Study of phase components of La1.5Ca1.5Mn2O7

2001 ◽  
Vol 16 (7) ◽  
pp. 2027-2031 ◽  
Author(s):  
J. L. Zhu ◽  
R. C. Yu ◽  
F. Y. Li ◽  
C. Q. Jin ◽  
Z. Zhang
Keyword(s):  
Electron Microscopy ◽  
Direct Evidence ◽  
Perovskite Phase ◽  
Layered Perovskite ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Phase Compound ◽  
Layered Perovskite Structure

The manganate with nominal composition La1.5Ca1.5Mn2O7, which is regarded as a single-phase compound with layered perovskite structure in the literature, was prepared using a standard ceramic process. The structures and morphology of the manganate were investigated by x-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy, and energy-dispersive x-ray microanalysis. However, no direct evidence of layered Sr3Ti2O7-type structure was observed in TEM experiments; instead, we observed multiphase mixtures of an orthorhombically distorted perovskite phase as majority and cubic perovskite phase as minority, as well as a small amount of calcium oxide. The measured magnetic and transport properties of this manganate arise mainly from the presence of hole-doped multiphase perovskite manganates. These physical properties demonstrated again the correctness of our phase component analysis.

scholarly journals Synthesis and application of pigments based on lanthanide orthoferrites

2020 ◽  
Vol 14 (2) ◽  
pp. 161-167
Author(s):  
Patrícia Pimentel ◽  
Jairo Dutra ◽  
Maria Câmara ◽  
Gerbeson Dantas ◽  
Osmar Bagnato ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Perovskite Phase ◽  
Visible Region ◽  
Ceramic Pigments ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Uv Visible ◽  
Cie Lab

In this work, we synthesized oxides with perovskite LnFeO3 type structure (where Ln = La, Pr and Nd), aiming their use as ceramic pigments. The as-synthesized powders, prepared by gelatin method, were thermally treated at 600 and 800 ?C to obtain the perovskite phase. The characterization was performed using X-ray diffraction technique, followed by Rietveld refinement, scanning and transmission electron microscopy, spectroscopy in the UV-Visible region and CIE Lab colorimetry. The calcined powders were also used for fabrication of ceramic pieces to evaluate the colour when 2 wt.% of the powders was added into a transparent glaze. The pigments presented shades ranging from pale brown for the powdered samples to yellowish when applied in the glazes.

Porous LaFeO3 with High Response to Acetone Synthesized from Biotemplates

2013 ◽  
Vol 575-576 ◽  
pp. 20-23 ◽  
Author(s):  
Yu Zhen Ma ◽  
Peng Song ◽  
Qi Wang
Keyword(s):  
Electron Microscopy ◽  
Gas Sensing ◽  
Perovskite Phase ◽  
Spherical Particles ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Microscopy Characterization

Biomorphic porous LaFeO3 samples were prepared using aspen leaves as biotemplates. The structural and microscopy characterization has been carried out with X-ray diffraction, scanning electron microscopy and transmission electron microscopy. XRD patterns confirm thatLaFeO3 shows perovskite phase with orthorhombic structure. The results of SEM and TEM revealed that the the obtained LaFeO3 with hollow and porous structure. And the porous LaFeO3 is composed of spherical particles with the size of 50-80 nm The gas sensing performance of as-prepared LaFeO3 nanocrystlas was investigated. It is found that porous LaFeO3 calcined at 700°C exhibit good sensitivity to acetone with rapid response.

scholarly journals Misfit phase (BiSe)1.10NbSe2 as the origin of superconductivity in niobium-doped bismuth selenide

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Machteld E. Kamminga ◽  
Maria Batuk ◽  
Joke Hadermann ◽  
Simon J. Clarke
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Impurity Phase ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Niobium Doped ◽  
Microscopy Techniques ◽  
Superconducting Behaviour

Abstract Topological superconductivity is of great contemporary interest and has been proposed in doped Bi2Se3, in which electron-donating atoms such as Cu, Sr or Nb have been intercalated into the Bi2Se3 structure. For NbxBi2Se3, with Tc ~ 3 K, it is assumed in the literature that Nb is inserted in the van der Waals gap. However, in this work an alternative origin for the superconductivity in Nb-doped Bi2Se3 is established. In contrast to previous reports, it is deduced that Nb intercalation in Bi2Se3 does not take place. Instead, the superconducting behaviour in samples of nominal composition NbxBi2Se3 results from the (BiSe)1.10NbSe2 misfit phase that is present in the sample as an impurity phase for small x (0.01 ≤ x ≤ 0.10) and as a main phase for large x (x = 0.50). The structure of this misfit phase is studied in detail using a combination of X-ray diffraction and transmission electron microscopy techniques.

The Preparation of Bi-Pb-Sr-Ca-Cu-O Superconducting Powder for Thick Film Pastes

1989 ◽  
Vol 169 ◽  
Author(s):  
J. Hagberg ◽  
A. Uusimäki ◽  
J. Levoska ◽  
S Leppävuori ◽  
R Rautioaho
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Surface Area ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
X Ray ◽  
A Value ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Oxalate Route

AbstractThe oxalate route was used to prepare (Bi-Pb) -Sr-Ca-Cu-O powder with the nominal composition Bi1.75Pb0.4Sr1.3Ca2.1Cu3.2Oy. This powder was decomposed/annealed at different temperatures between 434 and 795°C. They were investigated by thermogravimetric analysis, X-ray diffraction and transmission electron microscopy. Particle size distribution and surface area were also determined. The specific surface area decreased from a value of 16.5 m2/g for powder decomposed at 434 °C to 1.0 m2/g for powder decomposed at 795 °C. The measured mean particle size reached a minimum of 0.52 juri for powder decomposed at 589 °C.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Identification of calcium oxalate crystals in dried or fixed tobacco leaf

1984 ◽  
Vol 42 ◽  
pp. 288-289
Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Growth And Development ◽  
Polarized Light ◽  
Calcium Oxalate Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.

Electron Microscopy/Diffraction Study of the Ternary Mn-Er-S System

1990 ◽  
Vol 48 (1) ◽  
pp. 76-77
Author(s):  
A. R. Landa Canovas ◽  
L.C. Otero Diaz ◽  
T. White ◽  
B.G. Hyde
Keyword(s):  
Electron Microscopy ◽  
Gas Flow ◽  
Graphite Crucible ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Alumina Crucible ◽  
X Ray ◽  
Intermediate Phases ◽  
Twin Band ◽  
Ar Gas

X-Ray diffraction revealed two intermediate phases in the system MnS+Er2S3,:MnEr2S4= MnS.Er2S3, and MnEr4S7= MnS.2Er2S3. Their structures may be described as NaCl type, chemically twinned at the unit cell level, and isostructural with CaTi2O4, and Y5S7 respectively; i.e. {l13} NaCl twin band widths are (4,4) and (4,3).The present study was to search for structurally-related (twinned B.) structures and or possible disorder, using the more sensitive and appropiate technigue of electron microscopy/diffraction.A sample with nominal composition MnEr2S4 was made by heating Mn3O4 and Er2O3 in a graphite crucible and a 5% H2S in Ar gas flow at 1500°C for 4 hours. A small amount of this material was thenannealed, in an alumina crucible, contained in sealed evacuated silica tube, for 24 days at 1100°C. Both samples were studied by X-ray powder diffraction, and in JEOL 2000 FX and 4000 EX microscopes.

The Effect of the Microstructure of Diffusion Barriers on the Palladium Activation for Electroless Copper Deposition

2002 ◽  
Vol 716 ◽  
Author(s):  
Seok Woo Hong ◽  
Yong Sun Lee ◽  
Ki-Chul Park ◽  
Jong-Wan Park
Keyword(s):  
Electron Microscopy ◽  
Diffusion Barriers ◽  
Copper Deposition ◽  
X Ray Diffraction ◽  
Plan View ◽  
X Ray ◽  
Transmission Electron ◽  
Electroless Copper ◽  
Sheet Resistance Measurement ◽  
Scanning Electron

AbstractThe effect of microstructure of dc magnetron sputtered TiN and TaN diffusion barriers on the palladium activation for autocatalytic electroless copper deposition has been investigated by using X-ray diffraction, sheet resistance measurement, field emission scanning electron microscopy (FE-SEM) and plan view transmission electron microscopy (TEM). The density of palladium nuclei on TaN diffusion barrier increases as the grain size of TaN films decreases, which was caused by increasing nitrogen content in TaN films. Plan view TEM results of TiN and TaN diffusiton barriers showed that palladium nuclei formed mainly on the grain boundaries of the diffusion barriers.

Palladium Nanowire Thin Films via Template Growth

2003 ◽  
Vol 775 ◽  
Author(s):  
Donghai Wang ◽  
David T. Johnson ◽  
Byron F. McCaughey ◽  
J. Eric Hampsey ◽  
Jibao He ◽  
...  
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Conductive Substrate ◽  
Palladium Nanowires ◽  
Efficient Route ◽  
Silica Thin Film

AbstractPalladium nanowires have been electrodeposited into mesoporous silica thin film templates. Palladium continually grows and fills silica mesopores starting from a bottom conductive substrate, providing a ready and efficient route to fabricate a macroscopic palladium nanowire thin films for potentially use in fuel cells, electrodes, sensors, and other applications. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicate it is possible to create different nanowire morphology such as bundles and swirling mesostructure based on the template pore structure.

scholarly journals Quartz Crystallite Size and Moganite Content as Indicators of the Mineralogical Maturity of the Carboniferous Chert: The Case of Cherts from Eastern Asturias (Spain)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Celia Marcos ◽  
María de Uribe-Zorita ◽  
Pedro Álvarez-Lloret ◽  
Alaa Adawy ◽  
Patricia Fernández ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallite Size ◽  
Archaeological Sites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Infrared And Raman Spectroscopy ◽  
First Time ◽  
Geological Formations

Chert samples from different coastal and inland outcrops in the Eastern Asturias (Spain) were mineralogically investigated for the first time for archaeological purposes. X-ray diffraction, X-ray fluorescence, transmission electron microscopy, infrared and Raman spectroscopy and total organic carbon techniques were used. The low content of moganite, since its detection by X-ray diffraction is practically imperceptible, and the crystallite size (over 1000 Å) of the quartz in these cherts would be indicative of its maturity and could potentially be used for dating chert-tools recovered from archaeological sites. Also, this information can constitute essential data to differentiate the cherts and compare them with those used in archaeological tools. However, neither composition nor crystallite size would allow distinguishing between coastal and inland chert outcrops belonging to the same geological formations.

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