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Topic: Orthorhombic

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In the News (Tue 20 Aug 19)

  Orthorhombic greenish-tinged lead chromate pigments - Patent 4921541
The invention relates to orthorhombic greenish-tinged lead chromate pigments containing lead chromate and lead sulfate in a weight ratio of 91:9 to 100:0, which are distinguished by a very high tinctorial strength in application.
Orthorhombic lead chromate pigments in which the weight ratio of lead chromate to lead sulfate is 94:6 to 98:2 are preferred.
The orthorhombic lead chromate pigments obtained can additionally be treated with agents to improve their texture, for example with long-chain aliphatic alcohols, esters, acids or salts thereof, amines, amides, waxes or resinous substances, such as abietic acid or hydrogenation products, esters or salts thereof, and furthermore with nonionic, anionic or cationic surface-active organic agents.
www.freepatentsonline.com /4921541.html   (4604 words)

 materials science 01
is found to exhibit extremely unusual features which include pressure independence of the Curie temperature in the orthorhombic phase, a re-entrance of the rhombohedral phase at low temperatures, and a change of the type of the magnetic phase transition from second to first-order at the intersection of the structural and magnetic phase boundaries.
The orthorhombic (2 0 0) and (4 0 5) reflections were chosen to monitor the magnetic and structural phase-transitions, respectively.
When the crystal is compressed in the orthorhombic phase, the Mn-O-Mn angle is 180° by symmetry, and pressure cannot affect it, changing instead the inter-planar distances.
www.ill.fr /AR-97/page/20magnet.htm   (1066 words)

 Orthorhombic   (Site not responding. Last check: 2007-10-14)
In crystallography, the orthorhombic crystal system is one of the 7 lattice point groups.
Orthorhombic lattices result from stretching a cubic lattice along two of its lattice vectors by two different factors, resulting in a rectangular prism with a rectangular base (''a'' by b, which is different from a) and height (''c'', which is different from a and b).
There are four orthorhombic Bravais lattices: simple orthorhombic, base-centered orthorhombic, body-centered orthorhombic, and face-centered orthorhombic.
orthorhombic.iqnaut.net   (120 words)

 Bravais lattices
The simple orthorhombic is made by deforming the square bases of the tetragonal into rectangles, producing an object with mutually perpendicular sides of three unequal lengths.
The base orthorhombic is obtained by adding a lattice point on two opposite sides of one object's face.
And the face-centered orthorhombic is obtrained by adding one lattice point in the center of each of the object's faces.
phycomp.technion.ac.il /~sshaharr/intro.html   (352 words)

 Topaz - LoveToKnow 1911
Topaz crystallizes in the orthorhombic system, usually with a prismatic habit (figs.
It is, however, greatly inferior in hardness, the hardness of topaz being only 8; and it has lower refractivity and dispersive powers: moreover, being an orthorhombic mineral, it possesses double refraction.
From phenacite and from rock-crystal, for which it may be mistaken, it is distinguished by being biaxial and by having a much higher specific gravity.
www.1911encyclopedia.org /Topaz   (1125 words)

 Bob's Rock Shop: Introduction to Crystallography and Mineral Crystal Systems
Well, in the orthorhombic system, we will continue the 90 degree angular relationships between all 3 axes, but will vary the length of each individual axis.
However, we may discover after examining a large number of different orthorhombic minerals that we see a large number of prism forms expressed on a single crystal, and these forms cannot be expressed with unity in their numbers because their intersects upon the horizontal axes are not proportionate to their unit lengths.
A relatively large number of orthorhombic minerals are encountered with combinations of the various forms presented so far.
www.rockhounds.com /rockshop/xtal/part5.html   (1302 words)

 Highbeam Encyclopedia - Search Results for orthorhombic
The natural sulfate of strontium, SrSO 4, it is important as a source of strontium and of certain of its compounds, e.g., strontium hydroxide, used in refining beet sugar, and strontium nitrate,...
It has an orthorhombic system, massive or columnar aggregates, or hexagonal twinned crystals.
It is a white, orthorhombic crystalline compound at ordinary temperatures; above 100°C it assumes a monoclinic structure, and above about 250°C it assumes a hexagonal structure.
www.encyclopedia.com /SearchResults.aspx?Q=orthorhombic   (831 words)

 Orthorhombic Crystal System II
Because in the Orthorhombic System each crystallographic axis (the brachy axis (= a axis), macro axis (= b axis) and vertical axis (= c axis) is unique, each of the three corresponding mirror planes perpendicular to one of the axes (in the holohedric Forms) can be considered as unique.
As has been said, the 2-fold rotation axis perpendicular to this (now suppressed) mirror plane will be considered to be coincident with the crystallographic c axis which is (by convention) placed vertically.
We will now derive those same Forms by subjecting the basic faces (compatible with the Orthorhombic Crystal System) one by one to the symmetry operations of the present Class (the Rhombic-pyramidal Crystal Class).
www.geocities.com /jaap_bax/rhombic_2.html   (2525 words)

 Intro to Minerals: Crystal Class and System
The fourteen Bravais lattices are therefore the primitive cubic, body-centered cubic, face-centered cubic, primitive tetragonal, body-centered tetragonal, primitive orthorhombic, body-centered orthorhombic, single face-centered orthorhombic, multiple face-centered orthorhombic, primitive monoclinic, single face-centered monoclinic, primitive triclinic, single face-centered hexagonal, and rhombohedral lattices.
In crystals of the orthorhombic system the faces consist of two pairs of different isoceles triangles; the crystal is then termed a rhombic tetrahedron.
The rhombic pyramidal crystal class is thus a member of the orthorhombic crystal system, the tetragonal pyramidal class is a member of the tetragonal crystal system, and the trigonal and hexagonal pyramidal classes are members of the rhombohedral (trigonal) and hexagonal divisions of the hexagonal crystal system respectively.
dave.ucsc.edu /myrtreia/crystal.html   (4278 words)

 Orthorhombic Kristallsystem - Wikipedia, die freie Enzyklopädie
In der Kristallographie ist das orthorhombic Kristallsystem eine der 7 Gitterpunktgruppen.
Orthorhombic vergittert Resultat vom Ausdehnen eines Kubikgitters entlang zwei seiner Gittervektoren durch zwei unterschiedliche Faktoren, mit dem Ergebnis eines rechteckigen Prismas mit einer rechteckigen Unterseite (a durch b, das zu a unterschiedlich ist) und Höhe (c, das zu a und b unterschiedlich ist).
Es gibt vier orthorhombic Bravais-Gitter: einfaches orthorhombic, Unterseite-zentriertes orthorhombic, raumzentriertes orthorhombic und flächenzentriertes orthorhombic. /translate_c?hl=en&ie=UTF-8&oe=UTF-8&langpair=en%7Cde&u=http://en.wikipedia.org/wiki/Orthorhombic&prev=/language_tools   (142 words)

 Alkhalifah: Wave equation for orthorhombic anisotropy
Using a dispersion relation derived under the acoustic medium assumption for P-waves in orthorhombic anisotropic media, I obtain an acoustic wave equation valid under the same assumption.
Although this assumption is physically impossible for anisotropic media, it results in wave equations that are kinematically and dynamically accurate for elastic media.
The orthorhombic acoustic wave equation, unlike the transversely isotropic (TI) one, is a six-order equation with three sets of complex conjugate solutions.
sepwww.stanford.edu /public/docs/sep98/tariq2/paper_html   (146 words)

 Cubic-to-Orthorhombic Transition
The cubic to orthorhombic transition is described by three parameters: three stretches along three mutually perpendicular directions.
The homogeneous deformation that takes a cubic lattice into an orthorhombic lattice has gradient denoted as U which is called a transformation stretch matrix, and for the cubic-to-orthorhombic transition, there are two kinds of such matrices [1].
The transformation stretch matrices are the gradient of the deformations which take a cubic lattice into an orthorhombic lattice.
www.aem.umn.edu /people/faculty/shield/hane/orth.html   (331 words)

 Definition of Orthorhombic   (Site not responding. Last check: 2007-10-14)
Orthorhombic lattices result from stretching a cubic lattice along two of its lattice vectors by two different factors, resulting in a rectangular prism with a rectangular base (a by b, which is different from a) and height (c, which is different from a and b).
There are four orthorhombic Bravais lattices: simple orthorhombic, base-centered orthorhombic, body-centered orthorhombic, and face-centered orthorhombic.
The point groups (or crystal classes) that fall under this crystal system are listed below, followed by their representations in international notation and Schoenflies notation, and mineral examples.
www.wordiq.com /definition/Orthorhombic   (173 words)

 Orthorhombic Titanium Matrix Composite Subjected to Simulated Engine Mission Cycles
Titanium matrix composites (TMC's) are commonly made up of a titanium alloy matrix reinforced by silicon carbide fibers that are oriented parallel to the loading axis.
Orthorhombic titanium aluminide alloys are of particular interest for such TMC applications because their tensile and creep strengths are high in comparison to those of other titanium alloys (ref. 2).
The objective of this investigation was to assess, in simulated mission tests at the NASA Lewis Research Center, the durability of a SiC(SCS-6)/Ti-22Al-23Nb (at.%) TMC for compressor ring applications, in cooperation with the Allison Engine Company.
www.grc.nasa.gov /WWW/RT1996/5000/5120g.htm   (720 words)

 Orthorhombic Crystal System I
One uses to orient the orthorhombic axial system such that one axis is vertical which is then called the c axis.
The system of orthorhombic crystallographic axes and its orientation to the beholder is shown in Figure 1, while the equatorial plane of this axial system is shown in Figure 2.
In the orthorhombic Crystal Class denoted by the Hermann-Mauguin symbol m m 2, for example, the brachy axis is at right angles to a mirror (m), the macro axis is at right angles to a mirror (m), and the vertical axis is a 2-fold rotation axis (2).
metafysica.nl /rhombic_1.html   (5477 words)

The orthorhombic system is based on three unequal axes all at right angles to each other.
The model type crystal is called a disphenoid and is similar to the tetragonal disphenoid of the 22nd and the 24th classes and the tetrahedron of the 31st class.
The orthorhombic disphenoid has scalene triangular faces as opposed to the isosceles triangles of the tetragonal disphenoid and the equalateral triangles of the isometric tetrahedron.
mineral.galleries.com /minerals/symmetry/orthorho.htm   (510 words)

 Axial Ratios, Parameters, Miller Indices   (Site not responding. Last check: 2007-10-14)
So, for example, in 1896 the axial ratios of orthorhombic sulfur were determined to be nearly exactly the same as those reported above from x-ray measurements.
For example, in the orthorhombic crystal shown here, the large dark shaded face is the largest face that cuts all three axes.
To refer to a general face that intersects all three crystallographic axes where the parameters are not known, we use the notation (hkl).
www.tulane.edu /~sanelson/eens211/axial_ratios_paramaters_miller_indices.htm   (1584 words)

 MSD - entry 1lpe
The crystals belong to the orthorhombic space group P2(1)2(1)2(1) and have unit cell dimensions of a = 86.0 A, b = 40.9 A, and c = 53.3 A (1 A = 0.1 nm).
A second orthorhombic crystal form (P2(1)2(1)2(1) with cell dimensions differing from the first form) and a trigonal (P3(1)21) crystal form were also characterized.
The structures of the first orthorhombic and the trigonal form were determined by seleno-methionine multiwavelength anomalous dispersion, and the structure of the second orthorhombic form was determined by molecular replacement using the structure from the trigonal form as a search model.
www.ebi.ac.uk /msd-srv/msdlite/atlas/citation/1lpe.html   (1577 words)

 "MR34A-02" in fm06   (Site not responding. Last check: 2007-10-14)
Orthorhombic perovskites are a major lower mantle constituent whose properties are well studied and still controversial.
While end member properties have been most studied, the effects of the addition of other elements such as iron and aluminum are less known.
We have undertaken the study of several orthorhombic perovskites in order to develop a sensible thermodynamic model.
www.agu.org /cgi-bin/wais?hh=MR34A-02   (251 words)

 Batteries with Orthorhombic Sodium Manganese Oxide Cathodes   (Site not responding. Last check: 2007-10-14)
This material is based on an orthorhombic sodium manganese oxide, and has a capacity of approximately 160 mAh/g in sodium batteries in a voltage range compatible with polymer electrodes (3.4-2.2 V vs. Na).
Berkeley National Laboratory scientists can readily oxidize, reduce or use mild chemical routes to exchange the orthorhombic sodium manganese oxide to form a material suitable for use in lithium rechargeable cells.
The lithiated form of the orthorhombic sodium manganese oxide maintains its structural integrity upon deep discharge and prolonged cycling in lithium cells.
www.zyn.com /flcfw/fwtproj/Batterie.html   (171 words)

 Spartanburg SC | GoUpstate.com | Spartanburg Herald-Journal   (Site not responding. Last check: 2007-10-14)
The pyroxenes are a group of important rock-forming silicate minerals found in many igneous and metamorphic rocks.
They share a common structure comprised of single chains of silica tetrahedra and they crystalise in the monoclinic and orthorhombic system.
There is not complete solid solution in calcum content and Mg-Fe-Ca pyroxenes with calcium contents between about 15 and 25 mol.% are not stable with respect to a pair of exolved crystals.
www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=pyroxene   (876 words)

 Define The Orthorhombic system - Definition of The Orthorhombic system from Free-Online-Dictionary.org   (Site not responding. Last check: 2007-10-14)
Intro to Minerals: Crystal Class and System A lattice is an array of points which define a repeated spatial entity called a unit cell...
For the orthorhombic system, three lengths are required (a and b and c).
Rotation axes of the cube Define the location of the axis used to rotate the cube from the original position to the...
www.free-online-dictionary.org /define-The+Orthorhombic%0D%0A+++++++++system.html   (377 words)

 Solid-State 13C NMR Analyses of the Orthorhombic-to-Hexagonal Phase Transition for Constrained Ultradrawn Polyethylene ...
C upfield compared to the line in the orthorhombic phase.
C chemical shift has revealed that 7% gauche defects are included in the hexagonal phase.
jump rotation around the molecular chain axis is induced in the orthorhombic phase at temperatures near the orthorhombic-to-hexagonal phase transition.
pubs.acs.org /cgi-bin/jtext?mamobx/32/i17/abs/ma990701k   (260 words)

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