02434nas a2200277 4500008004100000022001400041245009900055210006900154260000900223300001600232490000700248520153700255653000801792653002401800653001401824653002901838653002301867653002601890100001801916700001801934700001801952700001801970700001801988700001902006856013102025 2020 eng d a0272-884200aCorrelation between multifunctional properties of lead free Iron doped BCT perovskite ceramics0 aCorrelation between multifunctional properties of lead free Iron cAUG  a17495-175070 v463 a

Present study investigates the effect of Fe doping on structural, microstructural, dielectric, ferroelectric, piezoelectric and magnetic properties of Barium calcium titanate (BCT) ceramics synthesized by solid state reaction route. The polycrystalline tetragonal structure of prepared ceramics was confirmed from XRD study. Analysis done using Rietveld refinement reveals reduction in lattice parameters as well as unit cell volume on substitution of Fe3+ ions in BCT lattice. Occurrence of four distinct Raman bands viz. 297 cm(-1) -302 cm(-1), 473 cm(-1)-475 cm(-1), 516 cm(-1) -524 cm(-1) and 729 cm(-1) -733 cm(-1) in Raman spectroscopic studies confirms the tetragonal phase of prepared ceramic compositions which are in accordance with XRD study. The Scanning Electron Microscopy analysis revealed polyhedral shaped grains whose average grain size decreased with increase in Fe content (x) in BCT ceramics. A diffused frequency independent phase transition was observed in temperature dependent dielectric measurements. Dielectric properties improved significantly, with shifting of transition temperature, T c close to room temperature with Fe doping. These studiessuggest applications of these ceramics in the development of environment friendly dielectric materials meeting X7R MLCCs specifications. The ferroelectric and piezoelectric properties of these ceramic compositions were found to decrease with increase in Fe concentration. Feeble room temperature ferromagnetism was observed for composition x = 0.020.

10aBCT10adielectric response10aFe doping10aferroelectric properties10aLead free ceramics10aMagnetic measurements1 aRedhu, Preeti1 aPunia, Rajesh1 aHooda, Ashima1 aMalik, B., P.1 aSharma, Geeta1 aSharma, Preeti uhttps://library.ncl.res.in/content/correlation-between-multifunctional-properties-lead-free-iron-doped-bct-perovskite-ceramics02761nas a2200313 4500008004100000022001400041245010000055210006900155260000800224300001600232490000700248520175300255653001902008653002302027653001902050653002802069653002802097653002302125653001702148653001802165653002602183100001802209700001902227700001802246700002102264700001802285700001802303856012602321 2021 eng d a0272-884200aRole of charge compensation mechanism and defect dipoles on properties of Mn doped BCT ceramics0 aRole of charge compensation mechanism and defect dipoles on prop cAPR a11491-115050 v473 a

Single-phase Mn doped Barium Calcium Titanate (BCT) (Ba0.80Ca0.20Ti1-xMnxO3; x = 0.000, 0.005, 0.010, 0.015 and 0.020) lead free ceramics have been prepared by conventional solid-state reaction method. XRD studies and Rietveld refinement confirmed the existence of tetragonal phase (P4mm) for all prepared ceramic compositions. The average grain size increased up to x = 0.005 and thereafter it decreased with increase in Mn content in BCT compositions. Analysis of temperature-dependent dielectric study revealed phase transformation from tetragonal to cubic phase and defect dipole induced anomaly in paraelectric region of temperature-dependent dielectric constant ( epsilon'-T) curve. Degree of diffusiveness increased with Mn doping in BCT ceramics as confirmed by evaluating diffused phase transition (DPT) parameters (gamma and delta(c)) by Power Law fitting and width of diffused phase transition (D') obtained from derivative of epsilon'-T curve. Ferroelectric (P-E loops) study revealed that ceramic composition with x = 0.015 Mn content showed the highest remnant polarization (P-r) and maximum polarization (P-max) of 14.10 mu C/cm(2) and 24.20 mu C/cm(2) respectively. Enhancement in energy storage properties with applied electric fields have been observed at room temperature. Maximum energy storage density W-rec similar to 190.89 mJ/cm(3) with an efficiency of 48.63% has been obtained for x = 0.015. A large piezoelectric charge coefficient (d(33)) of 460 pC/N has been obtained for x = 0.020. The room temperature magnetic measurements shows feeble ferromagnetism for Mn doped samples. These studies suggest the application of these ceramics for multilayer ceramic capacitors, energy storage, and high power applications..

10aDefect dipoles10aDielectric anomaly10aEnergy storage10aFerroelectric materials10aferromagnetic materials10aLead-free ceramics10aMn doped BCT10apiezoelectric10aWilliamson-Hall (W-H)1 aRedhu, Preeti1 aSharma, Preeti1 aHooda, Ashima1 aSingh, Anupinder1 aSharma, Geeta1 aPunia, Rajesh uhttps://library.ncl.res.in/content/role-charge-compensation-mechanism-and-defect-dipoles-properties-mn-doped-bct-ceramics01943nas a2200241 4500008004100000022001400041245011600055210006900171260000800240300000800248490000800256520112400264653002101388653002101409653001301430653002901443653002301472653002001495100001901515700001801534700001801552856013101570 2021 eng d a0947-839600aSynthesis of graphene from activated carbon at liquid nitrogen temperature and its detailed structural analysis0 aSynthesis of graphene from activated carbon at liquid nitrogen t cMAY a3190 v1273 a

The present study deals with the synthesis of graphene using thermal quenching of pre-heated activated carbon (a-C) (1370 K for 3 h) at liquid nitrogen temperature and its detailed structural analysis using XRD, TEM, FTIR and Raman spectroscopy. The analysis of lattice parameters (L-a, L-c,L- and d) of constituent nanographitic domains using XRD shows restoration of graphene-like structure in the resultant product (a-CL). TEM image reveals porosity and partially crystallinity (from SAED) in a-C. While thin layers of graphene are observed in the TEM images of a-CL Deconvoluted Raman spectra have been used to investigate the evolution of crystalline behaviour of a-C with temperature in view of Ferrari and Robertson's three-stage model. The evolution of G peak and increase in I-D/I-G reveals restoration of crystallinity in a-CL. The development of the D peak indicates disordering of graphite but ordering of amorphous carbon. The reported method is technologically beneficial for graphene synthesis for large number of applications such as supercapacitors, H-2 storage, gas separation and purification.

10aactivated carbon10aAmorphous carbon10agraphene10aH-2 storage applications10aRaman spectroscopy10aSupercapacitors1 aSharma, Preeti1 aSharma, Geeta1 aPunia, Rajesh uhttps://library.ncl.res.in/content/synthesis-graphene-activated-carbon-liquid-nitrogen-temperature-and-its-detailed-structural