scholarly journals Structural, Optical, and Magnetic Characterization of Spinel Zinc Chromite Nanocrystallines Synthesised by Thermal Treatment Method

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Salahudeen A. Gene ◽  
Elias Saion ◽  
Abdul H. Shaari ◽  
Mazliana A. Kamarudin ◽  
Naif M. Al-Hada ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Band Gap ◽  
Treatment Method ◽  
Band Gap Energy ◽  
Resonance Spectroscopy ◽  
Magnetic Characterization ◽  
X Ray ◽  
Gap Energy ◽  
Zinc Chromite

The present study reports the structural and magnetic characterization of spinel zinc chromite (ZnCr2O4) nanocrystallines synthesized by thermal treatment method. The samples were calcined at different temperatures in the range of 773 to 973 K. Polyvinylpyrrolidone was used to control the agglomeration of the nanoparticles. The average particle size of the synthesized nanocrystals was determined by powder X-ray diffraction which shows that the crystallite size increases from 19 nm at 773 K to 24 nm at 973 K and the result was in good agreement with the transmission electron microscopy images. The elemental composition of the samples was determined by energy dispersed X-ray spectroscopy which confirmed the presence of Zn, Cr, and O in the final products. Fourier transform infrared spectroscopy also confirmed the presence of metal oxide bands for all the samples calcined at different temperature. The band gap energy was calculated from UV-vis reflectance spectra using the Kubelka-Munk function and the band gap energy of the samples was found to decrease from 4.03 eV at 773 K to 3.89 eV at 973 K. The magnetic properties were also demonstrated by electron spin resonance spectroscopy, the presence of unpaired electrons was confirmed, and the resonant magnetic field and theg-factorof the calcined samples were also studied.

scholarly journals The Influence of Calcination Temperature on the Formation of Zinc Oxide Nanoparticles by Thermal-Treatment

2013 ◽  
Vol 446-447 ◽  
pp. 181-184 ◽  
Author(s):  
Naif Mohammed Al-Hada ◽  
Elias Saion ◽  
A.H. Shaari ◽  
M.A. Kamarudin ◽  
Salahudeen A. Gene
Keyword(s):  
Particle Size ◽  
Zinc Oxide ◽  
Thermal Treatment ◽  
Band Gap ◽  
Calcination Temperature ◽  
Zinc Oxide Nanoparticles ◽  
Treatment Method ◽  
Band Gap Energy ◽  
Oxide Nanoparticles ◽  
Gap Energy

Zinc oxide nanoparticles were synthesized by the thermal-treatment method. Polyvinyl pyrrolidone was used as capping agent and Zinc nitrate was used as a precursor. The samples were calcined at 500 and 550°C for removal of the organic compounds. The structural characteristics of the calcined samples were examined by X-ray diffraction and transmission electron microscopy. The results show that the average particle size increases with increase in calcination temperature. The optical properties were characterized at room temperature using a UV–Vis spectrophotometer in the wavelength range between 200–800 nm and the band gap energy was calculated from reflectance spectra using kubalka munk function and the results indicated that the band gap energy decreased from 3.23 eV at 500 oC to 3.21 eV at 600 °C due to an increase of particle size. This simple thermal-treatment method has advantages of the pure nanoparticles formation as no additional chemicals were required, a lack of by-product effluents, and environmentally friendly process.

scholarly journals Polymer Thermal Treatment Production of Cerium Doped Willemite Nanoparticles: An Analysis of Structure, Energy Band Gap and Luminescence Properties

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1118
Author(s):  
Ibrahim Mustapha Alibe ◽  
Khamirul Amin Matori ◽  
Mohd Hafiz Mohd Zaid ◽  
Salisu Nasir ◽  
Ali Mustapha Alibe ◽  
...  
Keyword(s):  
Solid State ◽  
Thermal Treatment ◽  
Band Gap ◽  
Optical Band Gap ◽  
Dopant Concentration ◽  
Blue Emission ◽  
Green Emission ◽  
Band Gap Energy ◽  
Solid State Lighting ◽  
Gap Energy

The contemporary market needs for enhanced solid–state lighting devices has led to an increased demand for the production of willemite based phosphors using low-cost techniques. In this study, Ce3+ doped willemite nanoparticles were fabricated using polymer thermal treatment method. The special effects of the calcination temperatures and the dopant concentration on the structural and optical properties of the material were thoroughly studied. The XRD analysis of the samples treated at 900 °C revealed the development and or materialization of the willemite phase. The increase in the dopant concentration causes an expansion of the lattice owing to the replacement of larger Ce3+ ions for smaller Zn2+ ions. Based on the FESEM and TEM micrographs, the nanoparticles size increases with the increase in the cerium ions. The mean particles sizes were estimated to be 23.61 nm at 1 mol% to 34.02 nm at 5 mol% of the cerium dopant. The optical band gap energy of the doped samples formed at 900 °C decreased precisely by 0.21 eV (i.e., 5.21 to 5.00 eV). The PL analysis of the doped samples exhibits a strong emission at 400 nm which is ascribed to the transition of an electron from localized Ce2f state to the valence band of O2p. The energy level of the Ce3+ ions affects the willemite crystal lattice, thus causing a decrease in the intensity of the green emission at 530 nm and the blue emission at 485 nm. The wide optical band gap energy of the willemite produced is expected to pave the way for exciting innovations in solid–state lighting applications.

Synthesis and characterization of a mixture of CoFe2O4 and MgFe2O4 from layered double hydroxides: Band gap energy and magnetic responses

2014 ◽  
Vol 369 ◽  
pp. 249-259 ◽  
Author(s):  
Ulises A. Agú ◽  
Marcos I. Oliva ◽  
Sergio G. Marchetti ◽  
Angélica C. Heredia ◽  
Sandra G. Casuscelli ◽  
...  
Keyword(s):  
Band Gap ◽  
Layered Double Hydroxides ◽  
Band Gap Energy ◽  
Synthesis And Characterization ◽  
Gap Energy ◽  
Double Hydroxides

Study on Band Gap Energy of F Doped TiO2 Nanotubes

2017 ◽  
Vol 889 ◽  
pp. 234-238
Author(s):  
Mohd Hasmizam Razali ◽  
Nur Arifah Ismail ◽  
Mahani Yusoff
Keyword(s):  
Band Gap ◽  
Diffuse Reflectance Spectroscopy ◽  
Small Diameter ◽  
Ultra Violet ◽  
Band Gap Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gap Energy ◽  
Transmission Electron ◽  
Xrd Patterns

Pure and F doped TiO2 nanotubes was synthesized using simple hydrothermal method. The hydrothermal was conducted using teflon-liner autoclave and maintained at 150oC for 24 hours. The characterization of synthesised product was carried out using x-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive of x-ray spectroscopy (EDX) and ultra violet – visible light diffuse reflectance spectroscopy (UV-Vis DRS) for band gap measurements. XRD patterns indicated that anatase TiO2 phase was remained after F doping suggested that fluorine was highly dispersed into TiO2 by substituted with O in the TiO2 lattice to formed TiO2-xFx solid solution. Morphology investigation using TEM found out small diameter of nanotubes structure within 8 – 10 nm of pure and F doped TiO2 nanotubes. The band gap energy (Eg) of both nanotubes samples were almost similar proposing that F doping does not modify the band gap energy.

Synthesis, Structural and Optical Properties of Cerium Oxide Nanoparticles Prepared by Thermal Treatment Method

2017 ◽  
Vol 268 ◽  
pp. 132-137 ◽  
Author(s):  
Anwar Ali Baqer ◽  
Khamirul Amin Matori ◽  
Naif Mohammed Al-Hada ◽  
Abdul Halim Shaari ◽  
Elias Saion ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Calcination Temperature ◽  
Treatment Method ◽  
Fluorite Structure ◽  
Band Gap Energy ◽  
Treatment Technique ◽  
Structural And Optical Properties ◽  
Gap Energy ◽  
Calcination Temperatures ◽  
Fesem Micrographs

A sample thermal treatment technique was utilised to synthesis cerium dioxide (CeO2) nanoparticles, using cerium (111) nitrate as a precursor, Polyvinylpyrrolidone as a capping agent, and deionized water as a solvent. The product underwent calcination treatment of 500, 550, 600, and 650 1C to crystallize the nanoparticles and to remove organic compounds. It was verified by XRD that by varying the calcination temperature, the cubic fluorite structure of CeO2 nanoparticles with pure products was achieved. Furthermore, the crystal sizes of the CeO2 nanoparticles were assessed to be 4 nm for the lowest calcination temperature and 23 nm for the highest calcination temperature. The FESEM micrographs of the CeO2 nanoparticles revealed a structure of CeO2 nanospherical that exhibited a tendency to amalgamate at higher calcination temperatures. The optical characteristics that were evaluated with the help of a UV-Vis spectrophotometer indicated a decrease in the band gap energy with an increase in calcination temperature as a result of the increase in the crystal sizes.

Spectroscopic Ellipsometry Analysis of InGaN/GaN and AlGaN/GaN Heterostructures Using a Parametric Dielectric Function Model

1999 ◽  
Vol 595 ◽  
Author(s):  
J. Wagner ◽  
A. Ramakrishnan ◽  
H. Obloh ◽  
M. Kunzer ◽  
K. Köhler ◽  
...  
Keyword(s):  
Band Gap ◽  
Dielectric Function ◽  
Spectroscopic Ellipsometry ◽  
Composition Dependence ◽  
Band Gap Energy ◽  
Function Model ◽  
Gap Energy ◽  
The Individual ◽  
Gap Data

AbstractSpectroscopic ellipsometry (SE) has been used for the characterization of AlGaN/GaN and InGaN/GaN heterostructures. The resulting pseudodielectric function spectra were analyzed using a multilayer approach, describing the dielectric functions of the individual layers by a parametric oscillator model. From this analysis, the dielectric function spectra of GaN, AlxGa1−xN (x≤0.16), and In0.13Ga0.87N were deduced. Further, the dependence of the AlxGa1−xN band gap energy on the Al mole fraction was derived and compared with photoluminescence data recorded on the same material. The SE band gap data are compatible with a bowing parameter close to 1 eV for the composition dependence of the AlxGa1−xN gap energy. Finally, the parametric dielectric functions have been used to model the pseudodielectric function spectrum of a complete GaN/AlGaN/InGaN LED structure.

scholarly journals Copper Oxide Films Deposited by Microwave Assisted Alkaline Chemical Bath

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 968
Author(s):  
Reina Galeazzi Isasmendi ◽  
Isidro Juvenal Gonzalez Panzo ◽  
Crisóforo Morales-Ruiz ◽  
Román Romano Trujillo ◽  
Enrique Rosendo ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Copper Oxide ◽  
Band Gap ◽  
Photoelectron Spectroscopy ◽  
Precursor Solution ◽  
Band Gap Energy ◽  
X Ray ◽  
Gap Energy ◽  
Glass Substrates ◽  
Microwave Assisted

Copper oxide (CuO) films were deposited onto glass substrates by the microwave assisted chemical bath deposition method, and varying the pH of the solution. The pH range was varied from 11.0 to 13.5, and the effects on the film properties were studied. An analytical study of the precursor solution was proposed to describe and understand the chemical reaction mechanisms that take place in the chemical bath at certain pH to produce the CuO film. A series of experiments were performed by varying the parameters of the analytical model from which the CuO films were obtained. The crystalline structure of the CuO films was studied using X-ray diffraction, while the surface morphology, chemical composition, and optical band-gap energy were analyzed by scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–Vis spectrophotometry, respectively. The CuO films obtained exhibited a monoclinic crystalline phase, nanostructured surface morphology, stoichiometric Cu/O ratio of 50/50 at%, and band-gap energy value of 1.2 eV.

Effect of bath temperature on the chemical bath deposition of PbSe thin films

1970 ◽  
Vol 6 (2) ◽  
pp. 126-132 ◽  
Author(s):  
Anuar Kassim ◽  
Tan Wee Tee ◽  
Ho Soon Min ◽  
Shanthi Monohorn ◽  
Saravanan Nagalingam
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Chemical Bath Deposition ◽  
Lead Nitrate ◽  
Bath Temperature ◽  
Band Gap Energy ◽  
Sodium Selenate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gap Energy

PbSe thin films are prepared by chemical bath deposition technique over microscope glass substrates from an aqueous acidic bath containing lead nitrate and sodium selenate. The influence of bath temperature on the properties of PbSe film is investigated. The X-ray diffraction analysis showed the deposited films were polycrystalline and having the (111) orientation. The surface morphology study revealed that the grains have cubic shape crystal. The band gap energy was decreased from 2.0 to 1.3 eV as the bath temperature was increased from 40 to 80°C. The films deposited at 80°C showed good crystallinity and uniformly distributed over the surface of substrate with larger grain sizes. Therefore, the optimum bath temperature is 80°C. Keywords: Lead selenide; X-ray diffraction; Band gap energy; Chemical bath deposition; Thin films DOI: 10.3126/kuset.v6i2.4021Kathmandu University Journal of Science, Engineering and Technology Vol.6. No II, November, 2010, pp.126-132

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