A Pure Bismuth A Site Polar Perovskite Synthesized at Ambient Pressure

The structural and electrical properties of lanthanum copper oxide were examined as a function of Sr addition. It was observed that the lanthanum oxide and copper oxide formed La2CuO4 with K2NiF4 structure when the powder mixture was heated at 800 °C in ambient pressure. Interestingly, the samples of Sr-doped (15∼25%) lanthanum copper oxides showed single perovskite-based phase after being heated at 800 °C. Without Sr addition, a single-perovskite phase of lanthanum copper oxide was observed only under the oxygen pressure as high as 65 kbar. The stabilization of perovskite structure in lanthanum copper oxide was effectively achieved by the addition of Sr. Based on the titration analysis and pertinent defect reactions, the enhancement of perovskite stability was due to the presence of trivalent copper ions that were created to balance the electrical charge of doping ion (SrLa′). With the increasing concentration of trivalent copper ions (or electron holes equivalently) in Sr-doped samples, lanthanum copper oxide also changed from a semiconductor to metallic conductor. When the Sr dopant exceeded its solubility limit of approximately 25% in the A-site sublattice, the Sr-rich second phases, La2SrCu2O6 and Cu2SrO3, appeared and suppressed the electronic conduction drastically.

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Structural, Elastic, and Electronic Properties of Antiperovskite Chromium-Based Carbides ACCr3(A = Al and Ga)

Advances in Condensed Matter Physics ◽

10.1155/2013/136274 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 6

Author(s):

D. F. Shao ◽

W. J. Lu ◽

S. Lin ◽

P. Tong ◽

Y. P. Sun

Keyword(s):

Fermi Level ◽

Density Functional ◽

Ambient Pressure ◽

Experimental Studies ◽

Lattice Parameter ◽

First Principles Calculation ◽

Functional Theory ◽

Multiple Band ◽

A Site ◽

Formation Energies

We theoretically investigated antiperovskite chromium-based carbides ACCr3through the first-principles calculation based on density functional theory (DFT). The structure optimization shows that the lattice parameter of ACCr3is basically proportional to the radius of A-site elements. The calculated formation energies show that AlCCr3and GaCCr3can be synthesized at ambient pressure and are stable with nonmagnetic ground states. Based on the calculation of elastic constants, some elastic, mechanical, and thermal parameters are derived and discussed. AlCCr3and GaCCr3show ductile natures and may have similar thermal properties. From the analysis of the electronic structures, it was found that there are electron and hole bands that cross the Fermi level for AlCCr3and GaCCr3, indicating multiple-band natures. The Fermi level locates at the vicinity of the density of states (DOSs) peak, which leads to a large DOS at Fermi level dominated by Cr-3d electrons. The band structures of AlCCr3and GaCCr3are very similar to those of the superconducting antiperovskite MgCNi3. The similarity may make AlCCr3and GaCCr3behave superconductively, which needs to be further investigated in theoretical and experimental studies.

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Ambient pressure synthesis and properties of LaCu3Fe2TiSbO12: New A-site ordered ferrimagnetic quadruple perovskite

Journal of Solid State Chemistry ◽

10.1016/j.jssc.2021.122433 ◽

2021 ◽

pp. 122433

Author(s):

Lalit Kumar ◽

Joydeep Datta ◽

Sujan Sen ◽

Partha Pratim Ray ◽

Tapas Kumar Mandal

Keyword(s):

Ambient Pressure ◽

Pressure Synthesis ◽

A Site

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Structure and magnetism of the A site scandium perovskite (Sc 0.94 Mn 0.06 )Mn 0.65 Ni 0.35 O 3 synthesized at high pressure

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2013.0012 ◽

2014 ◽

Vol 372 (2013) ◽

pp. 20130012 ◽

Cited By ~ 7

Author(s):

Chris I. Thomas ◽

Matthew R. Suchomel ◽

Giap V. Duong ◽

Andrew M. Fogg ◽

John B. Claridge ◽

...

Keyword(s):

Crystal Structure ◽

High Pressure ◽

Room Temperature ◽

Magnetic Measurements ◽

Ambient Pressure ◽

Oxidation States ◽

Formula Unit ◽

Triclinic Structure ◽

Bond Valence Sum ◽

A Site

Scandium perovskite (Sc 0.94 Mn 0.06 )Mn 0.65 Ni 0.35 O 3 , synthesized at high pressure and high temperature, has a triclinic structure (space group ) at room temperature and ambient pressure with a √2 a p ×√2 a p ×2 a p structure with α ≈90 ° , β ≈89 ° , γ ≈90 ° . Magnetic measurements show that the material displays Curie–Weiss behaviour above 50 K with C =2.11 emu K mol −1 ( μ eff =4.11 μ B per formula unit) and θ =−95.27 K. Bond valence sum analysis of the crystal structure shows that manganese is present in three different oxidation states (+2, +3, +4), with the +2 oxidation state on the A site resulting in a highly tilted perovskite structure (average tilt 21.2 ° compared with 15.7 ° calculated for LaCaMnNbO 6 ), giving the formula .

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Evidence for bulk superconductivity in pure bismuth single crystals at ambient pressure

Science ◽

10.1126/science.aaf8227 ◽

2016 ◽

Vol 355 (6320) ◽

pp. 52-55 ◽

Cited By ~ 71

Author(s):

Om Prakash ◽

Anil Kumar ◽

A. Thamizhavel ◽

S. Ramakrishnan

Keyword(s):

Magnetic Field ◽

Single Crystals ◽

Normal State ◽

Carrier Density ◽

Adiabatic Approximation ◽

Ambient Pressure ◽

Theoretical Work ◽

Critical Magnetic Field ◽

Bulk Superconductivity ◽

Pure Bismuth

At ambient pressure, bulk rhombohedral bismuth is a semimetal that remains in the normal state down to at least 10 millikelvin. Superconductivity in bulk bismuth is thought to be unlikely because of the extremely low carrier density. We observed bulk superconductivity in pure bismuth single crystals below 0.53 millikelvin at ambient pressure, with an estimated critical magnetic field of 5.2 microteslas at 0 kelvin. Superconductivity in bismuth cannot be explained by the conventional Bardeen-Cooper-Schrieffer theory because its adiabatic approximation does not hold true for bismuth. Future theoretical work will be needed to understand superconductivity in the nonadiabatic limit in systems with low carrier densities and unusual band structures, such as bismuth.

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Rapid synthesis, structure and photocatalysis of pure bismuth A-site perovskite of Bi(Mg3/8Fe2/8Ti3/8)O3

Dalton Transactions ◽

10.1039/c3dt53621a ◽

2014 ◽

Vol 43 (24) ◽

pp. 9255-9259 ◽

Cited By ~ 4

Author(s):

Wenjuan Zhang ◽

Jun Chen ◽

Xiaoxin An ◽

Qi Wang ◽

Longlong Fan ◽

...

Keyword(s):

Molten Salt ◽

Molten Salt Synthesis ◽

Rapid Synthesis ◽

Pure Bismuth ◽

A Site

Pure bismuth A-site perovskite Bi(Mg3/8Fe2/8Ti3/8)O3 particles were prepared by a sample molten salt synthesis.

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Eels Under Standing Wave Conditions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054911 ◽

1982 ◽

Vol 40 ◽

pp. 492-495

Author(s):

O.L. Krivanek ◽

J. TaftØ

Keyword(s):

Standing Wave ◽

Wave Conditions ◽

Set Up ◽

A Site ◽

Complex Crystal

It is well known that a standing electron wavefield can be set up in a crystal such that its intensity peaks at the atomic sites or between the sites or in the case of more complex crystal, at one or another type of a site. The effect is usually referred to as channelling but this term is not entirely appropriate; by analogy with the more established particle channelling, electrons would have to be described as channelling either through the channels or through the channel walls, depending on the diffraction conditions.

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