Study of optical,structural and chemical properties of neutron irradiated PADC film

We have investigated neutron irradiation effects on the optical, structural and chemical properties of polyallyl diglycol carbonate (PADC) polymer, commercially named as CR-39. For this purpose, PADC samples were exposed with 4 MeV Am–Be neutron source at fluences varying from 2.36 × 10⁶ to 5.94 × 10⁷ n/cm². The modifications so induced were analyzed using UV–Visible spectroscopy, X-ray diffraction Measurement (XRD), Photoluminescence (PL) and Fourier Transform infrared (FTIR) spectroscopy in the total attenuation reflection (ATR) mode. UV–Vis spectra of pristine and neutron irradiated PADC polymer sheets exhibit a decreasing trend in optical band gap. This decline in optical band gap with increasing fluence has been discussed on the basis of neutron irradiation induced defects in PADC. The XRD pattern of PADC shows the decreasing intensity of peak positions with increasing in fluence, which suggest that semicrystallinity of PADC changes slightly to amorphous phase after irradiation. At low fluence, crystallinity was found to increase but at higher fluence, it decreased which could be ascribed to neutron- induced defects in the polymer samples. Crystallite size calculated using Scherrer formula indicates a change and reflects the formation of disordered system in the irradiated polymer samples. The PL spectra show that the intensity of PL peak decreased with increase in fluence, which may be due to the disordered system via creation of defects in the irradiated polymer. The FTIR spectrum shows an overall reduction in intensity of the typical bands, indicating the degradation of PADC polymer after irradiation. These results so obtained can be used successfully in dosimetery using well reported protocols.     

光纤TiO2薄膜的制备及理化特性研究

用溶胶－凝胶法制得TiO2，通过提拉法在光纤上成膜。利用X射线衍射仪分析了TiO2薄膜的物相，结果表明其物相是锐钛矿相。通过酸碱浸泡实验及附着性能测试，得到了具有较好抗腐蚀性及良好附着性。从理论上对光纤TiO2薄膜光纤的光催化降解机理进行研究，结果表明其在处理污水方面具有可行性及优越性，并讨论其发展方向和所需的改进。     

Influence of bias voltage on the optical and structural properties of nc-Si:H films grown by layer-by-layer (LBL) deposition technique

The effects of applying a positive bias of 25 to 100 V on the optical, structural and photoluminescence (PL) properties of hydrogenated nanocrystalline silicon (nc-Si:H) films produced by layer-by-layer (LBL) deposition technique has been studied. Optical characterization of the films has been obtained from UV-VIS-NIR spectroscopy measurements. Structural characterization has been performed using X-ray diffraction, micro-Raman spectroscopy and field emission scanning electron microscope (FESEM). PL spectroscopy technique has been used to investigate the PL properties of the films. In general, the films formed shows a mixed phase of silicon (Si) nanocrystallites embedded within an amorphous phase of the Si matrix. The crystalline volume fraction and grain size of the Si nanocrystallites have been shown to be strongly dependent on the applied bias voltage. High applied bias voltage enhances the growth rate of the films but reduces the refractive index and the optical energy gap of the films. Higher crystalline volume fraction of the films prepared at low bias voltages exhibits room temperature PL at around 1.8 eV (700 nm).     

Thermal and optical properties of electron beam irradiated cellulose triacetate

Cellulose triacetate (CTA) is a polymer which is widely used in a variety of applications in the field of radiation dosimetry. In the present work, CTA samples were irradiated by electron beam in the dose range 10–200 kGy. The modifications in the electron irradiated CTA samples as a function of dose have been studied through different characterization techniques such as thermogravimetric analysis, differential thermal analysis and color-difference studies. The electron irradiation in the dose range 80–200 kGy led to a more compact structure of CTA polymer, which resulted in an improvement in its thermal stability with an increase in activation energy of thermal decomposition.

Also, the variation of melting temperatures with the electron dose has been determined using differential thermal analysis (DTA). The CTA polymer is characterized by the appearance of one endothermic peak due to melting. The results showed that the irradiation in the dose range 10–80 kGy causes defects generation that splits the crystals depressing the melting temperature, while at higher doses (80–200 kGy), the thickness of crystalline structures (lamellae) is increased, thus the melting temperature increased.

In addition, the transmission of these samples in the wavelength range 200–2500 nm, as well as any color changes, was studied. The color intensity ΔE^* was greatly increased with increasing the electron beam dose, and accompanied with a significant increase in the blue color component.     

Al浓度对AZO薄膜结构和光电性能的影响

采用射频溅射方法在Si基片上制备出AZO掺杂薄膜,对薄膜进行了XRD和AFM分析,并对其电性能作了研究.结果表明,掺杂量低于15%(原子分数)时,AZO薄膜结构为纤锌矿结构,呈c轴方向择优生长,没有Al2O3相出现.薄膜的可见光透过率均在80%以上,其最高电阻率出现在掺杂量为30%(原子分数),为1.3×107 Ω·cm.     

Structural and optical properties of SnS nanoparticles and electron-beam-evaporated SnS thin films

SnS nanoparticles were synthesised by the precipitation method using SnCl₂.2H₂O and Na₂S.xH₂O and the nanoparticles were characterised by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. From the particles’ XRD pattern, a strong peak at 2θ = 31.5? was observed, which confirms the Herzenbergite orthorhombic crystal structure of SnS. The FTIR result also confirmed the SnS nanoparticles at 2354 cm^?1 and 615 cm^?1. Second, thin SnS films were prepared on a glass substrate by the electron beam evaporation technique at room temperature and annealed at 100°C, 200°C and 300°C. The effect of the annealing temperature on structural and optical properties of the SnS films was characterised by XRD and ultraviolet–visible (UV–Vis) analysis. From the experimental studies, optical absorption of SnS films increases with respect to the annealing temperature, while the values of band gap energy (E_g) get reduced from 1.77 to 1.57 eV.     

Studies on the optical band gap and cluster size of the polyaniline thin films irradiated with swift heavy Si ions

Polyaniline thin films prepared by RF plasma polymerisation were irradiated with 92 MeV Si ions for various fluences of 1×10¹¹, 1×10¹² and 1×10¹³ ions/cm². FTIR and UV-vis-NIR measurements were carried out on the pristine and Si ion irradiated polyaniline thin films for structural evaluation and optical band gap determination. The effect of swift heavy ions on the structural and optical properties of plasma-polymerised aniline thin film is investigated. Their properties are compared with that of the pristine sample. The FTIR spectrum indicates that the structure of the irradiated sample is altered. The optical studies show that the band gap of irradiated thin film has been considerably modified. This has been attributed to the rearrangement in the ring structure and the formation of CC terminals. This results in extended conjugated structure causing reduction in optical band gap.     

Effects of physical growth conditions on the structural and optical properties of sputtered grown thin HfO2 films

HfO₂ thin films were prepared by reactive DC magnetron sputtering technique on (100) p-Si substrate. The effects of O₂/Ar ratio, substrate temperature, sputtering power on the structural properties of HfO₂ grown films were studied by Spectroscopic Ellipsometer (SE), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, and X-ray photoelectron spectroscopy (XPS) depth profiling techniques. The results show that the formation of a SiO_x suboxide layer at the HfO₂/Si interface is unavoidable. The HfO₂ thickness and suboxide formation are highly affected by the growth parameters such as sputtering power, O₂/Ar gas ratio during sputtering, and substrate temperature. XRD spectra show that the deposited films have (111) monoclinic phase of HfO₂, which is also supported by FTIR spectra. XPS depth profiling spectra shows that highly reactive sputtered Hf atoms consume some of the oxygen atoms from the underlying SiO₂ to form HfO₂, leaving Si-Si bonds behind.     

Study of microhardness and electrical properties of proton irradiated polyethersulfone (PES)

Polyethersulfone (PES) films were irradiated with 3 MeV proton beams in the fluence range 10¹³–10¹⁵ ions/cm². The radiation induced changes in microhardness was investigated by a Vickers’ microhardness tester in the load range 100–1000 mN and electrical properties in the frequency range 100 Hz-1 MHz by an LCR meter. It is observed that microhardness of the film increases significantly as fluence increases up to 10¹⁴ ions/cm². The bulk hardness of the films is obtained at a load of 400 mN. The increase in hardness may be attributed to the cross linking effect. There is an exponential increase in conductivity with log frequency and the effect of irradiation is significant at higher fluences. The dielectric constant/loss is observed to change significantly due to irradiation. It has been found that dielectric response in both pristine and irradiated samples obey the Universal law and is given by ɛ ∝ f ⁿ⁻¹. These results were corroborated with structural changes observed in FTIR spectra of irradiated samples.     

Effect of reduced graphene oxide (rGO) on structural,optical, and dielectric properties of Mg(OH)2/rGO nanocomposites

In this paper, we report the synthesis of Mg(OH)₂ NPs and Mg(OH)₂–rGO nanocomposites (NCs) by microwave assisted co-precipitation method. The crystal phase, structural morphology and functional groups of the as-synthesized samples were analyzed by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR). Raman spectroscopy was used to study the defects in the samples. Raman spectroscopy and the SEM results validate the growth of Mg(OH)₂ NPs on the rGO nanosheets. The chemical composition of the prepared samples was analyzed by EDAX. Optical properties of the as-synthesized samples were studied by UV–visible spectroscopy and the energy band gap was calculated by Tauc relation which shows a decrease in band gap with an increase in the amount of Graphene Oxide (GO) in the NCs. The dielectric properties were studied as a function of frequency over a range of 50 Hz to 5 MHz at room temperature. The value of dielectric constant decreases with an increase in frequency, this could be due to the existence of a polarization process at the border of the rGO sheets and Mg(OH)₂ NPs. The value of dielectric loss shows a decreasing trend with an increase in frequency whereas the larger value of AC conductivity in Mg(OH)₂–rGO NCs as compared to Mg(OH)₂ NPs approves the restoration of sp² network in the graphene sheets.     

Optical and structural properties of silicon oxynitride deposited by plasma enhanced chemical vapor deposition

We present an overview of the properties of silicon oxynitride material (SiON) deposited by plasma enhanced chemical vapor deposition (PECVD) for photovoltaic applications. SiON films were deposited using silane (SiH₄), ammonia (NH₃) and nitrogen protoxide (N₂O) as precursor gases in a low frequency PECVD. Varying the gas flow mixture leads to a whole range of SiON layers starting from the silicon oxide to the silicon nitride with unique stoichiometries and properties. Thanks to spectroscopic ellipsometry measurements we have confirmed the suitability of SiON for antireflection coating layers due to the range of the refractive indexes attainable. SiON structure was analyzed by X-ray photo-electron spectroscopy. We have thus highlighted the critical role of oxygen behavior on the SiON network and the progressive replacement of nitrogen by oxygen atoms when the oxygen precursor increases. The type of chemical bonds present in SiON layers was also investigated by infrared spectroscopy. The SiON layers also contain a non-negligible amount of hydrogen which might be useful for passivation applications. The behavior of hydrogen content was thus analyzed by elastic recoil decay analysis and desorption characterization. A typical rapid thermal annealing was performed on the SiON samples in order to simulate the solar cells contact annealing and to investigate its impact on the dielectric film properties. It was found that hydrogen becomes weakly bonded to the films and strongly decreases in quantity with the annealing. The surface passivation effect is presented in the last part of this paper. The trend before and after a rapid thermal annealing showed opposite results which could be explained by the high porosity of the layers and the formation of Si-O bonds.     

The role of the Zn buffer layers in the structural and photoluminescence properties of ZnO films on Zn buffer layers deposited by RF magnetron sputtering

Highly c-axis oriented ZnO thin films were grown on Si (100) substrates with Zn buffer layers. Effects of the Zn buffer layer thickness on the structural and optical qualities of ZnO thin films were investigated for the ZnO films with the buffer layers 90, 110, and 130 nm thick using X-ray diffraction (XRD), photoluminescence (PL) and atomic force microscopy (AFM) analysis techniques. It was confirmed that the quality of a ZnO thin film deposited by RF magnetron sputtering was substantially improved by using a Zn buffer layer. The highest ZnO film quality was obtained with a Zn buffer layer 110 nm thick. The surface roughness of the ZnO thin film increases as the Zn buffer layer thickness increases.     

The effect of substrate temperature on the structural, optical and electrical properties of vacuum deposited ZnTe thin films

The present paper reports the effect of substrate temperature on the structural, optical and electrical properties of vacuum deposited zinc telluride (ZnTe) thin films. X-ray diffraction (XRD) analysis of the films, deposited on glass substrates, revealed that they have cubic structure with strong (111) texture. Room temperature deposits are tellurium rich and an increase in the substrate temperature up to 553 °K results in stoichiometric films. Electrical conductivity has been observed to increase with the increase in substrate temperature, accompanied by increase in the carrier concentration and the mobility of the carriers. The optical bandgap energy and the thermal activation energy of the films have also been evaluated.     

Nitrogen ion implantation effects on the structural,optical and electrical properties of CdSe thin film

In the present study, thin films of cadmium selenide (CdSe) are deposited on ITO substrate by electrodeposition method using aqueous solution of 3CdSO₄·8H₂O and SeO₂. These films are implanted with 40 keV N⁺ ions with different fluencies i.e. 1?×?10¹⁵, 5?×?10¹⁵, 1?×?10¹⁶ and 5?×?10¹⁶ ions/cm² using a beam current of 0.9 µA. The structural, morphological, optical and electrical properties of pristine and nitrogen ion-implanted CdSe thin films are analyzed using XRD, SEM, AFM, UV-PL Spectrophotometer and I–V four probes setup. XRD analysis revealed the effects of nitrogen ions on the structural parameters such as grain size, FWHM, micro strain and dislocation density etc. Crystallanity of the material increased with increase in implantation dose. SEM and AFM analysis show decrease in the surface roughness with implantation. From the optical studies, band gap value decreased from 2.50 to 2.29 eV with increase in N⁺ implantation doses. Noticeable changes in the electrical properties are also reported. The effect of N⁺ ion implantation on the properties of CdSe thin films are discussed on the basis of lattice disorder.     

Effects of annealing temperature on the structural,morphology, optical properties and resistivity of sputtered CCTO thin film

CaCu₃Ti₄O₁₂ (CCTO) thin films with a thickness of 200 nm were deposited on ITO substrates by RF magnetron sputtering using a pure CCTO target. After the deposition, thin films were annealed at 400, 450, 500 and 550?°C, respectively, for 1 h. The effects of annealing temperature on the structural, surface morphology, optical properties and resistivity of (CCTO) thin films were investigated. The X-ray diffractometer results show that the thin films are polycrystalline in nature and are assigned to body-centered cubic perovskite configuration with a space group of Im-3. The intensity of the peaks and crystallinity gradually increased with the increase in annealing temperature. Microstructural investigation through FESEM showed that the grain size increased with increase in annealing temperature from 32 to 85 nm. The root mean square and roughness (Ra) were also enhanced with higher annealing temperatures, from 3.8 to 6.2 nm and from 4.7 to 7.7 nm, respectively, as confirmed by AFM. Increase in annealing temperature also affected the optical transmittance values which decreased to almost 60% at the visible range (550–850), as well as the optical energy band gap which decreased from 3.86 to 3.39 eV. The relevance between resistance behaviors and film microstructure is discussed. Therefore, it can be concluded that the desirable crystallinity, surface roughness, energy band gap and resistivity for 200 nm thick CCTO thin films deposited by RF magnetron sputtering can be achieved through the annealing process.     

Study of electrical and optical properties of Mn doped ZnS clusters

A simple, easy approach to the synthesis of manganese Mn doped zinc sulphide (ZnS) clusters is reported. The synthesis of Mn–ZnS clusters involved mixing and drying of zinc acetate, sodium sulphide and acrylic acid in appropriate ratio and adding Mn at proper conditions. These clusters were trapped in polyacrylic acid (PAA) to form PAA capping to provide stability. The clusters were characterized using high resolution SEM for morphological investigation; XRD for its crystalline nature; photoluminescence (PL) for optical characterization and electrical conductivity measurement. Clusters of Mn–ZnS were formed of the size ~ 10 nm.     

Synthesis and structural characterization of novel porous zinc substituted nanohydroxyapatite powders

This study reports the synthesis of new porous nanohydroxyapatites (HAPs) substituted with different Zn contents (HAP_Zn) employing calcium and zinc nitrates and diammonium hydrogen phosphate as precursors. The synthesis was conducted in the presence of a surfactant, L-asparagine, for controlling the pore size distribution and morphology of obtained nanopowders, using a co-precipitation route. Thus a new approach leading to HAP_Zn nanopowders with improved nucleation and crystallization ability was developed. After maturation treatment of dispersions and filtration, the precipitate was lyophilized and ground. Part of the samples was calcined at 300°C for 1 h. The zinc content in the nanoHAPs varies from 0.2 to 10 wt% (substitution degree of Ca by Zn from 0.3 to 15.8 mole %). XRD investigations indicated HAP as the unique phase present and the nanostructured nature of the obtained HAPs. FTIR spectra also confirmed the presence of HAP structure. TEM, SEM, and AFM images showed the morphology of the HAP_Zn samples. BET analysis led to the characterization of specific surface area and porosity for the samples. The new nanopowders are designed to be used in orthopedic surgery, particularly for the treatment of osteoporosis and as bone substitutes, and in dentistry for remineralization of enamel.     

Electrical, optical and structural properties of lead iodide

Lead iodide PbI₂ is an excellent and interesting candidate for high efficiency room temperature detectors working in the medium energy range of 1 keV–1 MeV. It can be widely applied in medicine, monitoring ecology, nondestructive defectoscopy and X-ray and gamma spectroscopy. The peculiarities of this material are high resistivity, ability to work in a wide range of temperatures and high chemical stability. The method of preparation was direct synthesis from lead and iodine. The material was further purified by zone melting and grown by Bridgman-Stockbarger method. In this work we have concentrated on the study of the influence of dopants such as lanthanides (Er,Gd, Ho, Tb, Tm, Yb, GdI₃, HoI₃, GdI₃) and elements of other groups, such as Au, Ag, Ge on the physical, electrical and optical properties of the PbI₂. These were evaluated by resistivity and low temperature photoluminescence measurements. The Synchrotron X-ray topography was successfully introduced to study defects. The quality of the material was analyzed after synthesis, zone melting and growth. The dependence on the concentration of dopants was investigated too.     

掺锡氧化锌纳米阵列的制备及其结构和光学特性的研究

在旋涂法制成的种子层基底上,用水热法生长氧化锌纳米阵列(ZNAs)和掺锡氧化锌纳米阵列(ZNAs∶Sn)。为了研究掺锡对氧化锌纳米阵列透光性的影响,用X射线衍射(XRD)、扫描电镜(SEM)、透射谱和椭圆偏振仪(SE)对样品进行了表征,并结合等效介质模型(EMA)理论模拟样品光学常数,根据太阳能光谱AM1.5计算透过光的总功率。XRD分析表明纳米棒垂直于基底沿(002)晶向生长,SEM和椭圆偏振仪表明样品表面形貌良好,制得的纳米棒直径约300 nm,长度约1.6μm。透射谱表明ZNAs掺锡之后,在300~800nm波段透过率增大。根据AM1.5计算获得在样品厚度相同的情况下,掺杂5%的ZNAs∶Sn透过光总功率是ZNAs的1.6倍。