Neha Tiwari

Thermoluminescence glow curve for UV induced ZrO2:Ti phosphor with variable concentration of dopant and various heating rate

Abstract The present paper reports the synthesis and characterization of Ti doped ZrO2 nanophosphors. The effects of variable concentration of titanium on thermoluminescence (TL) behaviour are studied. The samples were prepared by combustion a synthesis technique which is suitable for less time taking techniques also for large scale production for nano phosphors. The starting material used for sample preparation are Zr(NO3)3 and Ti(NO3)3 and urea used as a fuel. The prepared sample was characterized by X-ray diffraction technique (XRD) with variable concentration of Ti (0.05–0.5mol%) there is no any phase change found with increase the concentration of Ti. Sample shows cubic structure and the particle size calculated by Scherers formula. The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM) technique for optimized concentration of dopant. The good connectivity with grains and the semi-sphere like structure was found by FEGSEM. The functional group analysis was determined by Fourier transform infrared (FTIR) spectroscopic techniques. The prepared phosphor examined by thermoluminescence technique. For recording TL glow curve every time 2mg phosphor was irradiated by UV 254nm source and fixed the heating rate at 5°Cs−1. Sample shows well resolved peak at 167°C with a shoulder peak at 376°C. The higher temperature peak shows the well stability and less fading in prepared phosphor. Also the effect of Ti concentration at fixed UV exposure time was studied. The effect of UV exposure time and dose versus intensity plot was studied. Sample shows linear response with dose and broaden peak with high temperature shows the more stability and less fading in TL glow curve. The linear dose response, high stability and less fading phenomenon shows the sample may be useful for thermoluminescence dosimetry application. Trapping parameters are calculated for every recorded glow curve. The prepared phosphor with optimized concentration of dopant was studied for various heating rate method. The various heating rate (3°Cs−1 to 5°Cs−1) shows shifting in TL glow peaks at higher temperature side. That is opposite behaviour shows in TL glow curve with various heating rate method. The presence of transition metal ions changes (Ti) the TL glow curve structure either enhancing or quenching the TL efficiency. These changes are a consequence of the crystalline field perturbation due to the different characteristics of the dopant ions which supposedly replaces the Zr4+ sites. The traps and the glow curve structure are also dependent upon the morphology of the surface area which in turn depends on the nanocrystallite size. The nanocrystallite size depends also on the dopant ion. Furthermore, the obtained experimental results show that the presence of dopant ions also modifies the TL recombination efficiency which was found to be different for each irradiation type and the specific exposed material. It is important to notice that using the right dopant concentration, it is possible to maximize the TL efficiency and improve sensitivity and dose linearity for a specific irradiation type. For dual TL glow curve present in the sample it is very difficult to calculate the kinetic parameters from peak shape method. The kinetic parameters are calculated by (Computerized glow curve convolution technique) CGCD technique.

Effect of annealing temperature on thermoluminescence glow curve for UV and gamma ray induced ZrO2:Ti phosphor

Abstract The present paper reports the thermoluminescence (TL) properties of combustion synthesized Ti doped ZrO2 nanophosphors the effect of annealing on TL glow curve was also studied. The structural characterizations were done by X-ray diffraction technique (XRD), composition by Fourier transformation infrared spectroscopy and surface morphology was determined by field emission gun scanning electron microscopy (FEGSEM) technique. The prepared phosphor annealed at 600 °C, 700 °C, 800 °C and 900 °C and its thermoluminescence glow curve were recorded. The heating rate effect, the thermal quenching as well as the annealing temperature of the material were optimized for the TL glow curve of the sample. The TL glow curves for different UV, gamma doses and for Ti concentration were studied. The TL glow curve of prepared samples have glow peak at 173 °C. The kinetic parameters was calculated by Computerized glow curve convolution technique (CGCD) technique. Fading and reusability studies of the nanophosphor further confirmed the phosphors suitability for radiation dosimetry. The main conclusion is that Solution Combustion Synthesis is one of the appropriate method for synthesis of Ti doped ZrO2 nanophosphors, which is suitable for temperature sensing applications, the post-synthesis annealing regime being one of the parameters that can affect the intensity and other parameters.

TL glow curve analysis of UV, beta and gamma induced limestone collected from Amarnath holy cave

Abstract The paper reports themoluminescence glow curve analysis of UV (ultraviolet), β (beta) and γ (gamma) induced limestone collected from Amarnath holy cave. The collected natural sample was characterized by X-ray diffraction (XRD) technique and crystallite size calculated by Scherers formula. Surface morphology and particle size was calculated by transmission electron microscopy (TEM) study. Effect of annealing temperature on collected lime stone examined by TL glow curve study. The limestone was irradiated by UV radiation (254 nm source) and the TL glow curve recorded for different UV exposure time. For beta irradiation Sr90 source was used and is shows intense peak at 256 °C with a shoulder peak at higher temperature range. For gamma radiation Co60 source and TL glow curve recorded for different doses of gamma. The kinetic parameters calculation was performed for different glow curve by computerized glow curve deconvolution (CGCD) technique. The chemical composition of natural limestone was analyzed by energy dispersive X-ray spectroscopy (EDXS).

Mechanoluminescence, photoluminescence and thermoluminescence studies of SrZrO3:Ce phosphor

Abstract The present paper reports the synthesis and characterization, photoluminescence thermoluminescence and mechanoluminescence studies of Ce3+ doped SrZrO3 phosphors. The effects of variable concentration of Cerium on meachanoluminescence (ML) and photoluminescence behavior were studied. The samples were prepared by combustion a synthesis technique which is suitable for less time taking techniques also for large scale production for phosphors. The starting material used for sample preparation are Sr(NO3)3, Zr(NO3)3 XH2O and Ce(NO3)3 6H2O and urea used as a fuel. The prepared sample was characterized by X-ray diffraction technique (XRD) with variable concentration of Ce (0.05–0.5 mol%). There is no any phase change found with increase the concentration of Ce. Sample shows orthorhombic structure and the particle size calculated by Scherers formula. The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM) technique. Mechanoluminescence studies on SrZrO3phosphors doped with Ce and underwent an impulsive deformation with an impact of a piston for Mechanoluminescence (ML) investigations. Temporal characteristics in order to investigate about the luminescence centre responsible for ML peak, increasing impact velocity causes more number of electrons will be ionized to reach to the conduction band so there will be more number of electrons available to be recombined at recombination or luminescence centre. In photoluminescence study PL emission spectra show the isolated peak position observed at 388 nm near UV region of spectrum due to 5d–4f transition of Ce3+ion.Thermoluminescence study shows doping of Ce3+ ions reduced the TL intensity TL glow curve shows the high fading and less stability when it doped with cerium. The activation energy high for the doped SrZrO3 phosphor means that the trapped electron is highly trapped in trap level. The present study gives the advance application for fracture sensor, damage sensor including the biological sensor and development of solid state lighting.

Infrared spectroscopy and luminescence spectra of Yb3+ doped ZrO2 nanophosphor

Abstract The present paper reports infrared spectroscopy and luminescence spectra of Yb3+ doped ZrO2 nanophosphor. Sample was prepared by combustion synthesis method (CSM) for the variable concentration of ytterbium. The low temperature synthesis method was suitable for large scale production present method is an eco-friendly method as well as less time taking method as compared to other methods. The synthesized samples were characterized by X-ray diffraction (XRD) technique; scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) technique. The crystal size was calculated by Scherers formula. The particle size distribution in prepared sample was determined by SEM and TEM study. The photoluminescence spectra was recorded under the 980nm laser excitation with the variable concentration of ytterbium. Here the PL intensity increases with increasing the concentration of ytterbium. No concentration quenching were observed. The PL emission spectra shows intense emission peaks at 987, 998 and 1021nm all in infrared regions.

Mechanoluminescence induced by impulsive deformation in zirconium:Ti phosphor

The present manuscript provides a description of the phenomenon of mechanoluminescence (ML) in ZrO2:Ti (cubic) phosphors. When the ML is excited impulsively by the impact of a load on the phosphors the ML intensity increases with time, attains a maximum value and then it decreases. In the ML intensity versus time curve, the peak increases and shifts towards shorter time values with increasing impact velocities. The sample was synthesised using the combustion synthesis method with variable concentrations of Ti (0.1, 0.2, 0.5, 1, 1.5 mol%) and characterised by X-ray diffraction technique. The total ML intensity IT is defined as the area below the ML intensity versus time curve. Total ML intensity increases linearly with the mass of the phosphors for higher impact velocities. The ML intensity Im, corresponding to the peak of ML intensity versus time curve, increases linearly with the impact velocities. The time tm is found to be linearly related to 1000/V0. The ML induced by impulsive excitation in titanium-doped zirconium dioxide phosphors plays a significant role in the understanding of biological sensors and display device application. ML spectra are compared to their PL (photoluminescence spectra) and it is found in the blue region (469 nm) of titanium-doped ZrO2 phosphor.

Structural and optical analysis on europium doped AZrO3 (A=Ba, Ca, Sr) phosphor for display devices application

Behavior displayed by europium doped AZrO3 phosphor which was synthesized by solid state reaction method. For synthesis of BaZrO3, SrZrO3 and CaZrO3 phosphor with fixed concentration of europium ion was calcination at 1000°C and sintered at 1300°C following intermediate grinding. Synthesized sample was characterized by X-ray diffraction analysis and crystallite sized was calculated by Scherer’s formula. From PL spectra of prepared phosphors shows intense emission centred at 612nm (red emission) with high intensity for SrZrO3:Eu3+. For europium doped BaZrO3 and CaZrO3 (613nm) phosphor shows less intense PL spectra as compared to SrZrO3:Eu3+. The strong emission peak of AZrO3:Eu3+ phosphor is due to forced electric dipole transition of 5D0 to 7F2 centered at 612 and 613nm. It is characteristic red emission for europium ion. The excitation spectra of AZrO3:Eu3+ phosphor mainly consists of the charge transfer and (CTB) of Eu3+ located in 200–350 nm centred at 254nm. The present phosphors can act as single hos...