Al,Ni掺杂ZnO的电子结构与光学性质

利用基于密度泛函理论的第一性原理方法计算了纯ZnO和分别掺摩尔分数均为6.25%Al,Ni的ZnO的能带结构、电子态密度分布及光学性质。计算结果表明:ZnO掺杂Al,Ni后,其Fermi面均上移并进入导带;Zn0.9375Ni0.0625O的能带结构在导带底附近出现了4条杂质带。纯ZnO,Zn0.9375Al0.0625O和Zn0.9375Ni0.0625O的光学性质在低能处有较大的差异,其中Zn0.9375Al0.0625O在可见光区的吸收系数和反射率较之另外两种材料都相对较低,但三者的光学性质在高能处却非常相似。Zn0.9375Al0.0625O的吸收边有蓝移的趋势,而Zn0.9375Ni0.0625O的吸收边红移。掺杂Ni对ZnO的吸收系数等光学性质的改变更为明显。     

A1,Ni掺杂ZnO的电子结构与光学性质

利用基于密度泛函理论的第一性原理方法计算了纯ZnO和分别掺摩尔分数均为6.25%A1,Ni的ZaO的能带结构、电子态密度分布及光学性质.计算结果表明:ZnO掺杂A1,Ni后,其Fermi面均上移并进入导带;Zn0.9375Ni0.0625O的能带结构在导带底附近出现了4条杂质带.纯ZnO,Zn0.9375A10.0625和Zn0.9375Ni0.0625O的光学性质在低能处有较大的差异,其中Zn0.9375A10.0625O在可见光区的吸收系数和反射率较之另外两种材料都相对较低,但三者的光学性质在高能处却非常相似.Zn<<0.9375>A10.0625O的吸收边有蓝移的趋势,而Zn0.9375Ni0.0625O的吸收边红移.掺杂Ni对ZnO的吸收系数等光学性质的改变更为明显.     

La掺杂ZnO光电性质的研究

采用基于密度泛函理论的第一性原理平面波超软赝势方法,计算了不同原子百分比含量的La掺杂ZnO超晶胞的电子结构和光学性质。结果表明,随着La掺杂量的增加,掺杂体系的体积增加,形成能增加,稳定性降低。La掺杂后禁带宽度明显减少,费米能级向上移动进入导带,转化为n型半导体。与未掺杂ZnO相比,La掺杂后引起光吸收边发生蓝移,高能区的吸收峰发生红移。     

Fe、Ni掺杂ZnO纳米材料的光学、磁性及光催化性能的研究

采用草酸-氨水两步共沉淀法制备了ZnO以及Fe、Ni掺杂的Zn_(1-x)M_xO(0.00≤x≤0.06)纳米材料,利用XRD、UV-Vis、PL和VSM对其结构、光学和磁学性质进行表征与分析,并以亚甲基蓝溶液为模拟污染物,评价了Zn_(1-x)M_xO材料的光催化降解性能,考察Fe、Ni掺杂对ZnO结构、光学、磁学性质和光催化降解性能的影响。结果表明,所有的Zn_(1-x)M_xO样品都具有六方纤锌矿结构;Fe、Ni掺杂提高了ZnO的可见光吸收,且随着掺杂浓度的增加,Zn_(1-x)M_xO样品的带隙宽度减小;ZnO和Zn_(1-x)M_xO材料的光致发光主要有蓝光发射和绿光发射;Fe、Ni掺杂后的Zn_(1-x)M_xO样品表现出明显的室温铁磁性,随着掺杂浓度的增加,Zn_(1-x)Fe_xO的磁性增加,而Zn_(1-x)Ni_xO的磁性减小;Fe、Ni的掺杂浓度对ZnO的光催化降解性能产生较大的影响,高浓度掺杂反而降低了ZnO的光催化降解性能。     

Ni/ZnO的制备及其光催化降解对硝基苯酚的研究

采用水热法制备掺杂金属Ni的ZnO光催化剂,并通过XRD、UV-Vis等表征手段对其物相、光学性能进行了表征.以对硝基苯酚溶液为研究对象,采用正交试验优化了 Ni/ZnO 制备条件,并考察了光催化反应时间、Ni/ZnO用量对光催化性能的影响.实验结果表明:掺杂金属Ni可使ZnO对可见光的吸收强度增大;在140 ℃水热反应16 h,Ni的掺杂比为5％时所制备的Ni/ZnO催化性能较好,可使对硝基苯酚降解率达92％以上.     

稀土金属掺杂氧化锌光催化剂的合成与表征

为了提高半导体氧化锌(ZnO)的光催化性能,通过稀土金属铒(Er)和钕(Nd)共掺杂ZnO的方法研究了共掺杂对ZnO内部结构的影响。采用化学沉淀法和溶剂热法合成了不同形貌的ZnO,并通过X射线衍射(XRD),扫描电子显微镜(SEM),紫外-可见漫反射光谱(UV-vis)等表征手段分析掺杂样品结构性质。研究结果显示:溶剂热法合成的ZnO晶粒尺寸较纯ZnO大幅缩小; ZnO共掺杂后有更强的紫外和可见光发射,吸收带边出现红移。稀土元素Er和Nd共掺杂ZnO可以有效提高其光催化降解效率。     

Co掺杂ZnO微球的光降解及抗菌性能研究

采用简单的水热法制备不同Co掺杂量的ZnO微球。通过X射线衍射、X射线光电子能谱、扫描电镜等技术对Co-ZnO进行结构、形貌及光学性质分析。以亚甲基蓝为模型研究Co-ZnO在模拟太阳光下的催化性能,并以大肠杆菌为模型研究其抗菌活性。结果表明,在制备的催化剂中,物质的量分数5%Co-ZnO具有最佳的光催化及抗菌性能,这可能是由于掺杂的Co离子能够进入ZnO晶格中改变ZnO带隙宽度,且能够抑制在反应过程中产生的光生电子-空穴的复合,从而促进ZnO的光催化及抗菌性能。     

Co掺杂ZnO微球的光降解及抗菌性能研究

采用简单的水热法制备不同Co掺杂量的ZnO微球。通过X射线衍射、X射线光电子能谱、扫描电镜等技术对Co-ZnO进行结构、形貌及光学性质分析。以亚甲基蓝为模型研究Co-ZnO在模拟太阳光下的催化性能,并以大肠杆菌为模型研究其抗菌活性。结果表明,在制备的催化剂中,物质的量分数5%Co-ZnO具有最佳的光催化及抗菌性能,这可能是由于掺杂的Co离子能够进入ZnO晶格中改变ZnO带隙宽度,且能够抑制在反应过程中产生的光生电子-空穴的复合,从而促进ZnO的光催化及抗菌性能。     

掺杂ZnO光催化剂研究进展

ZnO作为半导体光催化剂,具有无毒性、高效性和低成本等优点得到广泛研究。但是ZnO禁带宽度较宽,为3.37 eV,仅能吸收紫外光,而且光生电子和空穴较容易复合,在太阳光照射下,表现出较低的光催化活性,不能满足工业应用要求。对ZnO进行改性能够提高ZnO对可见光的利用率及光催化活性。其中,对ZnO进行掺杂能够有效改变光催化剂的比表面积、颗粒大小和光催化活性等性质,适当引入一些金属或非金属离子有可能使催化剂对光的吸收范围扩展到可见光区。金属掺杂能使ZnO形成更多的晶格缺陷,降低电子和空穴的复合几率;而非金属掺杂能够在ZnO晶格中引入氧空位以及引起ZnO晶格膨胀,使ZnO禁带变窄,进而能吸收可见光;同时,掺杂两种非金属有可能比掺杂单一非金属更能改善ZnO对可见光的吸收。结合金属掺杂与非金属掺杂的优点,金属与非金属共同掺杂到ZnO中,使ZnO的各种缺点得到全面改善。此外,利用金属氧化物对ZnO进行掺杂,可改变ZnO晶格结构以及表面电子状态,提高ZnO光催化活性。需加强对掺杂理论的研究,掺杂虽能使ZnO能够吸收可见光,但是对可见光吸收不强,对太阳能利用率不高,需要对ZnO改性方法进行更深入研究,同时,光催化要进一步在工业上进行应用,应加强对光催化降解多组分废水及真实废水进行研究,其稳定性、固载化及其回收利用方面也应该得到更多关注。     

纳米CdSe_xS_(1-x)微晶玻璃的光吸收性能

半导体纳米微晶掺杂滤光玻璃由于具有优异光学性质 ,近年来已成为光电子材料科学与技术关注的焦点之一。以硼硅酸盐玻璃为基质 ,通过对掺杂微晶组成、结构的设计以及颗粒尺寸的控制 ,系统的研究了纳米微晶的组成、结构以及纳米颗粒尺寸效应等因素对玻璃光吸收性能的影响。结果表明 ,玻璃吸收曲线的截止波长位置以及截止吸收系数主要取决于半导体纳米CdSexS1-x微晶的组成 ,吸收曲线的斜率取决于纳米微晶的颗粒尺寸分布     

Tuning electronic structure and optical properties of ZnO monolayer by Cd doping

Structural, electronic and optical properties of Cd-doped ZnO monolayer have been investigated using first-principles density-functional theory based on the local density approximation plus Hubbard U approach, which precisely predicts the band gap. The formation energy of doped system is negative, implying a stable incorporation of Cd. The band gaps of Cd-doped ZnO monolayer decrease with increasing Cd concentration. Furthermore, Cd doping is found to result in a red-shift of the absorption peaks, enhancing the visible light absorption. These findings demonstrate that Cd-doped ZnO monolayer could display potential application in optoelectronic and photocatalytic fields.     

Effects of Ni doping on structural,optical and dielectric properties of ZnO

Structural, optical and dielectric properties of Ni doped ZnO samples prepared by the solid state route are presented. X-ray diffraction confirmed the substitution of Ni on Zn sites without changing the hexagonal structure of ZnO. NiO phase appeared for 6% Ni doping. Fourier transform infrared measurements were carried out to study phonon modes in Ni doped ZnO. Significant blueshift with Ni doping was observed in UV–visible studies, strongly supported by photoluminescence spectra that show a high intensity UV emission peak followed by the low intensity green emission band corresponding to oxygen vacancies and defects. The photoluminescence analysis suggest that doping of Ni can affect defects and oxygen vacancies in ZnO and give the possibility of band gap tuning for applications in optoelectronic devices. High values of dielectric constant at low frequency and a strong dielectric anomaly around 320 °C were observed.     

Effect of the Growth Parameters on Nonlinear Optical Properties of Al‐Doped ZnO Nano Films

The objective of this research work is to provide a systematic method to perform test and evaluation on the nonlinear optical properties of Al‐doped ZnO nano thin film structure for designing a high‐performance optical‐electronic structure. Some different kinds of samples can be manufactured for testing. The samples are designed by changing technical parameters such as sputtering power of Al and ZnO, pressure and sputtering time and each parameter has three levels. The test results show that the main factor is the sputtering power of Al, which means the doping density of Al. In the meantime, the Maxwell–Garnett theory is used to investigate the optical prosperities of Al‐doped ZnO nano thin films in the visible range. The optical band gap of Al‐doped ZnO nano thin films increases with the increasing of Al doping density, but it becomes slowly when the doping density is more than 16.0%. The results and the investigation method are useful for designing and manufacturing for nano thin films.     

Analysis of structural,optical and magnetic properties of Fe/Co co-doped ZnO nanocrystals

In this paper, the structural, optical and magnetic properties of pure ZnO and Fe/Co co-doped ZnO nanoparticles are presented. Rietveld refinement of XRD pattern revealed the single phase wurtzite structure for prepared samples. FTIR study confirmed the formation of tetrahedral coordination between zinc and oxygen ions. SEM and TEM techniques were used to examine the morphology of samples. The absorption spectra showed the decrease in optical energy band gap with Fe/Co co-doping in ZnO. PL spectra demonstrated five peaks correspond to the ultraviolet region, violet, violet-blue, blue-green and green in the visible region. Emission peak in the UV region is attributed to near band-edge excitonic emission. Other four emission peaks in PL spectra are related to different defect states. M-H curve showed room temperature ferromagnetic (RTFM) behaviour of doped ZnO sample. This paper enhances the understanding of structural, optical and magnetic properties of Fe/Co co-doped ZnO nanocrystals for application in spintronics, solar cells, and ceramics.     

Synthesis,properties and applications of ZnO nanomaterials with oxygen vacancies: A review

ZnO nanomaterials have attracted tremendous interest in the fields of photocatalysis, sensors, solar cells, supercapacitors, etc. However, the performance of intrinsic ZnO is limited by several factors such as insufficient light absorption, poor charge transport and low conductivity. Extensive studies have indicated that the controlled introduction of oxygen vacancies (V_O) into ZnO can manipulate their optical, electronic and surface properties, enabling their enhanced performance in various applications. Here, we present a state-of-the-art review on the various synthetic approaches of ZnO nanomaterials with V_O and their defect-related properties including structural characteristics, band structure, optical, electrical and ferromagnetic properties. In addition, their use in various applications such as photocatalysts, photoelectrodes, antibacterial agents, gas sensors, supercapacitors and other electronic devices related to V_O-rich ZnO are outlined. Furthermore, we offer some perspectives on the challenges and new directions in this field. We hope that this review would provide some useful information to the design, synthesis and applications of metal oxide nanomaterials with defects.     

Synthesis and characterization of ZnO:Ni thin films grown by spray-deposition

In the present study, nickel-doped zinc oxide thin films (ZnO:Ni) at different percentages (0–10%) were deposited on glass substrates by using a chemical spray technique. The effect of Ni concentration on the structural and optical properties of the ZnO:Ni thin films was investigated. The effect of Ni contents on the crystalline structure and optical properties of the films was systematically investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM), UV–vis, Photoluminescence spectra PL, and Raman spectrometry. The XRD analysis showed that both the undoped and Ni-doped ZnO films were crystallized in the hexagonal structure with a preferred orientation of the crystallites along the [002] direction perpendicular to the substrate. The XRD analysis also showed that the films were well crystallized in würtzite phase with the crystallites preferentially oriented towards (002) direction parallel to the c-axis. SEM study reveals the surface of NiZnO to be made of nanocrystalline particles. The SEM images showed a relatively dense surface structure composed of crystallites in the spherical form whose average size decreases when the [Ni]/[Zn] ratio increases. The optical study showed that all the films were highly transparent. The band gap decreased up to the 7 at% Ni doping level, but the band gap increased after 10 at% Ni doping level. All thin films exhibited approximately 80% and above transmittance in the visible region. PL spectra of undoped and Ni-doped ZnO thin films showed some marked peaks at 376, 389, 494, and 515 nm. The obtained results revealed that the structures and optical properties of the films were greatly affected by doping levels. These films are useful as conducting layers in electro chromic and photovoltaic devices. Finally, all results were discussed in terms of the nickel doping concentration.     

Fabrication of spray derived nanostructured n-ZnO/p-Si heterojunction diode and investigation of its response to dark and light

Fluorine doped ZnO thin films were grown by chemical spray pyrolysis technique of zinc acetate and ammonium fluoride, and the effect of fluorine content on structural, optical and electrical properties were evaluated. The structural, morphological, optical properties of ZnO films were investigated by XRD (X-ray diffraction), AFM (Atomic force microscopy), SEM (Scanning electron microscop) and UV–Vis spectroscopy, respectively. According to results, it was observed that all films had polycrystalline texture with hexagonal wurtzite crystal structure and film surface were made up of nano-scale grains, varied by fluorine content. Optical properties showed that optical band gap energy of ZnO changed from 3.28 to 3.24 eV with F content. Shrinkage effect was assessed as the cause in the variation of optical band gap values. Finally, current-voltage (I-V) analysis was performed in Au/ZnO:F/p-Si device in dark and light conditions and certain diode parameters such as ideality factor, barrier height and series resistance were calculated and discussed in detail.     

Effects of aluminium doping on structural and photoluminescence properties of ZnO nanoparticles

Structural and optical properties of Al doped ZnO nanoparticles prepared by the thermal decomposition method are presented. X-ray diffraction studies confirmed the substitution of Al on Zn sites without changing the hexagonal structure of ZnO. Also, lattice parameters, the crystallite size and other physical parameters such as strain, stress and energy density were calculated from various modified forms of W–H equation and their variation with the doping of Al is discussed. A blue shift in the energy band gap attributed to increase in carrier concentration (Burstein Moss Effect) is observed by absorption spectra. Photoluminescence studies show a strong and dominant peak corresponding to the near band edge emission in ultraviolet range and a broad band in the range 420–520 nm corresponding to defects and oxygen vacancies. Phonon modes were studied by FTIR measurements. The tunability of the band gap of ZnO nanoparticles could eventually be useful for potential optoelectronic applications.