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The synthesis and luminescence analysis of Tb3+-activated phosphors were reported. Y2SiO5 phosphors were synthesized by a modified solid-state reaction method with a variable doping concentration of Tb3+ ion (0.5–2.5 mol.%). As synthesized, the phosphors were characterized by X-ray diffraction (XRD) analysis. The XRD pattern confirmed the monoclinic structure of the prepared phosphor. Scanning electron microscopy and High-Resolution Transmission Electron Microscopy (HRTEM) studies revealed nearly uniform particle size distribution in the prepared phosphors. The photoluminescence excitation spectra of the Y2SiO5:Tb3+ (0.5–2.5 mol.%) phosphor displayed one broad, intense peak at 258–277 nm. When excited at the 258 nm wavelength, the phosphors showed emission peaks at 553 nm (5D4 → 7F5), 544 nm (5D4 → 7F5) and 489 nm (5D4 → 7F6). The 1931 CIE (x,y) chromaticity coordinates showed the distribution of the spectral region calculated from the photoluminescence emission spectra. The values of x = 0.25 and y = 0.46 were very close to light green emission. Therefore, the prepared phosphor is very useful for light-emitting diode (green component) applications. [ABSTRACT FROM AUTHOR]

In the present work, Ni0.6Cd0.4DyxFe2-xO4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) nanoparticles (NPs) were synthesized by using sol–gel method. X-ray diffraction (XRD) patterns confirmed that the pure and dysprosium substituted Ni–Cd ferrites are in single-phase spinel structures, while a trace of DyFeO3 appears as a minor phase for higher concentrations (x = 0.10, 0.15 and 0.20). The Debye–Scherrer's method and Williamson–Hall (W-H) method were used to evaluate the crystallite sizes and lattice strain. Scanning electron microscope (SEM) images show that reduction of grain size with Dy3+ content. Elemental composition features of samples were examined by Energy-dispersive X-ray spectroscopy (EDS). The average particles size estimated from transmission electron microscopy (TEM) analysis is in good agreement with results obtained from XRD. The results showed that saturation magnetization (Ms) decreases and coercivity (Hc) increases with an increase in Dy3+ concentrations. The dielectric constant was found to decrease with increasing Dy content in Ni–Cd ferrites. [ABSTRACT FROM AUTHOR]

Cadmium-substituted manganese ferrite nanoparticles with the general formula Mn1‒xCdxFe2O4(x = 0.0, 0.2, 0.4, 0.6, 0.8) were synthesised by the citrate‒gel auto combustion method. X-ray diffraction patterns revealed formation of a cubic phase spinel structure with F d 3 ˉ m space group. FT-IR confirms stretching vibration of tetrahedral and octahedral interstitial sites in the spinel lattice. Microstructural features observed by scanning electron microscopy (SEM) demonstrate that agglomerated particles were formed with an increase in average grain size according to Cd2+ content. Elemental composition features and particle size of samples were examined by energy dispersive spectroscopy (EDX) and Transmission electron microscopy (TEM). The magnetic properties characterised by the highly sensitive magnetometer system (SQUID VSM) at room temperature revealed ferromagnetism in all the samples. The values of dielectric permittivity ε ′ and tangent loss ( tan δ ) decreased exponentially at low frequencies and were in accordance with the Maxwell–Wagner model and Koop's theory. [ABSTRACT FROM AUTHOR]

This review includes research papers on different method of preparation of rare earth activated Sr2SiO4 phosphors and its luminescence studies. Here in Sr2SiO4 has attracted great interest due to its special structure features, excellent physical and chemical stability. Besides, it absorbs ultraviolet radiation and emits white light when activated by different rare earth ions. Different synthesis techniques were compared and it is found that sol–gel synthesis technique is best for preparation of rare earth activated Sr2SiO4 phosphors. Literature related to characterization techniques such as X-ray diffraction techniques, scanning electron microscopy, transmission electron microscopy and other studies are also compared. Photoluminescence studies for white light emitting diode of various rare earth phosphors are compared with Sr2SiO4 phosphor reported in this review. Also some luminescence techniques such as thermoluminescence glow curve analysis and some spectroscopic parameters are also compared. The review end with some important conclusion related to rare earth activated Sr2SiO4 phosphors with proper justifications. [ABSTRACT FROM AUTHOR]

Gadolinium-doped Y2O3 nanophosphor was synthesized by a solid-state reaction method, which could be used for large-scale production of phosphors. The structure of the phosphor sample was characterized by powder X-ray diffraction, field emission gun scanning electron microscopy and high-resolution transmission electron microscopy. The particle size was calculated from Scherer's formula. X-ray diffraction showed a grain size of 35-55 nm, in good agreement with the scanning electron microscopy image. The synthesized sample showed good morphology and connectivity, with grains and formation of a nano-sized prepared sample. The diffraction pattern was measured by transmission electron microscopy with a selected area diffraction pattern. The prepared phosphor was also examined by thermoluminescence; to record the glow curve, 1 mg phosphor was irradiated with ultraviolet at 254 nm at a fixed heating rate of 7 °C s−1. The sample showed a well-resolved peak at 99 °C for 1 mol% of Gd3+. A lower temperature peak showed less stability and more fading of the prepared sample. A thermoluminescence glow curve gives information about trapping parameters such as activation energy and trap depth, order of kinetics and frequency. All the kinetics were calculated by the peak shape method. [ABSTRACT FROM AUTHOR]

This paper reports the preparation of Eu 3+ doped Gadolinium oxyorthosilicate (Gd 2 SiO 5 :Eu 3+ ) phosphor with different concentration of Eu 3+ (0.1–2.5 mol%) using the modified solid state reaction method. The synthesis procedure of the Gd 2 SiO 5 :Eu 3+ phosphor using inorganic materials such as Gd 2 O 3 , silicon dioxide (SiO 2 ), europium oxide (Eu 2 O 3 ) and boric acid (H 3 BO 3 ) as flux is discussed in detail. The prepared phosphor samples were characterized by using X-Ray Diffraction (XRD), Field Emission Gun Scanning Electron Microscopy (FEGSEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Photoluminescence (PL) and Thermoluminescence (TL). The Commission Internationale de l′Eclairage(CIE) coordinates were also calculated. The PL emission was observed in the 350–630 nm range for the Gd 2 SiO 5 :Eu 3+ phosphor. PL excitation peaks were observed at 266, 275, 312 and 395 nm while the emission peaks were observed at 380, 416, 437, 545, 579, 589, 607, 615 and 628 nm. The emission peak at 615 nm was the most intense peak for all the different Eu 3+ concentration samples. From the XRD data, using the Scherrer's formula, the average crystallite size of the Gd 2 SiO 5 :Eu 3+ phosphor was calculated to be 33 nm. TL was carried out for the phosphor after both UV and gamma irradiation. The TL response of the Gd 2 SiO 5 :Eu 3+ phosphor for the two different radiations was compared and studied in detail. It was found that the present phosphor can acts as a single host for red emission (1.5 mol%) for display devices and light emitting diode (LED) and white light emission for Eu 3+ (0.1 mol%) and it might be used as a TL dosimetric material for gamma dose detection. [ABSTRACT FROM AUTHOR]

Abstract: Bimetallic nanoalloys (BMNAs) of 3d-series (Ni–Cu, Ni–Co and Ni–Zn) were prepared by hydrazine reduction of respective metal chloride in ethylene glycol at 60°C. These were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and particle size was found to be in the order of 34, 43 and 30nm, respectively. The thermolysis of ammonium perchlorate (AP) and AP-HTPB composite solid propellants was found to be catalyzed with BMNAs and burning rate was found to be enhanced considerably. TG and ignition delay studies demonstrated that higher temperature decomposition (HTD) of AP is enhanced enormously by these additives and Ni–Co nanoalloy is the best catalyst. [Copyright &y& Elsevier]

• Growth of orientation control low resistive nickel mono-silicide (NiSi) phase. • NiSi phase formation at room temperature under low energy ion irradiation. • The effect of Ni film thickness on NiSi phase formation and electrical properties. • Better crystalline phase is observed for higher Ni film thickness than lower one. • Most of the crystallites are oriented in (103) plane. Nickel mono-silicide (NiSi) is considered as a promising material for developing low resistance contacts in complementary metal-oxide-semiconductor technology. In the present work, we report the effect of Ni film thickness on orientation control of low resistive Nickel mono-silicide (NiSi) phase formation using low energy ion irradiation at room temperature. In order to study the effect of Ni film thickness on NiSi phase formation, the Ni films of thicknesses 30 nm and 60 nm were deposited on Si (111) substrate using thermal evaporation technique in a high vacuum chamber. The as prepared Ni/Si samples were then irradiated via 120 keV Si ions with different fluences of 7 × 1014, 1 × 1015, 3 × 1015 and 7 × 1015 ions-cm−2 at room temperature. The x-ray diffraction and transmission electron microscopy measurements clearly confirm the formation of mono-silicide phase. The composition of the NiSi phase is determined by Rutherford backscattering spectrometry measurements. The crystallinity of NiSi phase has been observed to be better for 60 nm Ni film as compared to the 30 nm Ni film on Si substrate. Most of the NiSi crystallites are found to be oriented in (103) lattice plane. The resistivity and sheet resistance of the NiSi/Si films are found to be very low. The role of composition of Ni and Si in NiSi phase on resistivity and sheet resistance of the films has been investigated carefully. The detailed mechanisms behind the above observations have been discussed in the paper. [ABSTRACT FROM AUTHOR]