Keval Gadani

Size-controlled electrical properties of sol–gel-grown nanostructured Gd0.95Ca0.05MnO3

In this communication, we report the results of the studies on electrical properties of cost-effective modified sol–gel-grown nanostructured Gd0.95Ca0.05MnO3 (GCMO) manganites sintered at different temperatures. Structural investigations, carried out using X-ray diffraction measurements, reveal the single-phasic nature of GCMO samples having orthorhombic unit cell structure. Frequency-dependent variation in AC conductivity (σAC) has been discussed on the basis of correlated barrier hopping (CBH) mechanism for the GCMO samples sintered at lower temperatures. Sintering temperature-induced transition from CBH mechanism to Maxwell–Wagner relaxation processes has been discussed in detail. Size-induced modifications in the impedance response of the samples have been understood, in detail, using size effects and Cole–Cole plots.Graphical Abstract

Mechanism of Anti-bacterial Activity of Zinc Oxide Nanoparticle Against Carbapenem-Resistant Acinetobacter baumannii

Acinetobacter baumannii is a multi-drug resistant opportunistic pathogen, which causes respiratory and urinary tract infections. Its prevalence increases gradually in the clinical setup. Carbapenems (beta-lactam) are most effective antibiotics till now against A. baumannii, but the development of resistance against it may lead to high mortality. Therefore, it is of utmost importance to develop an alternative drug against A. baumannii. In the present study, we have synthesized ZnO nanoparticle (ZnO-NP) and characterized by X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and UV-Visible spectroscopy. Prepared ZnO-NPs have the size of 30 nm and have different characteristics of ZnO-NPs. Growth kinetics and disk diffusion assay showed that ZnO-NP demonstrated good antibacterial activity against carbapenem resistant A. baumannii. We have also investigated the mechanism of action of ZnO-NPs on the carbapenem resistant strain of A. baumannii. The proposed mechanism of action of ZnO involves the production of reactive oxygen species, which elevates membrane lipid peroxidation that causes membrane leakage of reducing sugars, DNA, proteins, and reduces cell viability. These results demonstrate that ZnO-NP could be developed as alternative therapeutics against A. baumannii.

Investigations of magnetoelectric behavior in BiFe0.95Co0.05O3 nanoparticles

Nanophasic BiFe0.95Co0.05O3 (BFCO) particles were synthesized using low cost, easy, simple, environment friendly and low temperature acetate precursor based modified sol–gel method. Influence of particle size and magnetic field on the structural, dielectric, impedance and a.c. conductivity of BFCO is investigated. X-ray diffraction (XRD) measurement has been performed to understand the structural modifications in the samples upon increasing the sintering temperature. Crystallite size (CS) increases from 33.62nm to 39.56nm due to agglomeration effect between the smaller crystallites. Effect of sintering temperature on the dielectric, impedance and conductivity has been studied and understood in the context of the creation of crystallite (particle) size and oxygen vacancies created due to high temperature sintering process. Magnetic field induced modifications in all these electrical properties [magnetoelectric (ME) effects] for the presently studied BFCO samples have been discussed on the basis of magnetos...

Effect of sintering temperature on the structural and electrical properties of Zn0.95Cr0.05O

In this communication, we report the results of the studies on the sintering temperature dependent structural properties and dielectric behavior of 5% Cr doped Zn0.95Cr0.05O samples synthesized by cost effective sol-gel technique. Crystallographic orientations, crystallinity and crystallite size (CS) have been understood by performing X-ray diffraction (XRD) measurement at room temperature. Values of CS have been further verified by carrying out Williamson – Hall (W-H) plot analysis and the difference between the CS from XRD and W-H analyses has been discussed. Dielectric behavior has been studied and its dependence on the sintering temperature has been understood in the light of crystallite size, crystal boundary density and oxygen vacancies induced possible conductivity in the samples.

Investigations on structural disorder-induced modifications in the transport behaviour of rare-earth manganites

The results of the studies on structural disorder-induced modifications in the transport behaviour of La0.5Pr0.2Ca0.3−xBaxMnO3 (LPCBMO) (0.05 ≤ x ≤ 0.30) manganites were reported. Structural studies using X-ray diffraction (XRD) measurements confirmed the single phasic nature of all the samples without any detectable impurities. The A-site size disorder (σA2

Structural and Transport Studies on Mixed Valent Rare Earth Manganite Ceramics

{ {\sigma }}_{\mathrm{A}}^{\mathrm{2}}

Studies on structural and electrical properties of nanostructured RMnO3 (R = Gd & Ho)

) increased from 3.81 × 10−5 (x = 0.05) to 14.9 × 10−5 (x = 0.30). With the increase in structural disorder in LPCBMO system, the transport improved for the range: 0.15 ≤ x ≤ 0.30, which can be ascribed to the enhancement in one electron bandwidth which dominates over the structural disorder effect, while for lower values of x, strong competition existed between size disorder and one electron bandwidth. Below 50 K, all ρ–T plots showed resistivity minimum behaviour, which modified with disorder. This behaviour was discussed in detail on the basis of electron–electron interaction having the form: ρ=[1/(σ0+BT1/2)]+ρnTn

Effect of vanadium substitution on structural and electrical properties of sol–gel grown nanostructured zinc oxide

{\rho } {=} {[}\mathrm{1} {/} {(} {\sigma }_{\mathrm{0}} {+} {BT}^{\mathrm{1 {/}2}} {)} {]} {+} {\rho }_{ {n}} {T}^{ {n}}

Investigations on structural, optical and electrical properties of V2O5 nanoparticles

. Variation in temperature sensitivity with disorder was also discussed in context of granular morphology and phase segregation scenario.

Structural properties and gas sensing behavior of sol-gel grown nanostructured zinc oxide

ABSTRACT La0.5Pr0.2Ca0.3–xBaxMnO3 (LPCBMO) (x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30) ceramic manganites have been successfully synthesized by conventional solid state reaction method. Structural studies have been carried out by performing X-ray diffraction measurements and Rietveld refinements. Obtained value of crystallite size varies from 76 nm in lower doped sample (x=0.05) to 13 nm in the sample doped with x=0.30. Variation in crystallite size with x has been discussed in the context of size mismatch at A-site cationic lattice and structural disorder. In addition, all the samples exhibit metal to insulator transition at TP which gets increased with increase in Ba-content (x). Effect of crystallite size and other structural parameters on the transport properties of LPCBMO samples has been discussed in detail in the light of competition between the structural disorder and tolerance factor and shown that the tolerance factor can effectively modify the transport behaviour in manganites. Below 50 K, all the R-T plots of LPCBMO system show resistivity minimum behaviour which gets modified by Ba-content. This behaviour has been discussed in detail on the basis of electronelectron interaction having the form: ρ = [1/(σ0+BT1/2)]+ρnTn. GRAPHICAL ABSTRACT