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Phase Evaluation of Pure Nanocrystalline Barium Stannate by Two Different Milling Activations
摘要： Pure nanocrystalline BaSnO3 is prepared by two methods: mechanical activation (planetary ball milling) and mechanical hand mixing in agate mortar followed by sintering for both at 1350 °C/ 2 h. The phase formations during synthesis are analyzed by x-ray diffraction (XRD) studies and the crystallite size is measured by Scherrer’s formula from the major peaks of the diffractogram. The nanocrystalline barium stannate having single phase simple cubic perovskite structure is synthesized with a crystallite size about 50 nm. Fourier transform infrared spectroscopy (FTIR) is done to determine symmetric and asymmetric stretching of the bonds formed and co-ordination of the ions within crystal structure. FTIR studies justify the phases developed by XRD since the molecular signature and co-ordination of cations are verified. Microstructure and morphology are observed by scanning electron microscopy (SEM), while energy dispersive x-ray analysis (EDX) is done to determine the presence of the required element of composition formation. Ultra violet-visible spectroscopy (UV-VIS) shows absorption spectra of the sample within the UV region, while the band gap is calculated using the Tauc relation. The band gap evaluated for nanocrystalline barium stannate is about 2–2.78 eV for indirect transition, while for direct transition it is about 2.78–3.14 eV. The value is observed to be close to that of semiconductor-based materials.
关键词： FTIR,UV-VIS,nanocrystalline barium stannate,EDX,high energy planetary milling,XRD,SEM
更新于2025-09-23 15:22:29
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Synthesis, Structural and Luminescent Properties of Eu2+/Dy3+ Activated GdAlO3 Phosphors by Solid State Reaction Method Under Nitrogen Atmosphere
摘要： Synthesis, Structural and Luminescent Properties of Eu2+/Dy3+ Activated GdAlO3 Phosphors by Solid State Reaction Method Under Nitrogen Atmosphere. Eu2+ and Dy3+ singly doped and codoped GdAlO3 phosphor was synthesized by solid state reaction method in a reducing atmosphere of nitrogen. Samples were characterized by powder X-ray diffraction (PXRD) analysis. The average crystal size was obtained around 48 nm. Surface morphology was verified by scanning electron microscopy (SEM) analysis. The emission spectra of phosphors singly doped with Eu2+ and codoped with Eu2+; Dy3+ respectively were recorded under 354 nm excitation. The emission spectra of Eu2+ has intense emission peak at 515 nm. It was observed that the after codoping with Eu2+ and Dy3+ the emission bands of Eu2+ dominates along with a new emission band centred at 419 nm. CIE chromaticity diagram shows variation in emitted colour with Eu2+, Dy3+ singly doped and codoped phosphor. The investigation of Dy3+ codoping shows the colour tunable behaviour of the phosphor. This colour tunable behaviour of the phosphor makes it useful in the colour display applications.
关键词： CIE,XRD,Eu2+,photoluminescence,GdAlO3,Dy3+
更新于2025-09-23 15:22:29
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Investigation of local geometrical structure, electronic state and magnetic properties of PLD grown Ni doped SnO2 thin films
摘要： We have investigated the ferromagnetic behavior, electronic states and local geometrical structure of Ni (2 and 10 at %) doped SnO2 thin films. The films were successfully fabricated with the help of pulsed laser deposition (PLD) technique on Si (100) substrate under ultrahigh vacuum (UHV) condition. X-ray diffraction (XRD) results revealed the single phase character of SnO2 rutile lattice structure with P42/mnm space group. The inclusion of Ni ions into SnO2 matrix induced oxygen vacancy (Vo), enhanced the distortion in octahedral local symmetry and reduced the oxidation state of the host Sn4+ (SnO2) to Sn3+ (Sn2O3) these details have been estimated by Raman scattering, Near edge X-ray absorption fine structure (NEXAFS) spectra at Ni L3,2 and O K edges. Further quantitative details on the local geometrical structure around Ni ions were obtained via fitting the experimental Fourier transforms EXAFS spectra |X(R)| with FEFF6 code. The magnetization measurements performed at room temperature (RT) infers that the observed magnetic behavior of the films seems to be relevant to the same crystal growth condition (UHV) and might not be limited directly to the Ni dopant concentrations. The FM signal and the role of surface defects have been discussed based spin-split impurity band difference in the saturation moments even with increase the Ni content. Hence, the similarity in Ni doped SnO2 films displayed ferromagnetic (FM) signal, and there was no significant Ferromagnetism etc. percolation mechanism.
关键词： surface defects,XANES spectra,SnO2 nanostructured thin film,PLD,local symmetry,XRD,NEXAFS
更新于2025-09-23 15:22:29
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Synthesis Graphene Based Sensor for strain data and its characterization
摘要： Graphene material with fine structure is used to fabricate for the different types of sensors. Graphene are mostly 2D structure bounded by sp2 carbon atoms in a honeycomb lattice parameter prented. Strain sensors are immense interest over the past years, which is used to deduct the change in the human bodies. It applicable in various field such as chemical, mechanical, electrical and electronic sensor. Graphene based strain sensors fabricated in a form of stretchable rubber by the way of stamping technique. Under this process mechanical properties of the synthesized graphene materials was systamatically discussed and also investigated the x-ray diffraction, surface manufacturing studies, raman spectroscopy and I-V characteristics studies. Finally, strain sensor for human body was measured by connecting with the with glove and the strain was measured corresponding with resistance values. After stretching glove, the strain value become the original position. The strain change based on the resistivity during the exercise the period.
关键词： Graphene,XRD,Strain sensor,I-V charecteristics
更新于2025-09-23 15:22:29
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Growth and study of nonlinear optical P-dimethyl-aminobenzaldehyde crystal for photonic device application
摘要： Pera dimethyl-aminobenzaldehyde (p-DMAB) is a well known aromatic compound with nonlinear optical (NLO) properties in various application fields such as optoelectronics, photonics etc. The single crystal of p-DMAB is grown by slow evaporation technique (Constant Temperature Bath) at room temperature. These grown crystals are good in size with transparent appearance. The grown crystals are characterized using XRD, FTIR spectroscopy, Elemental analysis, UV-Spectroscopy, Second Harmonic Generation (SHG), Optical limiter behaviour, Photoluminescence (PL), Vickers hardness, Scanning Electron Microscopy (SEM). Single crystal XRD provides information about the crystal structure. The powder XRD shows that material is crystalline in nature. FTIR- Spectroscopy provides information about the relevant functional group present in the compound. CHN (Carbon-Hydrogen-Nitrogen) analysis shows appropriate composition of these elements within this material. UV-Vis study reveals that materials have wide window over the entire visible region. The observed order of refractive index points their use in anti-refracting coating devices. Good linear polarisability, susceptibility, optical conductivity data are also appropriate to decide their use in optical device fabrications. Wider optical band gap described dielectric behavior of material. Second harmonic generation test shows that material has 2.03 times greater efficiency than the reference material KDP. Moreover the emission of green light indicates that the material can be used to develop green-blue laser. Optical limiter behavior shows that material is suitable for fabrication of an optical limiter device. In PL study desecrate energy level indicates purity of grown crystals. The Vicker’s micro hardness study was also carried out on the sample. Vickers hardness test shows increment in hardness, yield strength and stiffness of material. SEM images show smooth morphology at different magnifications.
关键词： FTIR,Crystal growth,SEM,XRD,Vickers hardness,CTB method
更新于2025-09-23 15:22:29
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Electrical Transport Properties of Thin Film Composed of a-ZnO Nanorods
摘要： Background: Due to its wide band gap, high exciton binding energy and high breakdown strength, the nanostructures of ZnO may find applications for electronic, photonic devices, and high-frequency applications. Objective: The aim of the present work is to study electrical transport of thin film composed of a-ZnO nanorods. Method: Physical vapour condensation method was employed to fabricate the nanorods of ZnO. The morphology of these nanorods was investigated with the help of scanning electron microscope. X-ray diffraction pattern of as-prepared thin film was recorded using X-ray diffractometer. For dc conductivity measurements, four-probe method was used. Result: The as-prepared ZnO nanorods have diameter ranging from 10-20 nm and the length is of order of few hundred nanometers. XRD pattern of film composed of ZnO nanorods suggests the amorphous nature. Temperature dependence of dc conductivity has been studied over the temperature range of (297- 4.2K). For the temperature range of 297-120K, Mott’s three dimensional variable range hopping (VRH) is applied to explain the electrical conduction. For lower temperature range (120 - 4.2K), 2D-variable-range hopping in localized states near the Fermi level may be responsible for the transport of carriers. Conclusion: Variable range hopping mechanism (VRH) has been suggested for the entire temperature range (298-4.2K) on the basis of temperature dependence of dc conductivity data, which changes from 3D to 2D on moving to lower temperatures side (below 125K).
关键词： physical vapour condensation technique,variable range hopping,XRD,ZnO nanorods,SEM,Mott’s parameters,electrical conduction mechanism
更新于2025-09-23 15:22:29
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The influence of yttrium-ions on the optical and electrical behavior of PVA polymeric films
摘要： The polyvinyl alcohol (PVA) films doped with various wt% of yttrium nitrate salt were synthesized by standard solution casting technique in order to examine the functional electrical and optical properties. The degree of the crystalline structure that evaluated in the films were investigated by x-ray diffraction and Fourier transform infrared spectroscopy measurements. In addition, the surface images have been obtained via scanning electron microscopy (SEM). The optical parameters have been calculated from UV–visible-NIR transmittance spectroscopy. Also, the dielectric constant measurement and the DC resistance that are arisen in the PVA films with different wt% of Y3+ have been done. All the samples show semi-crystalline phases. The average size, of the cluster Y3+ in the SEM images, increase to 1.63 μm for PVA/37 wt% Y3+ sample. Therefore, the optical absorption of this sample is higher than the others. The value of the energy gap decrease from 5.11 eV to 4.47 eV for PVA/0.037 wt% Y3+ and PVA/37 wt% Y3+ samples, respectively. The nonlinear current—voltage behavior, at high applied voltage, of the polymeric films, is observed with different values of slope, which is a characteristic of the varistor materials. So, these films could be used in different applications like optoelectronic and varistor devices.
关键词： Varistor,Dielectric,XRD/FTIR,SEM,Optical energy gap,Y3+-doped PVA
更新于2025-09-23 15:22:29
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Effect of Ag incorporation on structural and opto-electric properties of pyrolized CdO thin films
摘要： We have investigated the structure, morphology and opto-electric properties of CdO and Ag-incorporated CdO thin films prepared by chemical spray pyrolysis (CSP) method. The X-ray diffraction (GIXRD) study confirms that CdO samples are highly polycrystalline with cubic structure. The AFM study shows smooth surfaces both for CdO and Ag-CdO thin films. The direct band gap energy varies from 2.25 to 2.50 eV depending on Ag content in the films. Urbach energy reversal in optical band gap indicates that several localized states are present above Fermi level or near at the conduction band. The optical properties, such as refractive index, optical conductivity and nonlinear optical susceptibility, are found dependent on Ag content. A combined effect on the transport properties has been observed with the incorporation of Ag in CdO. The metal-like electric conduction of CdO film has been removed up to a temperature Tc for Ag doping. The n-type carrier concentration of CdO is reduced with increasing Ag content and the concentration is of the order of ~ 1020 cm?3.
关键词： Band gap,Activation energy,Thin films,XRD,Urbach tail
更新于2025-09-23 15:21:21
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European Microscopy Congress 2016: Proceedings || The microstructure of ZnSnO and its correlation to electrical and optical properties
摘要： Over the last years, the interest in the field of transparent conductive oxides (TCOs) has grown dramatically due to their wide applicability and improved properties that may be reached when incorporating these materials into devices. TCOs are mainly used in the industry of low-emissivity windows, flat panel displays, light emitting diodes and photovoltaics [1]. For photovoltaic applications, the main purpose of TCOs is to let light enter into the solar cell and to extract the electric charges allowing them to be drifted towards the electric contacts. Therefore, it is necessary for these materials to be as transparent and as conductive as possible [2]. Ideally, TCOs should be indium-free, as indium is scarce and hence expensive [3]. The goal is therefore to optimize a material that is earth-abundant, low-cost and with good electrical and optical properties. As many steps in photovoltaic device fabrication require a high temperature, a crucial requisite for TCOs is also thermal stability. Based on these criteria, an amorphous compound of Zn-Sn-O (ZTO) deposited by sputtering was selected for the present study [4]. The microstructure of ZTO is known to strongly influence its electrical and optical properties, as well as its thermal stability. In that regard, transmission electron microscopy (TEM), in situ X-ray diffraction (XRD) experiments and conventional electrical and optical characterization were performed to assess the links between annealing treatments, ZTO microstructure and optical and electrical properties. First, samples were annealed in air, in an oven up to 150 and 500 °C and then investigated by transmission electron microscopy. While electrical and optical properties were measured to change significantly upon annealing, no major microstructural change was observed in TEM images. In situ theta-2theta XRD experiments were then performed by increasing the temperature up to 1000-1200°C in air and vacuum. Substrates resistant to these temperatures were employed, namely fused silica and sapphire. Different heating rates were used, ranging from 3°C/min up to 10°C/min. The XRD results (Fig.1) demonstrate that the amorphous phase is stable up to >500 °C when annealed in air and > 900 °C when annealed in 10-4 mbar, hence highlighting a strong influence of the annealing atmosphere on the crystallisation temperature. Rutile SnO2 is the first phase to crystallize and remains the main crystal structure observed throughout the whole process, with Al2ZnO4 forming at higher temperatures as a result of an interaction between the TCO layer and the sapphire substrate. Electrical properties were measured to decrease after annealing, with TEM measurements demonstrating that Zn migration at high temperature leads to the formation of a defective crystalline structure (Fig.2). This effect is more severe when annealing in air when compared to vacuum conditions. Indeed, the presence of oxygen in the surrounding atmosphere facilitates the formation of crystalline SnO2, a process that repeals Zn atoms to grain boundaries and surfaces of the TCO layer (Fig.3). On the other hand, the formation of crystalline SnO2 and the release of zinc are both delayed when annealing in vacuum. In general, crystallisation and Zn evaporation are observed to be detrimental to the electrical properties as it leads to the formation of voids in the structure. On a technological level, the high thermal stability of the defect-free amorphous ZTO microstructure in oxygen-poor atmospheres may enable its application in high efficiency photovoltaic architectures.
关键词： TEM,XRD,crystallization kinetics,transparent conductive oxides
更新于2025-09-23 15:21:21
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Effect of low-energy ion impact on the structure of hexagonal boron nitride films studied in surface-wave plasma
摘要： A high‐density surface‐wave plasma source is used to deposit hexagonal boron nitride (hBN) films in a gas mixture of He, H2, N2, Ar, and BF3 under a high ion flux condition using low‐energy ion irradiation. The ion energy is controlled between around zero and 100 eV by applying a negative or positive bias voltage to a substrate, while the ion flux is increased by locating a substrate upstream in the diffusive plasma. For ion energies above ～37 eV, the structure of the films depends upon ion energy more than substrate temperature, typical of subplantation processes. As a result, the structural order and crystallinity of sp2‐bonded phase in the films characterized by Fourier transform infrared spectroscopy and X‐ray diffraction are increased with decreasing ion energy, while the mass density of the films characterized by X‐ray reflectivity is retained relatively high with a slight dependence upon ion energy.
关键词： surface‐wave plasma,Fourier transform infrared spectroscopy (FTIR),chemical vapor deposition (CVD),hexagonal boron nitride (hBN),X‐ray diffraction (XRD),X‐ray reflectivity (XRR)
更新于2025-09-23 15:21:21