Oxygen Release and Incorporation Behaviors Influenced by A-Site Cation Order/Disorder in LaCa2Fe3O9 with Unusually High Valence Fe3.67+

2021 ◽  
Author(s):  
Haichuan Guo ◽  
Midori Amano Patino ◽  
Noriya Ichikawa ◽  
Takashi Saito ◽  
Rei Watanabe ◽  
...  
Keyword(s):  
Oxygen Release ◽  
Cation Order ◽  
A Site

scholarly journals La2SrCr2O7: Controlling the Tilting Distortions of n = 2 Ruddlesden–Popper Phases through A-Site Cation Order

2016 ◽  
Vol 55 (17) ◽  
pp. 8951-8960 ◽  
Author(s):  
Ronghuan Zhang ◽  
Brian M. Abbett ◽  
Gareth Read ◽  
Franz Lang ◽  
Tom Lancaster ◽  
...  
Keyword(s):  
Cation Order ◽  
A Site

Crystal Structure and Anomalous Sintering Behavior of (Sr0.7La0.3)1−xTiO3+δ Perovskites (0 ≤ x ≤ 0.12) Synthesized by the Pechini Method

2012 ◽  
Vol 9 (2) ◽  
Author(s):  
Masashi Mori ◽  
Kaoru Nakamura ◽  
Takanori Itoh
Keyword(s):  
Crystal Structure ◽  
Pore Formation ◽  
Perovskite Phase ◽  
Pechini Method ◽  
Phase Relationship ◽  
Sintering Behavior ◽  
Oxygen Release ◽  
Sintering Characteristics ◽  
Weight Decrease ◽  
A Site

The crystal structure, phase relationship and sintering characteristics of (Sr0.7La0.3)1−xTiO3+δ perovskites (0 ≤ x ≤ 0.12) have been studied using the Pechini method. High-temperature neutron diffraction analysis showed that (Sr0.7La0.3)TiO3+δ has an orthorhombic structure at room temperature and a cubic structure at 450 °C. (Sr0.7La0.3)0.88TiO3+δ showed a single perovskite phase and other samples with an A-site deficiency of 0 ≤ x ≤ 0.08 included secondary Ruddlesden-Popper phases. Sintering characteristics improved as the A-site deficiency increased and it was found that during sintering, (Sr0.7La0.3)0.88TiO3+δ expanded anomalously between 1400 °C and 1500 °C and for holding times between 0 h and 10 h at 1400 °C and 1500 °C. Additionally, observation of the samples by scanning electron microscopy showed that this expansion was caused by pore formation within the samples. All the samples showed a weight decrease at temperatures ≥1000 °C and the temperature at which oxygen release began rose as the A-site deficiency increased. The release of oxygen is likely to be related to pore formation.

A - and B - Site Order in (Na1/2La1/2)(Mg1/3Ta2/3)O3 Perovskites

1998 ◽  
Vol 547 ◽  
Author(s):  
L. Dupont ◽  
L. Chai ◽  
P.K. Davies
Keyword(s):  
Alkaline Earth ◽  
Ferroelectric Properties ◽  
Thermal Treatments ◽  
Ordered Structure ◽  
Site Lattice ◽  
Earth Systems ◽  
Cation Order ◽  
Local Charge ◽  
The Stability ◽  
A Site

AbstractThe “1:2” family of A2+(B2+1/3B+5+2/3)O3 (e.g. B2+ = Mg, Ni, Zn; B5+ = Nb, Ta) mixed metal perovskites typically adopt a 1:2 layered ordered structure when A = Ba and Sr, and a 1:1 ordered doubled perovskite structure for A = Pb. To understand the stability of the cation order in these systems and explore how the different cation correlations affect their dielectric and ferroelectric properties, the response of several members of this family of perovskites to a series of chemical substitutions and thermal treatments have been explored. In this paper we present results for a system where the divalent A cation is replaced by a 1:1 mixture of Na+ and La3+. At all temperatures this substitution stabilizes 1:1 B-site ordering. Below ~ 950°C an additional ordering reaction occurs on the A sub-lattice with Na and La occupying alternate layers along the c axis. The formation of different orientational variants of the A-site ordered phase produces a twinned nano-domain structure which in turn perturbs the length-scale, but not the symmetry, of the order on the B-site lattice. The presence of (Na1/2La1/2) on the A-site is apparently effective in destabilizing the 1:2 layering of the B-site cations observed in alkaline earth systems, possibly through unfavorable local charge imbalances.

Oxygen storage-related properties of substituted BaLnMn2O5+δ A-site ordered manganites

2014 ◽  
Vol 07 (06) ◽  
pp. 1440004 ◽  
Author(s):  
Konrad Świerczek ◽  
Alicja Klimkowicz ◽  
Anna Niemczyk ◽  
Anna Olszewska ◽  
Tomasz Rząsa ◽  
...  
Keyword(s):  
Single Phase ◽  
Storage Capacity ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
Partial Substitution ◽  
Reduction Kinetics ◽  
Cation Order ◽  
Structural Order ◽  
A Site ◽  
Perovskite Type

In this work, we present results showing modification of the oxygen storage-related properties of perovskite-type oxides based on BaYMn 2 O 5+δ, having A-site layer-type cation order. Y 3+ is the lightest among suitable cations, which allows to obtain such the structural order, and at the same time, it provides the highest theoretical oxygen storage capacity. However, substitution of Y 3+ by Sm 3+ cations may be beneficial, and BaY 0.5 Sm 0.5 Mn 2 O 5+δ material shows enhanced reduction kinetics. Furthermore, partial substitution of Ba 2+ by Sr 2+ increases reversible oxygen storage capacity, but at the same time slows down the reduction speed. In addition, for higher concentration of strontium, it is not possible to obtain single phase materials.

scholarly journals Emergence of A-Site Cation Order in the Small Rare-Earth Melilites SrREGa3O7 (RE = Dy–Lu, Y)

2021 ◽  
Author(s):  
Cécile Genevois ◽  
Haytem Bazzaoui ◽  
Marina Boyer ◽  
Sandra Ory ◽  
Yannick Ledemi ◽  
...  
Keyword(s):  
Rare Earth ◽  
Cation Order ◽  
A Site

Eels Under Standing Wave Conditions

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.

Head Size and DNA Content in Bacteriophage T4

1972 ◽  
Vol 30 ◽  
pp. 200-201
Author(s):  
Fred Eiserling ◽  
A. H. Doermann ◽  
Linde Boehner
Keyword(s):  
Electron Microscopy ◽  
Dna Content ◽  
Bacteriophage T4 ◽  
Head Size ◽  
Virus Particles ◽  
Altered Protein ◽  
A Cell ◽  
Bacterial Viruses ◽  
A Site ◽  
Protein Shell

The control of form or shape inheritance can be approached by studying the morphogenesis of bacterial viruses. Shape variants of bacteriophage T4 with altered protein shell (capsid) size and nucleic acid (DNA) content have been found by electron microscopy, and a mutant (E920g in gene 66) controlling head size has been described. This mutant produces short-headed particles which contain 2/3 the normal DNA content and which are non-viable when only one particle infects a cell (Fig. 1).We report here the isolation of a new mutant (191c) which also appears to be in gene 66 but at a site distinct from E920g. The most striking phenotype of the mutant is the production of about 10% of the phage yield as “giant” virus particles, from 3 to 8 times longer than normal phage (Fig. 2).

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