Theoretical study of room temperature ferromagnetism and band gap energy of pure and ion doped In2O3 nanoparticles

2018 ◽  
Vol 456 ◽  
pp. 263-268 ◽  
Author(s):  
A.T. Apostolov ◽  
I.N. Apostolova ◽  
J.M. Wesselinowa
Keyword(s):  
Band Gap ◽  
Room Temperature ◽  
Theoretical Study ◽  
Room Temperature Ferromagnetism ◽  
Band Gap Energy ◽  
Gap Energy ◽  
In2o3 Nanoparticles

scholarly journals Structural, Spectroscopic and Optical Properties of Monohydrated Adenine: A Theoretical Study

2016 ◽  
Vol 64 (2) ◽  
pp. 157-161
Author(s):  
M Alauddin ◽  
MM Islam ◽  
MA Aziz
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Theoretical Study ◽  
Minimum Energy ◽  
Band Gap Energy ◽  
Gap Energy ◽  
B3lyp Level ◽  
A Minor ◽  
Homo Lumo ◽  
Hydrogen Bonded

The structural, spectroscopic (IR, NMR and UV-Vis), electronic and optical properties of monohydrated adenine (monohydrated 6-aminopurine, C5H5N5.H2O) are investigated theoretically using DFT/B3LYP level of theory. Three minimum energy structures have been identified for monohydrated of adenine where H2O molecule is doubly hydrogen bonded with adenine.1H NMR analysis shows that the protons which are hydrogen bonded become deshielded and chemical shift moves to the higher frequency region.Five IR active mode of vibrations were found at 3108, 3295, 3665, 3676 and 3719 cm-1 which are assigned as bonded -OH vibration of H2O, Bonded -NH vibration of NH2, Free -NH vibration of adenine (9 N), Free -NH vibration of NH2, Free -OH vibration of H2O, respectively and agree well with the available experimental results. The investigation of electronic properties shows that the HOMO-LUMO band gap energy of monohydrated adenine at B3LYP level is 5.15 eV. The major electronic transition (from HOMO to LUMO (83%) (π→π*)) occurs at 258 nm (4.80 eV) with a minor transition at 237 nm (5.23 eV). Theoretically it is observed that the HOMO-LUMO band gap energy is for monohydrated adenine is lower than that of adenine. Dhaka Univ. J. Sci. 64(2): 157-161, 2016 (July)

Electronic Bandgap and Refractive Index Dispersion of Single Crystalline Epitaxial ZnGeN2

1999 ◽  
Vol 607 ◽  
Author(s):  
L.D. Zhu ◽  
P.E. Norris ◽  
L.O. Bouthillette
Keyword(s):  
Refractive Index ◽  
Band Gap ◽  
Room Temperature ◽  
Band Gap Energy ◽  
Organic Chemical ◽  
Refractive Index Dispersion ◽  
Electronic Band ◽  
Single Crystalline ◽  
Gap Energy ◽  
Prism Coupling

AbstractThe electronic band gap of single crystalline ZnGeN2 epitaxial layer grown on sapphire substrate by metal organic chemical vapor deposition has been measured by optical transmission and room temperature photoluminescence. The band gap energy is 2.99eV at room temperature, and the band gap is a direct transition type. The interference oscillations of the transmission spectra together with rutile prism coupling measurements have been used to determine the r fractive index and the dispersion characteristics of the single crystal ZnGeN2 below the band gap energy. The rutile prism coupling measurement displays the wave guide modes of the film at 6 2.8nm wavelength of the He-Ne laser, enabling determination of the film thickness and refractive index precisely at the wavelength. The refractive index of ZnGeN2 crystal is 2.35 at 6328Å wavelength. The measured refractive index dispersion curve can be fitted with the first-order Sellmeier equation n2(λ) = A + λ2/(λ2-B), using fitting parameters A=4.3 1, B=0.076.

scholarly journals A COMPARATIVE ANALYSIS OF EFFECT OF TEMPERATURE ON BAND-GAP ENERGY OF GALLIUM NITRIDE AND ITS STABILITY BEYOND ROOM TEMPERATURE USING BOSE–EINSTEIN MODEL AND VARSHNI’S MODEL

2017 ◽  
Vol 18 (2) ◽  
pp. 151-157 ◽  
Author(s):  
Md. Abdullah Al Humayun ◽  
AHM Zahirul Alam ◽  
Sheroz Khan ◽  
MohamedFareq AbdulMalek ◽  
Mohd Abdur Rashid
Keyword(s):  
Comparative Analysis ◽  
Temperature Dependence ◽  
Band Gap ◽  
Room Temperature ◽  
Band Gap Energy ◽  
Semiconductor Materials ◽  
Gap Energy ◽  
Einstein Model ◽  
S Model ◽  
Energy Dependent

High temperature stability of band-gap energy of active layer material of a semiconductor device is one of the major challenges in the field of semiconductor optoelectronic device design. It is essential to ensure the stability in different band-gap energy dependent characteristics of the semiconductor material used to fabricate these devices either directly or indirectly. Different models have been widely used to analyze the band-gap energy dependent characteristics at different temperatures. The most commonly used methods to analyze the temperature dependence of band-gap energy of semiconductor materials are: Passler model, Bose–Einstein model and Varshni’s model. This paper is going to report the limitation of the Bose–Einstein model through a comparative analysis between Bose–Einstein model and Varshni’s model. The numerical analysis is carried out considering GaN as it is one of the most widely used semiconductor materials all over the world. From the numerical results it is ascertained that below the temperature of 95o K both the models show almost same characteristics. However beyond 95o K Varshni’s model shows weaker temperature dependence than that of Bose–Einstein model. Varshni’s model shows that the band-gap energy of GaN at 300o K is found to be 3.43eV, which establishes a good agreement with the theoretically calculated band-gap energy of GaN for operating at room temperature.

Room Temperature Ferromagnetism and Band Gap Investigations in Mg Doped ZnO RF/DC Sputtered Films

2013 ◽  
Vol 1494 ◽  
pp. 115-120
Author(s):  
Sreekanth K. Mahadeva ◽  
Zhi-Yong Quan ◽  
J. C. Fan ◽  
Hasan B Albargi ◽  
Gillian A Gehring ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
Band Gap ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Band Gap Energy ◽  
Thickness Variation ◽  
Zno Films ◽  
Ambient Conditions ◽  
Partial Pressures

ABSTRACTMg@ZnO thin films were prepared by DC/RF magnetron co-sputtering in (N2+O2) ambient conditions using metallic Mg and Zn targets. We present a comprehensive study of the effects of film thickness, variation of O2 content in the working gas and annealing temperature on the structural, optical and magnetic properties. The band gap energy of the films is found to increase from 4.1 to 4.24 eV with the increase of O2 partial pressures from 5 to 20 % in the working gas. The films are found to be ferromagnetic at room temperature and the saturation magnetization increases initially with the film’s thickness reaching a maximum value of 14.6 emu/cm3 and then decreases to finally become diamagnetic beyond 95 nm thickness. Intrinsic strain seems to play an important role in the observed structural and magnetic properties of the Mg@ZnO films. On annealing, the as-obtained ‘mostly amorphous’ films in the temperature range 600 to 800°C become more crystalline and consequently the saturation magnetization values reduce.

Modification of optical properties of PC-PBT/Cr2O3 and PC-PBT/CdS nanocomposites by gamma irradiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20402
Author(s):  
Kaoutar Benthami ◽  
Mai ME. Barakat ◽  
Samir A. Nouh
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Color Difference ◽  
Band Gap Energy ◽  
Polybutylene Terephthalate ◽  
Γ Irradiation ◽  
Gap Energy ◽  
Vis Spectroscopy ◽  
Oxygen Atoms

Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.

Stability Investigation in the Optical Properties of Thermally Evaporated Ge5Se95-x Znx Thin Films

2015 ◽  
Vol 7 (3) ◽  
pp. 1923-1930
Author(s):  
Austine Amukayia Mulama ◽  
Julius Mwakondo Mwabora ◽  
Andrew Odhiambo Oduor ◽  
Cosmas Mulwa Muiva ◽  
Boniface Muthoka ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
Optical Transition ◽  
Bulk Material ◽  
Band Gap Energy ◽  
Optical Absorbance ◽  
Gap Energy ◽  
Constituent Elements

 Selenium-based chalcogenides are useful in telecommunication devices like infrared optics and threshold switching devices. The investigated system of Ge5Se95-xZnx (0.0 ≤ x ≤ 4 at.%) has been prepared from high purity constituent elements. Thin films from the bulk material were deposited by vacuum thermal evaporation. Optical absorbance measurements have been performed on the as-deposited thin films using transmission spectra. The allowed optical transition was found to be indirect and the corresponding band gap energy determined. The variation of optical band gap energy with the average coordination number has also been investigated based on the chemical bonding between the constituents and the rigidity behaviour of the system’s network.

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.

Phase transformation and heterojunction construction of bismuth oxyiodides by grinding-assistant calcination in the presence of thiourea and its photoactivity

2021 ◽  
Author(s):  
Zichen Shen ◽  
Huanzhen Liu ◽  
Xuemei Jia ◽  
Qiaofeng Han ◽  
Huiping Bi
Keyword(s):  
Phase Transformation ◽  
Band Gap ◽  
Layered Structure ◽  
Band Gap Energy ◽  
Gap Energy

Bismuth-rich oxyhalides are promising photocatalysts due to their special layered structure and adjustable band gap energy. In this work, a series of bismuth oxyiodides were fabricated by grinding-assistant calcining in...

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