Effect of Fe-doping on the structural,morphological and optical properties of ZnO nanoparticles synthesized by solution combustion process

The effect of Fe-doping on the structural, morphological and optical properties of ZnO nanoparticles synthesized by simple solution combustion process are reported. The powder XRD pattern indicates that the Fe-doped ZnO samples exhibit primary and secondary phases. The primary phase indicates the hexagonal wurtzite structure with the average crystalline size of around 25–50 nm and the secondary phase is associated with the face centered cubic structure of magnetite iron oxide. The elemental composition of pure and Fe-doped samples are evaluvated by EDX. The results of FE-SEM and HR-TEM cleary show that particles morphology have changed with respect to the incorporation of doping agent and particles are in aggregating nature. The vibrational properties of the synthesized ZnO nanoparticles are investigated by Raman scattering technique and it exhibits that the influence of Fe-doping significantly modify the lattice vibrational characteristics in ZnO sites. The optical properties of the Fe-doped ZnO nanoparticles are carried out by UV–vis absorption and PL spectra. The results of PL spectra show the near-band edge related emission as well as strong blue emissions in the Fe-doped ZnO nanoparticles.     

Structural,morphological, optical and antibacterial activity of rod-shaped zinc oxide and manganese-doped zinc oxide nanoparticles

Pure ZnO and Mn-doped ZnO nanoparticles were synthesized by Co-precipitate method. The structural characterizations of the nanoparticles were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. UV–Vis, FTIR and photoluminescence (PL) spectroscopy were used for analysing the optical properties of the nanoparticles. XRD results revealed the formation of ZnO and Mn-doped ZnO nanoparticles with wurtzite crystal structure having average crystalline size of 39 and 20 nm. From UV–Vis studies, the optical band-gap energy of 3.20 and 3.25 eV was obtained for ZnO and Mn-doped ZnO nanoparticles, respectively. FTIR spectra confirm the presence of ZnO and Mn-doped ZnO nanoparticles. Photoluminescence analysis of all samples showed four main emission bands: a strong UV emission band, a weak blue band, a weak blue–green band and a weak green band indicating their high structural and optical qualities. The antibacterial efficiency of ZnO and Mn-doped ZnO nanoparticles were studied using disc diffusion method. The Mn-doped ZnO nanoparticles show better antibacterial activity when higher doping level is 10 at% and has longer duration of time.     

High UV absorption efficiency of nanocrystalline ZnO synthesized by ultrasound assisted wet chemical method

Ultrasound assisted wet-chemical method has been carried out to incorporate different metal and non-metal ions such as; Li, S and Ag into ZnO. Characteristic studies on the structural and optical properties of the samples especially; the ultra-violet (UV) light absorption have been carried out. X-ray diffraction (XRD) analysis shows the formation of hexagonal crystal structure of ZnO along with changes in crystallinity and micro-strain with impurity doping. The morphology of the doped samples changes from particle like structure to flower and rod like structures showing the influence of dopant ions on nano ZnO growth. Infra-red (IR) transmittance spectra give information about the presence of metal–oxygen bond along with other stretching and bending modes. UV–visible absorption studies show the narrowing and sharpening of UV absorption band along with a blue shift for the doped samples. This shows the intensification in the excitonic absorption in ZnO after doping specific elements which will find application in UV blocking agents. Photoluminescence (PL) measurement shows the presence of excitonic emission and emissions due to intrinsic defects and external impurities in UV and visible regions respectively. These emission bands show a change in their position and intensity which has been explained on the basis of the existence of impurity levels in the band gap of ZnO.     

铕掺杂纳米氧化锌晶体结构和荧光光谱的研究

以醋酸锌、氧化铕、氢氧化钠为主要原材料,利用共沉淀法制备ZnO∶Eu3+纳米晶体.在X射线衍射谱中,只观察到氧化锌的峰,没有观察到氧化铕的特征峰.比较了ZnO和ZnO∶Eu3+拉曼光谱,在ZnO∶Eu3+样品拉曼光谱中观察到新的局部振动模.这些现象表明铕离子已经进入氧化锌晶格中.SEM形貌显示Eu3+离子掺入使ZnO晶...     

Effect of barium doping on the physical properties of zinc oxide nanoparticles elaborated via sonochemical synthesis method

The aim of this work is to study the effect of barium (Ba) doping on the optical, morphological and structural properties of ZnO nanoparticles. Undoped and Ba-doped ZnO have been successfully synthesized via sonochemical method using zinc nitrate, hexamethylenetetramine (HMT) and barium chloride as starting materials. The structural characterization by XRD and FTIR shows that ZnO nanoparticles are polycrystalline with a standard hexagonal ZnO wurtzite crystal structure. Decrease in lattice parameters from diffraction data shows the presence of Ba²⁺ in the ZnO crystal lattice. The morphology of the ZnO nanoparticles has been determined by scanning electron microscopy (SEM). Incorporation of Ba was confirmed from the elemental analysis using EDX. Optical analysis depicted that all samples exhibit an average optical transparency over 80%, in the visible range. Room-temperature photoluminescence (PL) spectra detected a strong ultraviolet emission at 330 nm and two weak emission bands were observed near 417 and 560 nm. Raman spectroscopy analysis of Ba-doped samples reveals the successful doping of Ba ions in the host ZnO.     

Optical and electrochemical characteristics of Pb ions doped ZnO nanocrystals

Herein, we report the optical and electrochemical properties of Pb ions doped ZnO nanocrystals fabricated via a simple chemical precipitation method. The structural and chemical compositions of the products are characterized by XRD, XPS, EDS and FT-IR spectroscopy. The observed results suggest that Pb ions are successfully incorporated into the ZnO lattice. The microstructures of the samples are analyzed by FESEM and confirmed by HRTEM. The PL emission spectra show an intensity quenching upon doping. Electrochemical performances show that the supercapacitor behavior of ZnO has been enhanced greatly on doping.     

Cr doping induced structural, phonon and excitonic properties of ZnO nanoparticles

We report systematic study of structural, phonon and optical properties of Cr-doped ZnO nanoparticles. These particles are synthesized through simple sol–gel technique. Structural studies carried out by X-ray diffraction method, confirm that the prepared particles are in hexagonal wurtzite structure and lattice parameters change considerably while increasing the doping. Raman and Fourier transform infrared spectral studies show that the intensity of the phonon modes decreased and also blue shift due to ion doping, respectively. Apart from this, transmission electron microscopic studies show reduction in particle size where the particle diameters reduced from 36 to 11 nm. Optical absorption spectral measurements show a blue shift in the band-gap and increment in excitonic oscillator strength. Photoluminescence studies show doping altered the near-band edge emission but there is no change in the other emission bands which is due to oxygen vacancy, surface defects and surface dangling bonds.     

Effects of Ga doping on optical and structural properties of ZnO epilayers

Effects of Ga incorporation on electrical, structural and optical properties of ZnO epilayers are systematically studied by employing structural and optical characterization techniques combined with electrical and secondary ion mass spectrometry measurements. A non-monotonous dependence of free electron concentrations on Ga content is observed and is attributed to defect formation and phase separation. The former process is found to dominate for Ga concentrations of around 2–3×10²⁰ cm^?3. The corresponding defects are suggested to be responsible for a broad red emission, which peaks at around 1.8 eV at 4 K. Characteristic properties of this emission are well accounted for by assuming intracenter transitions at a deep center, of which the associated Huang–Rhys factor and mean phonon energy are determined. For higher Ga doping levels, the phase separation is found to be significant. It is suggested that under these conditions only a minor fraction of incorporated Ga atoms form shallow donors, which leads to the observed dramatic decrease of carrier concentration.     

过渡金属与F共掺杂ZnO薄膜结构及磁、光特性

采用溶胶-凝胶法在玻璃衬底上制备了过渡金属元素与F共掺杂Zn_0.98-xTM_xF_0.02O (TM_x=Cu_0.02, Ni_0.01, Mn_0.05, Fe_0.02, Co_0.05)薄膜, 进而利用X射线衍射仪、扫描电子显微镜、紫外-可见透过谱、光致发光及振动样品磁强计等研究了薄膜的表面形貌、微结构、禁带宽度及光致发光(PL)和室温磁学特性. 研究表明: 掺杂离子都以替位的方式进入了ZnO晶格, 掺杂不会破坏ZnO的纤锌矿结构. 其中Zn_0.93Co_0.05F_0.02O薄膜样品的颗粒尺寸最大, 薄膜的结晶度最好且c轴择优取向明显; Zn_0.93Mn_0.05F_0.02O薄膜样品的颗粒尺寸最小, 薄膜结晶度最差且无明显的c轴择优取; Cu, Ni, Fe与F共掺杂样品的颗粒尺寸大小几乎相同. TM掺杂样品均表现出很高的透过率, 同时掺杂后的薄膜样品的禁带宽度都有不同程度的红移. PL谱观察到Zn_0.98-xTM_xF_0.02O薄膜的发射峰主要由较强的紫外发射峰和较弱的蓝光发射峰组成. Zn_0.93Mn_0.05F_0.02O薄膜样品的紫外发光峰最弱, 蓝光发射最强, 饱和磁化强度最大; 与之相反的是Zn_0.96Cu_0.02F_0.02O薄膜, 其紫外发光峰最强, 蓝光发射最弱, 饱和磁化强度最小. 结合微结构和光学性质对Zn_0.98-xTM_xF_0.02O薄膜的磁学性质进行了讨论.     

Co与Cu掺杂ZnO薄膜的制备与光致发光研究

采用溶胶-凝胶旋涂法在玻璃衬底上制备了Co, Cu单掺杂及Co,Cu共掺杂ZnO薄膜.用金相显微镜观察了Co与Cu掺杂对ZnO薄膜形貌的影响.X射线衍射（XRD）研究揭示所有ZnO薄膜样品都存在（002）择优取向,在Cu单掺的ZnO薄膜中晶粒尺寸最大.对所有样品的室温光致发光测量都观察到较强的蓝光双峰发射和较弱的绿光发射,其中长波长的蓝光峰和绿光峰都能够通过掺杂进行控制.对不同掺杂源的ZnO薄膜发光性能进行了分析,认为蓝光峰来源于电子由导带底到锌空位能级的跃迁及锌填隙到价带顶的跃迁,绿光峰是由于掺杂造成的 关键词： ZnO薄膜 溶胶-凝胶 Co Cu掺杂 光致发光     

生长条件对Ga掺杂ZnO薄膜微观结构及光致发光性能的影响

利用热氧化法在不同参数条件下生长了Ga掺杂范围较宽的ZnO薄膜, 研究了ZnO薄膜的表面微观结构和光致发光性能. 研究表明: Ga以Ga³⁺存在并掺入ZnO晶格取代Zn²⁺, Ga的掺入改变了ZnO薄膜中的缺陷类型及浓度、化学计量比、薄膜表面结晶质量, 进而影响了薄膜的光致发光性能. 随着热氧化温度升高, Ga掺杂量增大, ZnO薄膜的晶粒尺寸增大, 尺寸更均一, 紫外光与可见光强度比增大. 随着热氧化时间延长, Ga掺杂量降低, ZnO薄膜的晶粒尺寸均一性变差, 紫外光与可见光强度比减小.     

Structural and optical properties of the S-doped ZnO particles synthesized by hydrothermal method

Sulfur-doped ZnO particles have been synthesized by hydrothermal method. The structural and optical properties were studied systematically by XRD, scanning electron microscopy (SEM), and photoluminescence. SEM results show that the particle is hexagonal and the average size decreases with increasing sulfur doping, which means a retardant effect of sulfur on the growth of S-doped ZnO. XRD results show that the lattice parameters increase with more sulfur, which means an effective sulfur doping and increasing strain. Optical characterization also shows that the effective sulfur doping will enhance the green emission and suppress the near bandgap emissions.     

Characteraction of Ag-doped ZnO thin film synthesized by sol–gel method and its using in thin film solar cells

Pure 2% and 4% Ag-doped ZnO thin films have been synthesized on glass substrates by sol–gel method. The structure, morphology and optical properties of the samples have been studied by X-ray diffractometer (XRD), scanning probe microscope, UV–vis spectrophotometer, respectively. The XRD result shows that the pure ZnO has a wurtzite hexagonal structure, no phase segregation is observed. The surface morphology of pure ZnO thin film shows that the grains are growing preferentially along the c-axis orientation perpendicular to the substrates. The transmittance spectra reveal that all samples have high transmittance above 90% in visible region. With Ag doping content increase, a red shift is observed. The performance of Ag-doped ZnO films using in thin film solar cells are simulated. The results show that 4% Ag-doped ZnO thin film can greatly improve the absorption of the cells. Compare to pure ZnO, solar cell's energy conversion efficiency improvement of 2.47% is obtained with 4% Ag doped ZnO thin film.     

不同Yb掺杂浓度的ZnO的电子结构与光学特性

本文基于密度泛函理论(DFT)框架下的第一性原理计算方法,研究了不同Yb浓度掺杂ZnO体系的电子结构和光学性质.计算得到的结果证明,Yb掺杂ZnO后会造成电子结构和光学性质的明显改变.增加掺杂浓度使能带带隙逐渐变窄,其费米能级向上移动到导带,表现出n型半导体的特性;在Yb-4f态导带附近的带隙中产生了新的缺陷,同时观察到更好的吸收系数和折射率.因此,Yb掺杂ZnO对其电子性质和光学结构有很大的影响,为进一步深入了解掺杂ZnO性质的影响提供理论基础.     

Co,Sn共掺ZnO薄膜结构与光致发光的研究

采用溶胶-凝胶旋涂法在玻璃衬底上制备了Co,Sn掺杂ZnO系列薄膜.通过金相显微镜和X射线衍射(XRD)研究了Co与Sn掺杂对薄膜的表面形貌和微结构的影响.XRD结果表明,所有ZnO薄膜样品都存在(002)择优取向,特别Sn单掺ZnO薄膜的c轴择优取向最为显著,而且晶粒尺寸最大.XPS测试表明样品中Co和Sn的价态分别为2+和4+,证实Co²⁺,Sn⁴⁺进入了ZnO的晶格.室温光致发光谱(PL)显示在所有的样品中都有较强的蓝光双峰发射和较弱的绿光发 关键词： ZnO薄膜 溶胶-凝胶 掺杂 光致发光     

Property enhancement of transparent conducting zinc oxide thin films—Effect of simultaneous (Sn+F) doping

Undoped and simultaneously (Sn+F) doped ZnO thin films were fabricated using a simplified spray pyrolysis technique and the effects of Sn doping level on their electrical, structural, optical and surface morphological properties were studied. The XRD patterns confirmed the hexagonal wurtzite structure of ZnO. The minimum electrical resistivity of 0.45×10⁻² Ω cm was obtained for ZnO films having Sn+F doping levels of 8+20 at%. All the films exhibited average optical transmittance of 85% in the visible region, suitable for transparent electrode applications. The overall quality of the fabricated films was confirmed from photoluminescence (PL) studies. The PL and surface morphological studies along with the elemental analysis showed the increase of Sn diffusion into the ZnO lattice which was consistent with the concentration of Sn in the starting solution. The results of the analysis of physical properties of simultaneously doped ZnO films proved that these films might be considered as promising candidates for solar cells and other opto-electronic applications.     

The influence of Fe doping on the structural, magnetic and optical properties of nanocrystalline ZnO particles

We report the results of an investigation of Fe-doped nanocrystalline ZnO particles synthesized using the co-precipitation method with doping concentrations from 5 up to 31 at%. To understand how the dopant influenced the structural, magnetic and optical properties of nanocrystalline ZnO particles, X-ray diffraction, energy dispersive X-ray spectroscopy, infrared absorption spectroscopy, UV-vis spectroscopy, electron spin resonance spectroscopy (ESR) and vibrating sample magnetometer were employed. From the analysis of X-ray diffraction, our Fe-doped nanocrystalline ZnO particles are identified as having the wurtzite crystal structure and the unit cell volume increases with increasing doping concentrations. However, impurity phases are observed for Fe contents higher than 21 at%. Sample structures were further studied by infrared spectra, from which a broad and strong absorption band in the range of 400-700 cm⁻¹ and -OH stretching vibrational mode at approximately 3400 cm⁻¹ were observed. Ultraviolet-visible measurements showed a decrease in the energy gap with increasing Fe content, probably due to an increase in the lattice parameters. Magnetic measurements showed a ferromagnetic behavior for all samples. ESR results indicate the presence of Fe in both valence states Fe²⁺ and Fe³⁺.     

Effect of synthesis conditions on microstructures and photoluminescence properties of Ga doped ZnO nanorod arrays

Ga doped ZnO nanorod arrays were prepared on silicon substrates in a mixture solution of zinc nitrate hexahydrate, methenamine, and gallium nitrate hydrate. Effect of synthesis conditions on crystal structures, morphologies, surface compositions, and optical properties was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence techniques (PL). Experimental results reveal that Ga doping amount can reach 1.67 at% with the increase of gallium nitrate concentration. Ga doping greatly affects the morphologies of ZnO nanorod arrays. The photoluminescence spectra show a sharp UV emission and a broad visible emission. With Ga doping, UV emission has an apparent broadening effect and its peak shifts from 3.27 eV to 3.31 eV. The intensity ratio of UV emission to visible emission demonstrates that appropriate Ga doping amount is beneficial for the improvement of ZnO crystalline quality.     

Effect of Mn doping on the microstructures and photoluminescence properties of CBD derived ZnO nanorods

Mn-doped ZnO nanorods were synthesized from aqueous solutions of zinc nitrate hexahydrate, manganese nitrate and methenamine by the chemical solution deposition method (CBD). Their microstructures, morphologies and optical properties were studied in detail. X-ray diffraction (XRD) results illustrated that all the diffraction peaks can be indexed to ZnO with the hexagonal wurtzite structure. Scanning electron microscope (SEM) results showed that the average diameter of Mn-doped ZnO nanorods was larger than that of the undoped one. Photoluminescence (PL) spectra indicated that manganese doping suppressed the emission intensity and caused the blue shift of UV emission position compared with the undoped ZnO nanorods. In the Raman spectrum of Mn-doped ZnO nanorods, an additional mode at about 525 cm⁻¹ appeared which was significantly enhanced and broadened with the increase of Mn doping concentration.     

Influence of Mn doping on structural and optical properties of ZnO nano thin films synthesized by sol–gel technique

Undoped and Mn-doped ZnO samples with different percentages of Mn content (1, 5 and 10?at%) were synthesized by a dip-coating sol?Cgel method. We have studied the structural, chemical and optical properties of the samples by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible spectroscopy. The XRD spectra show that all the samples are hexagonal wurtzite structures. We note that doping favors c-axis orientation along (002) planes. Up to 5?at% of Mn doping level, the c-axis lattice parameter shifts towards higher values with the increase of manganese content in the films. The expansion of the lattice constant of ZnO?CMn indicates that Mn is really doped into the ZnO. The SEM investigations of all samples revealed that the crystallites are of nanometer size. The surface quality of the ZnO?CMn film increases with Mn doping but no significant change of the grain size is observed from SEM images. The transmittance spectra show that the transparency of all the samples is greater than 85?%. We note, also, that a small doping (1?%) lowered the refractive index while the thickness of the layers and the gap increase. However, on raising the proportion of Mn beyond 5?%, practically the same values of index and gap as pure ZnO are found.