Browsing by Author "Kumar, Prashant"

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    Synthesis, phase confirmation and electrical properties of (1 ? x)KNNS?xBNZSH lead-free ceramics
    (Springer, 2022-02-02T00:00:00) Kumar, Amit; Kumari, Sapna; Kumar, V.; Kumar, Prashant; Thakur, Vikas N.; Kumar, Ashok; Goyal, P.K.; Arya, Anil; Sharma, A.L.
    In the present work, lead-free piezoelectric ceramics (Rx)(K0.5Na0.5)(Nb0.96Sb0.04O3)?x(Bi0.5Na0.5)(Zr0.8Sn0.1Hf0.1)O3 [abb. as (Rx)KNNS?xBNZSH, 0 ? x ? 0.04] were prepared via solid-state sintering technique. The thermal behavior of mixed powders has been investigated for x = 0, 0.02, and 0.04 using TGA-DSC analysis to estimate the calcination temperature. The structural, morphological, dielectric, ferroelectric and piezoelectric properties are analyzed through the appropriate characterization techniques. The X-ray diffraction (XRD) patterns demonstrate a pure perovskite phase structure for all the sintered samples. Further, the coexistence of rhombohedral to orthorhombic (R-O) phase is observed in ceramic sample with x = 0.02. The morphology of all the sintered samples exhibits an inhomogeneous, dense microstructure with the rectangular grain, while for x = 0.02, a relatively homogeneous distribution of grains is observed. BNZSH doping decreases the average grain size from 2.22 to 0.33�?m for x = 0 to x = 0.04, respectively. Owing to the presence of multiple-phase coexistence as well as the improved microstructure and enhanced dielectric properties (dielectric constant ?r = 1080, ?max = 5301; Curie temperature - TC ~ 317��C; dielectric loss - tan? ~ 6%) the ceramics with x = 0.02 has been found to have a large piezoelectric coefficient (d33) of ~180 pC/N, remnant polarization (Pr) ~ 16.7 �C/cm2 and coercive field (Ec) ~ 10.7�kV/cm. We believe it will expand the range of applications for KNN-based ceramics. � 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
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    Transition-Metal-Free Cascade C-N Bond Formation: An Effective Strategy for the Synthesis of ?-Carboline N-Fused Imidazolium Acetates and Estimation of their Light-Emitting Properties
    (Georg Thieme Verlag, 2023-08-08T00:00:00) Singh, Manpreet; Vaishali, Vaishali; Deepika, Deepika; Jyoti, Jyoti; Sharma, Shubham; Banyal, Naveen; Kumar, Prashant; Budhalakoti, Bharti; Malakar, Chandi C.; Singh, Virender
    A simple, efficient, and practical metal-free protocol has been devised to synthesize imidazopyrido[3,4-b]indole-based fluorophores decorated with carbazole/ F-carboline/pyridine scaffolds via three consecutive C.N bond formations in a single operation. A wide range of aromatic amines (2-aminopyridines, 3-aminocarbazole, and anilines) were successfully applied to synthesize the complex imidazolium ions. The significant features of this strategy include high efficiency, mild and environmentally benign reaction conditions, no chromatographic purification, and broad substrate scope with excellent yields of the isolated products. Moreover, excellent photophysical properties (up to 85%) were exhibited by these fluorophores. � 2022 Georg Thieme Verlag. All rights reserved.