Deposition Of Nanolayers Research Articles

Layer-by-layer deposition of polyelectrolyte nanolayers on natural fibres: cotton

The layer-by-layer (LbL) deposition of poly(sodium 4-styrene sulfonate) (PSS)and poly(allylamine hydrochloride) (PAH) over cotton fibres is reported. Cottonfibres offer unique challenges to the deposition of nanolayers because of theirunique cross section as well as the chemical heterogeneity of their surface. Cationiccotton substrates were produced by using 2,3-epoxypropyltrimethylammoniumchloride. Attenuated total reflectance FTIR, x-ray photoelectron spectroscopy(XPS) and transmission electron microscopy (TEM) were used to validate thepresence of the nanolayers as well as to corroborate their self-organized structure.TEM images indicated conformal and uniform coating of the cotton fibres. XPSspectral data were found to be in quantitative agreement with previous publishedwork that studied the LbL deposition of PSS and PAH over synthetic substrates.

Microscopic Investigation of Nanoscale Polar Regions of Pb(Mg⅓Nb2/3)O3-PbTiO3 Relaxor Ferroelectric Thin Films

Thin films of Pb(Mg⅓Nb2/3)O3 - PbTiO3 were grown using highly dense ceramic target without excess PbO in the target. The lower electrode play the crucial role to control the microstructure of the thin films. The sizes of the grains depend upon the nucleation density and the rate of growth onto the lower electrode used. A microscopic strain effect, is observed in thin film heterostructures (at the interface), and which is gradually released after deposition of few nanolayers. Microstrain in the films along (001) direction, can be directly computed from the shift of peak position under applied field. An increase in electric field with increasing stress linearly and don't shows any phase transition up to 24 kV/cm electric field but shows ferroelectric behavior.

Characterization Of SnO2 Nanoparticles Deposited Via Layer-by-Layer Self Assembly And Investigation Of Their Sensing Properties

ABSTRACTA technique of Layer-by-Layer (LbL) self-assembly is used to deposit SnO2 nanoparticles on Quartz Crystal Microbalance (QCM) resonators, and on glass substrates which the authors believe has not been previously reported. Characterization of self-assembled SnO2 layers has been performed using QCM, Scanning Electron Microscopy (SEM), and Zeta Potential analysis.We have successfully deposited SnO2 nanoparticles on QCM resonator using self-assembly technique. LbL self-assembly is a method of organization of ultra-thin films by interlayer electrostatic attraction. The thickness and mass of the self-assembled layers can be characterized by the frequency shift obtained using the QCM and empirical equations relating change in frequency with mass and thickness of deposited layers. The deposition of SnO2 nanolayers exhibited a linear reproducibility and the process of self-assembly was independent of the residence time of QCM resonator in the SnO2 nanoparticle colloidal solution. High resolution SEM analysis reveals that the SnO2 nanoparticle layers are uniformly deposited across the entire substrate. Electrical characterization was performed on SnO2 nanoparticle layers self-assembled on glass substrates which were patterned for two point (current-voltage) IV characteristic measurements. Two classes of samples were used. One sample was self-assembled glass substrate patterned with electrical contacts and calcined (baked at 350°C for one hour) to eliminate interlayered polyions and the other sample was not calcined. Results revealed that the calcined samples demonstrated linear ohmic behavior but the uncalcined showed some spurious points which we believe are due to the polyion layers.Characterization of the self-assembled SnO2 nanoparticles is being carried out with the intention of fabricating a high-selectivity μ-gas sensor. A test chamber has been fabricated and results of resistance behavior of the sensor with variation in temperature have been presented.The sensor can find applications in high selectivity sensing of chemical, industrial, domestic, and hazardous environments. After further research and development, this μ-gas sensors could be made generic to sense a variety of gases and employed for integrated on-chip product analysis in multiple chemical microsystem applications.