Avinash Chander Gupta

57Fe Mössbauer investigation of nanostructured zinc ferrite irradiated by 100 MeV oxygen beam

Zinc ferrite nanoparticles of different size were irradiated in vacuum with 100 Mev O7+ ion beam at a fluence of 5×1013 ions/cm2. Presence of ZnO phase was observed after the irradiation in the samples. 57Fe Mossbauer spectroscopy shows the presence of well defined doublets in case of pristine and irradiated samples which are the attributes of superparamagnetism in the specimen. The variation of Mossbauer hyperfine parameters is discussed.

Doped Cobalt Ferrites for Stress Sensor Applications

The development of new magnetoelastic materials, suitable for use in magnetic stress sensors, has a high scientific and technological interest due to growing number of possible applications in automotive industry. In this study, a series of silicon-doped cobalt ferrite samples with compositions of CoSixFe2-xO4 were prepared by substituting silicon for iron. The samples were made using standard powder ceramic technique. The spinel structure and the presence of residual phases were checked by XRD analysis. To determine the influence of the substitution on the strength of the magnetic exchange interactions, Curie temperature (Tc) measurements were made. A dramatic decrease of Tc with the substitution of Si for Fe was observed. By adjusting the silicon content and the sintering process the material properties could be optimized for industrial application.

Investigation of ion beam mixing threshold value in Mn/Si system using swift heavy ions

A metal/semiconductor system (a-Si/Mn/a-Si) was deposited on the silicon substrate using the electron beam evaporation method. These samples were irradiated using 80 MeV Ni and 100 MeV Ag ions at different fluences ranging from 1×1013 to 1×1014 ions/cm2 for the investigation of mixing threshold. Pristine and irradiated samples have been characterized using Rutherford backscattering spectroscopy (RBS) for depth profile analysis and atomic force microscopy (AFM) for surface roughness study. RBS spectra revels that there is a mixing at 100 MeV Ag ion irradiations which increases with fluence, whereas there is no mixing observed at 80 Ni MeV ion irradiations. We have also tried to investigate the mixing threshold value in this system. The surface roughness, as investigated from AFM, has not significantly changed upon irradiation indicating no contribution of roughness in interface mixing.

Assessment of quantitative ultrasound densitometry in 100 persons with fractures due to osteoporosis

To assess the role of quantitative ultrasound densitometry on person with osteoporosis fracture. We measure BUA T-score of Os-calis in a sample of 100 persons (Male 54, Female46), aged 45-99 years at Rajindra Hospital, Patiala. We observed that none of the patient in our study had normal BUA T Score measured by quantitative ultrasound densitometry. All patient had BUA T-Score range -5.5 to -1.2, mean with SD -2.60 1.07. Thus quantitative ultrasound densitometry seems to be a good predictor of fracture risks due to osteoporosis. We also observed that in osteoporotic patient with age 45 years or over there was age related decline BUA T. Score. This was higher in women compared with men. We conclude that all patients with fractures due to osteoporosis had poor bone quality. Thus quantitative ultrasound densitometry may be mandatory for a person with osteoporosis facture.