Anjana Asthana

Michigan Technological University | MTU · Department of Materials Science & Engineering

Field Emission from Zinc Oxide Nanobelt - Volume 23 Issue S1 - A. Asthana, Y. K. Yap, R. S. Yassar

Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized bo...

We report here, the in-situ field emission (FE) property measurement on the individual ZnO nanobelts inside a high resolution transmission electron microscope (TEM) using a special scanning tunneling microscopy (STM)-TEM system. The field emission properties were found to be size scale dependent. It was found that the threshold voltage decreases an...

Boron nitride (BN) nanostructures can have varied structures. They can simply be nanoscale particles of various bulk BN materials, including hexagonal-phase BN (h-BN) and cubic-phase BN (c-BN). However, many of the BN nanostructures of popular interest were discovered in the past 20 years and are unique in their structures and properties. These inc...

Boron nitride (BN) nanostructures can have varied structures. ey can simply be nanoscale particles of various bulk BN materials, including hexagonal-phase BN (h-BN) and cubic-phase BN (c-BN). However, many of the BN nanostructures of popular interest were discovered in the past 20 years and are unique in their structures and properties. ese include...

The detection of piezoelectric current in one-dimensional semiconductor materials has been a controversial issue due to the possibility of charge annihilation at nanoscale dimensions. We report here, the mechanically triggered electrical current in uniaxially compressed individual ZnO nanobelts under no applied bias. The measurements were carried o...

In this work, piezoelectricity of individual ZnO nanobelts grown along the [0 1 ī 0] direction is studied using piezoresponse force microscopy (PFM). It is found that the effective piezoelectric coefficient of these NBs, $d_{33}^{\mathrm{eff}}$ , is increasing from 2.7 pm/V at 30 kHz to 44 pm/V at 150 kHz. The results were explained by the Debye...

A series of in situ transmission electron microscopy combined with scanning tunneling microscopy measurements were carried out to investigate the effect of mechanical deformation on the electrical transport properties of amorphous TiO2 nanotubes. Under no mechanical straining, it was found that the TiO2 nanotubes behave as electrical insulators. Ho...

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

We report here investigations of crystal and electronic structure of as-synthesized and annealed ZnO nanobelts by an in-situ high-resolution transmission electron microscope equipped with a scanning tunneling microscopy probe. The in-situ band gap measurements of individual ZnO nanobelts were carried out in scanning tunneling spectroscopy mode usin...

Rare-earth-doped gadolinium fluoride nanocrystals were synthesized by a single step synthesis employing ethylene glycol as solvent. Based on X-ray diffraction studies, stabilization of hexagonal modification of GdF(3) has been inferred. The microscopic studies show formation of uniformly distributed nanocrystals (~15 nm). The nanoparticles are read...

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

In this investigation, the size-scale in mechanical properties of individual [0001] ZnO nanowires and the correlation with atomic-scale arrangements were explored via in situ high-resolution transmission electron microscopy (TEM) equipped with atomic force microscopy (AFM) and nanoindentation (NI) systems. The Young's modulus was determined to be s...

In this work, a novel system of ethylene glycol/water (EG/W) was employed to synthesize LiFePO4, in which dodecyl benzene sulphonic acid sodium (SDBS) was used as soft template to control particle morphology. The samples were characterized by X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmiss...

We report here, the deformation driven modulation of the electrical transport properties of an individual TiO ₂ nanotube via in situ transmission electron microscopy (TEM) using a scanning tunneling microscopy system. The current-voltage characteristics of each individual TiO ₂ nanotube revealed that under bending deformation...

Physical Sciences SymposiaA Real Time Observation of Phase Transition of Anatase TiO2 Nanotubes into Rutile Particles by in situ Joule Heating Inside Transmission Electron MicroscopeArticle author queryasthana a [PubMed] [Google Scholar]shokuhfar t [PubMed] [Google Scholar]gao q [PubMed] [Google Scholar]heiden p [PubMed] [Google Scholar]friedri...

of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

We report here, an investigation on electrical and structural-microstructural properties of an individual ZnO nanobelt via in situ transmission electron microscopy using an atomic force microscopy (AFM) system. The I-V characteristics of the ZnO nanobelt, just in contact with the AFM tip indicates the insulating behavior, however, it behaves like a...

We report the synthesis, structure and low-field magnetotransport properties of Mischmetal (Mm)doped La(0.7-x)Mm(x)Ca(0.3)MnO(3) (0 <= x <= 0.45) manganite. Mischmetal-Mm-is a natural mixture of rare earth elements La, Ce, Pr and Nd with similar to 28%, 50%, 6% and 16% composition, respectively. All the samples crystallize in orthorhombic structure...

We report the effect of surfactant treatment on the structural and magnetic properties of Mn-doped ZnO bulk (Zn0.978Mn0.022O) and Mn- and Li-codoped ZnO nanoparticles (Zn0.96Mn0.03Li0.01O) prepared by low-temperature reaction. X-ray diffraction and transmission electron microscopy analyses of these samples showed the formation of impurity-free crys...

We performed structural–microstructural investigations of pure MgB2, ethyltoluene and both ethyltoluene- and SiC-added MgB2/Fe tapes. The analysis of the microstructure shows that the grain size for the pure and ethyltoluene-added MgB2 tape sample is in the range of 10–100 nm. However, with the addition of both ethyltoluene and SiC, the grain size...

Nanocrystalline (Th1−xFex)O2−δ particles with different Fe concentrations (x=0.0, 0.05, 0.10, 0.15, 0.20 and 0.25) have been prepared by a gel combustion method. Rietveld refinement analyses of X-ray diffraction data revealed the formation of an impurity free cubic type Th1−xFexO2−δ structure up to x=0.20. This observation is further confirmed from...

The perovskite Sr(1-x)Ho(x)CoO(3-delta) shows room temperature ferromagnetism (T(c)similar to 335 K) in a severely limited composition range 0.2 <= x <= 0.25. The formal Co valence is almost constant at +3 regardless of the Ho concentration (x >= 0.2); thus, the high-spin state or the intermediate spin state of 3d(6) Co should be mainly responsible...

The structural microstructural characterization and defect structure of Ru based magnetosuperconductor RuSr2Eu1.6Ce0.4Cu2O10-delta has been investigated by selected area electron diffraction pattern and high resolution electron microscopy. Under the present investigations, RuSr2Eu1.6Ce0.4Cu2O10-delta magnetosuperconductor shows the presence of both...

We report the synthesis of Th1–xMnxO2 (x = 0, 0.001, 0.002, 0.004, and 0.01 wt%) nanoparticles by the urea combustion method using thorium nitrate gel followed by heat treatment at a higher temperature (T). The obtained Th1–xMnxO2 nanocrystals were characterized by x-ray diffraction (XRD), direct-current magnetization (M) measurements and electron...

We have investigated the effect of base pressure of the sputtering chamber on the structure and magnetic properties of the FePt thin films. The A1-FePt thin films deposited at room temperature, at a low base pressure of 5.5 x 10 x 7 Torr was ordered to the L1(0) structure at a low annealing temperature of 200 degrees C and a highly ordered L1(0) ph...

We report the synthesis of nanoparticles of Zn0.96Mn0.03Li0.01O by a low-temperature solid-state pyrolitic reaction, followed by a surfactant-assisted calcination at 400°C. The X-ray diffraction and transmission electron microscopy analyses showed the formation of impurity free nanocrystals of Mn doped Li co-doped ZnO with wurtzite structure. XPS d...

Novel flower like microporous carbons with very high surface area have been synthesized for the first time using MCM-22 zeolite as a template and sucrose as a carbon source. The textural parameters of the materials can easily be tuned by the simple adjustment of the sucrose to MCM-22 weight ratio. It has been also found that the specific surface ar...

A novel nitrogen-doped mesoporous carbon with well-ordered two-dimensional (2D) structure has been successfully prepared for the first time using aniline as a source for both carbon and nitrogen, and SBA-15 as a template. The above material has been unambiguously characterized by various sophisticated techniques such as XRD, HRTEM, XPS, and nitroge...

Single phase Mn (2.5 at%) doped ZnO nanocrystalline samples were synthesized by reverse micelle method as characterized by Rietveld refinement analysis of X-ray diffraction data, high resolution transmission electron microscopy and selected area electron diffraction analyses. The X-ray photoelectron spectroscopy and electron paramagnetic resonance...

Iron substituted cubic cage type mesoporous molecular sieves (FeSBA-1) were synthesized for the first time in a highly acidic media using cetyltriethylammonium bromide as a template. The amount of Fe incorporation in SBA-1 can easily be controlled by the simple adjustment of the molar hydrochloric acid-to-silicon ratio. All the materials were unamb...

Light and heavy neutron-irradiation damage of highly oriented pyrolytic graphite ( HOPG) crystals was examined by means of X-ray diffraction and high-resolution high-voltage transmission electron microscopy (TEM). From the X-ray data analysis, it was found that there is an average increase of about 3% in the c-axis lattice parameter of the unit cel...

We report here the improvement of superconducting properties of MgB2 bulk samples by sintering at ambient pressure, employing RF induction heating. It has been found that Tc (R = 0) transition temperature of the sintered sample gets enhanced to ~40.00 K as compared to Tc (R = 0) ~25 K for the unsintered MgB2 sample. A high critical current density...

Synthesis of Hg(Tl)Ba 2 Ca 2 Cu 3 O 8+δ superconducting tapes have been accomplished by annealing the precursor tape, Ba 2 Ca 2 Cu 3 O y (fabricated by doctor blade tape casting technique) in an environment of Hg(Tl) vapour. Characterization of superconducting HTSC tape sample was carried out through XRD, TEM, SEM and R-T measuremen...

Pb-doped Hg-1223 HTSC tapes have been synthesized by annealing the precursor tape (fabricated by doctor blade tape casting technique) in the environment of Hg(Pb) vapor in an evacuated sealed quartz tube at 870°C for 8 h. The HTSC tapes with x ranging between 0.1 and 0.5 exhibit high temperature superconductivity at temperature falling in the range...

The present study is based on improving the intergranular connectivity of Tl HTSC tapes by passivation of grain boundaries through the addition of silver. HTSC tapes to which silver had been added were fabricated by the diffusion of Tl vapour in the precursor tape to which silver had been added. The tapes were cast by using a doctor-blade tape-cast...

(x = 0.1, 0.2, 0.3, 0.5 and 0.8) HTSC tapes have been synthesized through the reaction of a mixture of Hg-Tl vapour with the precursor tapes (fabricated by the doctor blade tape casting technique) in an evacuated sealed quartz tube at for 12 h. The Hg(Tl) tape having composition is found to possess and transport current density (20 K). The observed...