Last edited by Akinozil
Saturday, July 25, 2020 | History

2 edition of study of pyrochlore found in the catalog.

study of pyrochlore

Adriaan H van der Veen

study of pyrochlore

by Adriaan H van der Veen

  • 155 Want to read
  • 11 Currently reading

Published by Druk van J.J. Groen in Leiden .
Written in English

    Places:
  • Tanzania.
    • Subjects:
    • Nonmetallic minerals -- Tanzania.

    • Edition Notes

      Bibliography: p. 184-188.

      Statement[by] A.H. van der Veen.
      SeriesVerhandelingen van het Koninklijk Nederlands geologisch mijnbouwkundig genootschap. Geologische serie ;, deel 22, 1963.
      Classifications
      LC ClassificationsQE1 .N3492 deel 22
      The Physical Object
      Pagination188, [37] p. :
      Number of Pages188
      ID Numbers
      Open LibraryOL5479698M
      LC Control Number73202560
      OCLC/WorldCa33663583

      The formation of the spin-ice pyrochlore Ho 2 Ge 2 O 7 by two different high temperature, high pressure routes has been explored using in situ neutron diffraction. The first route involves the solid-state reaction of Ho 2 O 3 and GeO 2, and formation of the pyrochlore phase is observed at (27) °C and (2) GPa, which are significantly milder conditions than those previously reported. Pyrochlore Crystallography: Cell Dimensions: a = , Z = 10; V = 1, Den(Calc)= Crystal System: Isometric - Hexoctahedral H-M Symbol (4/m 3 2/m) Space Group: F d3m: X Ray Diffraction.

      Results. We study a sandwich structure consisting of a thin (few atomic layers) Y 2 Ir 2 O 7 film between the non-magnetic, large-gap band insulator Y 2 Hf 2 O 7, as shown in Fig. 1(a).We find quantitatively similar results if La 2 Ir 2 O 7 replaces Y 2 Ir 2 O “capping layers” of Y 2 Hf 2 O 7 serve mainly to stabilize the thin Y 2 Ir 2 O 7 films, but also strain the films and modify Cited by: Subramanian []. Asstatedearlier, the pyrochlores consideredinthis study are formed by combining a trivalent “A” cation and a tetravalent “B” cation although pyrochlores can also form in the A2+ 2B 5+ 2O 7 stoichiometry []. Due to this wide compositional range, pyrochlore compounds have many dif-File Size: 1MB.

      Development of acid-stable electrocatalysts with low overpotential for oxygen evolution reaction (OER) is a major challenge to produce hydrogen directly from water. We report in this paper a pyrochlore yttrium ruthenate (Y2Ru2O7−δ) electrocatalyst that has significantly enhanced performance toward OER in acid media over the best-known catalysts, with an onset overpotential of mV and Cited by:   New stannate pyrochlore based red emitting phosphor materials: CaLa1−x SnNbO7: xEu3+ were prepared by the conventional solid state route and characterized by Powder X-ray diffractometer, scanning electron microscope and fluorescence measurements. Optimization studies by way of varying the calcination temperatures show that CaLaSnNbO7: Eu3+ prepared at 1, °C Cited by:


Share this book
You might also like
Ocma Elec 4 Underground Armoured Cable Protected Against Solvent Penet & Corros Attack

Ocma Elec 4 Underground Armoured Cable Protected Against Solvent Penet & Corros Attack

Change among Indias Harijans: Maharashtra

Change among Indias Harijans: Maharashtra

The Sudanese Bourgeoisie

The Sudanese Bourgeoisie

House prices in the G. L. C. area, 1939-1971

House prices in the G. L. C. area, 1939-1971

Towards new horizons in primate toxicology

Towards new horizons in primate toxicology

Guidebook of the Tyrone-Big Hatchet Mountains-Florida Mountains Region

Guidebook of the Tyrone-Big Hatchet Mountains-Florida Mountains Region

Proceedings of the second Canadian mathematical congress

Proceedings of the second Canadian mathematical congress

economics of online bibliographic searching

economics of online bibliographic searching

art of cartooning

art of cartooning

Jeremiah 21-36

Jeremiah 21-36

Oil & Gas

Oil & Gas

Caviare

Caviare

Understanding the Endtime

Understanding the Endtime

Study of pyrochlore by Adriaan H van der Veen Download PDF EPUB FB2

With the pyrochlore structure' Borodin & Nazarenko () mainiain that this type of defect structure occurs in natural pyrochlore. "tg et at' () extended the pyrochlore series to include betafite rJ a3A-iite wiih the general formula Az-,BzXz'The writer's research *., n"utty complete before these last two publications became Size: 1MB.

Pyrochlore (Ca,Na)2Nb2O6(OH,F) c Mineral Data Publishing, version 1 Crystal Data: Cubic; typically metamict. Point D.D. () A study of pyrochlore and betafite. Can. Mineral., 6, – (4) Perrault, G. () La composition chimique et la structure cristalline du pyrochlore d’Oka, P.Q.

Can. Mineral., 9, – (in File Size: 69KB. Pyrochlore (Na,Ca) 2 Nb 2 O 6 (OH,F) is a mineral group of the niobium end member of the pyrochlore supergroup. The general formula, A 2 Study of pyrochlore book 2 O 7 (where A and B are metals), represent a family of phases isostructural to the mineral pyrochlore.

Pyrochlores are an important class of materials in diverse technological applications such as luminescence, ionic conductivity, nuclear waste Category: Oxide mineral. Pyrochlore magnets have been a playground for the physics of geometrical frustration as the A-site of cubic pyrochlores of the form A 2 B 2 O 7 form a network of corner-sharing tetrahedra, shown in Figure 36 [80].The family of rare earth titanates, R 2 B 2 O 7, has been study of pyrochlore book particular interest, as a range of R 3+ ions can occupy the A-site, and the B-site of the pyrochlore structure is occupied.

Here we report a Raman spectroscopy study of spin dynamics in the all-in-all-out magnetic state of the 5d pyrochlore Cd 2 Os 2 O 7.

Through a comparison between the two-magnon scattering and spin Cited by: Pyrochlore and betafite were investigated from several types of Canadian occurrences. Nine new analyses for 20 constituents and 11 analyses for 8 constituents are presented.

A general formula A xB 16 (O,OH) 48 (F,OH) 8 is proposed for the pyrochlore-betafite series with x representing vacant sites in the unit cell.

Differential thermal and Cited by: H. O’Brien, E. Hyvönen, in Mineral Deposits of Finland, Pyrochlore. Pyrochlore is the third mineral at Sokli providing evidence of a progressively fractionating system (Lee, ).Pyrochlore did not crystallize at Sokli until the magmas evolved to P2C2 compositions, but then it occurs in all later carbonatite magma types.

Using a first-principles electronic band calculation, we obtained a quasi flat-band near the Fermi level for the six pyrochlore oxides, A2B2O7. These quasi flat-bands are mostly characterized by the s-orbitals of the A-site. The band structures of these oxides are well described by the non-interacting Mielke model.

Spin-polarized calculations showed that the ground state of these compounds was Author: Izumi Hase, Takashi Yanagisawa, Kenji Kawashima. I understand the choice of the object of study. These are pyrochlores. I fully agree with authors that “ Pyrochlore oxides denoted by A 2 B 2 O 7 (or A 2 B 2 O 6 O’) have been paid much attention due to their rich variety of physical properties ”.

However, there is another class of oxides materials that are also promising for practical : Izumi Hase, Takashi Yanagisawa, Kenji Kawashima. The study also revealed that high Fe pyrochlore grains appear to be less recoverable than those with a lower Fe content, suggesting that pyrochlore flotation is at least partially linked to a.

The general formula for Pyrochlore is A 2 B 2 O 7, or more accurately: A 2 B 2 O 6 O'. In the case of nominal pyrochlore, F occupies the F' site. Pyrochlore is highly symmetric, and is face-centered.

The easiest way to begin to visualize the structure is by looking at the unit cell with only the F and Ca atoms (the A and O' atoms of the general.

Study of pyrochlore surface chemistry effects on collector adsorption by TOF-SIMS Article in Minerals Engineering December with 22 Reads How we measure 'reads'. @article{osti_, title = {Transmission electron microscopic study of pyrochlore to defect-fluorite transition in rare-earth pyrohafnates}, author = {Karthik, Chinnathambi and Center for Advanced Energy Studies, University Blvd, Idaho Falls, ID and Anderson, Thomas J.

and Gout, Delphine and Ubic, Rick and Center for Advanced Energy Studies, University Blvd, Idaho Falls, ID Author: Karthik, Chinnathambi. Pyrochlore is the more impure mineral of the two because it is more often accepting of the inclusion of elements such as tantalum, titanium, iron and uranium as well as the previously mentioned rare earth metals into its structure.

Some variety names of pyrochlore are known. "Hatchettolite" and "ellsworthite" both contain uranium and come from. The goal of this project is to study the lowest energy states, or ground states, of the classical Heisenberg antiferromagnet on the Pyrochlore lattice.

By a classical Heisenberg an-tiferromagnet, we mean a magnet whose total energy is given by the Heisenberg Hamiltonian, H= 1. Pyrochlore catalysts containing rare earth metals have been used by Ashcroft et al. to study dry-reforming, but their structure was not stable and they observed a breakdown of the pyrochlore structure during the dry-reforming at °C.

In our case, on the other hand, the XRD patterns for spent catalysts after dry- oxy- and bi-reforming Cited by: 9. Pyrochlore Perrierite-(Ce) Zircon Loparite-(Ce) Comments: Reddish black perrierite crystal, with orange-brown pyrochlore crystal, yellow-brown zircon, and grayish-black loparite.

Location: Buer, Bjorkedalen, Langesundfjord, Telemark, Norway. Both of these complexes contain pyrochlore and their SrO content of carbonate minerals ranges from wt.% and wt.% in Leo-Shilman and Sellai Pattai, respectively, consistent with igneous origin for the carbonates of the carbonatites.

We have investigated the structural, electronic, and magnetic properties of the pyrochlore iridates Eu2Ir2O7 and Pr2Ir2O7 using a combination of resonant elastic x-ray scattering, x-ray powder diffraction, and resonant inelastic x-ray scattering (RIXS).

The structural parameters of Eu2Ir2O7 have been examined as a function of temperature and applied pressure, with a particular emphasis on Cited by: Pyrochlore, a complex oxide mineral [(Na, Ca)2Nb2O6(OH,F)] composed of niobium, sodium, and calcium that forms brown to black, glassy octahedral crystals and irregular masses.

Tantalum atoms replace niobium atoms in the chemical structure, so that pyrochlore forms a solid-solution series with the. Much recent experimental progress has been made in the study of magnetic materials made up of antiferromagnetically-coupled magnetic moments residing on networks of corner-sharing tetrahedra.

Such networks of magnetic moments display phenomena known broadly as geometric frustration. They are found in nature in a variety of cubic pyrochlore, spinel and Laves phase Cited by: 1.Pyrochlore definition, a mineral, chiefly composed of niobates of the cerium metals, occurring in syenites in the form of brown crystals.

See more.Pyrochlores a group of minerals, complex oxides containing columbium (niobium) and tantalum. The chemical composition varies; the approximate formula is (Ca, Na, U, Ce, Y)2–m(Nb, Ta, Ti)2O6(OF),–2O.

U, Th, Ce, Y, Fe, and other elements are present in isomorphous admixture form and as adsorbed oxides. Numerous pyrochlore varieties are.