@article { ISI:000239555500035, title = {Enhancing cross-peak intensity in 2D-SLF spectroscopy - the role of equilibrium carbon magnetization in cross-polarization experiment}, journal = {Chemical Physics Letters}, volume = {426}, number = {4-6}, year = {2006}, month = {AUG }, pages = {422-425}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A modification to the standard Hartmann-Hahn cross-polarization experiment has been proposed in which the initial 90 degrees pulses are applied both on the I and S spins. The inclusion of the available equilibrium polarization in the static magnetic field for the S spins is shown to have a beneficial effect for the 2D-SLF experiment, contributing to an increase in the cross-peak intensity and hence to a better resolution of the dipolar cross-peaks. (c) 2006 Elsevier B.V. All rights reserved.

}, issn = {0009-2614}, doi = {10.1016/j.cplett.2006.04.069}, author = {Das, Bibhuti B. and Ajithkumar, Thalasseril G. and Ramanathan, K. V.} } @article { ISI:000274459600009, title = {Evidence for the co-existence of distorted tetrahedral and trigonal bipyramidal aluminium sites in SrAl12O19 from Al-27 NMR studies}, journal = {Solid State Communications}, volume = {150}, number = {5-6}, year = {2010}, month = {JAN}, pages = {262-266}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Strontium aluminate, SrAl12O19, is a ceramic material having the hexagonal magnetoplumbite-type structure, with multiple Al coordination environments. An earlier low-field Al-27 solid-state NMR study reported five different Al sites in this system: one AlO4, one AlO5, and three AlO6 sites; whereas a later high-field study showed that the AlO5 site is a distorted AlO4 site with a very large quadrupolar coupling constant (similar to 20 MHz). Our magic angle spinning (MAS) and 3-quantum magic angle spinning (3QMAS) NMR studies at 7.05 T unambiguously show evidence for an AlO5 site. However, evidence for the presence of a distorted AlO4 site is obtained from studies at high fields (16.4 and 17.6 T), in addition to the AlO5 site. Thus the present solid-state NMR studies give evidence for the simultaneous presence of both the five-coordinated and distorted four-coordinated sites in this system. (C) 2009 Elsevier Ltd. All rights reserved.

}, keywords = {Local structure, MQMAS, Nuclear magnetic resonance, Strontium aluminate}, issn = {0038-1098}, doi = {10.1016/j.ssc.2009.11.008}, author = {Harindranath, K. and Viswanath, K. Anusree and Chandran, C. Vinod and Braeuniger, Thomas and Madhu, Perunthiruthy K. and Ajithkumar, Thalasseril G. and Joy, Pattayil Alias} } @article { ISI:000354199900072, title = {Environmentally friendly route for grafting of molybdenum carbonyl onto a diaminosilane-modified SBA-15 molecular sieve and its catalytic behaviour in olefin epoxidation}, journal = {New Journal of Chemistry}, volume = {39}, number = {5}, year = {2015}, month = {FEB}, pages = {3758-3764}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A simple route has been established for grafting molybdenum carbonyl onto the surface of a diaminosilane-modified SBA-15 molecular sieve. The successful grafting of the molybdenum carbonyl species onto diamine-functionalized SBA-15 was evident from FT-IR studies. The resultant molybdenum-carbonyl-complex-grafted SBA-15 (SBA-DA-Mo) materials show promising activity for the epoxidation of various olefins with good conversion (90-95\%) and the formation of epoxide as the major product. The catalytic activity remains constant over several runs.

}, issn = {1144-0546}, doi = {10.1039/c4nj02402h}, author = {Baskaran, Thangaraj and Kumaravel, Raju and Christopher, Jayaraj and Ajithkumar, Thalasseril G. and Sakthivel, Ayyamperumal} } @article {48229, title = {Elucidating the influence of structure and Ag+ -Na+ ion-exchange on crack-resistance and ionic conductivity of Na3Al1.8Si1.65 P-1.8 O-12 glass electrolyte}, journal = {Acta Materialia}, volume = {227}, year = {2022}, month = {APR }, pages = {117745}, type = {Article}, abstract = {

Glasses are emerging as promising and efficient solid electrolytes for all-solid-state sodium-ion batteries. However, they still suffer from poor ionic conductivity and crack-resistance, which need to be improved for better battery performance, reliability, and service life. The current study shows a significant enhancement in crack resistance (from 11.3 N to 32.9 N) for Na3Al (1.8) Si-1.65 P1.8O12 glass (Ag-0 glass) upon Na+ -Ag+ ion-exchange (IE) due to compressive stresses generated in the glass surface while the ionic conductivity values (similar to 10(-5) S/cm at 473 K) were retained. In this study, magic angle spinning-nuclear magnetic resonance (MAS-NMR), molecular dynamics (MD) simulations, Vickers micro hardness, and impedance spectroscopic techniques were used to evaluate the intermediate-range structure, atomic structure, crack resistance and conductivity of the glass. MAS-NMR and MD simulations confirm the presence of Si-OAl-O-P groups in the glass, thus enabling formation of Na percolated channel regions. AC-conductivity analysis for Ag-0 and ion-exchanged Ag-0 glass suggests that the mobility of Na+ ion increases with increasing temperature. It is observed that the measured mean square displacement (root \< R-2(t(p))\>) for sodium cations using AC-conductivity isotherms is nearly constant up to 448 K and then increases with increasing temperature up to 523 K. From the impedance spectra for ion-exchanged Ag-0 glass, it is identified that the increase in root \< R-2 (t(nu))\> and thereby, the mobility of sodium-ions for Ag-0 glass is due to the structural variations in the Ag-0 glass with increasing the temperature. Overall, the mechanisms presented in this article helps in formulating better glass based electrolyte materials for room temperature or high temperature sodium-ion batteries. (C) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

}, keywords = {amorphous, Ion-exchange, Ionic-conductivity, MD simulations, Mechanical property}, issn = {1359-6454}, doi = {10.1016/j.actamat.2022.117745}, author = {Keshri, Shweta R. and Mandal, Indrajeet and Ganisetti, Sudheer and Kasimuthumaniyan, S. and Kumar, Rajesh and Gaddam, Anuraag and Shelke, Ankita and Ajithkumar, Thalasseril G. and Gosvami, Nitya Nand and Krishnan, N. M. Anoop and Allu, Amarnath R.} }