http://nopr.niscair.res.in/handle/123456789/8748 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/8900 Title: Dielectric studies of polycrystalline (Sr,Fe)TiO₃ ceramics <br/> <br/>Authors: Srivastava, K K P; Sinha, K K <br/> <br/>Abstract: The characteristic properties of polycrystalline (Sr,Fe)TiO₃ ceramics have been studied through Mössbauer, EPR, IR and differential scanning calorimetry because perovskite type dielectrics have useful applications in electronic industry. In Fe-doped materials, the small concentration of Fe atoms provides active centres that can be probed through Mössbauer and EPR methods which are precise enough to detect small lattice structural perturbations and yield valuable information. The present work deals with their dielectric properties including dielectric relaxation time that is considered an important study from a theoretical angle. It is found that the two-state Debye relaxation model is inadequate. These ceramics tend to behave like relaxors with ferroelectric transition temperature in the range 200-250°C depending upon iron concentration. <br/> <br/>Page(s): 884-888 Sat, 29 Oct 2005 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/8899 Title: Charge imbalance generated by tunnel injection in superconductors <br/> <br/>Authors: Mattoo, B A; Malik, M A <br/> <br/>Abstract: Using quasi– classical Green function, charge imbalance relaxation rates in tunnel injection experiments are calculated. It yields accurate results even when pair-breaking rate is comparable with the gap frequency. <br/> <br/>Page(s): 873-883 Sat, 29 Oct 2005 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/8898 Title: Surface plasmon resonance based refractive index sensor for liquids <br/> <br/>Authors: Mehan, Navina; Gupta, Vinay; Sreenivas, K; Mansingh, Abhai <br/> <br/>Abstract: A surface plasmon resonance (SPR) refractive index sensor for liquids was fabricated and characterized. A thin silver (Ag) film (545Å) was deposited on a prism face and surface plasmon modes were excited along the interfaces of Ag and air, Ag and water and Ag and sugar solutions by prism-coupling using a He-Ne laser. The experimental SPR reflectance curves shifted continuously with increase in sugar concentration. Theoretical fitting of the SPR dip angles yielded the dielectric constant of Ag and refractive indices of water and sugar solutions. A maximum sensitivity of 1.4×10^-4 R.I.U. (refractive index units) was achieved with SPR dip angle as variable parameter. With SPR reflectance as variable parameter at a fixed angle, the maximum sensitivity was 3.9×10^-5 R.I.U. in a selected narrow range of refractive index. <br/> <br/>Page(s): 854-858 Sat, 29 Oct 2005 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/8897 Title: Ultrasonic velocity of binary mixtures of acetone and dioxane with dimethylsulphoxide as one component <br/> <br/>Authors: Syal, V K; Chauhan, S; Kumari, Uma <br/> <br/>Abstract: Ultrasonic velocities, densities and viscosities of pure dimethylsulphoxide (DMSO), acetone (Ac) and DMSO + Ac mixture have been measured for different compositions at 25, 35and 45°C at 1 MHz and for DMSO + dioxane solvent systems at 25°C at 2 MHz.Various excess functions e.g. excess adiabatic compressibility (<img src='/image/spc_char/beta.gif' border=0>^E), excess volume (<i style="">V</i>^E), excess viscosity (<img src='/image/spc_char/Etta.gif' border=0>^E) etc. have also been evaluated from the measured data and discussed to substantiate the existence of intermolecular interactions present in liquid mixtures for both the solvent systems. <br/> <br/>Page(s): 844-848 Sat, 29 Oct 2005 22:58:59 GMT