Investigation of dual ion beam sputtered transparent conductive Ga-doped ZnO films

Ga-doped ZnO (GZO) transparent conducting films were deposited on sapphire (0001) substrates using dual ion beam sputtering deposition system. The impact of growth temperature on the structural, morphological, elemental, optical, and electrical properties was thoroughly investigated and reported. X-ray diffraction measurements explicitly confirmed that all GZO films had (002) preferred crystal orientation. The film deposited at 400 °C exhibited the narrowest full-width at half-maximum value of 0.24° for (002) crystalline plane and the lowest room temperature electrical resistivity of 4.11 × 10^?3 Ω cm. The Raman spectra demonstrated the vibrational modes at 576 and 650–670 cm^?1, associated with native oxygen vacancies and elemental Ga doping in ZnO lattice, respectively. All doped films showed an overall transmittance of above 95 % in the visible spectra. A correlation between structural, optical, elemental, and electrical properties with GZO growth temperature was established.     

A Novel Synthesis of Malic Acid Capped Silver Nanoparticles using Solanum lycopersicums Fruit Extract

Integration of green chemistry principles to nanotechnology is one of the key issues in nanoscience research. The development of the concept of green nanoparticle preparation has been growingly needed for environmentally benign metal nanoparticle synthesis protocols to avoid adverse effects in medical applications. Keep this in mind, in the present study, silver nanoparticles were synthesized using Solanum lycopersicums fruit extract. The prepared silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy techniques. The surface plasmon resonance peak was found at 445 nm. The synthesized silver nanoparticles were spherical in shape with the average size of 10 nm. The citric acid present in S. lycopersicums fruit extract acted as reducing agent and malic acid was responsible for capping of the bioreduced silver nanoparticles.     

Effect of air annealing on structural, optical, microscopic, electrical properties of cadmium selenide thin films

Cadmium selenide films have been deposited on glass substrate dip method. The resultant films were annealed upto 473 K temperature. The structural properties of cadmium selenide thin films have been investigated by X-ray diffraction techniques. The X-ray diffraction spectra showed that cadmium selenide thin films are polycrystalline. As deposited sample shows cubic phase whereas sample annealed at 473 K shows hexagonal phase. The optical properties showed direct band gap values were found to be in the region of 1.82–1.55 eV. The electrical studies shows conductivity increases with increase in annealing temperature. The optoelectric and structural data are discussed from the point of applications based on achieving high performance devices.     

Structural,optical and microscopic properties of chemically deposited Mo<Subscript>0.5</Subscript>W<Subscript>0.5</Subscript>Se<Subscript>2</Subscript> thin films

Mo_0.5W_0.5Se₂ thin films were obtained by using relative simple chemical route at room temperature. Various preparative conditions of the thin films are outlined. The films were characterized by X-ray diffraction, scanning electron microscope, optical and electrical properties. The grown films were found to be uniform, well adherent to substrate and brown in color. The X-ray diffraction pattern shows that thin films have a hexagonal phase. Optical properties show a direct band gap nature with band gap energy 1.44 eV and having specific electrical conductivity in the order of 10⁻⁵ (Ωcm)⁻¹.     

Blue shift of optical band-gap in LiNbO3 thin films deposited by sol-gel technique

Lithium niobate (LN) thin films were deposited on quartz substrates by sol-gel technique. The measured absorption and photoluminescence spectra show that the band structure of LN thin films is direct unlike indirect band-gap in bulk LN and the optical band-gap of these LN thin films was measured to be 4.7 eV which is ~ 1 eV greater than that for stoichiometric bulk LN. The dependence of the blue shift of band-gap on several parameters like quantum confinement, composition (Li:Nb ratios of LN thin films) and strain was also investigated. The results obtained show that the large blue shift in band-gap of LN thin films is primarily due to strain in the film.     

Behavior of dual ion beam sputtered MgZnO thin films for different oxygen partial pressure

Mg-doped ZnO (MgZnO) films were grown on p-Si (001) substrates by dual ion beam sputtering deposition system at a constant growth temperature of 600 °C for different oxygen partial pressure. The impact of oxygen partial pressure on the structural, electrical, elemental and morphological properties was thoroughly investigated. X-ray diffraction (XRD) spectra revealed that the deposited MgZnO films were polycrystalline in nature with preferred (002) crystal orientation. The peak of MgZnO (101) plane was reduced significantly as oxygen partial pressure was increased and disappeared completely at 80 and 100 % O₂. The maximum electron concentration was evaluated to be 5.79 × 10¹⁸ cm^?3 with resistivity of 0.116 Ω cm and electron mobility of 9.306 cm²/V s at room temperature, for MgZnO film grown with 20 % O₂. Raman spectra shows a broad peak at 434 cm^?1 corresponded to E ₂ ^high phonons mode of MgZnO wurtzite structure. The peak at 560 cm^?1 corresponded to the E₁ (LO) mode and was associated with oxygen deficiency in MgZnO films. Raman intensity at 560 cm^?1 reduced, on increasing oxygen partial pressure. A correlation between structural, electrical, elemental and morphological properties with oxygen partial pressure was also established.     

Structural, dielectric and multiferroic properties of Er and La substituted BiFeO3 ceramics

Erbium (Er) and lanthanum (La) substituted BiFeO₃ (BFO) ceramics have been prepared through conventional solid solution route. X-ray diffraction data indicated a gradual phase transition from rhombohedral to monoclinic structure in Bi_0·9?x La_0·1Er _x FeO₃ (x = 0·05, 0·07 and 0·1) (BLEFO _{x = 0·05, 0·07, 0·1}) ceramics. Differential thermal analysis (DTA) measurements of BFO samples showed a ferroelectric transition at 835°C, whereas it is shifted to 792°C for BLEFO _{x = 0·1}. The Raman spectra of BLEFO _{x = 0·05, 0·07, 0·1} samples showed the shift of Raman modes to higher wavenumbers and suppression of A₁ modes indicating decrease in ferroelectricity. The Raman spectra also indicated the structural transformation due to Er and La substitution in BFO. On subsequent erbium doping, the intrinsic dielectric constant is found to decrease from 68 (for pure BFO) to 52 for BLEFO _{x = 0·05} to 43 for BLEFO _{x = 0·07} but increased to 89 for BLEFO _{x = 0·1} when compared to pure BFO. The increase in Er content resulted in the increase in spontaneous magnetization (0·1178 emu/g at 8T for BLEFO _{x = 0·1}) due to collapse of spin cycloid structure. Ferroelectric remnant polarization of BLEFO _{x = 0·05} and BLEFO _{x = 0·07} decreases when compared to pure BFO while small remnant polarization (close to paraelectric behaviour) is evident for BLEFO _{x = 0·1}.     

Dehydration and Hydration Ktnetics, Phase Change, Solubility and Dissolution Behavior of Fenoprofen Calcium

The role of water of hydration on the crystal structure, the solubility and the rate of dissolution of fenoprofen calcium dihydrate was examined. The rate of dehydration of fenoprofen calcium dihydrate at 0% relative humidity (R.H.) increased from 0.0400 to 0.7488 fraction dehydratedhour over a temperature range of 50°C to 80 °C and appeared to occur by a combination of diffusion and nucleation processes. The enthalpy of dehydration was 21.897 kcal/mole. Hydration of dehydrated fenoprofen calcium occurred rapidly at 100% R.H. X-ray powder diffraction analysis showed that the upon dehydration fenoprofen calcium dihydrate underwent a change in its crystal structure to form anhydrous fenoprofen calcium. The rate of dissolution of fenoprofen calcium dihydrate tablets at 37°C was not significantly different than that of tablets containing anhydrous fenoprofen. The enthalpies of solution (δH_sol) of fenoprofen calcium dihydrate and anhydrous fenoprofen calcium were 2.0504 and 3.5583 kcaYmole respectively. The transition temperature at which the dihydrate and anhydrous fenoprofen had equal solubilities was approximately 59.91 °C.     

Privacy-preserving distributed mining of association rules using Elliptic-curve cryptosystem and Shamir’s secret sharing scheme

Distributed data mining has played a vital role in numerous application domains. However, it is widely observed that data mining may pose a privacy threat to individual’s sensitive information. To address privacy problem in distributed association rule mining (a data mining technique), we propose two protocols, which are securely generating global association rules in horizontally distributed databases. The first protocol uses the notion of Elliptic-curve-based Paillier cryptosystem, which helps in achieving the integrity and authenticity of the messages exchanged among involving sites over the insecure communication channel. It offers privacy of individual site’s information against the involving sites and an external adversary. However, the collusion of two sites may affect the privacy of individuals. To address this problem, we incorporate Shamir’s secret sharing scheme in the second protocol. It provides privacy by preventing colluding sites and external adversary attack. We analyse both protocols in terms of fulfilling the privacy-preserving distributed association rule mining requirements.