Crystal structure and properties of Silicon nitride

The longer stacking sequence results in the α-phase having higher hardness than the β-phase. However, the α-phase is chemically unstable compared with the β-phase. When a liquid phase is present at high temperatures, the α-phase always transforms into the β-phase. Therefore, β-Si3N4 is the major form used in Si3N4 ceramics. Abnormal grain growth may occur in doped β-Si3N4, whereby abnormally large elongated grains form in a matrix of finer equiaxed grains and can serve as a technique to enhance

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Crystalline bulk silicon is rather inert

Crystalline bulk silicon is relatively inert but becomes more reactive at high temperatures. Still, the formation of the vitreous dioxide rapidly increases between 950 °C and 1160 °C, and when 1400 °C is reached, atmospheric nitrogen also reacts to give the nitrides SiN and Si3N4. Silicon reacts with gaseous sulfur at 600 °C and gaseous phosphorus at 1000 °C. This oxide layer nevertheless does not prevent reaction with the halogens; fluorine attacks silicon vigorously at room temperature, but i

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Silver coated quartz crystal microbalance resonator were covered with CuO nanostructures

Both sides (5 mm in diameter) of a silver-coated quartz crystal microbalance (QCM) resonator were covered with CuO nanostructures; the resonator was used as a sensing probe in a quartz crystal resonator. The resonant frequency shift indicates the absorbance of HCN gas on the sensor. As the specific area of CuO nanostructure used for coating the probe changes from 9.3 m2/g to 1.5 m2/g, the sensitivity reduces from 2.26 to 0.31 Hz/μg. In both reports, the authors showed that the sensitivity of sen

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CuO crystal has monoclinic structure

CuO crystal has a monoclinic structure and belongs to symmetry. Cupric oxide has four formula units per unit cell. The coordination number of copper atoms is 4, linked to four oxygen neighbor atoms in an approximately square planar configuration in the (110) plane. In all crystallized solids, divalent copper surroundings are invariably distorted by a strong Jahn-Teller effect which often leads to more stable square planar groups. The Cu-O bond lengths in this plane are 1.88 and 1.96 Å, respectiv

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Single Crystal Calcium Hexaboride Nanowires

Calcium hexaboride (CaB6), one of the divalent alkaline-earth cubic hexaborides, has low density (2.45 g/cm3 ), high melting point (2235 °C), high hardness (Knoop: 2600 kg/ mm2 ), high Young's modulus (379 GPa), and high chemical stability. CaB6 has found applications as a high-temperature material, used for surface protection, and is a wear-resistant material. CaB6 is also a promising candidate for n-type thermoelectric (TE) materials because its power factor has been reported to be larger than

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Iron(III) oxide phase with a monoclinic crystal structure

No iron(III) oxide phase with a monoclinic crystal structure stable at atmospheric pressure and room temperature has ever been identified. Thus, ζ-Fe2O3 can be regarded as a new iron(III) oxide polymorphic family member. It is known that the stability of nanoscale Fe2O3 polymorphs is governed by two factors: the Gibbs free energy of the different i-Fe2O3 phases (i = α, β, γ, ε) and the energy barrier associated with the phase transformation. These two parameters, in turn, depend on many factors,

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βFe2O3 was found to transform into a completely new crystal structure

Surprisingly, β-Fe2O3 was found to transform into a completely new crystal structure following the Rietveld refinement of the synchrotron radiation XRD patterns recorded at pressures above 30 GPa. The analyses were carried out adopting the following scenario. At high pressures (42.9–64.4 GPa), α-Fe2O3 transforms into RO-Fe2O3 and PPV-Fe2O3 with consistent transition pressures compared with the previous reports. On the other hand, β-Fe2O3 transits to a different new phase. By indexing these new p

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The effect of pressure treatment on the crystal structure of β Fe2O3

The effect of pressure treatment on the crystal structure of β-Fe2O3 was investigated using high-pressure synchrotron radiation XRD measurements. Representative high-pressure synchrotron XRD spectra and the detailed Rietveld analyses of all the measured synchrotron radiation XRD patterns (including the values of the Rwp-factor) are depicted in Supplementary Figures S1–S7 in the Supplementary Material. At up to 10 GPa pressures, the sample consists of β-Fe2O3 and α-Fe2O3 in approximately the same

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Crystalline Flake Graphite

What is graphite?This variety of Graphite is typically formed by the metamorphism of coal beds or carbon-rich sediments associated with igneous activity. It is generally a soft, darker black-colored graphite, less reflective than other varieties of natural crystalline Graphite. Commonly found as "microcrystalline" particles, this variety of Graphite has a lower graphitic carbon level when compared to other naturally occurring crystalline graphite varieties. The family of graphite materials inclu

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Titanium Diboride (TiB2) Micron Powder

What is Titanium diboride?A hot pressing process prepared titanium diboride (TiB2) and its ceramic composites. The sintering process, phase evolution, microstructure, and mechanical properties of TiB2 ceramics prepared by using different milling media materials: tungsten carbide (WC/Co) or SiAlON was studied. It was found that the inclusion of WC/Co significantly improved the sinterability of the TiB2 ceramics. A core/rim structure was identified with pure TiB2 as the core and W-rich TiB2, i.e.,

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Will clear quartz to replace any crystal

What is Quartz powder?Quartz is a strong and crystalline mineral made of silicon and oxygen particles. It is one of the most popular and rich minerals with various applications discovered on Earth. It is a significant element of rocks and applications in all temperatures. Quartz is transparent or white in its purest form, but several impurities within the atomic structure can change color. There are many varieties of quartz with several uses. Quartz sand and ground quartz or quartz powder are ut

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Titanium aluminum carbide (Ti3AlC2) belongs to the hexagonal crystal system

Titanium aluminum carbide (Ti3AlC2) belongs to the hexagonal crystal system and has the characteristics of metal and ceramics: it has the same conductivity and heat conduction as metal but also has the same high elastic modulus and excellent high-temperature mechanical properties as ceramic with good conductivity and heat conduction capability, high elastic modulus and low Vickers hardness, and good damage resistance capability. It can be machined at room temperature, producing plastic deformati

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What is nano-diamond?

The manufacture of nano-diamond , especially its application, has become a hot research topic in recent years. Nanodiamond has been developed more than 30 years ago, but its application in the past is limited to making polycrystalline, polis

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What are the functions of boron nitride

Overview of Boron nitride Powder Industrial-grade Boron nitride is a pure white ceramic material with the hexagonal structure of a crystal similar to graphite. The material can stand temperatures of more than 2,000 degC. Depending upon the grade, its dielectric strengths are close to 1000 volts/millimeter. The Boron Nitride is hot-pressed to its form as billets which are easily transformed into rods (bars), plates, rods and even customized shapes . What are the main functions of Boron Nitride

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Which calcium is best for seniors

Calcium citrate, calcium carbonate and calcium with vitamin D are some of the more popular supplements used by seniors to stay healthy and strong. Hypercalcemia is when the calcium level in your blood is above normal. Too much calcium in your blood can weaken your bones, create kidney stones, and interfere with how your heart and brain work. Hypercalcemia is usually a result of overactive parathyroid glands. In the case of men and women taking medication, such as Fosamax or Evenity, for osteopor

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