Charge-response of magnetization in nanoporous Pd-Ni alloys

This work reports isothermal reversible variation of magnetization in nanoporous Pd-Ni alloys subjected to continuous charging and discharging of the sample in aprotic electrolyte medium. Polarizing metal surface with excess charge also finds strain in the nanoporous structure using the sample as working electrode. Therefore, it is proposed that pressure induced by strain is the key parameter for the observed reversible magnetization in the transition metal alloys.     

Low-macroscopic field emission from nanocrystalline Al doped SnO<Subscript>2</Subscript> thin films synthesized by sol–gel technique

We have observed low-macroscopic field electron emission from wide bandgap nanocrystalline Al doped SnO₂ thin films deposited on glass substrates. The emission properties have been studied for different anode-sample spacings and for different Al concentrations in the films. The turn-on field and approximate work function were calculated and we have tried to explain the emission mechanism from this. The turn-on field was found to vary in the range 5.6–7.5 V/μm for a variation of anode sample spacing from 80–120 μm. The turn-on field was also found to vary from 4.6–5.68 V/μm for a fixed anode-sample separation of 80 μm with a variation of Al concentration in the films 8.16–2.31%. The Al concentrations in the films have been measured by energy dispersive X-ray analysis. Optical transmittance measurement of the films showed a high transparency with a direct bandgap ∼3.98 eV. Due to the wide bandgap, the electron affinity of the film decreased. This, along with the nanocrystalline nature of the films, enhanced the field emission properties. PACS 81.20.Fw; 61.10.-i; 79.70.+q     

Electronic structure and magnetism of disordered bcc Fe alloys

We study the electronic structure and magnetic properties of disordered bcc Co_xFe_1-x, Cr_xFe_1-x and Mn_xFe_1-x alloys in their ferromagnetic phases using the Augmented Space Recursion (ASR) technique coupled with the tight-binding linearized muffin tin orbital (TB-LMTO) method. We calculate the density of states and magnetic moment of these alloys to show the variation upon alloying Fe with the other neighbouring 3d transition metals using arguments based on charge transfer, exchange splitting and hybridization effects. Received 10 April 2001 and Received in final form 15 August 2001     

Temperature dependent structural and optical properties of nanocrystallineCdO thin films deposited by sol–gel process

Nanocrystallites of cadmium oxide (CdO) thin films were deposited by sol–gel dip coating technique on glass and Si substrates. XRD and TEM diffraction patterns confirmed the nanocrystalline cubic CdO phase formation. TEM micrograph of the film revealed the manifestation of nano CdO phase with average particle size lying in the range 1.6–9.3 nm. UV–Vis spectrophotometric measurement showed high transparency (nearly 75% in the wavelength range 500–800 nm) of the film with a direct allowed bandgap lying in the range 2.86–3.69 eV. Particle size has also been calculated from the shift of bandgap with that of bulk value for the films for which the particles sizes are comparable to Bohr exitonic radius. The particle size increases with the increase in annealing temperature and also the intensity of XRD peaks increases which implies that better crystallinity takes place at higher temperature.This revised version was published online in August 2005 with a corrected issue number.     

Depth-resolved fluorescence measurement in a layered turbid medium by polarized fluorescence spectroscopy

We show that, when a turbid medium with a layered fluorophore distribution is excited by linearly polarized light, measurement of angle-resolved polarized fluorescence can provide depth-resolved fluorescence measurements.     

Growth and characterization of Cd1−xZnxTe thin films prepared from elemental multilayer deposition

Cd_1−xZn_xTe is a key material for fabrication of high-energy radiation detectors and optical devices. Conventionally it is fabricated using single crystal growth techniques. The method adopted here is the deposition of elemental multilayer followed by thermal annealing in vacuum. The multilayer structure was annealed at different temperatures using one to five repetitions of Cd-Zn-Te sequence. X-ray diffraction pattern for the multilayer with five repetitions revealed that annealing at 475 °C yielded single-phase material compared to other annealing conditions. EDX spectroscopy was carried out to study the corresponding compositions. Photoluminescence properties and change of resistance of the multilayer under illumination were also studied. The resistivity of the best sample was found to be a few hundreds of Ω cm.     

Proton induced modification in Poly(ethylene terephthalate)

A systematic investigation of 62 r MeV proton irradiated Poly(ethylene terephthalate) (PET) has been carried out using Fourier Transformed Infrared Spectroscopy, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction spectroscopy. The experiments revealed a restoration of the crystalline matrix and simultaneous decrease in thermal stability in the irradiated polymer as a function of dose, indicating that PET underwent both degradation and cross-linking by proton irradiation.