Bishop Heber College

About: Bishop Heber College is a based out in . It is known for research contribution in the topics: Thin film & Band gap. The organization has 548 authors who have published 692 publications receiving 7144 citations.

Thermodynamics of α″→β phase transformation and heat capacity measurements in Ti–15 at% Nb alloy

Abstract: The phase stability of Ti–15 at% Nb alloy has been studied in the temperature range 466–1258 K using inverse drop calorimetry. In the annealed condition, the alloy consists of orthorhombic α″-martensite and bcc β phases. The calorimetry experiments indicated the occurrence of two phase changes upon heating. They are (i) precipitation of hexagonal ω phase at 582±2 K followed by (ii) α″→β in the temperature domain 836–985±2 K. The enthalpy change due to ω formation is small; however, the α″→β phase transformation is associated with a measurable enthalpy effect of 57±3 J g−1. Since α″→β phase change occurs over a temperature interval, the measured enthalpy in the transformation domain derives from two principal contributions, namely, the matrix contribution coming from untransformed α″-martensite and β phase mix and another transformational component arising from continuous α″→β phase change. Since the fractional extent of α″→β transformation varies continuously with temperature the transformation enthalpy also exhibits similar temperature dependence. This aspect is modeled using Kolmogorov–Johnson–Mehl–Avrami formalism for treating the diffusional transformation kinetics. Further, the measured enthalpy variation with temperature has been subjected to standard analytical treatment to obtain a comprehensive thermodynamic description of entire α″+β region.

A comparative analysis on the dye degradation efficiency of pure, Co, Ni and Mn-doped CuO nanoparticles

Abstract: Pure, Co, Mn and Ni (1.0 wt%) doped CuO Nanoparticles (NPs) are synthesized by co-precipitation method for the catalytic property analysis. The powder X-ray diffraction pattern of pure, Co, Mn and Ni doped CuO NPs shows that the Co2+, Mn2+ and Ni2+ ions are successfully substituted to Cu2+ ion. Fourier transform infrared spectroscopy studies confirms the functional groups present in the synthesized samples. The band gap of pure CuO NPs is increased from 3.230 to 3.256 eV and 3.274 eV by adding the dopants Co and Ni. Whereas, the addition of Mn decreases the band gap to 3.207 eV. Scanning electron microscopy images show the considerable change in morphology from the nonuniform surface of nanostructure to nano flakes when Co, Mn and Ni are added as dopants. From photoluminescence spectrum, the broad green emission is observed at 521 nm. The electrical properties of synthesized materials are studied and compared by dielectric constant, dielectric loss and ac conductivity measurements. The electrochemical impedance properties of the prepared samples were also investigated. The degradation of environmental pollutants such as 4-Nitrophenol and Methylene blue dyes are analyzed by studying the catalytic activity of the synthesized material and reported.