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.

scholarly journals Ceramic-Reinforced γ-TiAl-Based Composites: Synthesis, Structure, and Properties

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 629 ◽  
Author(s):  
Daria Lazurenko ◽  
Andreas Stark ◽  
Maksim Esikov ◽  
Jonathan Paul ◽  
Ivan Bataev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Compressive Strength ◽  
Creep Behavior ◽  
Longitudinal Direction ◽  
Max Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intermediate Phases ◽  
Plasma Sintering ◽  
The Matrix

In this study, new multilayer TiAl-based composites were developed and characterized. The materials were produced by spark plasma sintering (SPS) of elemental Ti and Al foils and ceramic particles (TiB2 and TiC) at 1250 °C. The matrix of the composites consisted of α2-TiAl and γ-TiAl lamellas and reinforcing ceramic layers. Formation of the α2 + γ structure, which occurred via a number of solid–liquid and solid–solid reactions and intermediate phases, was characterized by in situ synchrotron X-ray diffraction analysis. The combination of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis revealed that an interaction of TiC with Ti and Al led to the formation of a Ti2AlC Mn+1AXn (MAX) phase. No chemical reactions between TiB2 and the matrix elements were observed. The microhardness, compressive strength, and creep behavior of the composites were measured to estimate their mechanical properties. The orientation of the layers with respect to the direction of the load affected the compressive strength and creep behavior of TiC-reinforced composites. The compressive strength of samples loaded in the perpendicular direction to layers was higher; however, the creep resistance was better for composites loaded in the longitudinal direction. The microhardness of the composites correlated with the microhardness of reinforcing components.

scholarly journals Structural and In Situ X-ray Diffraction Study of Hydrogenation of CaxMg1−xNi2 (0 ≤ x ≤ 1)

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 47
Author(s):  
Zia Ur Rehman ◽  
Mohsan Nawaz ◽  
Hameed Ullah ◽  
Pervaiz Ahmad ◽  
Mayeen Uddin Khandaker ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Powder Diffraction ◽  
Gas Flow ◽  
Hydrogen Gas ◽  
Laves Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Type ◽  
Diffraction Patterns

In the quasi-binary system CaNi2-MgNi2 solid-solutions CaxMg1−xNi2 (0 ≤ x ≤ 1) were prepared from the elements. They crystallize in the hexagonal Laves phase type (MgNi2, C36) for x ≤ 0.33 (P63/mmc, a = 482.51(7) pm, c = 1582.1(3) pm for x = 0, a = 482.59 (3), c = 1583.1(1) for x = 0.33) and in the cubic Laves phase type (MgCu2, C15) for 0.33 < x (Fd−3m, a = 697.12(3) pm for x = 0.5, a = 705.11(2) pm for x = 0.67, a = 724.80(2) pm for x = 1). After hydrogenation in an autoclave the X-ray diffraction patterns changed completely. Reflections assigned to CaNiH3, and Ni and Rietveld refinement confirmed this. The hydrogenation properties of CaxMg1−xNi2 (0 ≤ x ≤ 1) compounds were also studied in situ by X-ray powder diffraction. In situ X-ray powder diffraction of CaxMg1−xNi2 (0 ≤ x ≤ 1) compounds under 0.3 MPa hydrogen gas flow (15 sccm), data collected on a Rigaku SmartLab diffractometer in an Anton Paar XRK 900 Reactor Chamber using Cu-Kα1 radiation. Scanning electron microscopy and EDX spectroscopy confirmed the entitled materials and elemental composition, respectively. From the Transmission electron microscopy and Selected area electron diffraction concluded that the CaxMg1−xNi2 (0 ≤ x ≤ 1) compounds were crystalline.

Effects of V2O5 on the synthesis of Ba2Ti9O20 powders

2005 ◽  
Vol 20 (10) ◽  
pp. 2741-2744 ◽  
Author(s):  
Huixing Lin ◽  
Wei Chen ◽  
Lan Luo
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Scanning Electron Microscopy ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Eutectic Liquid ◽  
X Ray ◽  
Intermediate Phases ◽  
Phase Pure ◽  
Scanning Electron

Phase-pure Ba2Ti9O20 powders were made by doping 3 wt% of V2O5 to a Ba:Ti = 2:9 molar composition, and the effects of the dopant on the phase formation were investigated. The study shows that BaTiO3, BaTi2O5, and BaTi4O9 were the intermediate phases before the formation of Ba2Ti9O20 for samples with or without V2O5. However, with V2O5 doping, the temperature at which Ba2Ti9O20 occurred were lowered from 1150 to 1050 °C and single phase Ba2Ti9O20 powders was easily obtained at 1150 °C for 2 h. Microstructure of the powders was examined by field emission scanning electron microscopy. No evidence of V2O5–Ba2Ti9O20 solid-solution was found by x-ray diffraction and energy-dispersive spectroscopy. The benefit of V2O5 to facilitate the Ba2Ti9O20 synthesis is most probably due to a vanadium-containing eutectic liquid phase which accelerates the migration of reactant species.

Morphological and structural evolutions of nonequilibrium titanium-nitride alloy powders produced by reactive ball milling

1992 ◽  
Vol 7 (4) ◽  
pp. 888-893 ◽  
Author(s):  
M. Sherif El-Eskandarany ◽  
K. Sumiyama ◽  
K. Aoki ◽  
K. Suzuki
Keyword(s):  
Electron Microscopy ◽  
Titanium Nitride ◽  
Gas Flow ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Nitrogen Gas ◽  
X Ray ◽  
Grain Sizes ◽  
Transmission Electron

Nonequilibrium titanium-nitride alloy powders have been fabricated by a high energetic ball mill under nitrogen gas flow at room temperature and characterized by means of x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. Initial hcp titanium is completely transformed to nonequilibrium-fcc Ti–N after 720 ks of the milling time. The fcc Ti–N phase is stable at relatively low temperature and transforms at 855 K to Ti2N and δ phases. At the final stage of milling, the particle- and grain-sizes of alloy powders are 1 mm and 5 nm, respectively, and the lattice parameter is 0.419 nm.

Microwave Synthesis of BaTiO3 from BaCO3 and TiO2

2007 ◽  
Vol 336-338 ◽  
pp. 669-671
Author(s):  
Yan Yi Liu ◽  
Wei Pan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Microwave Oven ◽  
X Ray Diffraction ◽  
X Ray ◽  
Batio3 Powder ◽  
Domestic Microwave Oven ◽  
Intermediate Phases ◽  
Different Temperatures ◽  
Scanning Electron

BaTiO3 powder was synthesized from BaCO3 and TiO2 using a domestic microwave oven. The samples were synthesized under different temperatures with various holding times. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to examine the phase compositions and morphologies of the result samples. The main phase obtained at 950°C was BaTiO3, and the intermediate phases Ba2TiO4 and Ba4TiO9 were also detected. The pure, well-crystallized BaTiO3 powder could be obtained at 1050°C within 10 minutes and the particle size ranged from 300~500nm. In comparison with conventional synthesis, faster speed and finer grains could be achieved through microwave heating.

Pedogenic alteration of illite in subtropical China

Clay Minerals ◽  
2014 ◽  
Vol 49 (3) ◽  
pp. 379-390 ◽  
Author(s):  
W. Han ◽  
H. L. Hong ◽  
K. Yin ◽  
G. J. Churchman ◽  
Z. H. Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Mixed Layer ◽  
X Ray Diffraction ◽  
Subtropical China ◽  
X Ray ◽  
Intermediate Phases ◽  
Transmission Electron ◽  
Red Earth ◽  
Layer I

AbstractPedogenic alteration of illite from red earth sediments in Jiujiang in subtropical China was investigated using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Illite, hydroxy-interlayered vermiculite (HIV), kaolinite and mixed-layer illite-HIV (I-HIV) are present in the soils. The characteristic reflections of the clay phases were 14 Å, 10–14 Å, 10 Å, and 7 Å, respectively. After Mg-glycerol saturations, the 14 Å peak of the samples did not expand, and after heating at 350°C and 550°C it shifted to 13.8 Å and 12 Å respectively, with no residual 14 Å reflection, suggesting the occurrence of hydroxy-interlayered vermiculite. The randomly interstratified I-HIV clays were characterized by a broad peak at 10–14 Å, which did not change its position after Mg-glycerol saturation, but collapsed to 10 Å after heating at 350°C and 550°C. HRTEM analysis showed different lattice fringes of 12 Å, 10 Å and 7 Å . Mixed-layer I-HIV, HIV-K and illite-kaolinite (I-K) were observed in the HRTEM images which represented the intermediate phases during illite alteration. The merging of two 10 Å illite layers into a 12 Å HIV layer, lateral transformation of one HIV layer into one kaolinite layer and alteration of one illite layer into two kaolinite layers illustrated the mechanisms of illite-to-HIV, HIV-to-kaolinite and illite-tokaolinite transformation, respectively. The proposed pedogenic alteration of illite and the weathering sequence of the clay minerals in Jiujiang is illite → I-HIV → HIV → HIV-K → kaolinite. In addition, illite may transform directly to kaolinite.

Characteristics of TlBa2Ca2Cu3O9+δ powder as-synthesized and after grinding

1993 ◽  
Vol 8 (4) ◽  
pp. 713-719 ◽  
Author(s):  
P.J. Kung ◽  
M.P. Maley ◽  
P.G. Wahlbeck ◽  
D.E. Peterson
Keyword(s):  
Electron Microscopy ◽  
Magnetic Hysteresis ◽  
Weak Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intermediate Phases ◽  
Transmission Electron ◽  
Dependent Behavior ◽  
Field Dependent ◽  
Powder In Tube

Crystal structure and superconductivity of the Tl–Ba–Ca–Cu–O powder prepared by a solid-state reaction were studied. The results of x-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses indicate that the powder of a major single 1223 phase was synthesized with a cauliflower-like morphology; by grinding, the powder was partially transformed to an amorphous phase. The measurement of magnetic hysteresis was also performed in the temperature range of 7–75 K up to 5 T from which the weak field-dependent behavior of critical current density was observed. The as-synthesized powder, with Tc = 110 K measured from magnetometer and susceptometer, is considered to consist of weak-linked regions. The results obtained from comparing the as-synthesized and the ground powder imply that in the Tl-1223 system, the Ag-sheathed tapes fabricated by the powder-in-tube process may be benefited by forming other intermediate phases with plate-like morphologies to give better densification or grain alignment.

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.

Formation of U-type hexaferrites

2004 ◽  
Vol 19 (8) ◽  
pp. 2462-2470 ◽  
Author(s):  
Darja Lisjak ◽  
Darko Makovec ◽  
Miha Drofenik
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Stacking Faults ◽  
High Energy ◽  
Structural Defects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcination Temperatures ◽  
Intermediate Phases ◽  
Transmission Electron

The formation of U-type hexaferrites with the composition Ba4B2Fe36O60 (B = Co, Ni, Zn) was studied. Samples were characterized by means of x-ray diffraction, electron microscopy (with energy-dispersive spectroscopy), and thermogravimetric and thermomagnetic analyses. U-hexaferrites are formed from the intermediate phases M-hexaferrite (BaFe12O19) and Y-hexaferrite (Ba2B2Fe12O22), which at the same time represent units in the U-hexaferrites’ crystal structure. The preparation of monophase U-hexaferrites was made possible by combining high-energy milling or chemical coprecipitation with a calcination at 1250–1300 °C. Structural defects, such as stacking faults, were observed in monophase samples with a high-resolution transmission electron microscope. The observed defects can be regarded as seeds for the formation of other hexaferrite phases after prolonged calcination times or higher calcination temperatures.

ELECTRON MICROSCOPY STUDY OF THE SUPERCONDUCTOR “Bi2Sr2CaCu2O8+δ”

1988 ◽  
Vol 02 (01) ◽  
pp. 491-500 ◽  
Author(s):  
M. HERVIEU ◽  
C. MICHEL ◽  
B. DOMENGES ◽  
Y. LALIGANT ◽  
A. LEBAIL ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Double Perovskite ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Perovskite Layer ◽  
X Ray ◽  
Crystal Electron

The structural study of the superconductor Bi 2 Sr 2 CaCu 2 O 8+δ was performed by X-ray diffraction on a single crystal, electron diffraction and electron microscopy. The structure of this oxide which crystallizes in the space group Amaa, with [Formula: see text] and c≃30.7 Å can be described as an intergrowth of an oxygen deficient double perovskite layer [Sr2CaCu2O6]∞ with ( BiO y)2 layers. The E.D. patterns show the existence of satellites in incommensurate positions. The HREM images and their simulation suggest that the [BiOy]∞ layers are not [ Bi 2 O 2] Aurivillius type layers. Modulations along the a axis and much more rarely along b are observed. Stacking defects are rarely observed along c: they correspond to the intergrowth of a phase Bi 2 Sr 2 CuO 6+δ which is assumed to be the superconductor at 22K previously detected for the nominal composition “ Bi 2 Sr 2 Cu 2 O 7”.

Sign in / Sign up

Export Citation Format

Share Document