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Ba1-xPbxFe12O19 (x = 0.0 to 1.0) was synthesized by a co-precipitation method at room temperature. Parent compounds used were oxides of iron and lead, while barium was used in a carbonated form. Acids and Di-H2O were used as a solute. Na-Alkaline solution with molarity 5 was used for fertilization. Iron to barium ratio was kept 12. Washing played a vital role to minimize the impurities. It also improved the homogeneity. Semi-liquid-type material was obtained after overnight drying in an oven. It was further transformed into powder form which further processed, and pellets were formed for characterizations. These pellets were sintered for 3 h in a box furnace at 965 ± 5 °C. Growth along with its surface and dimensional modifications were analyzed by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). It showed almost 70% phase purity. Lead physical properties like higher mobility, ionic radii (Pb2+ = 1.76 A & Ba = 1.37 A), and occupancy preference were the important reasons for the investigation during heat treatment. Lead doping in R blocks was another big reason for these variations. SEM showed modification in all respect in each successive composition. Frequency-based analysis of whole composition from room temperature to 973 K with a step of 100 has discussed. Frequency precession analyzer was used from 20 Hz to 3 MHz for each sample. Obtained data was used to calculate dielectric constant, dielectric loss and dielectric loss factor, and AC conductivity. Determined parameters were further studied with respect to respective temperatures during whole applied frequency spectrum. The study contains almost different behaviors from each other. Prime factors were heat treatment, impurities, dopant (x), and variation of applied electric field. These behaviors and trends could be useful for today’s modern IT applications and other related electrical and electronic components like capacitors. It could also be useful for high frequency microwave and related network applications.

Currently, thermoelectric devices are receiving an immense attention from the renewable energy community due to their environment friendliness. We report a single step facile arc-melting method for developing Cu2Se thermoelectric material, which eliminates the need of expensive and time taking sintering process. The structural and thermoelectric properties measurement indicates that the proposed method is an alternative to the other reported methods for instance ball-milling followed by spark plasma sintering (SPS) with a great improvement in their efficiency. Based upon the optimized power factor and decreased total thermal conductivity, a higher figure-of-merit (ZT) value of 1.46 at 873 K was obtained from the arc-melted sample which is about 70% larger than that of its counterpart prepared through ball-milling followed by SPS process. This remarkable enhancement in the ZT value through a facile synthesis method opens up an avenue for cheaper and fast processing of Cu2Se and related materials.

Zinc-doped lithium ferrite nanoparticles with general formula Li0.46Zn0.04Fe2.5O4 were prepared by Co-precipitation method and their thin films were grown by spin coating method. X-ray diffraction (XRD) confirmed the spinel structure of the synthesized samples. Fine morphology of the films was obtained by controlling the parameters. AC electrical properties including dielectric constant (έ), dielectric loss tangent (tanδ), AC electrical conductivity (σac), and impedance (Z) were studied as a function of frequency at different temperatures and at 1 MHz frequency in a temperature range of 40–500 °C. Dielectric constant, dielectric loss tangent, and ac electrical conductivity showed the decreasing trend with increase in temperature while opposite trend was observed for impedance. Zinc-doped Li-ferrite has better absorption properties in the studied frequency and temperature range as compared to that of Li-ferrites.

A low-temperature co-precipitation technique was employed to synthesize Pb-doped Ba-hexaferrite (x = 0.0–1.0) for memory- and sensor-type applications. X-ray diffraction was used for structural study showing impurity phases generated and enhanced in successive composition. This was due to stresses and distortions by Pb due to its volatile nature and difference in ionic radius (1.76 A) than that of Ba. The nanomaterial has cation ratio Fe3+/Ba2+. Impurity phases enhanced to 30%, and dopant also caused the change in structural parameters. Scanning electron microscopy was employed for morphological study, and it confirmed variations and modification in crystallization process. DC electrical properties ‘Idc’ were measured from room temperature to 758 K, and that showed the decreasing trends in resistivity with increase in temperature. These physical properties of synthesized material could be useful for smart and sensitive applications like memory devices.

Stabilized un-doped Zinc Telluride (ZnTe) thin films were grown on glass substrates under vacuum using a closed space sublimation (CSS) technique. A dilute copper nitrate solution (0.1/100 mL) was prepared for copper doping, known as an ion exchange process, in the matrix of the ZnTe thin film. The reproducible polycrystalline cubic structure of undoped and the Cu doped ZnTe thin films with preferred orientation (111) was confirmed by X-rays diffraction (XRD) technique. Lattice parameter analyses verified the expansion of unit cell volume after incorporation of Cu species into ZnTe thin films samples. The micrographs of scanning electron microscopy (SEM) were used to measure the variation in crystal sizes of samples. The energy dispersive X-rays were used to validate the elemental composition of undoped and Cu-doped ZnTe thin films. The bandgap energy 2.24 eV of the ZnTe thin film decreased after doping Cu to 2.20 eV and may be due to the introduction of acceptors states near to valance band. Optical studies showed that refractive index was measured from 2.18 to 3.24, whereas thicknesses varied between 220 nm to 320 nm for un-doped and Cu doped ZnTe thin film, respectively, using the Swanepoel model. The oxidation states of Zn+2, Te+2, and Cu+1 through high resolution X-ray photoelectron spectroscopy (XPS) analyses was observed. The resistivity of thin films changed from ~107 &Omega, &middot, cm or undoped ZnTe to ~1 &Omega, cm for Cu-doped ZnTe thin film, whereas p-type carrier concentration increased from 4 &times, 109 cm&minus, 2 to 1.4 &times, 1011 cm&minus, 2, respectively. These results predicted that Cu-doped ZnTe thin film can be used as an ideal, efficient, and stable intermediate layer between metallic and absorber back contact for the heterojunction thin film solar cell technology.

Site occupancy plays an important role in the properties of the materials in general, and in the case of ferrites, this makes a significant effect. Barium ferrite has a wide range of applications ranging from everyday applications to sophisticated communication technologies. Two compositions Ba1−xPbxFe12O19 and BaPbxFe12−xO19 (x = 0.0–1.0) were synthesized by co-precipitation method using similar synthesis conditions. The aim was to understand the different behaviors when Pb replaced Ba in R and R* blocks in the first composition, while in the second composition it replaced iron in RSR*S* blocks. Microstructural and morphological variations in both synthesized compositions because of Pb dopant were responsible for affecting all properties. Higher ionic radius (1.76 A), lower melting point (950 °C) of lead and gradually increased concentration were responsible for generating stresses and distortions of different magnitudes in both compositions. Magnetic and DC electrical characterizations were investigated by applying similar conditions. Higher phase purity and better morphology are obtained when Ba is replaced by Pb. Strong variation in coercivity due to decrease in anisotropic energy is useful in high-density storage devices. For the other composition, when Fe is replaced by Pb, higher resistivity is obtained. The obtained range of resistivity is useful against eddy current losses in high-frequency devices.

Stabilized un-doped Zinc Telluride (ZnTe) thin films were grown on glass substrates under vacuum using closed space sublimation (CSS) technique. A dilute copper nitrate solution (0.1/100 ml) was prepared for copper doping known as ion exchange process in the matrix of ZnTe thin film. The reproducible polycrystalline cubic structure of undoped and Cu doped ZnTe thin films with preferred orientation (111) was confirmed by X-rays diffraction (XRD) technique. Lattice parameter analyses verified the expansion of unit cell volume after incorporation of Cu species into ZnTe thin films samples. The micrographs of scanning electron microscopy (SEM) were used to measure the variation in crystal sizes of samples. The energy dispersive X-rays was used to validate the elemental composition of undoped and Cu-doped ZnTe thin films. The bandgap energy 2.24 eV of ZnTe thin film decreased after doping Cu to 2.20 eV may be due to the introduction of acceptors states near to valance band. Optical studies showed that refractive index was measured from 2.18 to 3.24 whereas thicknesses varied between 220 nm to 320 nm for un-doped and Cu doped ZnTe thin film respectively using Swanepoel model. The oxidation states of Zn+2, Te+2 and Cu+1 through high resolution X-ray photoelectron spectroscopy (XPS) analyses was observed. The resistivity of thin films changed from ~107 Ω-cm for undoped ZnTe to ~1 Ω-cm for Cu-doped ZnTe thin film, whereas p-type carrier concentration increased from to respectively. These results predicted that Cu-doped ZnTe thin film can be used as an ideal, efficient and stable intermediate layer between metallic and absorber back contact for the heterojunction thin film solar cell technology.

Zinc Telluride (ZnTe) powder of 99.9% purity was used to deposit ZnTe thin films on ultra-sonically cleaned slides of glass. A locally manufactured Closed Space Sublimation (CSS) technique was used to deposit these thin films. As-deposited ZnTe thin films were further exposed to tellurium (Te) for different deposition times under high vacuum. Annealing was carried out after the deposition of Tellurium (Te) on as-deposited ZnTe thin films for diffusion of Te into ZnTe thin films. Cubic phases were found before and after enrichment of Te into as-deposited ZnTe thin films via X-ray Diffraction (XRD) studies. Preferred orientation was [111] and the crystallite size increased after enrichment of Te. The surface morphology was studied using scanning electron microscopy (SEM) which confirmed that grain sizes significantly increased after the enrichment of Te into ZnTe thin films. Energy dispersive X-rays (EDX) confirmed the elemental composition of zinc (Zn) and tellurium (Te). The transmittance decreased after the enrichment of Te into ZnTe thin films. A small change in energy band gap was calculated using Tauc relation. Hall measurement was carried out to study the electrical behavior of Te-enriched ZnTe thin films and found that electrical resistivity of as-deposited ZnTe thin films was of the order of 106 Ω-cm. The electrical resistivity reduced to 104 Ω-cm after Te enrichment. X-rays photoelectron spectroscopy (XPS) study was carried out to check the chemical bonding and states before and after Te-enrichment. Te-enriched ZnTe thin films showed better properties and found suitable for buffer layer of II generation solar cells.

Metal chalcogenides especially Cu2- x Se has gained much attention in thermoelectric community due to its complex crystal structure and superionic behavior. Here, we report a facile method to improve the thermoelectric efficiency by introducing ZnTe nanoinclusions into the matrix of Cu2- x Se. As a result, a substantial improvement of 32% in electrical conductivity of Cu2- x Se-ZnTe composite is observed. The increase in electrical conductivity is at the expense of Seebeck coefficient, which slightly decreases the power factor of the composite samples than that of pure Cu2- x Se. Furthermore, the introduction of secondary phase facilitates in declining the total thermal conductivity of Cu2- x Se-ZnTe composite up to 34% by suppressing the lattice thermal contributions. Thus, the moderate power factor and lower thermal conductivity values result in an improved figure of merit ( zT ) value of ~0.40 in mid-range temperature (750 K) for Cu2- x Se-ZnTe composite with 10 wt.% of ZnTe, which is about 40% higher than that of its pure counterpart. Hence, it is believed that the incorporation of ZnTe nanoinclusions in the matrix of Cu2- x Se may be an important route to improve the thermoelectric properties of Cu2- x Se based compounds.

Cadmium sulphide (CdS) is the n-type, wide band gap II-VI semiconducting material by offering applications in photovoltaics. Among the range of applications offered by CdS thin films, it has found application as a window layer in second generation solar cells by creating photon traps, thereby quantum efficiency. Closed space sublimation (CSS) offers a trivial yet effective approach for the synthesis of thin films for solar cell applications at moderate temperatures. CdS thin films of controlled thicknesses were synthesized by CSS technique by varying exposure time. X-rays diffraction data of these thin films revealed polycrystalline nature with a preferred orientation along (002) direction. The scanning electron microscopy (SEM) based morphological studies showed grain size variation with an increase in thickness of deposited thin films in the range of 300–500 nm. The electrical studies revealed high resistivity of the order of 106 Ω-cm. Spectrophotometric studies performed for CdS thin films concluded with the calculation of the optical parameters such as refractive index, absorption coefficient employing the Swanepoel model, and energy band gap of ∼2.42 eV using the Tauc relation in addition to thin film thickness confirmation. The variations in thickness affect the structure, surface, optical (Khan et al. 2018), electrical properties.

Cadmium sulfide (CdS) has been investigated extensively for II generation solar cell as an efficient window layer with n type conductivity. The significance of CdS is because of its large energy band gap tune-ability and native n-type conductivity. In this report, energy band gap engineering of CdS films was carried out by means of controlled silver (Ag) doping to modify their optical properties along with electrical properties. Closed space sublimation (CSS) technique has been employed to synthesize as-deposited CdS thin films. One of the advantages of CSS grown films is roughness which offers more trapping/absorbing of light. Ion exchange solution process was carried out for Ag-doping, which resulted in widening of the band gap from 2.15 eV to a value of 2.45 eV, showing the increased capability of solar energy harvesting. Un-doped CdS thin films showed a high resistivity of the order of ∼106 Ω-cm, which reduced to only ∼102 Ω-cm with the Ag-doping, as probed by four-point probe, offering great advantage for the system to be used in II-VI solar cells. Un-doped and Ag-doped films showed n-type conductivity. We studied the Ag-doping effects on the surface morphological and correlated the morphological modification with changing optical and electrical behaviour of CdS thin films. It is believed that enhanced properties offer great potential for these films to be used for the solar cell applications.

Bismuth iron oxide (BiFeO3) is amongst the class of multiferroic materials that has attracted world attraction because of its antiferromagnetic Neel temperature and high ferroelectric Curie temperature of 643K and 1103K respectively. However, synthesis of pure phase BiFeO3 is extremely difficult due to volatile nature of Bi2O3. This results in the presence of bismuth deficient and bismuth rich phases in pure bismuth iron oxide. In the past attention was focused on obtaining pure BiFeO3 phase with variation in annealing/calcination temperature in the range 400-700˚C, and very little consideration is given to the changes in Bi/Fe ratio during synthesis. We here report synthesis of pure phase bismuth iron oxide thin films using cost effective sol-gel method. The ratio of Bi/Fe is varied as 0.90, 1.0 and 1.10. The films are annealed at 300˚C in vacuum under the application of 500 Oe magnetic field. XRD results show that with Bi/Fe ratio of 1.10 pure phase BiFeO3 can be obtained at low temperature of 300˚C. Bi/Fe ratios of 0.9 and 1.0 result in the presence of bismuth impurity phase. The films show ferromagnetic behavior as opposed to antiferromagnetic nature of bulk BiFeO3 due to suppression of spiral spin structure.

Closed space sublimation (CSS) technique was employed to deposit thin films of zinc telluride (ZnTe) on a glass substrate under high vacuum. Two sets of ZnTe thin films and Zn enriched ZnTe thin films were prepared for comparative study. The enrichment for Zn onto the as-deposited ZnTe thin films was done by the novel manner of layer by layer deposition with subsequent annealing. X-ray diffraction (XRD) studies revealed before and after the enrichment of Zn the preferred orientation is [1 1 1] having cubic phase. The lattice constant was found to be increased and the crystallite size decreased 28 nm to 24 nm after the enrichment of Zn. A morphological study was carried out through a scanning electron microscope (SEM). For Zn enriched samples the average grain size is smaller as compared to ZnTe thin films. The local compositions of Zn and Te were confirmed by energy dispersive x-rays (EDX) from 51 atomic % of as-deposited ZnTe thin films to 68 atomic % in Zn enriched ZnTe thin films. The Zn enriched samples have a slight decrease in optical transmission in UV-VIS-NIR range as compared to the as-deposited ZnTe thin films. Due to the deposition of Zn there is a very small change in optical band gap energy. A four-probe technique was used to study electrical properties of as-deposited and Zn-enriched ZnTe thin films. These results shows that the as-deposited samples had the resistivity of 106 Ω • cm. For Zn enrichment samples resistivity increases from 106 Ω • cm to 108 Ω • cm, which shows that Zn-enriched samples are not suitable for back contact of II-VI solar cells. X-rays photoelectron spectroscopy (XPS) was used to confirm the elemental compositions and its bonding strength before and after the enrichment of Zn.

Cadmium sulfide (CdS) is a prominent material for its tunable band gap used as a window layer in II–VI semiconductor solar cells. The light trapping capability of window layer is one of the powerful tools to enhance the efficiency of the cell. CdS and zinc (Zn) powders were mixed mechanically with different weight percents to make CdZnS (CZS) powder. CZS was deposited onto an ultrasonically cleaned glass substrate using close spaced sublimation (CSS) technique. CZS as-deposited thin films were characterized for structural, surface morphology with energy dispersive X-rays (EDX) and optical properties for the use of window layer in CdS/CdTe based solar cells. The different Zn concentrations in CZS played a vital role on crystallite size in structural analysis and optical properties e.g. transmission, absorption coefficient and energy band gap, etc. The crystallite size of as-deposited CZS thin films were increased as Zn concentration was increased up to certain value. The energy band gap varies from 2.42 eV to 2.57 eV for as-deposited CZS thin films with increasing Zn concentrations and surface morphology changes also. These changes were occurred due to zinc diffusion in CdS thin films. An angle resolved transmission data was taken to check the behavior of CdS and CZS thin film at different angles. A comparative study was carried out between CdS thin films and CZS thin films for the use of good window layer material.

Zinc telluride (ZnTe) thin films were fabricated by using closed space sublimation (CSS) technique on glass substrate under vacuum. Pre-fabricated ZnTe thin films were doped with silver (Ag) by ion exchange method. X-ray diffraction showed the preferred orientation (111) of ZnTe thin film with polycrystalline behavior. Scanning electron microscope images were taken to estimate the grain boundaries; energy dispersive X-ray results confirmed the Ag composition in doped-ZnTe samples. Electrical measurements were performed to determine the resistivity, mobility and carrier concentrations of un-doped thin films and Ag-doped samples. The electrical resistivity was of the order of 10 6 Ω-cm before doping. Ag-doped ZnTe samples exhibits low resistivity of the order of 10 3 Ω-cm along with a change in the carrier concentrations and mobility as well at room temperature. The angle resolved optical transmission data, taken by spectrophotometer, was used to find the optical properties before and after Ag doping. Energy band gap showed decreasing trend with increasing Ag doping time.

Thin films of CdS were fabricated by close spaced sublimation technique under vacuum of ∼10−5 mbar at a source temperature of 550 °C for various periods of time. These as-deposited thin films were immersed into Cu (NO3)2 solution at 80 ± 5 °C for variety of time to ensure Cu doping. The structural, surface, optical and electrical analyses were completed with the help of X-Ray Diffraction, Scanning Electron Microscope with Energy Dispersive X-Ray, UV-VIS-NIR Spectrophotometer and Hall Measurement System respectively. The transmittance of as-deposited sample is reduced from 80% to 30% with increasing copper immersion time. The mobility increased from 6.67 × 101 to 1.15 × 103 cm2/Vs due to the change in the carrier concentration.

Thin films of cadmium sulfide with very well defined preferential orientation and relatively high absorption coefficient were fabricated by thermal evaporation technique. The research is focused to the fabrication and characterization of the compositional data of CdS thin films obtained by using X-ray diffraction, scanning electron microscope along with energy dispersive X-ray spectroscopy. The optical properties were studied by using a UV-VIS-NIR spectrophotometer. The effects of silver-doping by ion exchange process on the properties of as-deposited CdS thin films have been investigated.

This paper introduces a novel model for analyzing the optical interface performance degradation due to scratches on optical fiber end face. The model indicates that the contribution to the return loss (RL) of a scratch is determined by its size, location, and its relative reflectivity, which is defined as the ratio of the average reflectivity of the scratch to the base reflectivity of the defectless end face. Based on this new model, the effects on RL are analyzed for scratches of various numbers, different sizes, with different relative reflectivities, and at different locations. This quantified analysis provides a solid base to establish the specifications of inspection criteria of optical fiber connectors. With the new model, the relative reflectivity of a scratch was tested, and estimations of the RL of scratched connectors were performed, which were in good agreement with measurement results.

Stimulated Raman scattering (SRS) degrades the performance of wavelength-division-multiplexed (WDM) optical fiber communication systems by amplifying the longer-wavelength channels at the expense of shorter-wavelength channels, and making the spectral profile of transmission tilted. The spectral transmission tilt due to SRS of single-mode fiber span is measured by using a technique to separate it from the total loss profile of the fiber. An empirical model is developed to predict the transmission tilt for single-mode fiber of any fiber length under various optical power levels. The application of the model in test and evaluation of gain-flattened optical fiber amplifiers is introduced.

A quantitative description of the effects of fiber endface defects such as scratches and digs does not exist in the literature. We show, by considering surface scattering from the fiber endface, that such a description can be given in terms of a single parameter, which is a measure of the increase in backscattering due to the defect. We present our results in terms of some assumed values of this parameter.

Closed space sublimation (CSS) technique was used to deposit pure (99.99%) zinc selenide(ZnSe) powder on to glass substrates for fabricating the ZnSe thin films. The temperatures of source, substrate and the deposition time were optimized to deposit thin films of different thicknesses. Silver (Ag) was used as a dopant by ion exchange process in the ZnSe thin films. The structural analysis showed that as-deposited ZnSe thin films were polycrystalline having preferred orientation (111) direction. Micro structural parameters such as crystallite size, lattice parameter were determined using X-rays diffraction (XRD). Grains boundaries, roughness on surface and the grain density of the thin film samples were measured by scanning electron and atomic force microscopy before and after Ag doping.As-deposited, Ag-doped ZnSe samples before and after annealing were optically characterized by spectrophotometer in ultra violet, visible and infrared regions. The energy band gap of as-deposited ZnSe thin films for varying thicknesses were ranging from 2.62-2.67 eV which was reduced after Ag doping.The electrical properties showed that as-deposited thin films were highly resistive of the order of 10 -cm and after Ag immersion, it was reduced to 1 -cm. Deposition parameters and Ag doping 8

Cadmium sulfide (CdS) thin films of different thicknesses were deposited on corning glass by closed space sublimation (CSS) technique in a vacuum. Structural, electrical, optical, Fourier transform infrared (FTIR) with Raman spectrometric properties were investigated. X-rays diffraction used to identify the preferred orientation of CdS thin films as well as crystalline size, dislocation density and strain vs thickness was estimated. The electrical properties like resistivity, mobility vs thickness was calculated at room temperature. Optical properties were investigated from UV-VIS-NIR ranges which were used to calculate band gap, thickness of the films, also samples were placed at different angles in spectrophotometer to investigate the effect of angles variation on %T and band gap. Raman spectroscopy for identification of vibration modes in thin films by varying thickness.

A novel test methodology is established to evaluate the strain relief boot on optoelectronic components and optical fiber components by measuring the fiber bend radius in side pull test. The technique is developed for qualifying the boot design rather than for lot testing. The criterion and process are provided.

This presentation introduces a novel model for analyzing the optical interface performance degradation due to scratches on optical fiber endface. The model indicates that the contribution to the return loss of a scratch is determined by its size, location and its relative reflectivity, which is defined as the ratio of the average reflectivity of the scratch to the base reflectivity of the defectless endface. Based on this new model, the effects on return loss are analyzed for scratches of various numbers, different sizes, with different relative reflectivities, and at different locations. This quantified analysis provides a solid base to establish the specifications of inspection criteria of optical interface. With the new model, the relative reflectivity of a scratch was tested, and estimations of the return loss of scratched connectors were performed, which were in good agreement with measurement results.