Sampat Raj Vadera

Bio: Sampat Raj Vadera is an academic researcher from Indian Institute of Technology, Jodhpur. The author has contributed to research in topics: Nanoparticle & Ferrite (magnet). The author has an hindex of 26, co-authored 63 publications receiving 2242 citations. Previous affiliations of Sampat Raj Vadera include Andhra University.

Lifetime shortening in doped ZnS nanophosphors

Abstract: ZnS : Mn nanophosphor has been doped with quencher impurity Ni using the colloidal precipitation method with capping agent polyvinylpyrrolidone. The formation of ~2.5 nm sized nanoparticles has been confirmed by x-ray diffraction and transmission electron microscope studies. Energy and time resolved photoluminescence spectra of the synthesized nanophosphors have been studied at room temperature. Photoluminescent spectra for ZnS : Mn, Ni show three peaks at 412 nm, 433 nm and 590 nm corresponding to Ni impurity, sulphide vacancies (Vs) and Mn impurity, respectively. The ZnS : Mn nanophosphor show typical nanosecond lifetimes for defect-related emission and millisecond lifetimes for Mn impurity-related emission. However, the ZnS : Mn, Ni samples showed lifetime shortening, with variation of dopant concentration for defect-related (420 nm) as well as impurity-related emission (590 nm), which is attributed to exchange interaction between Mn2+ and nearest neighbour Ni2+ impurities.

Nanotechnology Applications for Chemical and Biological Sensors

Abstract: Recent discoveries indicate that when the materials are brought down to sizes in the range 1–100 nm, theseexhibit unique electrical, optical, magnetic, chemical, and mechanical properties. Methods have now beenestablished to obtain the monodisperse nanocrystals of various metallic and semiconducting materials, single-walled and multi-walled nanotubes of carbon and other metallic and non-metallic materials together withorganic nanomaterials such as supra-molecular nanostructures, dendrimers, hybrid composites with tailoredfunctionalities. The high surface-to-volume ratio with an added element of porosity makes these highly potentialcandidates for chemical and biological sensor applications with higher degree of sensitivity and selectivity ascompared to their bulk counterparts. The paper reviews the recent developments and applications of chemicaland biological sensors based on nanomaterials of various structural forms. Defence Science Journal, 2008, 58(5), pp.636 -649 , DOI:http://dx.doi.org/10.14429/dsj.58.1686

A facile low temperature method for the synthesis of CoFe2O4 nanoparticles possessing excellent microwave absorption properties

Abstract: CoFe2O4 nanoparticles, synthesized via a co-precipitation method at 120 °C, exhibited excellent microwave absorption properties, with minimum reflection loss of −55 dB (∼99.99%) at 9.25 GHz. To the best of our knowledge, these synthesized CoFe2O4 nanoparticles show the highest minimum reflection loss in comparison with the reported CoFe2O4 based materials.

Graphene-Based Materials: Synthesis, Characterization, Properties, and Applications

Abstract: Graphene, a two-dimensional, single-layer sheet of sp(2) hybridized carbon atoms, has attracted tremendous attention and research interest, owing to its exceptional physical properties, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Other forms of graphene-related materials, including graphene oxide, reduced graphene oxide, and exfoliated graphite, have been reliably produced in large scale. The promising properties together with the ease of processibility and functionalization make graphene-based materials ideal candidates for incorporation into a variety of functional materials. Importantly, graphene and its derivatives have been explored in a wide range of applications, such as electronic and photonic devices, clean energy, and sensors. In this review, after a general introduction to graphene and its derivatives, the synthesis, characterization, properties, and applications of graphene-based materials are discussed.

Broadband and Tunable High‐Performance Microwave Absorption of an Ultralight and Highly Compressible Graphene Foam

Abstract: The broadband and tunable high-performance microwave absorption properties of an ultralight and highly compressible graphene foam (GF) are investigated. Simply via physical compression, the microwave absorption performance can be tuned. The qualified bandwidth coverage of 93.8% (60.5 GHz/64.5 GHz) is achieved for the GF under 90% compressive strain (1.0 mm thickness). This mainly because of the 3D conductive network.