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Topic: Perovskite Structure


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In the News (Thu 25 Apr 19)

  
  Perovskite - Wikipedia, the free encyclopedia
Perovskite is found in contact metamorphic rocks and associated mafic intrusives, nepheline syenites, and rare carbonatites.
Perovskite was discovered in the Ural mountains of Russia by Gustav Rose in 1839 and named for Russian mineralogist, L. Perovski (1792-1856).
Perovskite is also the name of a more general group of crystals which take the same structure.
en.wikipedia.org /wiki/Perovskite   (256 words)

  
 Crystal structure - Wikipedia, the free encyclopedia
A crystal structure is composed of a unit cell, a set of atoms arranged in a particular way; which is periodically repeated in three dimensions on a lattice.
The crystal structure of a material is often discussed in terms of its unit cell.
The space group of the crystal structure is composed of the translational symmetry operations in addition to the operations of the point group.
en.wikipedia.org /wiki/Crystal_structure   (1142 words)

  
 FD1
perovskite is believed to be the predominant phase in the Earth's lower mantle, and as such is the most prevalent terrestrial silicate.
1.2 Examine a ball-and-spoke model of perovskite and identify the A and B atoms and the rotation axes parallel to [111].
On transforming to the low-temperature structure the possible domain orientations are as indicated in Fig.
www.msm.cam.ac.uk /phase-trans/abstracts/GD1.htm   (1200 words)

  
 [No title]
ÒThermal conductivity of magnetic perovskites: colossal magnetoresistance as a lattice-dynamics transistion.Ó 78.20 (1997): 3947 3950.
ÒThe observation of a surface resonane state in the valence-band structure of the perovskite La0.65Ba0.35MnO3.Ó 9 (1997): 1031-1038.
Ferromagnetic compounds of manganese with perovskite structure.Ó 82.3 (1951): 403-405.
www.tcd.ie /Physics/People/Michael.Coey/oxsen/biblio/bbl.txt   (4690 words)

  
 Geos 306, Fall 2004, Lecture 11, The Lower Mantle
The structure type is quite important in industry because it is the proto-type structure for the high-temperature superconductors.
The NiAs structure is the hcp equivalent to the ccp rock salt structure.
As pressure is increased, Fe-Fe bonding dominates to the extent that O is removed from the structure altogether.
www.geo.arizona.edu /xtal/geos306/fall04-11.htm   (517 words)

  
 Materials Chemistry - Superconductors   (Site not responding. Last check: 2007-10-23)
In this stage the crystalline structure is formed by the interdiffusion of ions, but it has a deficit of oxygen (dÅ 0.5).
X-ray and neutron diffraction studies were most important in the elucidation of the 1-2-3 oxide structure, which belongs to a crystal family known as perovskites.
This structure is made up by corner sharing of TiO6 octahedra with Ca ions in the large cavities at the corners of the unit cell.
imr.chem.binghamton.edu /labs/super/superc.html   (2059 words)

  
 GdFeO3 (Perovskite)   (Site not responding. Last check: 2007-10-23)
The GdFeO3 structure is a distorted form of perovskite.
It occurs when the A-site cation is too small for its 12 coordinate cavity in the cubic perovskite structure.
This distortion of the perovskite structure is the predominant for perovskites with tolerance factors smaller than ~0.98 (the best way to calculate tolerance factors is to use 12-coordinate radii for the A-site cation, 6-coordinate radii for the M-site cation, and 2-coordinate radii for the anion).
www.chemistry.ohio-state.edu /~woodward/ch754/struct/GdFeO3.htm   (335 words)

  
 [No title]   (Site not responding. Last check: 2007-10-23)
The crystal structure of CaGeO3 perovskite and the crystal chemistry of the GdFeO3-type perovskites
Structural Characterization of R2BaCuO5 (R=Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Eu and Sm) Oxides by X-ray and Neutron Diffraction
Structural and Thermodynamic Characterization of the Perovskite-Related Ba(1+y)UO3+x and (Ba,Sr)1+yUO3 Phases
www.chemistry.ohio-state.edu /~mlufaso/spuds/reference.html   (4684 words)

  
 [No title]
The crystal structure of Sr2LaFe3O8.94 at room temperature and 50K" Journal of Solid State Chemistry 84 271-279 (1990) 189.
"Structural tuning of the colossal magnetoresistance of ferromagnetic perovskites" (pp) 303.
Ferromagnetic compounds of manganese with perovskite structure" Phys.
tcd.ie /Physics/People/Michael.Coey/oxsen/biblio/biblio_oxides_0197.txt   (1562 words)

  
 Mineral Gallery - THE PEROVSKITE GROUP   (Site not responding. Last check: 2007-10-23)
First, every member of this group has rare earth metals as trace elements in their structures and second, the structure of this group is unique and many ceramic, synthetic and useful substances can be created using the structure.
In the mineral perovskite's case, each oxygen (-2 charge) is connected to two titanium ions which have a charge of (+4) and are in themselves connected to six oxygens for a ratio of 1/3.
The result is a variety of symmetries from isometric to tetragonal to orthorhombic to monoclinic depending on the degree of distortion to the basic ideal structure.
mineral.galleries.com /minerals/OXIDES/perovski.htm   (453 words)

  
 [No title]
perovskite: Evidence for structural phase transitions and implications for the lower mantle, J.
Nekvasil, H., and W.J. Carroll, Experimental constraints on the high-temperature termination of the anhydrous 2 feldspar + L curve at 11.3 kbar, Amer.
Parise, J.B., Structural case studies of inclusion phenomena in zeolites: Xe in RHO and stilbene in ZSM-5, J.
www.mpi.stonybrook.edu /Publications/ByYear.html   (7060 words)

  
 Geos 306, Fall 2005, Lecture 11, The Lower Mantle
Candidate phases for the lower mantle are found by fitting the seismic data to crystallographic data.
The volume abundance's are in the order of 20 % magnesio-wüstite, and the rest adopts the perovskite structure, with a small amount of free silica in the form of stishovite.
perovskite is the most abundant mineral in the earth, since the lower mantle is the largest part of the earth.
www.geo.arizona.edu /xtal/geos306/fall05-11.htm   (535 words)

  
 Oxide Structures & Networks
Rationalize the structures of Non-Metallic elements from the 8-N rule and the concept of Network Connectivity
The structures differ in the structure of the 'filling' in the 'sandwich' of copper oxide layers - known as
fullerene's solid structure is not fully described by the network approach, we must also consider the arrangement of C
www.chem.ox.ac.uk /icl/heyes/structure_of_solids/Lecture4/Lec4.html   (440 words)

  
 l1_qstb2
One quarter of silicon atoms octahedrally co-ordinated and 10% increase in density of pyroxene.
Garnet transforms to perovskite structure, pyroxene transforms to spinel structure.
All the minerals have a very compact perovskite structure.
www.le.ac.uk /gl/art/gl209/lecture1/qsts/l1_qstsb.html   (292 words)

  
 Functional and Smart Materials - Structural Evolution and Structure Analysis
Description: This book describes several crystal structure systems that are frequently observed in oxide functional materials, examining basic modules that are the building blocks of all related structures.
Links the structural evolution of each system with mixed valences of rare-earth and transitional metal elements.
Early chapters describe structure types such as rock, salt, and rutile, with an emphasis on connection among different structure systems.
www.knovel.com /knovel2/Toc.jsp?BookID=906   (504 words)

  
 ISODISPLACE example
Since the structure is cubic, we only need to enter the value for a.
If we had this file at the beginning, we could have entered the information about the parent structure by simply uploading this file instead of entering the information manually.
The heavy gray lines in the drawing indicate the outlines of the unit cell of the distorted structure (I4/mcm) and the unit cell of the original parent structure (Pm-3m).
stokes.byu.edu /iso/isodisplaceexample.html   (1675 words)

  
 Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations   (Site not responding. Last check: 2007-10-23)
An attempt was made to produce ferromagnetics with Perovskite structure using LaFeO/sub 3/-Sr(Ni/sub 0.5/W/sub 0.5/) O/sub 3/.
The first compound has antiferromagnetic properties, while the second is a paramagnetic with ordered Ni/sup 2+/ and W/sup 6+/ ion distribution in octahedric positions.
The polyerystalline specimens were prepared from finely crushed oxides, twice annealed at 1100 and 1350 deg C. An x-ray-diffraction analysis indicates a solid solution of Perovskite structure.
www.osti.gov /energycitations/product.biblio.jsp?osti_id=4792680   (177 words)

  
 Find in a Library: Perovskite : a structure of great interest to geophysics and materials science
Find in a Library: Perovskite : a structure of great interest to geophysics and materials science
Perovskite : a structure of great interest to geophysics and materials science
WorldCat is provided by OCLC Online Computer Library Center, Inc. on behalf of its member libraries.
worldcatlibraries.org /wcpa/ow/ddd4eac31d9e6b77a19afeb4da09e526.html   (83 words)

  
 Magnetic phase transitions in the bismuth-containing manganites with perovskite structure
Magnetic phase transitions in the bismuth-containing manganites with perovskite structure
The results are explained in terms of the superexchange interaction via anions and local distortions of the crystal structure.
In particular, reselling and systematic downloading of files is prohibited.
stacks.iop.org /0953-8984/8/11205   (238 words)

  
 The Cubic Perovskite (E2_1) Structure
Cubic Perovskite is actually the high temperature phase of the compounds listed below.
By removing one atom type we get various structures, all with space group
Removing the Calcium or Titanium and the Oxygen atoms leads to the
cst-www.nrl.navy.mil /lattice/struk/e2_1.html   (169 words)

  
 [No title]
Structure of Bi4Ti3O12, Arkiv för kemi 1, 463 (1949).
Physical properties for some compounds exhibiting the perovskite type structure.
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www.fos.su.se /~fredrik/thesis.doc   (390 words)

  
 Polymorf - Knowhwere- Perovskite   (Site not responding. Last check: 2007-10-23)
In the perovskite structure 25% of the octahedral voids of each successive layer of
(calcium titanium oxide, perovskite) (Ti - A ; O, Ca - X)
The lattice model demonstrates the FCC staggering order of the TiO
www.polymorf.net /matter43.htm   (160 words)

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