NOPR Collection:

Surface acidity /basicity and catalytic activity of ternary oxides of Al, Ce and Dy

2016-07-20T06:15:08Z

Title: Surface acidity /basicity and catalytic activity of ternary oxides of Al, Ce and Dy Authors: Sugunan, S; Jacob, Bindhu Abstract: The surface acidity and basicity of ternary oxides of Al, Ce and Dy have been determined using a set of Hammett indicators. The data have been correlated with the catalytic activity of these oxides towards the liquid phase reduction of cyclohexanone in 2-propanol. The reaction is favoured by the higher basicity of the ternary oxide. Page(s): 120-122

Mathematical evaluation of temperature of a burning droplet

2016-07-20T06:14:08Z

Title: Mathematical evaluation of temperature of a burning droplet Authors: Sarathy, C P; Natarajan, R Abstract: The liquid-phase temperature is an important parameter in the droplet combustion. While in a very simplified quasisteady theory it is assumed equal to a constant value, viz., the boiling point at the prevailing pressure, in all non-steady analysis its temporal variation is taken into account, and in fact is considered to represent one of the most important aspects of the intrinsically non-steady nature of the droplet combustion process. The liquid-phase temperature is calculated here from the equation from thermal energy transfer to the burning droplet, with due consideration for the reduction in heat transfer because of the outward mass transfer. The mass transfer shielding can be taken into account in one of the two ways, viz., (i) as a reduction in the convective heat transfer to the droplet, through a function involving the transfer number, or (ii) non-availability of the portion of the thermal energy which is carried outward by; the exuding vapour as superheat. The trends in the temperature variation in both these cases seen to be different. Page(s): 117-119

Optical and transport properties of Se_0.7Te_0.3 and Se_0.3 Te_0.7alloy thin films

2016-07-20T06:13:09Z

Title: Optical and transport properties of Se_0.7Te_0.3 and Se_0.3 Te_0.7alloy thin films Authors: Balasubramaniam, T; Narayandass, Sa K; Mangalaraj, D Abstract: Preparation and the study of optical and transport properties on Se_0.7Te_0.3 and Se_0.3Te_0.7in the form of vacuum deposited thin films are undertaken. Material preparation consists of two processes, i.e., (i) preparation of bulk selenium telluride alloys and (ii) fabrication of thin films for characterizing the above mentioned properties. The thicknesses of various films have been measured by multiple beam interference technique. Rutherford Backscattering Spectrometry (RBS) analyses clearly indicate the presence of the parental elements in two different compositions. The XRD studies revealed the polycrystalline nature of the Se_0.7Te_0.3 and Se_0.3Te_0.7 thin films. Optical constants in the 500-2500 nm region, band gap and the transition type have been determined from the transmission data. Hall and thermopower measurements are made on these two different compositions and the Hall parameters are calculated. Page(s): 112-116

Effect of Co²⁺ substitution on electrical and magnetic properties of hot pressed Mn-Zn ferrites

2016-07-20T06:12:21Z

Title: Effect of Co²⁺ substitution on electrical and magnetic properties of hot pressed Mn-Zn ferrites Authors: Babbar, Vijay K; Puri, Rajinder K Abstract: Mn-Zn-Co ferrites of the composition Mn_0.6Zn_0.4-xCo_xFe₂O₄ (0≤x≤0.4) have been prepared by the normal ceramic and hot pressing techniques. The dc resistivity decreases while the dielectric constant and the Curie temperature increase continuously with increase in x. The initial permeability and saturation magnetization increase for x≤0.05 and x≤0.25, respectively. The results have been qualitatively explained on the basis of the relevant physical phenomena and existing models. The hot pressed ferrite with x=0.05 possess an optimum combination of electrical and magnetic properties which makes it suitable for magnetic recording applications. Page(s): 106-111

NOPR Collection:

Surface acidity /basicity and catalytic activity of ternary oxides of Al, Ce and Dy

Mathematical evaluation of temperature of a burning droplet

Optical and transport properties of Se0.7Te0.3 and Se0.3 Te0.7 alloy thin films

Effect of Co2+ substitution on electrical and magnetic properties of hot pressed Mn-Zn ferrites

Optical and transport properties of Se_0.7Te_0.3 and Se_0.3 Te_0.7alloy thin films

Effect of Co²⁺ substitution on electrical and magnetic properties of hot pressed Mn-Zn ferrites