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In the present study, lithium nickel manganese oxide powders grafted with camphoric nano-carbons have been exploited to fabricate high voltage, high capacity rechargeable electrodes for Li storage. The prepared lithium nickel manganese oxide particles were pyrolyzed using a camphoric solution to graft porous camphoric carbon layer on to the surface. A detailed study was performed to elucidate the effect of carbon content on the performance of the electrode. Relative contributions of capacitive and diffusion-controlled processes underlying these composite electrodes have been mathematically modeled. The lithium nickel manganese oxide composites showed two times higher conductivity as compared to the pristine samples. These electrodes exhibited a specific capacity value of ~154 mAhg -1 and showed good rate capability. The capacity fading was found to be ~17% at the end of 200 cycles for 100% depth of discharge. The specific capacity and capacity retention for these blends were found to be ~10% and ~40% higher respectively than pristine powders which are promising considering their low cost and facile fabrication process.

The present study reports an approach by which thin films of sucrose added olivine type LiMnPO4-Ccomposite and pristine LiMnPO4 is made by a technique of electrophoretic co-deposition in which pristine and composite samples were synthesized by a sol-gel route. These thin films with enhanced surface area is used to fabricate cathodes for rechargeable Li ion batteries. XRD confirms phase pure single crystalline orthorhombic structure. Transmission Electron Microscopy (TEM) images shows the carbon coating over LiMnPO4 and the particle size restricted in the nano regime. The presence of sp2 hybridized carbon on LiMnPO4 particles is confirmed by X-ray Photon spectroscopy (XPS). To explore the electrochemical behavior, cyclic voltammetry (CV) and cycling studies were performed. The specific capacity for LiMnPO4-C is found to be increased by 43% in comparison to the pristine LiMnPO4. It also exhibited 86% retention in capacity compared to the pristine LiMnPO4 (52%). The result indicates that a proper carbon coating can significantly improve the electronic conductivity and hence the specific capacity.

In this work we report the electrochemical performance comparison of two new hybrid supercapacitors one based on graphene as negative electrode and lead dioxide thin film as positive electrode and the other with graphene as negative electrode and lead dioxide-carbon nanotube composite as positive electrode in 0.1 M KOH electrolyte. In the present work, PbO2 was synthesized using sol-gel method which is one of the promising materials for hybrid supercapacitors. The XRD confirmed the single phase of the PbO2 and the grain size is 39 nm which has been determined using Scherrer's formula. Thin films of PbO2, PbO2-CNT composite and graphene were coated on the titanium substrate by electrophoretic deposition. Further material characterisation has been carried out using SEM, TEM, XPS and electrochemical characterisation using CV, charge/discharge and electrochemical impedance spectroscopy (EIS) for obtaining energy density and power density, cyclic stability and internal resistance respectively. The present results revealed that PbO2-CNT composite/graphene asymmetric hybrid supercapacitor exhibits large specific capacitance and energy density over PbO2/graphene based system. The PbO2-CNT composite/graphene asymmetric hybrid supercapacitor exhibited maximum power density and energy density of 1200 W/Kg and 65 Wh/Kg respectively at a current density of 2 A/g. The PbO2-CNT composite/graphene asymmetric hybrid system exhibited excellent cycling stability with the capacitance retained 85% of its maximum value up to 3000 cycles.

The present study highlights a low temperature process by which 1D stacked 3D microstructures of nickel sulfide comprised of nanospikes have been synthesized and assembled as cathodes for lithium chalcogenide batteries. These micro/nano-clusters were synthesized hydrothermally under different conditions. These clusters exhibited a surface area of 15 m 2 g −1 . The present study also provides the first reports on the electrochemical performance of these NiS microclusters as cathode materials in lithium fluoro-Tris-sulfonimide electrolyte for lithium ion batteries. A detailed study has been performed to elucidate how surface morphology and redox reaction behaviors underlying these electrodes impact the cyclic behavior and specific capacity. This electrode−electrolyte combination showed minimal dissolution of the electrode in the electrolyte which was confirmed by inductively coupled plasma atomic emission spectroscopy. From the electrochemical analysis performed an intrinsic correlation between the capacity, self-discharge property and the surface morphology has been deduced and explained on the basis of relative contributions from the redox reactions of nickel sulfide in lithium fluoro-Tris-sulfonimide electrolyte. A working model of lithium battery in a coin cell form is also shown exhibiting a specific capacity of 550 mAh g −1 .

In contrast to the conventional DSSC systems, where the dye molecules are used as light harvesting material, here a solid-state absorber was used as a sensitizer in conjunction with the dye. The materials like ZnO and Al2O3 : C, which will show optically stimulated luminescence (OSL) upon irradiation were used as extremely thin absorber layers. This novel architecture allows broader spectral absorption, an increase in photocurrent, and hence, an improved efficiency because of the mobility of the trapped electrons in the absorber material after irradiation, to the TiO2 conduction band. Nanocrystalline mesoporous TiO2 photoanodes were fabricated using these solid-state absorber materials and after irradiation, a few number of samples were co-sensitized with N719 dye. On comparing both the dye loaded photoanodes (ZnO/TiO2 and Al2O3 : C/TiO2), it can be concluded from the present studies that, the Al2O3 : C is superior to ZnO under photon irradiation. Al2O3 : C is more sensitive to photon irradiation than ZnO and hence there can be more trap centres produced in Al2O3 : C.

The present study demonstrates a facile approach by which TiO2-graphene nanocomposites can be processed into bulk powders via molten salt technique. A detailed study had been performed to elucidate the effect of graphene content (0.2–10 wt%) in these nanocomposites and its impact on the opto-electrical properties. From the analysis an intrinsic correlation between the graphene content and conductance of the composite has been explained on the basis of relative band gap and work function properties. Fluorescence spectroscopy measurements showed the excitonic intensity to be lower in these nanocomposites indicating that the recombination of photo-induced electrons and holes can be effectively inhibited. Conductivity measurements revealed mean specific conductance values about 15–55% higher than that of the TiO2 nanoparticles. Preliminary studies have shown that an efficiency of 5.4% could be attained by employing TiO2-graphene nanocomposites as photoanodes in dye sensitized solar cells.

The present study investigates in detail the synthesis and characterization of PEDOT: PSS/MnO 2 hybrid sponge electrodes for supercapacitor/battery applications. These hybrid sponges were prepared using freeze drying technique and showed hierarchical pores ranging from micron to nanometric size. Scanning electron microscopy-energy dispersive X-ray showed uniform dispersion of MnO 2 along the PEDOT: PSS matrix. Thermo gravimetric-differential thermal analysis showed higher thermal stability for these hybrid constructs compared to PEDOT: PSS sponges. From the electrochemical studies, an intrinsic correlation between overall specific capacitance, morphology and weight percentage of MnO 2 in the PEDOT: PSS matrix has been defined and explained in KOH electrolyte system. High cyclic stability was observed at the end of 2000 cycles for these hybrid sponges with less than 5 % capacitance fading. These sponges exhibit mass specific capacitance values as high as 10688 F g −1 which was found to be 35% higher compare to PEDOT: PSS sponges as obtained from Weibull statistics. The application of these electrodes was explored in a fully functional asymmetric coin cell unit where an energy and power density of 200 mWh kg −1 and 6.4 kW kg −1 , was obtained, respectively.

Camphoric carbon wrapped NiS powders have been profitably exploited to fabricate high surface area electrodes for Li storage. The NiS morphology showed a network of interconnected nanoscale units with rod like profiles which terminated into needle-like apexes spanning diameters of about 50–80 nm. These particles were pyrolyzed using a camphoric solution to form a carbon sheath wrapping. These carbon functionalized NiS powders were processed into high-surface-area cathodes for a fully functional coin cell unit. A detailed study was performed to elucidate the effect of carbon content on the performance of these coin cells. BET surface area analysis revealed that these carbon sheathed NiS could exhibit a high surface area of 32 m2 g−1 compared to pristine powders which exhibited surface area values of 20 m2 g−1. From the analysis of relevant electrochemical parameters, an intrinsic correlation between the specific capacity, internal resistance and temperature has been deduced. Relative contributions of capacitive and diffusion-controlled processes underlying these thin-film electrodes have been mathematically modeled. These thin-film electrodes exhibited specific capacity values as high as 500 mA h g−1 as determined from charge discharge curves. The present study shows that this functional material can provide the advantages of simple processing technique, low cost, and scalability.

The present study demonstrates a novel electrodeposition approach by which Ce 3+ doped NiO nanoparticles coated on titanium foils can be processed into a high surface area electrode for rechargeable energy storage applications. A detailed study has been performed to elucidate how cerium substitution doping and redox reaction behaviors underlying these electrodes impact the cyclic and capacitive behavior of the electrode. These nanoparticles were synthesized via molten salt technique and exhibited particle size of ∼ 65 nm. From the analysis of the relevant electrochemical parameters, an intrinsic correlation between the substitutional doping amount, capacitance and the internal resistance has been deduced and explained on the basis of relative contributions from the faradic properties of the Ce 3+ doped NiO nanoparticles in different electrolytes of varied concentrations. These thin film electrodes exhibited specific mass capacitance value as high as 1500 Fg −1 and 1077 Fg −1 (1 Ag −1 ) measured from cyclic voltammetry and charge discharge curves respectively, which was found to be 5 times higher than the pristine NiO nanoparticles with a capacitance retention of >70% at the end of 2000th cycle. Further, a working model button cell employing these rechargeable electrodes is also demonstrated exhibiting an energy and power density of 92 Wh Kg −1 and 10 kW Kg −1 , respectively. It has been shown that electrodes based on such nanoparticles can allow significant room for improvement in the cyclic stability and performance of a hybrid capacitor/battery system.

In this present study, we demonstrate the size dependent charge transfer from CdTe quantum dots (QDs) into TiO2 substrate and relate this charge transfer to the actual behavior of a CdTe sensitized solar cell. CdTe QDs was synthesized using mercaptopropionic acid as the capping agent. The conduction band offset for TiO2 and CdTe QDs indicates thermodynamically favorable band edge positions for smaller QDs for the electron-transfer at the QD–TiO2 interface. Time-resolved emission studies were carried out for CdTe QD on glass and CdTe QD on TiO2 substrates. Results on the quenching of QD luminescence, which relates to the transfer kinetics of electrons from the QD to the TiO2 film, showed that at the smaller QD sizes the transfer kinetics are much more rapid than at the larger sizes. I–V characteristics of quantum dot sensitized solar cells (QDSSC) with different sized QDs were also investigated indicating higher current densities at smaller QD sizes consistent with the charge transfer results. The maximum injection rate constant and photocurrent were obtained for 2.5 nm CdTe QDs. We have been able to construct a solar cell with reasonable characteristics (Voc = 0.8 V, Jsc = 1 mA cm−2, FF = 60%, η = 0.5%).

The present study provides the first reports of a novel approach of electrophoretic co-deposition technique by which titanium foils are coated with LiFePO4-carbon nanocomposites synthesized by sol gel route and processed into high-surface area cathodes for lithium ion batteries. The study elucidates how sucrose additions as carbon source can affect the surface morphology and the redox reaction behaviors underlying these cathodes and thereby enhance the battery performance. The phase and morphological analysis were done using XRD and XPS where the LiFePO4 formed was confirmed to be a high purity orthorhombic system. From the analysis of the relevant electrochemical parameters using cyclic voltammetry and electrochemical impedance spectroscopy, a 20% increment and 90% decrement in capacity and impedance values were observed respectively. The composite electrodes also exhibited a specific capacity of 130 mA h/g. It has been shown that cathodes based on such composite systems can allow significant room for improvement in the cycling performance at the electrode/electrolyte interface.

In the present study, ultrafine TiO2 nanowires (∼80 nm in diameter) exhibiting large aspect ratio in the order of 103 were synthesized hydrothermally. Phase and morphological analysis of the nanowires was carried out using X-ray diffractometry, X-ray photoelectron spectroscopy and scanning electron microscopy. High resolution transmission electron microscopy revealed the wire exhibiting growth in (101). A Tauc plot derived from UV analysis showed the average band gap values for nanowires to be less than for nanoparticles of similar diameter. It was observed that nanowires exhibited a high degree of photoactivity in an eosin-based dye system which was found to be 20 – 30 % more than that of nanoparticles. This high photoactivity in nanowires was attributed to the longer charge retention which was observed during lifetime measurements, resulting in easy radical formation and dye degradation. Lifetime measurements on the nanowires showed the recombination time to be 54 ns as compared to 43 ns for nanoparticles.

The present study investigates a novel approach by which MnO2 nanoparticle and camphoric carbon nanobead blends are coated on Ti-foils for rechargeable energy storage applications. Depending on the amount of nanocarbon blended onto the MnO2 nanoflake system, these thin film nanocomposite electrodes can exhibit a specific mass capacitance value as high as 1020 F g−1. It has been shown that electrodes based on such a composite system can allow significant room for improvement in the cyclic stability of a rechargeable electrode system.

Nanowires of NiO were successfully synthesized using a simple hydrothermal route. The nanowires were characterized for phase composition and morphology by X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques, respectively. XRD analysis showed that the powders produced were of high purity cubic NiO phase. Selected area electron diffraction (SAED) analysis during TEM showed the growth direction of NiO nanowires in (1 0 0), while exhibiting an average diameter of ∼ 65 nm. BET analysis showed these nanowires exhibiting a surface area of 153.2 m2/g. These nanowires were electrophoretically deposited on titanium foils as thin layer (∼5 μm thickness) and were studied for their capacitive behavior as electrodes for supercapacitor applications. Image analysis and atomic force microscopy (AFM) studies revealed the thin film coating to be highly porous (>50%). Cyclic voltammetry (CV) studies on these electrodes exhibited a specific mass capacitance of 750 F/g with 12% capacitance fade at the end of 1000 cycles. The present study elucidates how NiO surface morphology and OH− adsorption/desorption behaviors underlying these electrodes impact the chemical and structural stability performance.

The present study reports the electrospinning of commercially available polyaniline-carbon black composite to develop conductive nanofibrous mats using polyvinyl alcohol as a binder solution. This binder solution was sublimated at 230 � C to attain a complete conducting nanofiber network. The binder sublimation was confirmed using thermo gravimetric analysis (TGA). Ultra-violet visible spectroscopy was used to determine the refractive index values for porosity measurements. It was observed that the heat treatment reduced the fiber diameter from ∼ 250 nm to ∼ 160 nm and increased the porosity from 41 ± 1.2% to 70 ± 2%. The spatial specific conductance mapping using Scanning Electro-Chemical Microscopy showed that the presence of polyvinyl alcohol binder in polyaniline-carbon black composite could introduce percolation threshold. The heat-treated fibers showed four times increase in specific conductance values on removal of binder phase from the fiber structure. The role of nanoscaled Schottky barriers in determining conductive pathways through polymer by hopping mechanism and also along carbon black particles are also been proposed in this study.

In this letter, we report on the process of preparation of a high performance supercapacitor electrode using activated carbon of nanoscale size ( 95%) and hence maximally contribute to the surface area of the carbon for charge storage purposes. The designed supercapacitor electrode with nanoscale activated carbon not only has excellent storage capacity (specific capacitance of 1071 F g −1 and area capacitance of 0.48 F cm −2 ) but also good control of discharge when used as a power source. The above process used by us is a cost-effective and novel technique, which expands the application of activated carbon for high performance supercapacitor electrodes by achieving the desired performance.

Vertical ZnO nanotubes were electrochemically deposited onto an indium doped tin oxide glass substrate. These nanotubes were surface treated with zinc acetate and annealed at 450 °C, resulting in a nanotubes/nanoparticles composite layer. Scanning electron microscopy of the surface treated samples showed nanoparticles been dispersed uniformly along the ZnO tubular matrix, which was confirmed by X-ray diffractrometry. Photoluminescence and fluorescence microscopy showed untreated ZnO nanotubes exhibiting blue emission, while the treated samples exhibited green emissions. Ultra-violet spectroscopy of treated samples revealed lower band gap values compare to their untreated counterparts. Lifetime measurements showed higher excitonic lifetimes in treated samples. Conductance studies using atomic force microscopy showed significant improvement in the conductance values for the treated samples. A significant increase in photocurrent was observed in treated samples when used as photo-anodes in dye sensitized solar cells.

The main objective of this study is to show the effect of TiO2 nanotube length, diameter and intertubular lateral spacings on the performance of back illuminated dye sensitized solar cells (DSSCs). The present study shows that processing short TiO2 nanotubes with good lateral spacings could significantly improve the performance of back illuminated DSSCs. Vertically aligned, uniform sized diameter TiO2 nanotube arrays of different tube lengths have been fabricated on Ti plates by a controlled anodization technique at different times of 24, 36, 48 and 72 h using ethylene glycol and ammonium fluoride as an electrolyte medium. Scanning electron microscopy (SEM) showed formation of nanotube arrays spread uniformly over a large area. X-ray diffraction (XRD) of TiO2 nanotube layer revealed the presence of crystalline anatase phases. By employing the TiO2 nanotube array anodized at 24 h showing a diameter ∼80 nm and length ∼1·5 μm as the photo-anode for back illuminated DSSCs, a full-sun conversion efficiency (η) of 3·5 % was achieved, the highest value reported for this length of nanotubes.

+� oxide nanoparticles was produced by hydrothermal method and ceric (3 + � oxide nanoparticles were produced by hydrolysis method. The different synthesis routes adopted helped in synthesizing nanoparticles of similar size but exhibiting different properties. Detailed characterization of the nanoparticles proved that the synthesized cerium oxide nanoparticles were different in their stoichiometry. The selective toxicity of cerium oxide towards the normal and the cancer cell lines was evaluated. The nanoparticles were found to be nontoxic towards normal cell lines (L929) but cytotoxic towards prostate cancer cell lines (PC-3) as analyzed by MTT assay. Cellular uptake was confirmed by the conjugation of cerium oxide nanoparticle with a fluorescent dye rhodamine- 123 followed by optical detection of the uptake.

The present study demonstrates a novel approach by which titanium foils coated with LiMn2O4nanocrystals can be processed into a high-surface-area electrode for rechargeable batteries. A detailed study has been performed to elucidate how surface morphology and redox reaction behaviors underlying these electrodes impact the cyclic and capacity behavior. These nanocrystals were synthesized by in situ sintering and exhibited a uniform size of ∼55 nm. A direct deposition technique based on electrophoresis is employed to coat LiMn2O4nanocrystals onto titanium substrates. From the analysis of the relevant electrochemical parameters, an intrinsic correlation between the cyclability and particle size has been deduced and explained in accordance with the Li intercalation/deintercalation process. Depending on the particle size incorporated on these electrodes, it is seen that in terms of capacitance fading, for nanoparticles cyclability is better than their micron-sized counterparts. It has been shown that electrodes based on such nanocrystalline thin film system can allow significant room for improvement in the cyclic performance at the electrode/electrolyte interface.

V ertical ZnO nanotube (ZNT) arrays were synthesized onto an indium doped tin oxide (ITO) glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron microscopy (SEM) showed formation of well-faceted hexagonal ZNT arrays spreading uniformly over a large area. X-ray difiraction (XRD) of ZNT layer showed substantially higher intensity for the (0002) difiraction peak, indicating that the ZnO crystallites were well aligned with their c-axis. Profllometer measurements of the ZNT layer showed an average thickness of »7 „m. Diameter size distribution (DSD) analysis showed that ZNTs exhibited a narrow diameter size distribution in the range of 65{120 nm and centered at »75 nm. The photoluminescence (PL) spectrum measurement showed violet and blue luminescence peaks that were centered at 410 and 480 nm, respectively, indicating the presence of internal defects. Ultra-violet (UV) spectroscopy showed major absorbance peak at »348 nm, exhibiting an increase in energy gap value of 3.4 eV. By employing the formed ZNTs as the photo-anode for a dye-sensitized solar cell (DSSC), a full-sun conversion e‐ciency of 1.01% was achieved with a flll factor of 54%. Quantum e‐ciency studies showed the maximum of incident photon-to-electron conversion e‐ciency in a visible region located at 520{550 nm range.

Poly(methylmethacrylate) (PMMA) with various molecular weights exposed using 50keV electron beam have been investigated at subzero developer temperatures. Contrast curves for Methyl Isobutyl Ketone (MIBK):Isopropyl Alcohol (IPA)=1:3 and MIBK:IPA=1:7 developers were determined. The contrast curves for different molecular weight PMMA resists converge into a single curve at lower temperatures. At low temperatures, the line edge roughness and resolution improved. However, minimum line pitch shows no significant improvement while dose latitudes for a particular line pitch increased. It is shown that at low temperatures, linewidth resolution and periodicity are invariant for the different PMMA molecular weights (50K to 2.2M) used in this work.Poly(methylmethacrylate) (PMMA) with various molecular weights exposed using 50keV electron beam have been investigated at subzero developer temperatures. Contrast curves for Methyl Isobutyl Ketone (MIBK):Isopropyl Alcohol (IPA)=1:3 and MIBK:IPA=1:7 developers were determined. The contrast curves for different molecular weight PMMA resists converge into a single curve at lower temperatures. At low temperatures, the line edge roughness and resolution improved. However, minimum line pitch shows no significant improvement while dose latitudes for a particular line pitch increased. It is shown that at low temperatures, linewidth resolution and periodicity are invariant for the different PMMA molecular weights (50K to 2.2M) used in this work.

To explore the full capabilities of proton beam writing (PBW) as a lithographic tool it is important to investigate potential new resist materials. In PBW the interactions of the protons with the resist are comparable to the electron interactions with the resist in electron beam writing. In both techniques the induced secondary electrons will modify the molecular structure of the resist, therefore electron beam resists are potential candidates for PBW. Here we discuss resist properties such as contrast and sensitivity of two new negative resists for PBW. The first resist is a spin-coatable TiO2 resist for which sub 10 nm resolution has been reported using electron beam writing. In PBW smooth side walls have been observed for this resist. Despite a relative low sensitivity of this resist for PBW (8000 nC/mm2) it has potential applications in the area of integrated optical components such as waveguides and gratings because of its high refractive index. WL-7154 is a UV-sensitive negative resist and shows high sensitivity for PBW (4 nC/mm2). This resist could function as a mold for Ni electroplating to fabricate Ni stamps for nanoimprint- and soft-lithography.

Two-photon polymerization of photosensitive materials irradiated by femtosecond laser pulses is now considered as an enabling technology for the fabrication of 3D structures, especially photonic crystals and photonic crystal templates. Depending on the topology and dielectric constant contrast of photonic crystals, their optical properties can be tailored in a desired manner. Since 1987, when the concept of 3D photonic crystal was introduced by Yablonovitch and John, photonic crystals have been a subject of intensive research. In spite of this, the fabrication of photonic crystals with a full 3D (or omni-directional) bandgap in the visible range is still a challenging task. To realize photonic crystals with a full photonic bandgap, 3D structuring of high refractive index materials is required. The high refractive index (ca. 2.4) and high transparency in the visible spectrum makes TiO2 a very promising photonic material. For many applications, it is desirable to have a simple technique for patterning this material in twoand even three dimensions. Conventionally, TiO2 is patterned by sputtering it onto a pre-patterned organic resist followed by lift-off. When thick films of TiO2 or complicated features are desired, the lift-off process does not work well. For 3D fabrication, the most attractive option so far has been to fabricate templates which were later infiltrated with a high refractive index material, followed by the removal of the original template structure. Another approach is to use inorganic–organic photosensitive materials (ormocers) for the fabrication of photonic crystals. In this case, there exists a possibility to skip the replication steps and to fabricate 3D inorganic structures directly. However, the inorganic content in these materials is not very high and the attempts to fabricate in three dimensions have resulted in porous structures. In order to eliminate the issue of making templates and their subsequent infiltration with a high refractive index material, a direct 3D fabrication of structures appears to be an attractive option. As2S3, a chalcogenide glass, was directly patterned in three dimensions by exploiting its photo-induced metastability. On the other hand, examples of direct patterning of oxides are nonexistent. In this paper, we will demonstrate a direct 3D patterning of TiO2 structures using femtosecond laser pulses. To enable such fabrication, a photosensitive sol– gel-based spin-coatable TiO2 resist was developed. The experimental setup used for the patterning is shown in Figure 1 and is similar to that used before. The TiO2 resist is transparent (refractive index = 1.68) to the femtosecond laser radiation of 780 nm wavelength, and therefore, allows focusing of laser pulses tightly into the material volume. In the focal area, where the intensity of femtosecond laser pulses is high enough to initiate multiphoton processes, bond-breaking in the TiO2 resist makes the irradiated regions insoluble in organic solvents such as acetone. This allows the fabrication of any computer-generated 3D structure by direct laser “recording” into the volume of the TiO2 resist. Because of the threshold behavior and nonlinear nature of this bond-breaking proC O M M U N IC A TI O N

A new form of yield theories considering an anisotropic parameter for porous sintered powder metallurgy metals have been derived and proposed in this technical paper. In addition to these, the flow rule with anisotropic parameter for porous metal is introduced. The mathematical expression for the calculation of flow stress in the case of simple compression of tension test is deduced from the yield theories for the P/M sintered preforms of the metals. These yield theories are used for the determination of the limit strains in connection with the swift’s plastic instability condition for diffuse necking and the Hill’s plastic instability condition for localized necking.

Electron beam-sensitive spin-coatable Al2O3 resists were prepared by chemically modifying aluminium tri-sec-butoxide with various β-ketoesters (R-acetoacetates, R = methyl, ethyl, isopropyl, isobutyl, isoamyl, heptyl, benzyl and 2-[methacryloyloxy] ethyl) in isopropyl alcohol. The reaction product was a chelated complex. With increasing molecular weight of R, there was an increase in electron beam sensitivity of spin-coatable Al2O3 resists. This appears to be due to decreased stability of the chelated complex formed by higher molecular weight R-acetoacetates. Fourier transform infrared (FTIR) spectroscopy studies indicate that exposure to an electron beam results in the breakdown of chelate rings, making the exposed area insoluble during development. Electron beam nanolithography produced 8 nm wide lines. These are the smallest oxide lines written using a sol-gel-based resist.

We describe a direct write technique using an electron beam to pattern ZrO2 on a sub-10 nm scale that bypasses the conventional method of sputtering and lift-off. This technique utilizes spin-coatable ZrO2 resist prepared by chemically reacting zirconium n-butoxide with benzoyl acetone in ethanol. The patterned resist has a sensitivity and contrast of and 3, respectively. Baking the resist at 85 °C increases the sensitivity to . The electron-beam-exposed regions become insoluble in acetone, thus yielding negative patterns. This property was exploited to write high-resolution patterns as small as 9 nm wide. Such negative patterns can be written with a pitch as close as 30 nm.

Conventional methods for electron beam patterning of TiO2 are based on sputtering and lift-off. This poses significant problems in producing high aspect ratio and stoichiometric structures, especially in the sub-100 nm size range. We describe an alternative approach of preparing spin-coatable TiO2 resists by chemically reacting titanium n-butoxide with benzoylacetone in methyl alcohol. They have an electron beam sensitivity of ∼35 mC cm-2 and are >107 times more sensitive to an electron beam than sputtered TiOx and crystalline TiO2 films. Fourier transform infrared studies suggest that exposure to an electron beam results in the gradual removal of organic material from the resist. This makes the exposed resist insoluble in organic solvents such as acetone, thereby providing high-resolution negative patterns as small as 8 nm wide. Such negative patterns can be written with a pitch as close as 30 nm.

Highly porous (~ 70%) polyaniline-carbon black composite nanofiber mats with good conductivity were fabricated via electrospinning. The fiber mat was electrospun using polyvinyl alcohol as carrier solution which was later decomposed at ~ 230 °C to get a complete conducting nanofiber network. This heat treatment reduced the fiber diameter from ~ 250 nm to ~ 170 nm and the porosity of the fiber mat increased from ~ 41% to 70%. The removal of the carrier phase was confirmed by Fourier transform infrared spectroscopy and did not result into any structural collapse. The localized conductance measurements using scanning electro-chemical microscopy showed that the removal of insulating carrier solution substantially reduced the percolation threshold and increased the fiber-mat conductance.

A new form of yield criterion considering an anisotropic parameter for porous sintered powder metallurgy metals has been proposed in this technical paper. In addition to the above, the flow rule with anisotropic parameter for porous metal is introduced. The mathematical expression for the calculation of flow stress in the case of simple compression or tension test is deduced from the yield criteria for the P/M sintered preforms of the metals. Further, a new generalised form of yield criteria with five parameter constants for porous sintered powder metallurgy sheet metals has also been proposed in this technical paper.

A monomer having a free-radical polymerizable methacryloyl group and a photocrosslinkable functional group (pendant chalcone unit) was synthesized and polymerized in MEK at 70°C using benzoyl peroxide as an initiator. The prepared polymer was characterized by UV, IR, 1 H-NMR and 13 C-NMR spectra. The molecular weights ( M w and M n ) of the polymer were determined by gel permeation chromatography. The thermal stability of polymer was assessed by thermogravimetric analysis of the polymer in air/nitrogen atmosphere. The glass transition temperature of the polymer was determined by differential scanning calorimetry. The photocrosslinking property of the polymer was studied as a thin film, and in solution, and the results were discussed.

Laser surface hardening is an effective technique used to improve the tribological properties and also to increase the service life of automobile components such as camshafts, crankshafts, lorry brake drums and gears. High power CO 2 lasers and Nd–YAG lasers are employed for localized hardening of materials and hence are of potential application in the automobile industries. All steel surfaces can be hardened with high power laser sources, the degree of hardenability and fineness in microstructure obtained depending on the laser processing variables and on the absorption coatings employed. In this investigation, the microstructrual features occurring in CO 2 laser hardened En18 steel are discussed with the use of optical microscopic and scanning electron microscopic analysis. Moreover, the correlation between the surface temperature and cooling rate on the resulting hardness is explained. Theoretical thermal profile studies are made and their effect on the coupling coefficient values, hardness and the microstructural changes observed are discussed. The effect of laser hardening on wear resistance is described.

This paper discusses the effect of CO 2 laser alloying of pre-placed BN coating with Ti–6Al–4V alloy. The formation of titanium boride and titanium nitride investigated using energy dispersive X-ray diffraction (EDXRD) result were related to the microhardness and microstructure. The nitrogen and boron diffusion during the laser boronising process identified using secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectrometry (XPS) analysis was compared with the EDXRD results. The surface hardness HV1500–1700 observed at the boronised layer was five to six times higher than that of untreated Ti–6Al–4V alloy. This was compared with needle platelet and dendrite type microstructures. Theoretically estimated surface temperature values were used to interpret the compound formation in the laser alloyed layer.

Laser surface treatment provides excellent wear resistance with good oxidation and corrosion resistance. Laser surface nitriding is one such technique resulting in high surface hardness to a depth of a few microns. This can be carried out in pure nitrogen and dilute nitrogen environments. This paper investigates the effect of laser nitriding on Space Shuttle Main Engine (SSME) Ti-5.0Al-2.5Sn alloy under pure nitrogen environment. The nitriding was carried out using 3 kW CW CO2 laser at different laser powers 900 W, 1.0 kW, and 1.2 kW with scan speeds 0.5 m min-1, 1.0 m min-1 and 1.5 m min-1 respectively. Optical microscopic and Vickers hardness tests were conducted on the test specimen to reveal the effect of laser nitriding in melt zone of laser nitrided trail. The extra high surface hardness of 3785 VHN at 25-50 (m depth was observed using the laser variable 1.0 kW laser power, 1.0 m min-1 speed and 3 mm beam dia. This may be attributed to the TiN dendrite formation. The melt zone of laser nitr...

The present study demonstrates an original approach by which Au nanoparticles (approximately 10 nm) are embedded into TiO2 fibers via electrospinning. The photocatalytic performance of the resultant fibrous material was studied and related to the architecture and the nature of the internal interfaces in the composite. It was found that embedment of nano Au particles into the TiO2 fiber significantly improved the photocatalytic performance as compared to non-embedded ones. Electrospun fibers with the Au nanoparticles (approximately 10 nm) showed an average fiber diameter of approximately 380 nm. The photocatalytic studies of Au embedded TiO2 fibers using ultra-violet (UV) visible spectroscopy showed approximately 35% increase in photocatalytic activity when compared to the TiO2 fibers without the Au nanoparticles after 7 hrs of UV irradiation. This increase in photocatalysis was attributed to the ability of Au to increase charge separation in TiO2 and also to the ability of Au to transfer plasmonic energy to the dye.