Opaline Hydrogels: Polycrystalline Body-Centered-Cubic Bulk Material with an in Situ Variable Lattice Constant

2007 ◽  
Vol 19 (25) ◽  
pp. 6095-6100 ◽  
Author(s):  
R. Goldberg ◽  
H. J. Schöpe
Keyword(s):  
Lattice Constant ◽  
Bulk Material ◽  
Body Centered Cubic ◽  
Polycrystalline Body

In Situ Diagnostics of Vuv Laser Cvd of Semiconductor Interfaces by Ftir Spectroscopy and Spectroscopic Ellipsometry

1995 ◽  
Vol 397 ◽  
Author(s):  
M. Barth ◽  
J. Knobloch ◽  
P. Hess
Keyword(s):  
Film Thickness ◽  
Bulk Material ◽  
Substrate Surface ◽  
Cluster Formation ◽  
Interface Layer ◽  
Native Oxide ◽  
Initial Growth ◽  
Difference Spectra ◽  
Si Substrates

ABSTRACTThe growth of high quality amorphous hydrogenated semiconductor films was explored with different in situ spectroscopic methods. Nucleation of ArF laser-induced CVD of a-Ge:H on different substrates was investigated by real time ellipsometry, whereas the F2 laser (157nm) deposition of a-Si:H was monitored by FTIR transmission spectroscopy. The ellipsometric studies reveal a significant influence of the substrate surface on the nucleation stage, which in fact determines the electronic and mechanical properties of the bulk material. Coalescence of initial clusters occurs at a thickness of 16 Å for atomically smooth hydrogen-terminated c-Si substrates, whereas on native oxide covered c-Si substrates the bulk volume void fractions are not reached until 35 Å film thickness. For the first time we present a series of IR transmission spectra with monolayer resolution of the initial growth of a-Si:H. Hereby the film thickness was measured simultaneously using a quartz crystal microbalance with corresponding sensitivity. The results give evidence for cluster formation with a coalescence radius of about 20 Å. Difference spectra calculated for layers at different depths with definite thickness reveal that the hydrogen-rich interface layer stays at the substrate surface and does not move with the surface of the growing film. The decrease of the Urbach energy switching from native oxide to H-terminated substrates suggests a strong influence of the interface morphology on the bulk material quality.

scholarly journals The influence of physical state on shikimic acid ozonolysis: a case for in situ microspectroscopy

2014 ◽  
Vol 14 (19) ◽  
pp. 10761-10772 ◽  
Author(s):  
S. S. Steimer ◽  
M. Lampimäki ◽  
E. Coz ◽  
G. Grzinic ◽  
M. Ammann
Keyword(s):  
Degradation Rate ◽  
Shikimic Acid ◽  
Bulk Material ◽  
Water Mixture ◽  
Gas Uptake ◽  
X Ray ◽  
Scanning Transmission ◽  
Dry Conditions ◽  
Semi Solid

Abstract. Atmospheric soluble organic aerosol material can become solid or semi-solid. Due to increasing viscosity and decreasing diffusivity, this can impact important processes such as gas uptake and reactivity within aerosols containing such substances. This work explores the dependence of shikimic acid ozonolysis on humidity and thereby viscosity. Shikimic acid, a proxy for oxygenated reactive organic material, reacts with O3 in a Criegee-type reaction. We used an environmental microreactor embedded in a scanning transmission X-ray microscope (STXM) to probe this oxidation process. This technique facilitates in situ measurements with single micron-sized particles and allows to obtain near-edge X-ray absorption fine structure (NEXAFS) spectra with high spatial resolution. Thus, the chemical evolution of the interior of the particles can be followed under reaction conditions. The experiments show that the overall degradation rate of shikimic acid is depending on the relative humidity in a way that is controlled by the decreasing diffusivity of ozone with decreasing humidity. This decreasing diffusivity is most likely linked to the increasing viscosity of the shikimic acid–water mixture. The degradation rate was also depending on particle size, most congruent with a reacto-diffusion limited kinetic case where the reaction progresses only in a shallow layer within the bulk. No gradient in the shikimic acid concentration was observed within the bulk material at any humidity indicating that the diffusivity of shikimic acid is still high enough to allow its equilibration throughout the particles on the timescale of hours at higher humidity and that the thickness of the oxidized layer under dry conditions, where the particles are solid, is beyond the resolution of STXM.

INVESTIGATION OF BIAXIAL ELASTIC MODULUS AND CTE OF BaTiO3 FILMS

2009 ◽  
Vol 23 (24) ◽  
pp. 4933-4941
Author(s):  
GUI-FANG HUANG ◽  
WEI-QING HUANG ◽  
LING-LING WANG ◽  
ZHONG XIE ◽  
BING-SUO ZOU ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Thermal Cycle ◽  
Laser Scanning ◽  
Stress Measurement ◽  
Coefficient Of Thermal Expansion ◽  
Bulk Material ◽  
Good Reliability ◽  
Scanning Method ◽  
As Stress

To develop high-quality film device with good reliability, it is often essential to be able to evaluate the parameters such as stress, the biaxial elastic modulus, and coefficient of thermal expansion (CTE) of film. Based on the stress measurement in situ during the thermal cycle by laser scanning method, two techniques were used to measure the biaxial elastic modulus and CTE of BaTiO 3 films deposited on substrate. The value of the biaxial elastic modulus and CTE for BaTiO 3 films determined from two methods is close, in which the biaxial elastic modulus of BaTiO 3 films is higher than that of corresponding bulk while the CTE of BaTiO 3 films is a little smaller than that of bulk material.

Highly Densified MgB2 Bulks by Reactive Mg Liquid Infiltration

2006 ◽  
Vol 47 ◽  
pp. 7-16 ◽  
Author(s):  
Giovanni Giunchi ◽  
Giovanni Ripamonti ◽  
Elena Perini ◽  
Stefano Ginocchio ◽  
Enrico Bassani ◽  
...  
Keyword(s):  
Polycrystalline Material ◽  
Bulk Material ◽  
Analytical Description ◽  
Liquid Infiltration ◽  
In Situ Method ◽  
New Process ◽  
Conventional Sintering ◽  
Reactive Liquid ◽  
Mgb2 Superconductors

The issues in the conventional sintering of the MgB2 superconductors have conducted to the discovery of a new way to densify this material. The new process is an “in situ” method that relies on the reactive liquid infiltration (RLI) of liquid Magnesium into Boron powders packed preform. The RLI process allows to obtain highly dense manufacts without the use of hot pressing apparatus and can be applied to the manufacture of large superconducting pieces. One of the peculiarities of the MgB2 superconductivity, that withstand up to 39 K, is represented by the relative insensitiveness of the supercurrent percolation to the orientation of the grain boundaries. This property allows to use polycrystalline material without loosing superconducting performance, granted that a good connectivity between the crystalline grains must be realized, as the RLI process allows to do. The microstructure of the bulk material obtained by RLI shows a variety of morphologies, according to the kind of the used Boron powders and to the process variables. A detailed analysis of the microstructure of the MgB2 obtained by RLI will be presented, as well as its analytical description and the correlation with the superconducting characteristics.

Low-Temperature Epitaxial Growth of IN-Situ HeavilY B-Doped Si1-xGex, Films Using Ultraclean LPCVD

1998 ◽  
Vol 533 ◽  
Author(s):  
A. Morrya ◽  
M. Sakuraba ◽  
T. Matsuura ◽  
J. Murota ◽  
I. Kawashima ◽  
...  
Keyword(s):  
Low Temperature ◽  
Partial Pressure ◽  
Epitaxial Growth ◽  
Lattice Constant ◽  
Deposition Rate ◽  
Epitaxial Films ◽  
Similar Degree ◽  
Gas Mixture ◽  
Heavy Doping

AbstractIn-situ heavy doping of B into Si1-xGex epitaxial films on the Si(100) substrate have been investigated at 550°C in a SiH4(6.0Pa)-GeH4(0.1−6.0Pa)-B2H6(1.25 ×10−5−3.75 × 10−2Pa)-H2(17–24Pa) gas mixture by using an ultraclean hot-wall low-pressure CVD system. The deposition rate increased with increasing GeH4 partial pressure, and it decreased with increasing B2H6 partial pressure only at the higher GeH4 partial pressure. As the B2H6 partial pressure increased, the Ge fraction scarcely changed although the lattice constant of the film decreased. These characteristics can be explained by the suppression of both the SiH4 and GeH4 adsorption/reactions in a similar degree due to B2H6 adsorption on the Si-Ge and/or Ge-Ge bond sites. The B concentration in the film increased proportionally up to 1022cm3 with increasing B2H6 partial pressure.

scholarly journals In situ microstructural evolution in face-centered and body-centered cubic complex concentrated solid-solution alloys under heavy ion irradiation

2020 ◽  
Vol 198 ◽  
pp. 85-99 ◽  
Author(s):  
Calvin Parkin ◽  
Michael Moorehead ◽  
Mohamed Elbakhshwan ◽  
Jing Hu ◽  
Wei-Ying Chen ◽  
...  
Keyword(s):  
Solid Solution ◽  
Microstructural Evolution ◽  
Ion Irradiation ◽  
Heavy Ion ◽  
Body Centered Cubic ◽  
Heavy Ion Irradiation ◽  
Face Centered

scholarly journals Descriptors for predicting the lattice constant of body centered cubic crystal

2017 ◽  
Vol 146 (20) ◽  
pp. 204104 ◽  
Author(s):  
Keisuke Takahashi ◽  
Lauren Takahashi ◽  
Jakub D. Baran ◽  
Yuzuru Tanaka
Keyword(s):  
Lattice Constant ◽  
Body Centered Cubic ◽  
Cubic Crystal

scholarly journals Anti-twinning in nanoscale tungsten

2020 ◽  
Vol 6 (23) ◽  
pp. eaay2792
Author(s):  
Jiangwei Wang ◽  
Zhi Zeng ◽  
Minru Wen ◽  
Qiannan Wang ◽  
Dengke Chen ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Shear Displacement ◽  
Atomic Scale ◽  
Deformation Mechanisms ◽  
Body Centered Cubic ◽  
Plastic Shear ◽  
Transmission Electron ◽  
20 Nm ◽  
Scale Shear

Nanomaterials often surprise us with unexpected phenomena. Here, we report a discovery of the anti-twinning deformation, previously thought impossible, in nanoscale body-centered cubic (BCC) tungsten crystals. By conducting in situ transmission electron microscopy nanomechanical testing, we observed the nucleation and growth of anti-twins in tungsten nanowires with diameters less than about 20 nm. During anti-twinning, a shear displacement of 1/3〈111〉 occurs on every successive {112} plane, in contrast to an opposite shear displacement of 1/6〈1¯1¯1¯〉 by ordinary twinning. This asymmetry in the atomic-scale shear pathway leads to a much higher resistance to anti-twinning than ordinary twinning. However, anti-twinning can become active in nanosized BCC crystals under ultrahigh stresses, due to the limited number of plastic shear carriers in small crystal volumes. Our finding of the anti-twinning phenomenon has implications for harnessing unconventional deformation mechanisms to achieve high mechanical preformation by nanomaterials.

Study of Abrasive Wear Mechanism through Nano Machining

2011 ◽  
Vol 462-463 ◽  
pp. 931-936 ◽  
Author(s):  
Sumaiya Islam ◽  
Raafat N. Ibrahim ◽  
Raj Das
Keyword(s):  
Abrasive Wear ◽  
Wear Mechanism ◽  
Bulk Material ◽  
Elastic Recovery ◽  
In Situ Observation ◽  
Nano Scale ◽  
Nickel Coatings ◽  
Machining Operations ◽  
Tip Radius

The objective of this paper is to understand the abrasive wear mechanism for producing a nano scale groove on a bulk material through nano machining. A nano indenter equipped with a nano scratching attachment was used for nano machining operation and in situ observation of the machined surfaces. Two different tools (Berkovich and Conical) with the same tip radius (100nm) but different edge geometries were used to machine both Copper and Nickel coatings. It was found that the percentage of elastic recovery was lower for Cu than Ni during this nano machining operations. Hence, the deformation mechanism in nano machining operation was identified as elasto-plastic in nature as opposed to the well established completely plastic mode of conventional machining operations. The pile up volume due to plastic deformation was utilized to distinguish between the ploughing and cutting modes of abrasive wear mechanisms. The results reveal that the ploughing mechanism was dominant for Cu and the cutting mechanism was dominant for Ni machining. Moreover, both mechanisms ploughing and cutting were the dominant modes of abrasive wear using the Berkovich tip compared to the Conical tip for producing a nano scale groove through nano machining.

Sign in / Sign up

Export Citation Format

Share Document