Characterizing high-pressure compressed C60 whiskers and C60 powder

2003 ◽  
Vol 18 (1) ◽  
pp. 166-172 ◽  
Author(s):  
Kun'ichi Miyazawa ◽  
Minoru Akaishi ◽  
Yusuke Kuwasaki ◽  
Tadatomo Suga
Keyword(s):  
High Pressure ◽  
Electrical Resistivity ◽  
Electrical Properties ◽  
Vickers Hardness ◽  
High Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Of Dislocations ◽  
Mechanical And Electrical Properties

Structural, mechanical, and electrical properties were examined for C60 whiskers, high-pressure sintered C60 whiskers, and C60 powder. A high density of dislocations was observed in the C60 whiskers, and the C60 whiskers with diameters of a few hundred nanometers were found to be flexible. Although both the specimens sintered under the same condition showed similar surface x-ray diffraction profiles with a strong accumulation of [110]tr orientation, the sintered C60 whiskers showed a higher micro-Vickers hardness and an electrical resistivity four orders of magnitude lower than that of the sintered C60 powder.

Development of CNT-Silicon Nitrides with Improved Mechanical and Electrical Properties

2006 ◽  
Vol 45 ◽  
pp. 1723-1728 ◽  
Author(s):  
Csaba Balázsi ◽  
Ferenc Wéber ◽  
Péter Arató ◽  
Balazs Fényi ◽  
Norbert Hegman ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Electrical Properties ◽  
Room Temperature ◽  
Hot Isostatic Pressing ◽  
Ceramic Composites ◽  
X Ray Diffraction ◽  
Nano Structure ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Gas Pressure Sintering

This work is focusing on exploring preparing processes to tailor the microstructure of carbon nanotube (CNT) reinforced silicon nitride-based ceramic composites. Samples with different porosity’s and different amount (1, 3 or 5 wt%) of carbon nanotubes have been prepared by using gas pressure sintering or hot isostatic pressing. In comparison, composites with 1wt%, 5wt% or 10wt% carbon black and graphite have been manufactured. We measured the room temperature mechanical and electrical properties, examined the micro and nano structure by X-ray diffraction and electron microscopy. It was found that it is possible to develop CNT-silicon nitride composite for applications where a decent electric conductivity and good mechanical properties are required.

Thermoelectric properties of Tl9BiTe6 / Tl9BiSe6 solid solutions

2000 ◽  
Vol 626 ◽  
Author(s):  
Bernd Wölfing ◽  
Christian Kloc ◽  
Ernst Bucher
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
State Of The Art ◽  
High Resistivity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Vegard’S Law

ABSTRACTThe compounds Tl9BiTe6 (TBT) and Tl9BiSe6 (TBS) crystallize in the tetragonal space group I4/mcm. Tl9BiTe6 has a thermopower of 185 μV/K and an electrical resistivity of 5.5 mΩcm at 300K, resulting in a power factor of S2/ρ = 0.6 mW/mK2. Compared to Bi2Te3 which is the state of the art material at this temperature this is about a factor of 7 lower. At 300 K TBS has a thermopower of 750 μV/K but a high resistivity of 130 Ωcm. To optimize the thermoelectric properties of TBT solid solutions have been formed with TBS. The resistivities and have been measured on Tl9BiTe1-xSex with x = 0.05, 0.08, 0.2 and 0.5. In addition to the electrical properties the lattice constants have been measured by X-ray diffraction. The dependence of the lattice constants on the Te/Se ratio clearly deviates from Vegard's law. Different affinities of Te and Se towards the two chalcogenide sites in the crystal can explain this behavior.

Thermoelectric properties of InxPbxCo4Sb12 prepared by HPHT

2016 ◽  
Vol 09 (01) ◽  
pp. 1650008 ◽  
Author(s):  
Le Deng ◽  
Li Bin Wang ◽  
Jie Ming Qin ◽  
Xiao Peng Jia ◽  
Hong An Ma
Keyword(s):  
Thermal Conductivity ◽  
High Pressure ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Substantial Reduction ◽  
X Ray Diffraction ◽  
X Ray

We prepared InxPbxCo4Sb[Formula: see text] by high-pressure and high-temperature (HPHT) method. Samples were characterized by X-ray diffraction (XRD), electron microprobe analysis and thermoelectric properties measurements. The Seebeck coefficient, electrical resistivity and thermal conductivity of InxPbxCo4Sb[Formula: see text] samples were all performed in the temperature range of 323–723[Formula: see text]K. With the increasing synthetic pressure, the Seebeck coefficient of In[Formula: see text]Pb[Formula: see text]Co4Sb[Formula: see text] samples, which synthesized between 1.5 GPa–2.3 GPa, showed an obvious increase while the thermal conductivity exhibited a substantial reduction.

X-ray diffraction, Mössbauer spectroscopic and electrical resistivity studies on Lohawat meteorite under high-pressure up to 9 GPa

Geochemistry ◽  
2013 ◽  
Vol 73 (2) ◽  
pp. 197-203 ◽  
Author(s):  
Usha Chandra ◽  
G. Parthasarathy ◽  
N.V. Chandra Shekar ◽  
P.Ch. Sahu
Keyword(s):  
High Pressure ◽  
Electrical Resistivity ◽  
X Ray Diffraction ◽  
X Ray

Influence of Substitution of Fe by Mo on Heat Treatment Behavior in Ti-Mo-Fe Alloys

2021 ◽  
Vol 1016 ◽  
pp. 162-169
Author(s):  
Kyosuke Mizuta ◽  
Shotaro Miyake ◽  
Masahiko Ikeda ◽  
Masato Ueda
Keyword(s):  
Heat Treatment ◽  
Electrical Resistivity ◽  
Diffusion Coefficient ◽  
Vickers Hardness ◽  
Partial Substitution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Ti Alloys ◽  
Fe Alloys

In order to reduce the cost of β-type Ti alloys, the use of Fe as an alloying element has been studied. However, Fe is known to have a very high diffusion coefficient in β-Ti of about 2.6×10-12 m2/s at 1200 K, and its behavior during heat treatment is expected to be difficult to control. By contrast, Mo, which is also a β-stabilizing element, has a diffusion coefficient of only about 2.5×10-14 m2/s at 1200 K, i.e., roughly 100 times smaller than that of Fe1), 2). In this study, the effect of the partial substitution of Fe with Mo on the aging behavior of β-Ti alloys was investigated using X-ray diffraction, electric resistivity, and Vickers hardness measurements. Ti-Mo-Fe alloys were solution-treated by holding at 1173 K for 3.6 ks and then quenching in ice water. In the X-ray diffraction patterns for the resulting samples, only peaks associated with the β phase were identified. It was found that the electrical resistivity and Vickers hardness decreased with increasing Mo content. As the Mo-to-Fe ratio increased, the decrease in electrical resistivity and the increase in Vickers hardness occurred later during the isothermal aging process. This was due to a delay in isothermal ω-phase precipitation.

scholarly journals Microstructure and Mechanical Properties of Pressure-Quenched SS304 Stainless Steel

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 290 ◽  
Author(s):  
Peng Wang ◽  
Yang Zhang ◽  
Dongli Yu
Keyword(s):  
High Pressure ◽  
Metallographic Analysis ◽  
Polycrystalline Materials ◽  
Test Results ◽  
X Ray Diffraction ◽  
X Ray ◽  
Self Heating ◽  
Density Of Dislocations ◽  
Transmission Electron ◽  
Quenching Method

Bulk SS304 polycrystalline materials with ultrafine microstructures were prepared via a high-pressure self-heating melting and quenching method. Analyses of phase composition, grain size and microstructure were performed using metallographic analysis, X-ray diffraction, Rietveld refinement and transmission electron microscope (TEM). The effects of pressure and cooling rate on the solidification of SS304 were analyzed. Mechanical property test results show that, compared with the as-received sample, the hardness and the yield strength of the pressure-quenched (PQ) samples were greatly increased, the ultimate tensile strength changed minimally, and the elongation rate became small, primarily due to the large density of dislocations in the sample. The high-pressure self-heating melting and quenching method is an exotic route to process a small piece of steel with moderate properties and ultrafine microstructure.

scholarly journals Strengthening Al-Zn-Mg Alloys via Ultra-Fine Lamella Structures Containing a High Density of Dislocations and Clusters

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 140 ◽  
Author(s):  
Yonggui Qin ◽  
Sicong Lin ◽  
Shenbao Jin ◽  
Jizi Liu
Keyword(s):  
Electron Microscope ◽  
Yield Strength ◽  
High Density ◽  
Mechanical Processing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Of Dislocations ◽  
Transmission Electron ◽  
Peak Aged ◽  
Fractographic Features

A new method of thermo-mechanical processing has been designed by introducing pre-aging before general cold rolling for an Al-Zn-Mg alloy. This process results in an increase of 200 MPa in yield strength compared to that of the peak-aged samples. The microstructures were examined by transmission electron microscope and X-ray diffraction. It has been found that the enhanced strength is mainly contributed to by ultra-fine lamella structures containing a high density of dislocations pinned by nanoprecipitates. Extra strength is provided by the “interlocking” of precipitates and dislocations. Fractographic features analysis shows that crack propagation along the interface of the lamella structures is the direct reason for resulting in fracture, due to intra-granular strength exceeding grain boundary cohesion.

HIGH PRESSURE-HIGH TEMPERATURE ELECTRICAL RESISTIVITY STUDIES ON Nd0.9Ca0.1Ba2Cu3O7-δ

2006 ◽  
Vol 20 (29) ◽  
pp. 4885-4890
Author(s):  
R. SELVA VENNILA ◽  
S. REZA GHORBANI ◽  
N. VICTOR JAYA
Keyword(s):  
High Pressure ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Bulk Modulus ◽  
Structural Changes ◽  
X Ray Diffraction ◽  
Heating Coil ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Electrical Resistivity Study

High pressure-high temperature electrical resistivity study on composition-controlled Nd 0.9 Ca 0.1 Ba 2 Cu 3 O 7-δ high T c superconductor (HTSC) is carried out by a four-probe technique using Bridgman anvils. A simple heating coil arrangement is used for heating the samples. Electrical resistivity behavior under pressure (up to a maximum of 8 GPa) at various temperatures (up to a maximum of 523 K) were studied and reported in this paper. Simulation of energy dispersive X-ray diffraction confirms substitution of calcium at the Nd site of Nd -123. Variation of the electrical resistivity under pressure is compared with that of the structural changes and the bulk modulus was determined.

High-Pressure and High-Temperature Synthesis of a Novel Perovskite Compound: Magnetic and Electric Properties of the Rhodium Oxide SrRhO3

2002 ◽  
Vol 718 ◽  
Author(s):  
K. Yamaura ◽  
D.P. Young ◽  
E. Takayama-Muromachi
Keyword(s):  
High Pressure ◽  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Oxygen Vacancies ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Liquid Behavior ◽  
Rhodium Oxide ◽  
Polycrystalline Form

AbstractNovel perovskite compound SrRhO3 was synthesized in a polycrystalline form by high-pressure technique at 6 GPa and 1500°C, followed by measurements of magnetic susceptibility, electrical resistivity, thermopower, and specific heat. Powder x-ray diffraction study found the slightly distorted perovskite structure, GdFeO3-type, to be likely to SrRhO3; space group was Pnma and lattice parameters were α = 5.5394(2) Å, b = 7.8539 (3) Å, and c = 5.5666(2) A. Oxygen vacancies in the perovskite were quantitatively investigated by thermogravimetric analysis and then found either absent or at least insignificant. The title compound shows a Fermi-liquid behavior in its electrical resistivity. The magnetic susceptibility is large [χ(300) ∼1.1x10-3 emu/mol-Rh], and the characteristics seem to be intermediate between enhanced Pauli- and Curie-Weiss-type paramagnetism.

Effect of Crystallization on the Electrical Resistance and Structure of Amorphous Fe-Co-Cr-B-Si Alloys / Wpływ Krystalizacji Na Oporność Elektryczną I Strukturę Amorficznych Stopów Fe-Co-Cr-B-Si

2012 ◽  
Vol 57 (4) ◽  
pp. 1031-1039
Author(s):  
H. Solomon ◽  
N. Solomon
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Amorphous Alloys ◽  
Melt Spinning ◽  
Amorphous Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Investigation Methods ◽  
Melt Spinning Technique

The goal of this paper is to present the influence of temperature variation and iron substitution with Co on the structure and electrical properties of amorphous Fe75-xCoxCr1B7Si17 alloys (where x=1, 4, 7, and 10 at.%), obtained by melt-spinning technique. The electrical resistivity of the samples was measured by using a usual four-probe method from -160°C to 750°C. The electrical resistivity was also measured at room temperature for the amorphous Fe75-xCoxCr1B7Si17 ribbons annealed at various temperatures for different holding time. The annealed samples were also investigated by Vickers microhardness test. The amorphous structure of tested materials was examined by X-ray diffraction (XRD), Mossbauer spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) methods. Experimental results confirmed the utility of applied investigation methods and the influence of the Co content and annealing process on the crystallization, structure and electrical properties of examined amorphous alloys.

Sign in / Sign up

Export Citation Format

Share Document