Ritamay Bhunia

Free-standing flexible nanocrystalline-ZnO-impregnated polyvinylidene fluoride composite thin films

Free-standing flexible films of nanocrystalline ZnO impregnated polyvinylidene fluoride composites were prepared by sol-gel technique. Effect of ZnO loading on the optical properties of the polyvinylidene fluoride host matrix was studied critically for the as-deposited as well as the poled samples. Bonding environment was studied by X-ray photoelectron spectroscopy and Fourier transformed infrared spectroscopy measurements. Modulation of optical and microstructural properties with ZnO loading was also addressed.

Free-standing nanocrystalline-Cadmium sulfide/Polyvinylidene fluoride composite thin film: synthesis and characterization

Nanocrystalline Cadmium sulfide (CdS) impregnated polyvinylidene fluoride (PVDF) composite free-standing flexible films were prepared by sol–gel technique. The films were poled in vacuum under high electric field. Effect of CdS loading in PVDF host matrix on the optical properties was studied critically for the as-deposited and poled samples. The reduction in the relative intensities of the peaks arising out of α -PVDF as compared to that of β-PVDF for the poled samples was observed in X-ray diffraction (XRD) studies. This type of observation indicates a possible transition from α to β phase due to poling. Modulation of optical and microstructural properties with CdS loading was also addressed. Bonding environment was studied by X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared spectroscopy measurements. XPS studies indicated the presence of highly aligned CdS nanocrystallites in the poled PVDF matrix which may effectively modulate the piezoelectric behavior of the composite film. The Photoluminescence (PL) spectra recorded as above for a representative unpoled and poled nano-CdS/PVDF composite film.

H 2 S Gas Sensor Based on Nanocrystalline Copper/DLC Composite Films

Diamond-like carbon films with embedded copper nanocrystallites were deposited on SnO2-coated glass substrates by using electrochemical technique. These composite films were subjected to sensing H2S gas. Change in the intensity of the characteristic surface plasmon resonance (SPR) peak was recorded with time, and it was observed that the SPR peak disappeared within a short time after exposure to hydrogen sulphide gas. Sensing mechanism was critically analysed.

Structural and Optical Studies on Sol-gel Composites of Nickel-Doped Nanocrystalline Zinc Oxide/Polyvinylidene Fluoride

ABSTRACT Nickel-doped nanocrystalline ZnO with three different Ni concentrations was incorporated in polyvinylidene fluoride thin film for obtaining free-standing flexible film by sol-gel technique. The effect of Ni–ZnO loading on the optical and microstructural properties of the Ni–ZnO/polyvinylidene fluoride composite films was studied. X-ray photoelectron spectroscopy and Raman studies were performed to characterize the bonding environment. Fluorine-terminated surface showed a strong F1 s peak located at ∼695 eV arising out of C–F bonds. Existence of β phase of polyvinylidene fluoride along with the presence of ZnO nanocrystals were indicated by Raman studies. Secondary ion mass spectrometry studies indicated the distribution of Ni–ZnO particles in the polyvinylidene fluoride matrix. GRAPHICAL ABSTRACT

Local structure studies of Ni doped ZnO/PVDF composite free-standing flexible thin films using XPS and EXAFS studies

Free-standing flexible films of Ni-ZnO/PVDF with three Ni concentrations were obtained by sol–gel technique. The as-deposited and the poled composite Ni-ZnO/PVDF films contained three different amount of Ni doping in ZnO nanocrystals as Zn1−xNixO (x = 0.01, 0.04, and 0.09). XANES, XPS measurements have been carried out to investigate the valence states of the host and dopant ions in samples while local environments surrounding Zn and Ni sites have been critically examined using extended EXAFS and XPS measurements to throw a clear insight on the bonding environment in the Ni-ZnO/PVDF films

Room Temperature Magnetism in Free-Standing Nano-Ni/PVDF Composites

ABSTRACT Nanocrystalline Ni was incorporated in polyvinylidene fluoride (PVDF) in three different proportions to obtain free-standing flexible film by sol-gel technique. Effect of nano-Ni loading in the PVDF matrix on the optical, microstructural, and magnetic properties of the nano-Ni/PVDF composite material was studied. Variation of magnetic moments with magnetic field at different temperatures was recorded in the composite-free-standing films. X-ray photoelectron spectroscopy studies indicated that incorporated Ni was in Ni2+ and Ni4+ states. Ni2+ atomic concentration was found to be significantly larger than Ni4+ concentration in all the samples suggesting Ni2+ in the PVDF lattice are responsible for observed room temperature ferromagnetism. GRAPHICAL ABSTRACT