate complex.

Trivalent dysprosium-doped strontium silicate (Sr 2 SiO 4 ) phosphors were prepared by sol–gel synthesis using tetra ethyl orthosilicate (TEOS) as precursor. The synthesis temperature could be brought down to 600 °C for formation of a single phase sample. The material was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), photoluminescence (PL), and thermally stimulated luminescence (TSL). The luminescence study revealed strong 4 F 9/2 → 6 H 13/2 transition at 577 nm (yellow), strong 4 F 9/2 → 6 H 15/2 transition at 482 nm (blue) and weak 4 F 9/2 → 6 H 11/2 transition at 677 nm (red), when excited by 250 nm (Charge transfer band, CTB) or 352 nm (f–f band). The concentration of the dopant ion and the temperature of annealing were optimized for maximum PL intensity. The critical energy-transfer distance for the Dy 3+ ions was evaluated based on which, the quenching mechanism was verified to be a multipole–multipole interaction. The thermally stimulated luminescence studies of Sr 2 SiO 4 :Dy 3+ sample showed main TSL glow peak at 413 K. The trap parameters namely activation energy ( E ), order of kinetics ( b ), and frequency factor ( s ) for this peak were determined using glow curve shape method.

Due to the multi-electronic nature, uranium is having line rich emission spectra and is expected to interfere during the determination of analytes at the trace level in uranium matrix. Therefore, chemical separation of uranium followed by the determination of trace metallic impurities in the raffinate by ICP-AES is generally adopted procedure in nuclear industries. There is restriction on choosing alternate analytical lines of elements by photomultiplier tube based ICP-AES associated with the polychromator while monochromator needs significant time to scan different analytical lines of all the elements. Since charged coupled detector (CCD) consists of array of pixels, it is having more option in choosing alternative analytical lines of the analytes. Therefore, an attempt was made to study the spectral interference of uranium on different analytical lines of analytes viz. Al, Ga, In, Si, Li, Ti, Mg, Sr, K, Ce, Nd, Lu, Sc, V, Er, Y, Ba, Bi, Pb, W, La, Tl, Sn, Yb, Mo, Sb, Pr and Zr; and the correction factors were evaluated (where ever necessary) using CCD based ICP-AES technique. The sensitivity and the detection limits of the analytical channels of the elements in presence of uranium matrix were calculated. The present study also deals with the identification of suitable analytical lines of uranium and its detection limits.

Synthesis, X-ray diffraction and photoluminescence investigations of Eu3+-doped SrBPO5 phosphor has been carried out in order to characterize the material. PL emission spectrum of air heated SrBPO5:Eu3+ phosphor exhibits bands at 590, 614, 651 and 702 nm under 238 nm excitation, assigned to the 5D0→7FJ (J=1, 2, 3, 4) transitions of Eu3+ ions. Of these transitions, the emission centered at 614 nm is the most prominent. Photoluminescence decay time and Time-resolved emission spectrometric (TRES) studies of Eu3+ were carried out with λem=614 nm and λex=238 nm. It suggested that Eu3+ ions are present at two different sites and predominantly occupying Sr2+ sites in the host lattice. Judd–Ofelt intensity parameters and other radiative properties were evaluated from the emission spectrum by adopting standard procedure. The trend observed in the J–O parameters (Ω2>Ω4) confirms the covalency exiting between the Eu3+ ion and ligands as well as the asymmetry around the metal ion site. The color coordinates of the system were evaluated (x=0.558 and y=0.355) and plotted on a standard CIE index diagram. The observations showed that the SrBPO5:Eu3+ phosphor is very close to the red emission material. Photoluminescence intensity was compared with that of a commercial red phosphor for commercial utility purpose. It is observed that, the photoluminescence intensity of the prepared phosphor was 60% as compared to the commercial phosphor Y2O3: Eu.

Eu3+-doped ZnAl2O4 phosphors were successfully synthesized in air atmosphere at 900 °C. The phosphors were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermally stimulated luminescence (TSL) and photoluminescence (PL) techniques. The average particle size of the system as determined from SEM was found to be 100–150 nm (for samples annealed at 900 °C). PL spectra of the doped phosphors showed emission peaks corresponding to Eu3+ ions. Lifetime studies revealed Eu3+ ions to be in two different sites. The asymmetric ratio (I616/I592) was observed to be about 3.75. This suggested that Eu3+ ion entered the host mainly substituting Al3+ site distorting the local environment and is partly located on surface of the phosphors. A prominent glow peak at 430 K was observed in the TSL of γ-irradiated Eu3+-doped ZnAl2O4 phosphors. Trap parameters for this peak have been determined and the probable mechanism for the glow peak is proposed. CIE chromaticity coordinates for the system were evaluated. It was observed that, the system could be employed as a potential red emitting phosphor. Commercial utility of the phosphor was investigated by comparing it with commercial red phosphor. The PL intensity of the as prepared phosphors was 63% of that of the commercial phosphor. Apart from this, various radiative properties such as the Judd–Ofelt intensity parameters, spontaneous emission probabilities, luminescence branching ratios, radiative lifetimes and quantum efficiency were evaluated for the system.

Trivalent dysprosium-doped strontium zirconate perovskite (SrZrO3) phosphors were prepared by gel-combustion synthesis using citric acid as fuel and ammonium nitrate as oxidizer. X-ray diffraction patterns confirmed the formation of orthorhombic phase of SrZrO3 with minor impurity, which completely disappears at high temperature. The morphological investigation was carried out using scanning electron microscopy (SEM). Photoluminescence studies showed that no emission from the host is observed, indicating the efficient energy transfer from the ZrO32− group to Dy3+ ions. The emission line is purely because of f–f transitions of Dy3+. Moreover, these phosphors predominantly exhibit near white light emission, when excited by 229 nm UV light due to strong 4F9/2→6H13/2 transition at 577 nm (yellow), strong 4F9/2→6H15/2 transition at 482 nm (blue), and weak 4F9/2→6H9/2 transition at 677 nm (red). Enhancement in emission intensity was observed with increase in the annealing temperature of the phosphor. The CIE chromaticity coordinates of the SrZrO3:Dy3+ phosphors were observed to fall in the white light domain of the chromaticity diagram, which indicate that such fine tuning might be possible after varying the temperature of annealing.

Alkali-based barium borosilicate glasses having similar composition to the Trombay nuclear research reactor waste base glass containing iron were prepared and irradiated by gamma rays. The radiation-induced defect centers were investigated using electron paramagnetic resonance (EPR) technique. The results showed the formation of silicon hole centers and electron trap centers apart from boron-based oxy hole centers in the glass due to the irradiation. The EPR Hamiltonian parameters for these radicals were evaluated by simulation technique using Bruker SIMFONIA computer program. Glasses with varying iron content were irradiated with the same dose to evaluate the effect of iron content on the defect center concentration. A spin counting technique was employed to evaluate the number of defect centers produced in each glass. It was observed that the defect center concentration reduced as a function of increasing iron content. This was attributed to the charge trapping process of ferric ions in the amorphous system.

Americium from analytical solid waste containing U and metallic impurities was separated using hollow fiber supported liquid membrane (HFSLM) technique impregnated with DHOA–TODGA from nitric acid medium. An aliquot of 5 g of the solid waste containing Am (19.95 mg) as minor actinide and of U (2,588 mg), Fe (1,360 mg), Ca (1,810 mg) and Na (3,130 mg) as major impurities was processed. The feed solution obtained after the dissolution of the residue in ~4 M HNO3 was passed through HFSLM module. In the first stage using 1 M DHOA–dodecane U was recovered while Am and other impurities were left in the raffinate. In the second stage, 0.5 M DHOA + 0.1 M TODGA/dodecane was used for the separation of Am from other impurities. Though, majority of the elements were separated in this cycle, Ca was co extracted along with the americium. CMPO extraction chromatographic technique was used for further separation of americium from Ca. Significant decontamination factors were achieved in this three step separation process with respect to U, Fe, Na and Ca with ~77 % recovery of americium.

Strontium silicate (Sr 2 SiO 4 ) samples doped with varying Eu 3+ content were prepared via sol–gel route and characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), dynamic light scattering (DLS) and photoluminescence (PL) techniques. The synthesis temperature could be brought down to 600 °C for formation of a singe phase sample. The concentration of the dopant ion and the temperature of annealing were optimized for maximum PL intensity. The critical energy-transfer distance for the Eu 3+ ions was evaluated based on which the quenching mechanism was verified to be a multipole–multipole interaction. Based on the time-resolved emission data (TRES), it was inferred that, two different types of Eu 3+ ions were present in the matrix. The first type was a long lived species ( τ =4.7 ms) present at 10-coordinated ‘Sr’sites and the other was a short lived species ( τ =1.2 ms) present at the 9-coordinated ‘Sr’sites which gets selectively excited at 296 nm. Judd–Ofelt ( J – O ) intensity parameters for both the species were evaluated. The trend observed for the two species in the J – O parameters, Ω 2 and Ω 4 were different confirming their existence in two different environments. The color coordinates of the system were evaluated and plotted on a CIE index diagram. Commercial utility of the phosphor was investigated by comparing it with commercial red phosphor.

Vanadate garnet systems namely Ca 2 NaMg 2 V 3 O 12 , individually doped with Dy and Sm and also co-doped with both the RE ions were synthesized via the solid-state reaction route and their photoluminescence (PL) properties were investigated. The method of synthesis was verified by the formation of single phase compound through X-ray diffraction (XRD) studies. Existence of energy transfer in between the host and the dopant ions was established by PL investigation. Color coordinates of all the compounds were calculated and plotted on the CIE diagram. It was seen that the co-doped system has a near white light emission. It was concluded that this single phosphor is capable of converting the ultraviolet emission of a UV-LED into white light.

Due to the scarcity of good quality uranium resources, the growth of nuclear technology in India is dependent on the utilization of the vast thorium resources. Therefore, Advance Heavy Water Reactor is going to acquire significant role in the scenario of Indian nuclear technology, where (Th, Pu)O2 will be utilized as fuel in the outermost ring of the reactor core. This will lead to a complex matrix containing thorium as well as americium, which is formed due to β- decay of plutonium. The amount of americium is dependent on the burn up and the storage time of the Pu based fuels. In the present case, attempt was made to develop a method for the determination of americium as well as thorium by ICP-AES. Two emission lines of americium were identified and calibration curves were established for determination of americium. Though the detection limit of 283.236 nm line (5 ng mL−1) of americium was found to be better than that of 408.930 nm (11 ng mL−1), the former line is significantly interfered by large amount of thorium. Three analytical lines (i.e. 283.242, 283.730 and 401.913 nm) of thorium were identified and calibration curves were established along with their detection limits. It was observed that 283.242 and 401.913 nm line are having similar detection limits (18 and 13 ng mL−1, respectively) which are better than that of 283.730 nm (60 ng mL−1). This can be attributed to the high background of 283.273 nm channel of thorium. The spectral interference study revealed that even small amount of americium has significant contribution on 283.242 nm channel of thorium while the other two channels remain practically unaffected. Considering both these facts, spectral interference and analytical performance (detection limits and sensitivity), it was concluded that 401.913 nm line is the best analytical line out of the three lines for determination of thorium in presence of americium.

Three diglycolamide functionalized calix[4]arenes (calix[4]-nDGA) were synthesized and evaluated for their extraction behaviour towards lanthanide/actinide ions. Exceptionally high D(Am) and D(Pu) values indicate these radiotoxic elements can be selectively removed from nuclear waste solutions. Transport and laser induced fluorescence studies indicated strong complexation of the trivalent metal ions with the calix[4]-4DGA ligand.

Nano-fluorides with attractive optical properties have been proposed as potential phosphors for solid state lighting and bio-applications. In the present work, redispersible YF3: Ln3+ and YF3: Ce3+/Ln3+ nanocrystals were obtained by a simple one step ethylene glycol mediated soft chemical synthesis. Uniformly distributed nanoparticles with a leaf-like morphology and particle size of 10–15 nm were observed. X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FT-IR), photoluminescence (PL) and decay studies were employed to characterize the samples. The highly intense emissions of various activators (Dy3+, Tb3+, Eu3+ and Sm3+) in the presence of Ce3+, their long lifetimes (∼ms) and significant reduction in the lifetime of Ce3+ proved an efficient energy transfer operating in the nanocrystals. The time resolved emission studies indicated towards the presence of two different sites for the activator ions. Under ultraviolet irradiation, the emission color of YF3: Ce3+/Ln3+ nanophosphors can be easily tuned by changing the Ln3+ ions. Bright blue (Dy3+), green (Tb3+), red (Eu3+) and purple (Sm3+) emissions were observed from corresponding YF3: Ce3+, Ln3+ nanocrystals under ultraviolet light.

SrZrO3:Eu3+ nanoparticles with a size of about 100 nm were synthesized by a simple gel combustion route and characterized by X-ray diffraction, scanning electron microscopy, dynamic light scattering, and photoluminescence techniques. Based on the time-resolved emission data, it was inferred that three different types of Eu3+ ions were present in the matrix. The first type was a long-lived species (~τ = 6.0 ms) present at symmetric “Sr2+” sites, observed for excitations at 229 and 393 nm. The second was a short-lived species (τ = 1.0 ms) observed for excitations at 229, 296, and 393 nm, while for 296-nm excitation, a long-lived species (τ = 4.0 ms) was also observed. This suggested that Eu3+ ions can be present at relatively lower symmetric “Zr4+” sites with two different environments, which differ in the presence of charge-compensating defects. The color coordinates of the system were evaluated and plotted on a CIE index diagram.

Eu 3+ doped boro-tellurite glasses with the chemical composition (69 − x )B 2 O 3 – x TeO 2 –15Mg 2 O–15K 2 O–1Eu 2 O 3 (where x = 0, 10, 20, 30 and 40 wt%) have been synthesized and its thermal, structural and spectroscopic behavior were studied and reported. The thermal behavior of the Eu 3+ doped boro-tellurite glasses were explored through DTA thermograms. The presence of varying tellurium dioxide results in structural and spectroscopic changes around Eu 3+ ions and are explored through XRD, FTIR, UV–vis, Luminescence and lifetime measurements. The XRD pattern confirms the amorphous nature and the FTIR spectra reveal the formation of the local structural units BO 3 and BO 4 in the prepared glasses. The bonding parameters ( β and δ ) have been calculated based on the observed band positions of the absorption spectra. The Judd–Ofelt (JO) parameters were determined from the absorption and luminescence spectra and the results are presented. The variation in the JO intensity parameters Ω λ ( λ = 2, 4 and 6) and the hypersensitive band positions with the change in chemical composition have been discussed in detail. The JO parameters have been used to derive important radiative properties like transition probabilities ( A ), branching ratios ( β R ) and peak stimulated emission cross section ( σE / P ) for the 5 D 0 → 7 F J ( J = 1, 2, 3 and 4) transitions of the Eu 3+ ions. The varying optical properties of the prepared glasses with the change in tellurium dioxide have been studied and compared with similar results.

During the simultaneous extraction of plutonium and uranium using anion exchange chromatographic technique from analytical waste in hydrochloric acid medium, 241Am which is invariably present in the plutonium bearing fuel samples remains in the effluent. A two step separation scheme was developed for the recovery and purification of Am from the assorted waste to facilitate the disposal of large volume of aqueous waste and the purified Am solution was utilized for spectroscopic investigation. The separation scheme involved solvent extraction using 0.1 M TODGA + 0.5 M DHOA for separation of americium from Fe, Pb, Ni and Na followed by extraction chromatographic technique using CMPO on inert support as stationary phase for separation of Ca from Am. A systematic study on the extraction behavior of Am from hydrochloric acid medium revealed that out of four extraction systems well known for actinide partitioning namely 0.1 M TODGA + 0.5 M DHOA, 1 M DMDBTDMA, 0.2 M CMPO + 1.2 M TBP and 30% TRPO, only 0.1 M TODGA + 0.5 M DHOA extracts americium from 7.5 M HCl feed acidity. A comparative study involving CMPO solvent extraction and column chromatographic technique revealed that elution of Am from column is satisfactory as compared to inefficient stripping of Am from organic phase in solvent extraction technique using 0.1 M HNO3. The purity of the final solution was checked for 17 elements of interest and was found to be 98% pure, while the overall recovery of this two step separation scheme was found to be 95%.

Spectroscopic investigations were carried out on electron beam irradiated sodium barium borosilicate glasses, which is the base glass for immobilization of nuclear high level radioactive waste, generated from the research reactors at Bhabha Atomic Research Centre, Trombay. This was done in order to access the defects generated in it under long term irradiation. Electron paramagnetic resonance was used to identify the defect centers generated in the borosilicate glass after irradiation. In addition, positron annihilation spectroscopy and infrared investigations were done on the samples to evaluate the radiation induced changes in the glass. It was found that, boron–oxygen and silicon based hole centers along with E′ centers are getting formed in the glass after irradiation due to the breaking of the Si O bonds at regular tetrahedron sites of Si O Si. The positron annihilation spectroscopy data gave an idea regarding the free volume size and fraction of the glasses before and after irradiation. It was seen that, after irradiation the free volume size in the glass increased with creation of additional sites. Microwave power variation and temperature variation studies suggested the formation of at least five different radicals in the irradiated glasses. The spin Hamiltonian parameter of all the radical species were determined by computer simulation. An electron paramagnetic resonance spin counting technique was employed to evaluate the defect concentration in the glasses after irradiation.

Gamma radiation induced changes were investigated in sodium–barium borosilicate glasses containing Eu. The glass composition was similar to that of nuclear waste glasses used for vitrifying Trombay research reactor nuclear waste at Bhabha Atomic Research Centre, India. Photoluminescence (PL) and electron paramagnetic resonance (EPR) techniques were used to study the speciation of the rare earth (RE) ion in the matrix before and after gamma irradiation. Judd–Ofelt ( J – O ) analyses of the emission spectra were done before and after irradiation. The spin counting technique was employed to quantify the number of defect centres formed in the glass at the highest gamma dose studied. PL data suggested the stabilisation of the trivalent RE ion in the borosilicate glass matrix both before and after irradiation. It was also observed that, the RE ion distributes itself in two different environments in the irradiated glass. From the EPR data it was observed that, boron oxygen hole centre based radicals are the predominant defect centres produced in the glass after irradiation along with small amount of E’ centres. From the spin counting studies the concentration of defect centres in the glass was calculated to be 350 ppm at 900 kGy. This indicated the fact that bulk of the glass remained unaffected after gamma irradiation up to 900 kGy.

Trap level spectroscopic studies were carried out on γ-irradiated Tb (1 mole%) doped SrBPO5 were carried out using photoluminescence (PL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) techniques. The incorporation of Tb in the 3+ oxidation state was ascertained from PL studies. Life time for Tb3+ emission corresponding to the intense transition 5D4 → 7F5 at 543 nm was determined. The spectral characteristics of the TSL glows have shown that Tb3+ ions act as the emission center for the glow peak at 475 K. The trap parameters of the glow peak were determined. EPR investigations at room temperature/77 K revealed the stabilization of three boron oxygen hole trapped centers (BOHC's) and oxygen centered radicals such as O− and O2− and trapped electrons in room temperature γ-irradiated samples. TSL glow peak at 475 K was found to be associated with recombination of electron released from trapped electron center and the BOHC2 center.

Trace metallic impurity analysis by spectroscopic techniques is one of the important steps of chemical quality control of nuclear fuel materials. Depending on the burn-up and the storage time of the fuel, there is an accumulation of 241Am in plutonium based fuel materials due to β decay of 241Pu. In this paper, attempts were made to develop a method for separation of 241Am from 1.2 kg of analytical solid waste containing 70% U, 23% Pu, 5% Ag and 1–2% C as major constituents along with other minor constituents generated during trace metal assay of plutonium based fuel samples by d. c. arc carrier distillation atomic emission spectrometry. A combination of ion exchange, solvent extraction and precipitation methods were carried out to separate ~45 mg of 241Am as Am(NO3)3 from 15 L of the analytical waste solution. Dowex 1×4 ion exchange chromatographic method was used for separation of Pu whereas 30% TBP–kerosene was utilized for separation of U. Am was separated from other impurities by fluoride precipitation followed by conversion to nitrate. The recovery of Pu from ion exchange chromatographic separation step was ~93% while the cumulative recovery of Am after separation process was found to be ~90%.

DHOA (Di-n-hexyl-octanamide) is one of the alternative extractants to TBP (tri-n-butyl phosphate) known for the extraction of uranium from moderate nitric acid medium without significant extraction of the fission products. Analytical application of DHOA was explored to develop a methodology for determination of trace metallic constituents in uranium based nuclear materials. This involved the separation of uranium matrix by 1.1 M DHOA-dodecane followed by the analysis of the raffinate for trace constituents by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). A systematic study showed that four contacts of 1.1 M DHOA-dodecane were required for quantitative extraction of U from 4 M HNO3 feed for the sample size of 1 g in 10 mL. The feasibility of using DHOA for extraction of U from trace metallic constituents in U based fuel materials without losing trace quantities of analytes of interest was studied by using synthetic samples after appropriate spiking of common impurities and critical elements at their required specification limits (common elements—5 ppm, critical elements—1 ppm). A systematic study was carried out to compare the analytical performance of DHOA with TBP, which revealed that DHOA could successfully be employed for the determination of 19 trace constituents with lower estimation limits of 5 ppm for common impurities and 1 ppm for critical elements.

Lithium titanate ceramics doped with Eu were synthesized and their photoluminescence (PL) and emission spectral characteristics were investigated. PL spectra of the sample showed peaks corresponding to the 5D0→7FJ (J=0, 1, 2, 3 and 4) transitions under 230 nm excitation. The fluorescence lifetimes of Eu3+ ions were found out to be 645 μs. Strong red emission coming from the hypersensitive 5D0→7F2 transition of Eu3+ ion suggested the presence of the dopant ion in highly asymmetric environment. Further analysis of the emission spectrum revealed that the symmetry of the metal ion is very low i.e. C2. The emission intensity of the sample was compared with a commercial phosphor to get an idea about the commercial utility of the phosphor. Various emission properties for the system namely Judd–Ofelt intensity parameters, spontaneous emission probabilities, branching ratios, radiative lifetimes and quantum efficiency were evaluated for the dopant ion by adopting standard procedure.

Sorption of Eu(III) by silica from aqueous solutions of varying pH (4.0–8.0), fixed ionic strength of 0.1 M (NaClO4) and at room temperature has been studied by batch sorption experiments as well as time resolved fluorescence spectroscopy (TRFS). The percentage sorption of Eu(III) (5.0 × 10−5 M) by silica was found to increase with the pH of the suspension and remaining close to 100% beyond pH 7.0. In the presence of alpha hydroxy isobutyric acid (HIBA) (2.5 × 10−3 M) the sorption edge was shifted to higher pH indicating decreased sorption, in the pH range of 5.5–7.0, with respect to that in absence of HIBA. The supernatant solutions of Eu(III) equilibrated silica suspensions were found to have significant concentration of silicon, indicating dissolution of silica. The complexation of Eu(III) by silicic acid dominated the speciation of Eu(III) even in the presence of HIBA. TRFS measurements of the Eu(III) sorbed on silica showed two components, with life time close to 150 and 400 s. This information has been used in the surface complexation modeling (SCM), which explains the sorption data in terms of two surface complexes, namely (SiO)2Eu+, and (SiO)2Eu(OSi(OH)3)2−.

An analytical method was developed for the determination of indium and gallium in plutonium samples. A solvent extraction technique was employed by using 30% TBP in CCl4 for the quantitative separation of plutonium from the sample solution and subsequent determination by radial inductively coupled plasma atomic emission spectrometry (ICP-AES). The quantitative recovery of In and Ga in the separated samples was confirmed from radiometric/tracer studies. Recording of spectral profile at 303.396 nm for In and 403.298 nm for Ga has clearly indicated that the determination of Ga and In at lower concentrations will be affected by the presence of significant amounts of residual Pu in the aqueous phase due to spectral interference. These elements can be determined from ppm to % HNO3 and appropriate (100 mg and 1 g) sample size. The analytical range obtained for Ga and In was 0.1–1000 μg/mL and 0.05–500 μg/mL respectively by ICP-AES. Synthetic samples of plutonium containing indium and gallium in the range of 50–20000 ppm were analyzed.

Europium (Eu 3+ ) activated strontium fluoropatite (Sr 5 (PO 4 ) 3 F) phosphor powders were prepared by a combustion method. The structure and luminescence properties of this potential red emitting phosphor are explored. In order to improve the luminescent properties the obtained powders were also annealed at 900 and 1200 °C. The X-ray diffraction (XRD) data indicated that the major crystalline phases from the as-prepared or annealed powder samples were identical to the hexagonal apatite structure of Sr 5 (PO 4 ) 3 F. The Eu 3+ occupied two different sites (C s (S1) and C 3 (S2)) of Sr in the Sr 5 (PO 4 ) 3 F host, giving rise to two emission sites, as inferred from the time resolved luminescence spectroscopy (TRES) data. The photoluminescence (PL) intensity of Eu 3+ from the as prepared sample was found to be more intense than the annealed samples. In addition from the PL data it was evident that a reduction of the Eu 3+ to Eu 2+ occurred.

Lithium titanate ceramics doped with three rare earth (RE) ions namely Eu 3+ , Dy 3+ and Tb 3+ were synthesized and their photoluminescence (PL) properties were investigated. PL spectra of Eu doped sample showed peaks corresponding to the 5 D 0 → 7 F j ( j =0, 1, 2, 3 and 4) transitions under 230 nm excitation. Strong red emission coming from the hypersensitive 5 D 0 → 7 F 2 transition of Eu 3+ ion suggested the presence of the dopant ion in a highly asymmetric environment. Dy doped samples showed the Dy 3+ emission characteristic due to 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions. Their relative intensity ratios also suggested the presence of asymmetric environment around the metal ion. In case of the Tb 3+ doped sample blue-green emission corresponding to the 5 D 4 → 7 F j ( j =6, 5 and 4) transitions was seen. The fluorescence lifetimes of Eu 3+ , Dy 3+ and Tb 3+ ions were found to be 645, 900 and 740 μs, respectively. PL intensity of the individual rare earth doped samples was compared with commercial red and green phosphors. It was found that the emission from Eu doped titanate sample was 46% of the commercial red phosphor and in case of the Tb samples it was 30% when excited at 230 nm. However, the synthesized Eu doped titanate sample showed better color purity as compared to the commercial phosphor. The titanate host was doped with all the three rare earths to get white light emission from the system. The individual rare earth ion content was optimized so as to get a near white light emission. The color coordinates of the triple doped systems were evaluated and plotted on the CIE x – y diagram. Our results suggest that lithium titanate has enough potential to be a phosphor material.

Rare earth ion (Eu and Gd) bearing sodium–barium borosilicate glasses, used for vitrification of Trombay research rector nuclear waste were characterized by photoluminescence (PL) technique. This was done in order to identify the oxidation states and the coordination geometries of the ions in the glass matrix. It was observed that both the RE ions were stabilized in their 3+ oxidation state in an asymmetric geometry. Spectral analysis of the Eu-glass was carried out to evaluate the J–O intensity parameters and various radiative properties such as radiative transition rate (AR), radiative and non-radiative lifetimes (τR and τNR) and luminescence branching ratio (βR). These properties suggested that amount of covalence existing between the rare earth ions and surrounding oxygens is relatively higher and there is existence of short range ordering in the glass.

Synthesis, X-ray diffraction, and photoluminescence (PL) investigations of SrZnO2 doped with Eu3+ were carried out in order to characterize the material. The emission spectra showed a broad band emission at 525 nm attributed to oxygen defect centers in the host matrix, along with peaks corresponding to the 5D0 → 7Fj (j = 1, 2) transitions of Eu ion under 250 nm excitation. PL decay time studies were done to confirm these investigations. Time-resolved emission spectrometric (TRES) study was carried out to extract the emission spectra of the Eu ion which was buried under the broad band emission. After giving suitable delay times and by choosing a proper time gate, transitions due to 5D0 → 7Fj (j = 0, 1, 2, 3, and 4) could be observed. Judd–Ofelt intensity parameters and other radiative properties for the system were evaluated from this emission spectrum and decay time data by adopting standard procedure. The color coordinates of the system were also evaluated and plotted on a standard CIE index diagram. The observations showed that the SrZnO2:Eu3+material has near white light emission (also considering the emission from host) whereas, the extracted emission spectrum due to only Eu ions has a near red emission.

A variety of serpentines collected from Cuddapah region of India was investigated through X-ray diffraction (XRD), photoacoustic spectroscopy (PAS) and electron paramagnetic resonance (EPR) studies. XRD studies indicated the presence of only one phase in one of the serpentines (sample 1) whereas three other serpentines (samples 2, 3 and 4) were either biphasic or triphasic. The deconvoluted PAS spectra showed prominent peaks around 350, 374, 440, 510, 630 and 850 nm. According to the ligand field theory, these peaks were attributed to the presence of isolated Fe3+ and Fe2+ ions. EPR studies revealed the presence of Mn2+ in octahedral site (g = 2.004, D = 80 G, AMn = 95 G) and spin counting suggested that it was present at trace level. Apart from this, two more signals at g = 4.2 and g = 2.00 were observed and were assigned to Fe3+ ions at tetrahedral and octahedral sites. An unusually broad EPR signal was observed at room temperature in samples 2, 3 and 4, which was attributed to the presence of iron clusters or MgFe2O4.

Photoluminescence (PL) and photoacoustic spectroscopic (PAS) studies were performed on uranium oxide and uranium oxide and thorium oxide immobilized in sodium barium borosilicate glasses. The glass composition was similar to that of the proposed Advanced Heavy Water Reactor nuclear waste glass. These investigations were aimed at understanding the oxidation state and coordination behavior of the uranium ion in the glass matrix and the effect of Th codoping on them. The PL spectrum of both the glasses showed a green emission band at 538 nm without any vibronic structure along with excitation peaks at 275, 323, 348, and 412 nm. These data indicated the presence of uranium as uranate (UO6)6− in the glass matrix. On codoping with Th, PL emission output as well as the lifetime was reduced. PAS utilizing nonradiative energy transfer revealed absorption peaks at 348 and 412 nm, similar to those in the excitation spectrum indicating the stabilization of uranium in the hexavalent state. No absorbance peak corresponding to tetravalent U was observed. In accordance with the PL data, the PAS data revealed that the incorporation of ThO2 produces additional defect centers in the glass structure.

Energy dispersive X-ray fluorescence (EDXRF) methods have been developed for the direct determination of 14 trace metallic impurities in graphite powder without any need for sample dissolution. Using synthetic standards, calibration curves were established for different elements after optimizing the spectrometer parameters. Two synthetic samples were analyzed to evaluate the performance of the developed analytical methods. The estimates for most of the analytes were in good agreement with the added amounts. Three graphite powder samples were analyzed by the present method as well as by D.C. arc emission spectrometric technique for comparison and the agreement between the analyte values determined, using both methods was good. Samples in pellet form were analyzed using a separate calibration with standards in pellet form. The present method is rapid, as it alleviates the need for any chemical treatment and gives good precision.

Al 2 O 3 :Si,Ti, prepared under oxidizing condition at high temperature, gives PL emission around 430 nm when excited with 240 nm. The Al 2 O 3 :C, TL/OSL phosphor, also shows emission around 430 nm, which corresponds to characteristic emission of F-center. Thus, to identify the exact nature of luminescent center in Al 2 O 3 :Si,Ti, fluorescence lifetime measurement studies were carried out along with the PL,TL and OSL studies. The PL and TL in Al 2 O 3 :Si,Ti show emission around 430 nm and the time-resolved fluorescence studies show lifetime of about 43 μs for the 430 nm emission, which is much smaller than the reported lifetime of ∼35 ms for the 430 nm emission (F-center emission) in Al 2 O 3 :C phosphor. Therefore, the emission observed in Al 2 O 3 :Si,Ti phosphor was assigned to Ti 4+ charge transfer transition. Fluorescence studies of Al 2 O 3 :Si,Ti do not show any traces of F and F + centers. Also, Ti 4+ does not show any change in the charge state after gamma-irradiation. On the basis of the above studies, a mechanism for TSL/OSL process in Al 2 O 3 :Si,Ti is proposed.