Synthesis, Characterization and Thermoluminescence Studies of LiNaSO4: Eu3+ Nanophosphor

Na2SO4, LiNaSO4 and LiNaSO4: Eu3+ nanophosphors were successfully synthesized by slow evaporation technique followed by calcination at 400° C. The resultant products were characterized by using powder X- ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), UV – Vis, scanning electron microscope (SEM) and transmission electron microscope (TEM). Doping with Li+ ion stabilized the thenardite phase (Phase V) while, codoping with Eu3+ promoted the phase transformation from stable thenardite to metastable mirabilite (Phase III) crystal structure. The average crystallite size was calculated by using Debye – Scherrer’s formula and Williamson – Hall (W – H) plots. The optical energy band gap (Eg) of Na2SO4, LiNaSO4 and LiNaSO4: Eu3+ were estimated from Wood and Tauc’s relation which varies from 4.2 – 4.33 eV. Thermoluminescence (TL) studies were investigated by using ã – irradiation in the dose range 0.5 – 5 kGy at a heating rate of 5 °C s-1. A well resolved glow peaks at ~ 180 °C, ~ 150 °C and ~115 °C were recorded for Na2SO4, LiNaSO4 and LiNaSO4: Eu3+ nanophosphors respectively. It was observed that isovalent doping of Li+ served as quencher, while codoping of hypervalent Eu3+ acted as activator to enhance the TL intensity of glow peak. In the present study, the extent of TL fading of LiNaSO4: Eu3+ was 31 % compared to LiNaSO4 (52 %) and Na2SO4 (59 %). So, LiNaSO4: Eu3+ phosphor might also have potential use in dosimetry. The kinetic parameters namely activation energy (E), frequency factor (s) and order of kinetics (b) was estimated and the results were discusse

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

Na2SO4, Na2SO4:Dy3+, LiNaSO4 and LiNaSO4:Dy3+ nanoparticles were successfully synthesized by slow evapn. technique followed by calcination at 400°. The resultant products were characterized by powder x-​ray diffraction, SEM, TEM, FTIR and UV-​visible spectroscopy. The av. crystallite size was calcd. using Debye-​Scherrer's formula and Williamson-​Hall's (W-​H) plots. The optical energy band gap (Eg) was estd. from Wood and Tauc's relation, which varies from 3.70 to 4.45 eV. The variation in band gap values is attributed to a large degree of structural defects. Thermoluminescence (TL) studies were studied using γ-​irradn. in the dose range 0.5-​5 kGy at a heating rate of 5 K s-​1. The samples Na2SO4 and LiNaSO4 showed a well-​resolved glow peak at ∼180 and ∼170°, resp. The prominent glow peak at ∼175° along with a shouldered peak at ∼60° was obsd. for Na2SO4:Dy3+. LiNaSO4:Dy3+ showed a prominent glow peak at ∼100° and a small shoulder peak at ∼180°. The addn. of isovalent (Li+) quenches the TL intensity, whereas the hypervalent (Dy3+) increases the intensity from Na2SO4. The variations of TL intensity for all the phosphors follow linear behavior up to 5 kGy and were useful in radiation dosimetry. The kinetic parameters (E, b and s) were estd. from the glow peak shape method

Influence of Rare Earth Doping on Microstructure and Luminescence Behaviour of Sodium Sulphate

Na2SO4, Na2SO4: Li, and Na2SO4: Li, Eu, Dy phosphors were prepared by using slow evaporation technique followed by subsequent calcination at 400°C for 4 h. Doping with Li+ ion stabilized the thenardite phase of host matrix, while codoping with RE3+ stabilized the phase transformation from stable thenardite to metastable mirabilite crystal structure. The microstructure and morphology were studied by using scanning electron microscopy and transmission electron microscopy. The thermoluminescence studies revealed that isovalent doping of Li+ served as a quencher and addition of codopant introduces the additional trap sites in the host matrix. The room temperature emission spectra of Li-doped, RE3+-codoped, and undoped Na2SO4 were studied under ultraviolet radiation. For pure Na2SO4 the two peaks which appeared are at 364 and 702 nm, respectively. The emission intensities of RE3+-codoped samples increase with increase in dopant concentration

Preparation, characterization, and luminescence properties of orthorhombic sodium sulphate

A highly efficient thermoluminescence Na2SO4 phosphor with thenardite polymorphic structure was prepared by simple slow evaporation technique followed by subsequent calcination at 200°C, 400°C, and 600°C for 4 h and the resultant crystals were characterized by various analytical techniques. All the samples exhibited thermodynamically stable thenardite phase and the grain growth was increased for the calcined samples. SEM analysis indicated the fine distribution of twinned orthogonal prism and pyramidal structure without any agglomeration. The electron spin resonance spectroscopy showed the existence of S O 4 - radicals as trap centre. The thermoluminescence behavior suggested the charge carrier recombination dynamics in the thenardite sample followed second-order kinetics. The trapping parameters such as activation energy (E), order of kinetics (b), and frequency factor (s) have been determined using Chen's peak shape method. Further fading of the TL intensity of Na2SO4 showed that thenardite is quite suitable for radiation dosimetry even up to 15 days. The photoluminescence band of Na2SO4 reduced in its intensity after γ-irradiation, suggesting that defects are unstable and decay rapidly. © 2013 Y. S. Vidya and B. N. Lakshminarasappa

The effect of isovalent and hypervalent ion doping on the structural and luminescence properties of sodium sulfate

Na2SO4, Na2SO4: Li, Na2SO4: Li, Eu, Na2SO4: Li, Dy and Na2SO4: Li, Eu, Dy phosphors were prepared using a slow evaporation technique followed by their subsequent calcination at 400 °C for 4 h. Doping with a Li+ ion stabilized the thenardite phase of the host matrix, while codoping with rare earth stabilized the phase transformation from stable thenardite to a metastable mirabilite crystal structure. The microstructure and morphology were studied using scanning electron microscopy and transmission electron microscopy. Thermoluminescence studies revealed that the isovalent doping of Li+ served as a quencher and the addition of the codopant introduced additional trap sites in the host matrix. The TL intensity followed the order Na2SO4: Li, Eu >Na2SO4: Li, Eu, Dy >Na2SO4: Li, Dy >Na2SO4Na2SO4: Li. The room temperature emission spectra of Li-doped, RE3+-codoped and undoped Na2SO4 were studied under ultraviolet radiation. For pure Na2SO4, the two peaks that appeared were at 364 nm and 702 nm. The emission intensities of RE3+-codoped samples increases with increase in dopant concentration. © 2014 IOP Publishing Ltd

Synthesis and characterization and X-ray/gamma ray absorption properties of tin oxide synthesized via solution combustion method

Tin oxide (SnO2) nanoparticles (NPs) are synthesized via solution combustion method using Glycine as a fuel followed by the calcination and characterization. The Bragg reflections clearly confirms the formation of tetragonal rutile phase with crystallite size 10 nm. The irregular shaped agglomerated NPs are observed on the surface morphology. The energy band gap was determined (3.7 eV). Theoretically, mass attenuation coefficient is determined which is an essential data required in diverse fields

2-Deoxy-d-glucose functionalized zinc oxide nanodrug for kidney cancer treatment

For the first time, zinc oxide (ZnO) nanoparticles (NPs) are synthesized by the green combustion method using apple peel extract as a reducing agent. Further, ZnO-Deoxy-d-Glucose (2DG) nanohybrids were synthesized by the sputtering method. These synthesized biomolecule-coated NPs and nanohybrids are characterized with different techniques. The Bragg reflections confirm the hexagonal Wurtzite structure for ZnO. A decrease in crystallite size and an increase in energy band gap were observed for ZnO and ZnO-2DG. The tuning of the band gap plays a vital role in cytotoxicity, arbitrated by intracellular reactive oxygen species. The cytotoxic properties, such as the percentage of inhibition and the percentage of the proliferation of ZnO and ZnO-2DG nanohybrid, are examined against the Kidney cancer Vero cell line and also compared with the standard drugs Levofloxacin and Doxorubicin. Compared to ZnO, ZnO-2DG shows excellent cytotoxic properties, even better than the standard drug against the Vero cell line. Thus, the present ZnO-2DG nanohybrid might be used as a nanodrug and go on to replace Levofloxacin and Doxorubicin as standard drugs in kidney cancer cell therapy

Effect of nickel doping on magnetic and dielectric properties of orthorhombic calcium ferrite nanoparticles

Nickel (10∼50 mol%) doped calcium ferrite nanoparticles (NPs) are synthesized by the solution combustion method using lemon juice extract as a reducing agent, followed by calcination at 500°C. The calcined samples are characterized with different techniques. The Bragg reflections of Nickel doping confirm the formation of a single orthorhombic calcium ferrite phase. The crystallite size is estimated using both Scherrer's and the W-H plot method. The surface morphology consists of irregular size and shaped agglomerated NPs along with pores and voids. A blueshift and a broad absorption spectrum is observed with an increase in the direct energy band gap. The direct energy band gap estimated from Wood and Tauc's relationship was found to be 2.91∼2.97 eV with an increase in dopant concentration. The magnetic analysis provided values for saturation magnetization (Ms), remanence (Mr), and coercivity (Hc), while dielectric studies demonstrated a dielectric constant of 2.81, 2.14, and 1.67 with increasing dopant concentration. The variation of dielectric properties of the sample as a function of frequency in the range 0.1∼20 MHz has been studied at room temperature. The dielectric properties of CaFe2O4: Ni (1∼9 mol%) NPs clearly indicate that there is a more pronounced dispersion at lower frequencies, gradually reaching saturation as the frequency increases. The dielectric loss was found to decrease from 4.62, 3.22, and 2.32 with an increase in Ni2+ substitution (10, 30, and 50 mol%) respectively. These results indicate the suitability of these samples for applications in memory devices and high-frequency applications

Sunlight photocatalytic performance of Mg-doped nickel ferrite synthesized by a green sol-gel route

We report an environmentally friendly synthetic strategy to synthesize new nickel ferrite and Mg doped nickel ferrite photocatalysts under modified green sol-gel route in which Aloe Vera gel acts as a natural template. The crystalline phase, surface morphology and size of the prepared photocatalysts were characterized by PXRD, SEM, TEM and HRTEM analysis. The energy band gap of the nanoparticles (NPs) can be tuned in the range of 2.55–2.34 eV by varying the dopant concentration. The photoluminescence analysis indicates that the present NPs are an effective white component in display applications. These synthesized NPs were used for photocatalytic decomposition of recalcitrant pollutants in aqueous media under sunlight irradiation. Among investigated samples, the NiFe2O4: Mg2+ (1 mol %) exhibits the highest photocatalytic efficiency for the decomposition of recalcitrant pollutants, which is higher than that of the commercial P25. This enhancement in photocatalytic performance can be mainly attributed to the balance between the parameters, crystallanity, band gap, morphology, crystallite size, defects, dopant amount and combined facets of photocatalysis. It opens a new window to use this simple greener route to synthesize bi-functional NPs in the area of photocatalysis particularly waste water treatment and display applications. Keywords: NiFe2O4:Mg2+NPs, Green sol-gel route, Photoluminescence, Photo-Fenton catalytic performanc