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Study of Structural, Optical, Electrical and Dielectric Properties of Gd-Doped ZnO Composites Synthesized by Solid State Reaction Method
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作者 Santosh Kumar Kundara Kanhaiya Chawla +3 位作者 Dinesh Kumar Yadav Chhagan Lal Balram Tripathi Narendra Jakhar 《Open Journal of Composite Materials》 2024年第2期91-108,共18页
In this manuscript, we are reporting structural, bonding, optical, dielectric, and electrical properties of Gd-doped ZnO composite samples (Zn<sub>1</sub><sub>−</sub><sub>x</sub>Gd&... In this manuscript, we are reporting structural, bonding, optical, dielectric, and electrical properties of Gd-doped ZnO composite samples (Zn<sub>1</sub><sub>−</sub><sub>x</sub>Gd<sub>x</sub>O, x = 0, 0.05, 0.10) prepared by solid-state reaction method. XRD spectra confirm the wurtzite hexagonal phase with a grain size distribution of 42 - 47 nm. The FT-IR spectra confirm bonding behavior like Zn-O, O=C=O, and O-H stretching modes. FESEM micrographs show that the grains of crystallites possess nearly spherical morphology. Optical absorption spectra confirm that the optical band gap decreases systematically from 3.19 eV to 3.15 eV for x = 0.0 to x = 0.10 samples. For all samples, PL spectra exhibited near-band emission, blue emission, and green emission peaks. The dielectric constant decreases as the applied frequency increases. Hall effect results show that with increasing doping concentration of Gd, mobility and resistivity increase while bulk concentration decreases. Current-Voltage study shows that current increases when temperature is increased. Rare earth-doped ZnO is potential material used for optoelectronics and spintronics device applications. Properties of Gd-doped ZnO are studied by various research groups, but dielectric studies are limitedly reported. Therefore, the present research work aims to study the change of electrical, optical, and dielectric properties of Gd-doped ZnO for device applications. 展开更多
关键词 ZnO:Gd Composites optical band Gap Green Emission Dielectric Constant
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Glass Formation and Optical Band Gap Studies on Bi_2O_3-B_2O_3-BaO Ternary System 被引量:1
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作者 陈飞飞 戴世勋 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2009年第5期716-720,共5页
The glass forming region of Bi2O3-B2O3-BaO ternary system was investigated. A serial of glass samples with high Bi2O3 content in Bi2O3-B2O3-BaO system were prepared by using conventional melting and quenching meld, an... The glass forming region of Bi2O3-B2O3-BaO ternary system was investigated. A serial of glass samples with high Bi2O3 content in Bi2O3-B2O3-BaO system were prepared by using conventional melting and quenching meld, and the refractive indexes and absorption spectra of samples were measured. It is found that the refractive index of samples as well as the UV absorption increase with the increase of BaO content. According to the Tauc law, optical band gap Eopg which is assumed to be the effective energy band gap Eg is calculated and decreases with the increasing BaO content, and the ratio of Eg/Eopg is 1.3. 展开更多
关键词 glass formation bismuth glass refractive index optical band gap
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Influence of Cu doping in Magnesium Hydroxide Nanoparticles for Bandgap Engineering
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作者 SYED Masood Raza S NASEEM Shah +1 位作者 ADEEL Tahir YASMEEN Bibi 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第3期485-489,共5页
Cu doped Mg(OH)_(2) nanoparticles were synthesized with varying concentrations from 0 to 10%by a chemical synthesis technique of coprecipitation.X-rays diffraction (XRD) of the samples confirms that all the samples ac... Cu doped Mg(OH)_(2) nanoparticles were synthesized with varying concentrations from 0 to 10%by a chemical synthesis technique of coprecipitation.X-rays diffraction (XRD) of the samples confirms that all the samples acquire the hexagonal crystal structure.XRD results indicated the solubility limit of dopant in the host material and the secondary phase of CuO was observed beyond 3%Cu doping in Mg(OH)_(2).The reduction in the size of nanoparticles was observed from 166 to 103 nm for Mg(OH)_(2) and 10% Cu doped Mg(OH)_(2)samples,respectively.The shift in absorption spectra exhibited the systematical enhancement in optical bandgap from 5.25 to 6.085 eV.A good correlation was observed between the bandgap energy and crystallite size of the nanocrystals which confirmed the size induced effect in the nanoparticles.The transformation in the sample morphology was observed from irregular spherical particles to sepals like shapes with increasing the Cu concentration in the host material.The energy dispersive X-Ray (EDX) analysis confirmed the purity of mass percentage composition of the elements present in the samples. 展开更多
关键词 Cu doped Mg(OH)_(2) NANOPARTICLES phase purity optical band gap MORPHOLOGIES
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The Signatures of Acid Concentration on the Optical Band Gap and Associated Band Tails of Chitosan from Shrimp for Application in Optoelectronic Devices
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作者 Edwin Atego John O. Agumba Godfrey O. Barasa 《Advances in Chemical Engineering and Science》 2022年第1期1-12,共12页
Over the recent years, the global increase of electronic wastes from electrical and electronic devices (e-wastes) has been on an alarming trend in quantity and toxicity and e-waste<span style="font-family:Verd... Over the recent years, the global increase of electronic wastes from electrical and electronic devices (e-wastes) has been on an alarming trend in quantity and toxicity and e-waste<span style="font-family:Verdana;">s</span><span style="font-family:""><span style="font-family:Verdana;"> are non-biodegradable resulting in its cumulative increase over time. Changes in technology and unrestricted regional movement of electrical devices have facilitated the generation of more e-wastes leading to high levels of air, soil and water pollution. To address these challenges, biodegradable organic components such as chitosan have been used to replace their inorganic counterparts for optoelectronic device applications. However, in-depth knowledge on how such materials can be used to tune the optical properties of their hybrid semiconductors is unrivaled. Thus, systematic studies of the interplay between the preparation methods and optical </span><span style="font-family:Verdana;">band gap and Urbach energy of such organic components are vital. This study has thus been dedicated to map out the effect of acid concentrations</span><span style="font-family:Verdana;"> during chitosan extraction on the corresponding optical band gap and Urbach energy with a view to improving its applications in optoelectronic devices. The,</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">1.0 to 2.5 molar hydrochloric acid (HCl) was used for 12 hours at room temperature during demineralization and 2.0 molar sodium hydroxide (NaOH) during deprotonation processes. The absorbance spectrum of the samples was collected by UV-Vis spectrophotometer and band gap energies were analyzed by performing Tauc’s plot. This study revealed that the energy band gap of chitosan extracted from 1 M HCl, 1.5 M HCl, 2.0 M HCl and 2.5 M HCl were 3.72 eV, 3.50 eV</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> 3.45 eV and 3.36 eV respectively. Furthermore, the Urbach energy of chitosan extracted from 1 M HCl, 1.5 M HCl, 2.0 M HCl and 2.5 M HCl were 0.60496 eV, 0.5292 eV, 4724 eV and 0.2257 eV, respectively.</span> 展开更多
关键词 Chitosa optical band Gap Urbach Energy Absorbance Spectrum Tauc Plot
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Dual-phase coexistence enables to alleviate resistance drift in phase-change films
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作者 Tong Wu Chen Chen +2 位作者 Jinyi Zhu Guoxiang Wang Shixun Dai 《Journal of Semiconductors》 EI CAS CSCD 2024年第7期55-59,共5页
The amorphous phase-change materials with spontaneous structural relaxation leads to the resistance drift with the time for phase-change neuron synaptic devices. Here, we modify the phase change properties of the conv... The amorphous phase-change materials with spontaneous structural relaxation leads to the resistance drift with the time for phase-change neuron synaptic devices. Here, we modify the phase change properties of the conventional Ge_2Sb_2Te_5(GST) material by introducing an SnS phase. It is found that the resistance drift coefficient of SnS-doped GST was decreased from 0.06 to 0.01. It can be proposed that the origin originates from the precipitation of GST nanocrystals accompanied by the precipitation of SnS crystals compared to single-phase GST compound systems. We also found that the decrease in resistance drift can be attributed to the narrowed bandgap from 0.65 to 0.43 eV after SnS-doping. Thus, this study reveals the quantitative relationship between the resistance drift and the band gap and proposes a new idea for alleviating the resistance drift by composition optimization, which is of great significance for finding a promising phase change material. 展开更多
关键词 phase change films X-ray methods resistance drift optical band gap
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Synthesis of Poly (3-acetylpyrrolyl methine) with Azobenzene Side Groups and Study on Its Third-order Nonlinear Optical Property 被引量:4
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作者 Zhigang ZHANG Hongcai WU +1 位作者 Lingjie MENG Wenhui YI 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2005年第5期715-718,共4页
A novel soluble π-conjugated polymer, poly [(3-acetylpyrrole-2, 5-diyl) p-(N, N-dimethylamino) azobenzylidene] (PAPDMAABE), was synthesized by condensation of 3-acetylpyrrole with 4-aldehyde-4'-dimethylaminoaz... A novel soluble π-conjugated polymer, poly [(3-acetylpyrrole-2, 5-diyl) p-(N, N-dimethylamino) azobenzylidene] (PAPDMAABE), was synthesized by condensation of 3-acetylpyrrole with 4-aldehyde-4'-dimethylaminoazobenzene (ADMAA). The chemical structure of PAPDMAABE was characterized by Fourier transform infrared spectroscopy (FTIR), ^1H-NMR, and UV-Vis-NIR spectra. Transmission electron microscope (TEM) analysis for PAPDMAABE indicates that part of PAPDMAABE is in crystal state, due to the short-range order of the polymer. Thermogravimetric analysis (TGA) curve shows that the polymer has good thermal stability and its decomposition temperature is 248℃. The optical band gap of PAPDMAABE obtained from the optical absorption spectrum is about 1.73 eV. The resonant third-order nonlinear optical property of PAPDMAABE at 532 nm was studied using degenerate four-wave mixing (DFWM) technique. The resonant third-order nonlinear optical susceptibility of the polymer is about 7.48×10^-8 esu. 展开更多
关键词 Poly [(3-acetylpyrrole-2 5-diyl) p-(N N-dimethylamino) azobenzylidene] Small optical band gap Degenerate four-wave mixing Third-order nonlinear property
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Synthesis,Crystal Structure,and Optical Property of Zero-dimensional Quaternary Thioborate:Ba9B3GaS15 被引量:1
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作者 王金秋 刘鹏飞 +1 位作者 黎艳艳 吴立明 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2016年第12期1860-1867,共8页
A new zero-dimensional(0D) thioborate Ba_9B_3GaS_(15) has been discovered by conventional high-temperature solid-state reaction. The compound crystallizes in orthorhombic space group Pbca with a = 8.4759(8),b = ... A new zero-dimensional(0D) thioborate Ba_9B_3GaS_(15) has been discovered by conventional high-temperature solid-state reaction. The compound crystallizes in orthorhombic space group Pbca with a = 8.4759(8),b = 22.266(2),c = 31.426(3) ?,V = 5931(2) ?~3,Z = 8,Mr = 1819.11,Dc = 4.075 g/cm3,μ = 13.684 mm^(-1),F(000) = 6320,S = 1.034,(Δρ)max = 5.039,(Δρ)min = –5.409 e/?~3,the final R = 0.0362 and w R = 0.1053 for 19243 observed reflections with I 〉 2σ(I). The structure is constructed by discrete [BS_3]^(3–) trigonal planes and isolated [GaS_4]^(5–) tetrahedra with Ba^(2+) and isolated S^(2–) filled among them. The UV-Vis-near-IR spectrum reveals a wide band gap of 3.15 eV that agrees with the electronic structure calculation. 展开更多
关键词 thioborate high-temperature solid-state reaction crystal structure optical band gap electronic structure calculation
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Microwave-assisted synthesis of Mg:PbI2 nanostructures and their structural,morphological,optical,dielectric and electrical properties for optoelectronic technology
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作者 Mohd.Shkir Ziaul Raza Khan +4 位作者 T Alshahrani Kamlesh VChandekar M Aslam Manthrammel Ashwani Kumar S AlFaify 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第11期420-426,共7页
This work reports the cost-effective growth of Mg:PbI2 nanostructures with 0,1,2.5 and 5.0 wt.%Mg doping concentrations.Structural,vibrational,morphological properties are analyzed using x-ray diffraction(XRD),Raman s... This work reports the cost-effective growth of Mg:PbI2 nanostructures with 0,1,2.5 and 5.0 wt.%Mg doping concentrations.Structural,vibrational,morphological properties are analyzed using x-ray diffraction(XRD),Raman spectroscopy and scanning electron microscopy(SEM).XRD and Raman studies confirm the monophasic hexagonal system of Mg:PbI2,and no additional impurity peaks are detected.The Scherrer formula is used to determine sizes of crystallites to be in the range of 47-52 nm.EDX/SEM e-mapping analyses confirm the incorporation of Mg in PbI2 matrix and its uniform distribution throughout the sample.The hexagonal nanosheet-and nanoplate-like morphologies are detected in SEM images for pure and Mg-doped PbI2.An optical band gap of nanostructures is obtained from Tauc’s relation to be in the range 3.0-3.25 eV.Dielectric and electrical properties are found in significant enhancement as Mg doping in PbI2 matrix,also the conduction mechanism is discussed. 展开更多
关键词 Mg:PbI2 nanostructures structural properties optical band gap dielectric constant ac conductivity
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Zn-Cu-codoped SnO_2 nanoparticles: Structural, optical, and ferromagnetic behaviors
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作者 Syed Zulfiqar Zainab Iqbal 吕建国 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第12期397-401,共5页
Zn-Cu-codoped SnO2 nanoparticles have been synthesized by chemical precipitation method. All nanoparticles are crystalline, with the average size increases from 2.55 nm to 4.13 nm as the calcination temperature increa... Zn-Cu-codoped SnO2 nanoparticles have been synthesized by chemical precipitation method. All nanoparticles are crystalline, with the average size increases from 2.55 nm to 4.13 nm as the calcination temperature increases from 400℃ to 600℃. The high calcination temperature can enhance the crystalline quality and grain growth. The oxygen content decreases with decreasing calcination temperature; at a low temperature of 400℃, Zn-Cu-codoped SnO2 nanoparticles are in a rather oxygen-poor state having many oxygen vacancies. The optical band gap energies of Zn-Cu-codoped SnO2 nanoparticles calcined at 400℃ and 600℃ are decreased from 3.93 eV to 3.62 eV due to quantum confinement effects. Both samples exhibit room-temperature ferromagnetism, with a larger saturation magnetization at 400℃ due to the presence of large density of defects such as oxygen vacancies. Zn-Cu-codoped SnO2 nanoparticles exhibit large optical band gap energies and room temperature ferromagnetism, which make them potential candidates for applications in optoelectronics and spintronics. 展开更多
关键词 SnO2 nanoparticles Zn-Cu codoping optical band gap energy FERROMAGNETISM
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Linear and nonlinear optical properties of Sb-doped GeSe_2 thin films
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作者 张振营 陈芬 +4 位作者 陆顺斌 王永辉 沈祥 戴世勋 聂秋华 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第6期483-487,共5页
Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises ... Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises and the optical band gap decreases from 2.08 eV to 1.41 eV with increasing the Sb content. X-ray photoelectron spectra further confirm the formation of a covalent Sb--Se bond. The third-order nonlinear optical properties of thin films are investigated under femtosecond laser excitation at 800 nm. The results show that the third-order nonlinear optical properties are enhanced with increasing the concentration of Sb. The nonlinear refraction indices of these thin films are measured to be on the order of 10-18 m2/W with a positive sign and the nonlinear absorption coefficients are obtained to be on the order of 10-10 m/W. These excellent properties indicate that Sb-doped Ge-Se films have a good prospect in the applications of nonlinear optical devices. 展开更多
关键词 chalcogenides films refractive index optical band gap nonlinear optical properties
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Optical Absorption Properties of Electron Beam Evaporated a-Si_(1-x)Gd_x Films
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作者 甘润今 张仿清 +2 位作者 张津岩 刘国汉 陈光华 《Journal of Rare Earths》 SCIE EI CAS CSCD 1991年第4期289-293,共5页
Optical absorption properties of electron beam evaporated a-Si films(a-Si_(1-x)Gd_x films)are studied for various composition x.It is shown from the experimental results that variation of chemical composition in this ... Optical absorption properties of electron beam evaporated a-Si films(a-Si_(1-x)Gd_x films)are studied for various composition x.It is shown from the experimental results that variation of chemical composition in this kind of materials will lead to a change in near infrared absorption.For 0.1 at%<x<1.0 at%,the changes of op- tical absorption in the films are more sensitive.The optical band gap narrows with increasing content x from 1.52 to 1.36 eV.Doping Gd element properly will be able to compensate the dangling bonds in a-Si films to improve thermal stability and mechanical properties of a-Si films. 展开更多
关键词 optical absorption The rare earth element a-Si film optical band gap
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Nonlinear Optical Properties in Bismuth-based Glasses
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作者 章健良 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2011年第1期61-64,共4页
A series of glasses with high Bi2O3 content of Bi2O3-B2O3-WO3 ternary system were chosen and prepared .Their densities and linear refractive indices increase with increasing WO3 content. The optical band gaps Eopt of ... A series of glasses with high Bi2O3 content of Bi2O3-B2O3-WO3 ternary system were chosen and prepared .Their densities and linear refractive indices increase with increasing WO3 content. The optical band gaps Eopt of glasses obtained from ultraviolet absorption edges decreases with increase of WO3 content. Z-scan technique was carried out to investigate the third-order nonlinear optical properties of the glasses. It is found that the nonlinear refraction γ increases with decreasing the optical band gap Eopt, since an increase of WO3 content can promote the non-bridging oxygen ion content, and the highest γ value of samples is 1.173×10-14 cm2/W. The results show that these glasses are potential materials in the application of third-order nonlinear optics field. 展开更多
关键词 bismuth glasses optical band gap third-order nonlinear Z-SCAN
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Ab-initio calculations of bandgap tuning of In1-xGaxY(Y=N,P)alloys for optoelectronic applications
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作者 Muhammad Rashid Jamil M +3 位作者 Mahmood Q Shahid M Ramay Asif Mahmood A Ghaithan H M 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第11期467-474,共8页
The III–V alloys and doping to tune the bandgap for solar cells and other optoelectronic devices has remained a hot topic of research for the last few decades.In the present article,the bandgap tuning and its influen... The III–V alloys and doping to tune the bandgap for solar cells and other optoelectronic devices has remained a hot topic of research for the last few decades.In the present article,the bandgap tuning and its influence on optical properties of In1-xGaxN/P,where(x=0.0,0.25,0.50,0.75,and 1.0)alloys are comprehensively analyzed by density functional theory based on full-potential linearized augmented plane wave method(FP-LAPW)and modified Becke and Johnson potentials(TB-mBJ).The direct bandgaps turn from 0.7 eV to 3.44 eV,and 1.41 eV to 2.32 eV for In1-xGaxN/P alloys,which increases their potentials for optoelectronic devices.The optical properties are discussed such as dielectric constants,refraction,absorption,optical conductivity,and reflection.The light is polarized in the low energy region with minimum reflection.The absorption and optical conduction are maxima in the visible region,and they are shifted into the ultraviolet region by Ga doping.Moreover,static dielectric constant e1(0)is in line with the bandgap from Penn’s model. 展开更多
关键词 density functional theory direct bandgap III-V semiconductors tuning of optical band gap solar cell applications
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Infrared and Optical Properties of Amorphous Fluorinated Hydrocarbon Films Deposited with the Method of ECR Plasma
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作者 辛煜 许圣华 +6 位作者 宁兆元 陈军 陆新华 项苏留 黄松 杜伟 程珊华 《Plasma Science and Technology》 SCIE EI CAS CSCD 2004年第3期2337-2341,共5页
Using CH4 and CF4 precursor gases, amorphous fluorinated hydrocarbon (a-C:F:H) films were prepared with the method of microwave electronic cyclotron resonant (ECR) plasma chemical vapor deposition. Deposition rate of ... Using CH4 and CF4 precursor gases, amorphous fluorinated hydrocarbon (a-C:F:H) films were prepared with the method of microwave electronic cyclotron resonant (ECR) plasma chemical vapor deposition. Deposition rate of the film firstly increases and then decreases with variable flow ratios R {[CF4]/([CF4] + [CH4]} due to the competition between deposition and etching process. Results from Fourier-transform infrared transmission spectroscopy of these films show that C-F bond configuration in a-C:F:H films evolves with the variable gas flow ratios R. The locations of the C-F peaks in IR spectra shift to higher frequency with the increase of R, and finally the structure in films with R >75% takes on a PTFE-like structure, which mainly consists of -CF2- chain. The change of optical band gap Eg deduced by a Tauc plot with R is also discussed. 展开更多
关键词 a-C:F:H films FTIR UV-VIS optical band gap
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Synthesis of Poly[(3-octanoylpyrrole-2,5-diyl)-p-nitrobenzylidene] and Its Third-order Nonlinear Optical Property
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作者 ZHANGZhi-gang WUHong-cai YIWen-hui 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2005年第2期220-223,共4页
A novel soluble π-conjugated polymer, poly[(3-octanoylpyrrole-2,5-diyl)-p-nitrobenzylidene] (POPNBE), was synthesized by a five-step reaction. As a result of introducing a long acyl to pyrrole at 3-position, the poly... A novel soluble π-conjugated polymer, poly[(3-octanoylpyrrole-2,5-diyl)-p-nitrobenzylidene] (POPNBE), was synthesized by a five-step reaction. As a result of introducing a long acyl to pyrrole at 3-position, the polymer can be easily solved in polar solvents and be processed into films. The chemical structures of the intermediates and POPNBE were characterized by FTIR, 1H NMR, and UV-Vis-NIR spectrometries. The absorption band in the range of 400-600 nm in the UV-Vis-NIR spectrum is due to the π-π * band gap transition. The optical band gap of POPNBE obtained from the optical absorption is about 1.72 eV. The resonant third-order nonlinear optical property of POPNBE at 532 nm was studied by using the degenerate four-wave mixing(DFWM) technique. The resonant third-order nonlinear optical susceptibility of POPNBE is about 3.42×10 -8 esu. 展开更多
关键词 Poly[(3-octanoylpyrrole-2 5-diyl)-p-nitrobenzylidene] Small optical band gap Degenerate four wave-mixing technique Third-order nonlinear optical property
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Nonlinear Optical Properties in Bi_2O_3-B_2O_3-SiO_2 Glasses
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作者 聂秋华 陈燕飞 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2007年第B12期806-808,共3页
A series of bismuth borate silica glasses were prepared and their densities, linear refractive indices and transmission spectra were measured. The optical gaps Eopt were obtained from the extrapolation of the linear p... A series of bismuth borate silica glasses were prepared and their densities, linear refractive indices and transmission spectra were measured. The optical gaps Eopt were obtained from the extrapolation of the linear portions to zero absorption. A decrease in the value of Eopt with increasing bismuth content may be explained by suggesting that the non-bridging oxygen ion content increases .It was found that high refractive index and narrow bandgap could lead into high third-order optical nonlinearity. 展开更多
关键词 optical band gap optical nonlinearity bismuth oxide
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Optical, Structural and Morphological Properties of Photocatalytic ZnO Thin Films Deposited by Pray Pyrolysis Technique
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作者 Durgam Komaraiah Eppa Radha +3 位作者 Y. Vijayakumar J. Sivakumar M. V. Ramana Reddy R. Sayanna 《Modern Research in Catalysis》 CAS 2016年第4期130-146,共17页
Photocatalytic ZnO thin films have been deposited onto glass substrate by spray pyrolysis technique. The sprayed solution consists of 0.1 M of zinc acetate dihydrate dissolved in double distilled water and sprays onto... Photocatalytic ZnO thin films have been deposited onto glass substrate by spray pyrolysis technique. The sprayed solution consists of 0.1 M of zinc acetate dihydrate dissolved in double distilled water and sprays onto ultrasonically cleaned glass substrates maintained at 350&deg;C, through an air-atomizing nozzle. The X-ray diffraction (XRD), scanning electron microscopy (SEM), EDX and UV-VIS spectrophotometer were applied to describe the structural, morphological, compositional and optical properties of ZnO catalyst. XRD analysis confirms that the films were found to be single phase hexagonal wurtzite structure. The SEM micrograph of the films is shown highly uniform, crack free and found to be fiber like structures. The optical transmittance spectra of the ZnO thin films were found to be transparent to visible light and the average optical transmittance was greater than 85%. The direct optical band gap energy values of the films shift towards the lower energy as a consequence of the thermal annealing. The Urbach energy of the films was found to increase with annealing temperature. The refractive index of the films was calculated and the refractive index dispersion curve of the films obeys the single oscillator model. The values of oscillatory energy E<sub>o</sub>, dispersion energy E<sub>d</sub>, and static dielectric constant ε<sub>s</sub> for the ZnO thin films were determined. The films were evaluated for their ability to degrade methylene blue. The Langmuir-Hinshelwood kinetic model was used to interpret quantitatively the observed kinetic experimental result. The photocatalytic activity of ZnO thin films was enhanced by annealing temperature. 展开更多
关键词 ZnO Thin Film Spray Pyrolysis optical band Gap Refractive Index Photo Catalysis
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Structural,optical,electrical,and dielectric relaxation properties of rare earth containing sodium bismuth titanate Na_(0.5)Bi_(0.5)TiO_(3) perovskite:Effect of ionic radius 被引量:1
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作者 Rajdip Roy Abhigyan Dutta 《Journal of Rare Earths》 SCIE EI CAS CSCD 2024年第2期383-391,I0006,共10页
The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE^(3+)(RE=La,Sm,Dy,and Ho) on structural and various physical properties of sodium bismuth titanate(Na_(0.... The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE^(3+)(RE=La,Sm,Dy,and Ho) on structural and various physical properties of sodium bismuth titanate(Na_(0.5)B_(0.5)TiO_(3),NBT) based perovskite nanomaterials.The X-ray diffraction data indicate the successful formation of the rhombohedral phase(space group R3c) of NBT nano perovskite incorporated with various rare earth ions in Bi-site.The lattice parameters were found to increase linearly with the ionic radius of the dopant cation.The ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared compositions.The grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic radius.Field emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and stoichiometry.The UV-Vis spectra reveal that La-doped NBT composition exhibits the lowest optical band gap,which unfolds the application of NBT-based perovskite as photoactive material.The ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius,i.e.,La-doped NBT compound,exhibits the highest dc and bulk conductivity with the lowest activation energy.The frequency-dependent dielectric data follows Havriliak-Negami(HN) formalism and non-Debye type relaxation phenomena.Results also indicate that La-doped NBT composition exhibits the highest dielectric strength value.Thus,this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the Bi-site of NBT perovskite improves its microstructural,optical,and electrical properties. 展开更多
关键词 Rare earth doped NBT Microstructural analysis optical band gap AC Conductivity Dielectric relaxation Rare earths
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Exciton radiative lifetime in CdSe quantum dots
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作者 Zhimin Ji Zhigang Song 《Journal of Semiconductors》 EI CAS CSCD 2023年第3期104-113,共10页
Colloidal CdSe quantum dots(QDs)are promising materials for solar cells because of their simple preparation pro-cess and compatibility with flexible substrates.The QD radiative recombination lifetime has attracted eno... Colloidal CdSe quantum dots(QDs)are promising materials for solar cells because of their simple preparation pro-cess and compatibility with flexible substrates.The QD radiative recombination lifetime has attracted enormous attention as it affects the probability of photogenerated charges leaving the QDs and being collected at the battery electrodes.However,the scaling law for the exciton radiative lifetime in CdSe QDs is still a puzzle.This article presents a novel explanation that recon-ciles this controversy.Our calculations agree with the experimental measurements of all three divergent trends in a broadened energy window.Further,we proved that the exciton radiative lifetime is a consequence of the thermal average of decays for all thermally accessible exciton states.Each of the contradictory size-dependent patterns reflects this trend in a specific size range.As the optical band gap increases,the radiative lifetime decreases in larger QDs,increases in smaller QDs,and is weakly depend-ent on size in the intermediate energy region.This study addresses the inconsistencies in the scaling law of the exciton life-time and gives a unified interpretation over a widened framework.Moreover,it provides valuable guidance for carrier separa-tion in the thin film solar cell of CdSe QDs. 展开更多
关键词 solar cells CdSe quantum dot radiative lifetime scaling law optical band gap exciton fine structure room temperat-ure
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Synthesis of rare earth sulfides and their UV-vis absorption spectra 被引量:16
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作者 袁海滨 张剑辉 +1 位作者 余瑞金 苏锵 《Journal of Rare Earths》 SCIE EI CAS CSCD 2009年第2期308-311,共4页
Rare earth sulfides were systematically synthesized via the sulfurization of their commercial oxide powders using CS2 gas to shorten sulfurization time, and their UV-vis absorption spectra were investigated. The appro... Rare earth sulfides were systematically synthesized via the sulfurization of their commercial oxide powders using CS2 gas to shorten sulfurization time, and their UV-vis absorption spectra were investigated. The appropriate sulfurization conditions were studied. For the rare earth sulfides with the same crystal structure, the sulfurization temperature showed increasing tendency with the decrease of rare earth element atomic radii. The UV-vis absorption spectra of rare earth sulfides did not depend on the crystal structure of rare earth sulfides, but on the 4f electronic structure of rare earth element. The data showed that the optical band gaps of rare earth sulfides were irregular, and the values ranged from 1.65 to 3.75 eV. 展开更多
关键词 rare earth sulfides carbon disulfide UV-vis absorption spectra optical band gap
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