Unveiling the Mechanism of Exsolution of Silver Nanoparticles for Decorating Lanthanum Strontium Ferrite.

Lanthanum strontium ferrite (LaSrAgFeO = 0; LSFO) and its silver-doped derivative (LaSrAgFeO = 0.05; LASFO) are synthesized using mild conditions by a sol-gel method. Both oxides present a perovskite-like structure with orthorhombic symmetry due to octahedral tilting; thus, the incorporation of silver in the A-site does not significantly modify the perovskite structure.

Stability and Evolution of the Crystal Structure of TbBaCoO During Thermal Oxygen Release/Uptake.

A-site ordered double perovskites with the general formula LnBaCoO (where Ln is a lanthanide element) present electrical and electrocatalytic properties that make them attractive as possible ceramic electrode materials for solid oxide cells or alkaline electrolyzers. The properties are highly influenced by the anion vacancy concentration, which is strongly related to the Co-oxidation state, and their location in the structure. Awareness of the stable phases is essential to synthesize, evaluate, and optimize the properties of LnBaCoO oxides at operating conditions in different applications.

Antibacterial Ability of Sodium Hypochlorite Activated with PUI vs. XPF File against Bacteria Growth on Mature Biofilm.

The objectives of the present study were to assess the antibacterial effectiveness of two sodium hypochlorite (NaOCl) concentrations (2.5% and 5.25%) activated by means of two techniques, passive ultrasonic irrigation (PUI) and XP-endo Finisher (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) (XPF) against bacteria growth in intracanal mature biofilm.

3D to 2D Magnetic Ordering of Fe Oxides Induced by Their Layered Perovskite Structure.

The antiferromagnetic behavior of Fe oxides of composition REBaCaFeO, REBaCaFeO, and REBaCaFeO (RE = Gd, Tb) is highly influenced by the type of oxygen polyhedron around the Fe cations and their ordering, which is coupled with the layered RE/Ba/Ca arrangement within the perovskite-related structure. Determination of the magnetic structures reveals different magnetic moments associated with Fe spins in the different oxygen polyhedra (octahedron, tetrahedron, and square pyramid). The structural aspects impact on the strength of the Fe-O-Fe superexchange interactions and, therefore, on the Néel temperature () of the compounds.

Efficacy of EDTA and HEDP Chelators in the Removal of Mature Biofilm of by PUI and XPF File Activation.

Background: Biofilm removal from the root canal during endodontic treatment is necessary to prevent further complications. Irrigation is essential to success. Several irrigants have been proposed without a proper comparison.

Superior Performance as Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cells of the Ruddlesden-Popper = 2 Member EuSrCoFeO with Low Cobalt Content.

The effects of the contents of iron and cobalt on the crystal structure, oxygen content, thermal expansion coefficient, and electrical-electrochemical properties of materials EuSrCoFeO ( = 0.50 and 1.00) are reported.

The Effects of Sr Content on the Performance of NdSrCoO Air-Electrode Materials for Intermediate Temperature Solid Oxide Fuel Cells under Operational Conditions.

The potential of the perovskite system NdSrCoO ( = 1/3 and 2/3) as cathode material for solid oxide fuel cells (SOFCs) has been investigated via detailed structural, electrical, and electrochemical characterization. The average structure of = 1/3 is orthorhombic with a complex microstructure consisting of intergrown, adjacent, perpendicularly oriented domains. This orthorhombic symmetry remains throughout the temperature range 373-1073 K, as observed by neutron powder diffraction.

Unprecedented rock-salt ordering of A and B cations in the double perovskite NdCaMgTiO and defect association.

The partial substitution of up to 5% Nd+3 by Ca+2 results in the oxide Nd1.90Ca0.10MgTiO5.

Novel Perovskite Materials for Thermal Water Splitting at Moderate Temperature.

Materials with the formula Sr CoNb Ti O (x=1.00, 0.70; δ=number of oxygen vacancies) present a cubic perovskite-like structure.

A Critical Review of Existing Criteria for the Prediction of Pyrochlore Formation and Stability.

Depending on intrinsic (e.g., radius ratio rule r/ r) and extrinsic factors (e.

Structure and Electrical-Transport Relations in Ba(Zr,Pr)O Perovskites.

Members of the perovskite solid solution BaZrPrO (0.2 ≤ x ≤ 0.8) with potential high-temperature electrochemical applications were synthesized via mechanical activation and high-temperature annealing at 1250 °C.

Defect Chemistry, Electrical Properties, and Evaluation of New Oxides Sr CoNb Ti O (0≤x≤1) as Cathode Materials for Solid Oxide Fuel Cells.

The perovskite series Sr CoNb Ti O (0≤x≤1) was investigated in the full compositional range to assess its potential as cathode material for solid oxide fuel cell (SOFC). The variation of transport properties and thus, the area specific resistances (ASR) are explained by a detailed investigation of the defect chemistry. Increasing the titanium content from x=0-1 produces both oxidation of Co to Co (from 0 up to 40 %) and oxygen vacancies (from 6.

Structural and microstructural characterization and properties of new phases in the Nd-Sr-Co-(Fe/Mn)-O system as air-electrodes in SOFCs.

New oxides of the (NdSr)MO (M = Co and Mn or Fe) series are reported. Compounds of composition NdSrCoFeO, NdSrCoMnO and NdSrCoMnO are the n = 1 members of the Ruddlesden-Popper homologous series (KNiF structural type) as determined by X-ray diffraction and different transmission electron microscopy techniques. Their crystal structure consists of connected (Co-Fe/Mn)O octahedra blocks separated by (Nd/Sr)O rock-salt like layers along the c-axis.

Effect of Internal Pressure and Temperature on Phase Transitions in Perovskite Oxides: The Case of the Solid Oxide Fuel Cell Cathode Materials of the LaSrCoTiO Series.

The symmetry of the room-temperature (RT) structure of title compounds LaSrCoTiO changes with x, from P2/n (0 ≤ x ≤ 0.2) to Pnma (0.3 ≤ x ≤ 0.

Synthesis of a 12R-type hexagonal perovskite solid solution Sr3NdNb(3-x)Ti(x)O(12-δ) and the influence of acceptor doping on electrical properties.

A solid solution forms for Sr3NdNb(3-x)Ti(x)O(12-δ) with approximate limits 0 ≤ x ≤ 0.06. The system crystallizes with a 12R-type hexagonal perovskite structure in the space group R3, as determined by neutron diffraction and selected area electron diffraction.

Synthesis and characterization of NaNiF3·3H2O: an unusual ordered variant of the ReO3 type.

A new hydrated sodium nickel fluoride with nominal composition NaNiF3·3H2O was synthesized using an aqueous solution route. Its structure was solved by means of ab initio methods from powder X-ray diffraction and neutron diffraction data. NaNiF3·3H2O crystallizes in the cubic crystal system, space group Pn3̅ with a = 7.

Complex magnetic behaviour of Sr2CoNb1-xTixO6 (0 ≤ x ≤ 0.5) as a result of a flexible microstructure.

We report the rich magnetic behaviour of Sr2CoNb1-xTixO6 (0 ≤ x ≤ 0.5) oxides as a result of their complex microstructure. Although these oxides show an average simple-cubic perovskite structure, they present a flexible microstructure due to short-range ordering between Co/Ti and Nb cations in the perovskite B-sites.

A-site sub-stoichiometry and oxygen vacancies as the origin of the electrical properties of Sr2-yLuNb1-xTixO6-δ perovskite-like materials.

Aliovalent substitution of Nb(5+) by Ti(4+) in Sr2LuNbO6 is limited to 10% of Nb atoms. A full structural determination by NPD confirms this and reveals that the structure is better described as a superstructure of the simple cubic perovskite (as previously reported) with the monoclinic cell 2(1/2)ap× 2(1/2)ap× 2ap and β≈ 90° (S.G.

Microwave-assisted synthesis, microstructure, and physical properties of rare-earth chromites.

The full rare-earth (RE) chromites series (RE)CrO(3) with an orthorhombic distorted (Pnma) perovskite structure and the isostructural compound YCrO(3) can be synthesized through a simple microwave-assisted technique, yielding high-quality materials. Magnetization measurements evidence that the Néel temperature for antiferromagnetic Cr(3+)-Cr(3+) ordering strongly depends on the RE(3+) ionic radius (IOR), and a rich variety of different magnetic spin interactions exists. Dielectric spectroscopy on sintered pellets indicates electronic inhomogeneity in all samples as manifested by the presence of at least two dielectric relaxation processes associated with grain boundary and grain interior bulk contributions.

High-pressure investigation of Li2MnSiO4 and Li2CoSiO4 electrode materials for lithium-ion batteries.

In this work, the high-pressure behavior of Pmn2(1)-Li(2)MnSiO(4) and Pbn2(1)-Li(2)CoSiO(4) is followed by in situ X-ray diffraction at room temperature. Bulk moduli are 81 and 95 GPa for Pmn2(1)-Li(2)MnSiO(4) and Pbn2(1)-Li(2)CoSiO(4), respectively. Regardless of the moderate values of the bulk moduli, there is no evidence of any phase transformation up to a pressure of 15 GPa.

Lattice dynamics of β-V2O5: Raman spectroscopic insight into the atomistic structure of a high-pressure vanadium pentoxide polymorph.

We report here the Raman spectrum and lattice dynamics study of a well-crystallized β-V(2)O(5) material prepared via a high-temperature/high-pressure (HT/HP) route, using α-V(2)O(5) as the precursor. Periodic quantum-chemical density functional theory calculations show good agreement with the experimental results and allow one to assign the observed spectral features to specific vibrational modes in the β-V(2)O(5) polymorph. Key structure-spectrum relationships are extracted from comparative analysis of the vibrational states of the β-V(2)O(5) and α-V(2)O(5) structures, and spectral patterns specific to the basic units of the two V(2)O(5) phases are proposed for the first time.

New perovskite materials of the La(2-x)Sr(x)CoTiO6 series.

Substitution of La(3+) by Sr(2+) in the double perovskite La(2)CoTiO(6) yields materials of the La(2-x)Sr(x)CoTiO(6) series showing a significant amount of trivalent cobalt ions when prepared at ambient atmosphere. The as-prepared compounds can be reduced in severe conditions retaining the perovskite structure while inducing the formation of a large amount of oxygen vacancies. The limit of aliovalent substitution in this series was found to extend up to x = 1.

Insight into ramsdellite LI(2)Ti(3)O(7) and its proton-exchange derivative.

Despite being proven to be a good lithium-ion conductor 30 years ago, the crystal structure of the ramsdellite-like Li(2)Ti(3)O(7) has remained uncertain, with two potential models for locating the lithium ions in the structure. Although the model presently accepted states that both lithium and titanium occupy the octahedral sites in the framework, evidence against this model are provided by (6)Li and (7)Li MAS NMR spectroscopy. Thus, about 14% of these octahedral positions are empty since no lithium in octahedral coordination is present in the material.

Structural characterization and NMR study of NaNbWO(6) and its proton-exchanged derivatives.

The structural characterization of NaNbWO(6), prepared by the ceramic route, has been performed. Electron diffraction has shown the presence of two related phases in a 1:1 ratio, whose lattice parameters correspond to those of the well-known tetragonal tungsten bronzes (TTB) and those of a monoclinically distorted phase. In addition to basic unit cells, the morphology of the two phases has been found to be similar, but they present a slight difference in the W/Nb ratio.