K Ramachandran
Articles written in Bulletin of Materials Science
Volume 25 Issue 4 August 2002 pp 329-334 Semiconductors
On the symmetry of phosphorous doped ZnSe
The site symmetry of P doped ZnSe is analysed in detail here, as the recent experiments suggest two possible symmetries $T_d$ and $C_{3V}$. The reduction to $C_{3V}$ is attributed to the presence of natural impurity, Ga. Our calculations based on molecular model and Green’s functions suggest that the symmetry $C_{3V}$ is possible with ZnSe : P when Jahn Teller distortion of about ∼ 0.2 Å (towards one of Zn atom) is assumed. This has been supported by other experiments.
Volume 25 Issue 4 August 2002 pp 335-340 Semiconductors
P Murugan R Pothiraj S D D Roy K Ramachandran
Theoretical studies are carried out to ascertain the dominant mechanism of Si diffusion in GaAs. Lattice dynamical model calculations have shown that the most probable diffusion mechanism is through a single vacancy even though several experiments cannot fix the mechanism as substitutional, substitutional–interstitial pair or neutral defect pair.
Volume 27 Issue 5 October 2004 pp 403-407 Phase Transitions
Phase transition in L-alaninium oxalate by photoacoustics
M Sivabarathy S Natarajan S K Ramakrishnan K Ramachandran
Phase transition in L-alaninium oxalate is studied by using TG, DTA and photoacoustic spectroscopy. A sharp transition at 378 K by photoacoustics is observed whereas at the same temperature the endothermic energy change observed by TG and DTA is not very sharp. This is discussed in detail with reference to the other known data for the organic crystals.
Volume 28 Issue 3 June 2005 pp 233-238 Thin Films
Thermal and structural properties of spray pyrolysed CdS thin film
P Raji C Sanjeeviraja K Ramachandran
Using photo acoustic technique, the thermal properties of CdS thin films grown by spray pyrolysis are measured. Thermal diffusivity and conductivity in these films decrease at least two orders compared with bulk. These results are compared with our study on nano CdS and the other available literature. The comparison is good. The dependence of thermal diffusivity on the thickness of the layer or the size of the particles on the glass substrate are analysed from the present measurement and discussed. The dependence of thermal diffusivity on the thickness of the layer on the glass substrate is discussed.
Volume 28 Issue 7 December 2005 pp 675-679 Alloys
Optical, thermal and phase transition studies in Sn1–𝑥Ge𝑥Te
M Sivabharathy N Sankar R Saravanan K Ramachandran
The optical and thermal properties of the mixed semiconducting alloy, Sn1–𝑥Ge𝑥Te, is studied by photo acoustics, for various Ge concentrations and phase transition for a particular concentration is also studied by the same method. The results are compared with the available literature values and discussed.
Volume 30 Issue 4 August 2007 pp 345-348 Thermal Properties
Effect of nickel substitution on thermal properties of Na0.9CoO2
J Meena Devi N Gayathri A Bharathi K Ramachandran
We report on the effect of nickel substitution in Na0.9CoO2 by examining their thermal properties at room temperature. Experimental results indicate that thermoelectric efficiency is enhanced upon nickel substitution in sodium cobaltate.
Volume 31 Issue 6 November 2008 pp 863-868 Thermal Studies
Thermal diffusion in nanostructured porous InP
Nanostructured porous InP samples were prepared by electrochemical anodic dissolution of InP for various current densities and etching periods. The samples were characterized by SEM and photoluminescence (PL) where a blue shift was observed in PL. Thermal properties studied by photoacoustic (PA) spectroscopy revealed one order decrease in thermal conductivity of porous InP compared to the bulk. Further it is shown that the thermal conductivity of porous InP decreases with decrease in size of the particles.
Volume 34 Issue 2 April 2011 pp 371-375
Lattice dynamical investigations on Zn diffusion in zinc oxide
P Vinotha Boorana Lakshmi K Ramachandran
Zinc self diffusion in bulk zinc oxide is studied by lattice dynamical approach here to get more insight into the diffusion in nano ZnO. The results reveal that only cationic self diffusion is dominant over anionic self diffusion and that too by single vacancy mechanism. The results are compared with the available experiments and discussed.
Volume 46, 2023
All articles
Continuous Article Publishing mode
Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020
Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
Physical Sciences 2020
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