Quantum Research Group talk by Dr Aline Simo:

Quantum Research Group talk by Dr Aline Simo:

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QUANTUM RESEARCH GROUP

Invites you to a talk by

DR ALINE SIMO

from:iThemba Labs, Materials Research Department,

Nanosciences Laboratories

entitled

PHYSICAL PROPERTIES OF VANADIUM DIOXIDE NANOPARTICLES :

Application as 1-D Nanobelts room temperature for hydrogen gas sensing

Date: Thursday, 24 APRIL 2014 @ 12h20

Venue: NITheP Seminar Room, 3 Level, H-Block,

ABSTRACT

Transition metal oxides magneli phases present crystallographic shear structure which is of great interest in multiple applications because of their wide range of valence, which is exhibited by the transition metals. The latter affect chemical and physical properties of the oxides. Amongst them we have nanostructures VOsystem of V and O components which are studied including chemical and physical reactions based on non-equilibrium thermodynamics. Due to their structural classes of corundum, rocksalt, wurtzite, spinel, perovskite, rutile, and layer structure, these oxides are generally used as catalytic materials which are prepared by common methods under mild conditions presenting distortion or defects in the case of VO. Existence of an intermediate phase is proved using an x-ray thermodiffraction experiment providing structural information as the nanoparticles are heated. Potential application as gas sensing device has been the first time obtained due to the high surface to volume ratio, and good crystallinity, purity of the material and presence of suitablenucleating defects sites due to its n-type semiconductor behavior. The I-V behavior obtained in the single nanograin VO describes the charge carrier originating from the soliton tunneling conductivity of the material with abrupt jump current correlated to the abruptMott insulator without structural phase transition. This was observed by inducing internal holes charges of about 0.018% in the holeslevels into conduction band with a source drain field or gate field which make possible the semi-conductor to be used as high frequency oscillator (microwave).

In addition, annealing effect on nanostructures VO nanobelts shows a preferential gas reductant of Ar comparing to the Ngas. Also, the hysteresis loop shows that there is strong size dependence to annealing treatment on our samples. This is of great interest in the need of obtaining high stable and durable material for Mott insulator transistor and Gas sensor device at room temperature.