High-temperature phases of NaNbO3 and NaTaO3

1999 ◽  
Vol 55 (1) ◽  
pp. 24-30 ◽  
Author(s):  
C. N. W. Darlington ◽  
K. S. Knight
Keyword(s):  
High Temperature ◽  
Structural Changes ◽  
Single Phase ◽  
Phenomenological Theory ◽  
Single Temperature ◽  
Neutron Spallation Source ◽  
Structure Determinations ◽  
Spallation Source ◽  
Diffraction Patterns ◽  
First Time

The high-temperature phases of the perovskites sodium niobate, NaNbO3, and sodium tantalate, NaTaO3, have been re-examined using the high-resolution powder diffractometer HRPD at the ISIS neutron spallation source; the two materials show the same sequence of phases with tilted octahedra. Diffraction patterns were measured every 5 K allowing structural changes with temperature within a single phase to be determined for the first time. Previous structure determinations within one phase had been performed at a single temperature only. The octahedra are tilted about pseudocubic \langle100\rangle directions and are also deformed; the magnitude of the deformation is shown to be proportional to the square of the angle of tilt as expected from a phenomenological theory applied to such transitions. The structures of NaNbO3 between 753 and 793 K and of NaTaO3 below 758 K are not as reported in the literature.

Structural Changes of Liquid Pb-Bi Eutectic Alloy

2012 ◽  
Vol 706-709 ◽  
pp. 878-883 ◽  
Author(s):  
Paolo Deodati ◽  
Franco Gauzzi ◽  
Roberto Montanari ◽  
Alessandra Varone
Keyword(s):  
Dynamic Modulus ◽  
Structural Changes ◽  
Distribution Functions ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
Neutron Spallation Source ◽  
Driven System ◽  
Spallation Source ◽  
Accelerator Driven System ◽  
Diffraction Patterns

Liquid Pb–Bi eutectic (LBE) alloy has been selected as coolant and neutron spallation source for the development of MYRRHA, an accelerator driven system (ADS). The alloy has been characterized in liquid state from melting (125 °C) to 750 °C by mechanical spectroscopy, i.e. internal friction (IF) and dynamic modulus measurements. The experiments have been carried out using hollow reeds of austenitic stainless steel filled with Pb-Bi alloy and sealed at the extremities. Dynamic modulus showed a remarkable drop in the range 350-520 °C. In the same temperature range radial distribution functions (RDFs), determined from X-ray diffraction patterns, evidenced variations of the mean distance between the 1st nearest neighbour atoms. The phenomenon has been explained as a structural re-arrangement of atoms in the liquid metal.

Mechanical Spectroscopy Investigation of Liquid Pb-Bi Alloys

2012 ◽  
Vol 184 ◽  
pp. 434-439 ◽  
Author(s):  
Roberto Montanari ◽  
Alessandra Varone
Keyword(s):  
Distribution Functions ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
X Ray ◽  
Neutron Spallation Source ◽  
Driven System ◽  
Spallation Source ◽  
Accelerator Driven System ◽  
The Mean ◽  
Diffraction Patterns

Liquid Pb–Bi eutectic alloy has been selected as coolant and neutron spallation source for the development of MYRRHA, an accelerator driven system. The alloy has been characterized in liquid state from melting (125 °C) to 650 °C by mechanical spectroscopy. Experiments have been carried out using hollow reeds of austenitic stainless steel filled with the Pb-Bi alloy and sealed at the extremities. From 350 °C to 520 °C modulus shows a remarkable drop accompanied by a broad internal friction maximum. In the same temperature range radial distribution functions, determined from X-ray diffraction patterns, evidenced variations of the mean distance between the 1st nearest neighbour atoms. The anelastic phenomena have been attributed to a structural re-arrangement of liquid metal. For comparison, other alloys of the Pb-Bi system with hypo-eutectic composition have been investigated.

scholarly journals 4D Bragg Edge Tomography of Directional Ice Templated Graphite Electrodes

2020 ◽  
Vol 6 (12) ◽  
pp. 136
Author(s):  
Ralf F. Ziesche ◽  
Anton S. Tremsin ◽  
Chun Huang ◽  
Chun Tan ◽  
Patrick S. Grant ◽  
...  
Keyword(s):  
Li Ion Battery ◽  
Graphite Electrodes ◽  
Neutron Spallation Source ◽  
Spallation Source ◽  
Li Ion ◽  
Tomography Method ◽  
First Time ◽  
Pulsed Neutron ◽  
Tomography Data ◽  
Insight Into

Bragg edge tomography was carried out on novel, ultra-thick, directional ice templated graphite electrodes for Li-ion battery cells to visualise the distribution of graphite and stable lithiation phases, namely LiC12 and LiC6. The four-dimensional Bragg edge, wavelength-resolved neutron tomography technique allowed the investigation of the crystallographic lithiation states and comparison with the electrode state of charge. The tomographic imaging technique provided insight into the crystallographic changes during de-/lithiation over the electrode thickness by mapping the attenuation curves and Bragg edge parameters with a spatial resolution of approximately 300 µm. This feasibility study was performed on the IMAT beamline at the ISIS pulsed neutron spallation source, UK, and was the first time the 4D Bragg edge tomography method was applied to Li-ion battery electrodes. The utility of the technique was further enhanced by correlation with corresponding X-ray tomography data obtained at the Diamond Light Source, UK.

scholarly journals One-step ultra-rapid fabrication and thermoelectric properties of Cu2Se bulk thermoelectric material

RSC Advances ◽  
2019 ◽  
Vol 9 (19) ◽  
pp. 10508-10519 ◽  
Author(s):  
Tiezheng Hu ◽  
Yonggao Yan ◽  
Si Wang ◽  
Xianli Su ◽  
Wei Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermoelectric Properties ◽  
Single Phase ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Thermoelectric Energy ◽  
Rapid Fabrication ◽  
One Step ◽  
First Time

Cu2Se is a promising material for thermoelectric energy conversion. Fully dense single-phase bulk Cu2Se was prepared by the combination of self-propagating high-temperature synthesis with in situ quick pressing for the first time.

Reduced-pressure MOCVD of highly crystalline BaTiO3 thin films

1992 ◽  
Vol 7 (3) ◽  
pp. 542-545 ◽  
Author(s):  
Peter C. Van Buskirk ◽  
Robin Gardiner ◽  
Peter S. Kirlin ◽  
Steven Nutt
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Total Pressure ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Reduced Pressure ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Diffraction Patterns ◽  
First Time

Epitaxial BaTi3 films have been grown on NdGaO3 [100] substrates by reduced pressure MOCVD for the first time. The substrate temperature was 1000 °C and the total pressure was 4 Torr. Electron and x-ray diffraction measurements indicate highly textured, single phase films on the NdGaO3 substrate which are predominantly [100], with [110] also present. TEM and selected area electron diffraction (SAED) indicate two specific orientational relationships between the [110] and the [001] diffraction patterns.

The effect of Li+ ions on the luminescent properties of a single-phase white light-emitting phosphor α-Sr2P2O7:Dy3+

2015 ◽  
Vol 44 (17) ◽  
pp. 7854-7861 ◽  
Author(s):  
Bing Han ◽  
Pengju Li ◽  
Jingtao Zhang ◽  
Jie Zhang ◽  
Yongfei Xue ◽  
...  
Keyword(s):  
High Temperature ◽  
Solid State ◽  
White Light ◽  
Single Phase ◽  
Luminescent Properties ◽  
Solid State Method ◽  
Light Emitting ◽  
Conventional Solid State Method ◽  
State Method ◽  
First Time

Two series of phosphors, α-Sr2(1−x)Dy2xP2O7 and α-Sr2(1−2x)Dy2xLi2xP2O7, with different x values were synthesized successfully using a conventional solid-state method at high temperature for the first time, and their luminescence properties were investigated comparatively.

Electron spectroscopic imaging and diffraction

1991 ◽  
Vol 49 ◽  
pp. 706-707
Author(s):  
M. Rühle ◽  
J. Mayer ◽  
J.C.H. Spence ◽  
J. Bihr ◽  
W. Probst ◽  
...  
Keyword(s):  
Materials Science ◽  
Electron Spectroscopic Imaging ◽  
Magnetic Filter ◽  
Magnetic Imaging ◽  
Illumination System ◽  
Probe Size ◽  
Diffraction Patterns ◽  
Fritz Haber ◽  
Koehler Illumination ◽  
First Time

A new Zeiss TEM with an imaging Omega filter is a fully digitized, side-entry, 120 kV TEM/STEM instrument for materials science. The machine possesses an Omega magnetic imaging energy filter (see Fig. 1) placed between the third and fourth projector lens. Lanio designed the filter and a prototype was built at the Fritz-Haber-Institut in Berlin, Germany. The imaging magnetic filter allows energy-filtered images or diffraction patterns to be recorded without scanning using efficient area detection. The energy dispersion at the exit slit (Fig. 1) results in ∼ 1.5 μm/eV which allows imaging with energy windows of ≤ 10 eV. The smallest probe size of the microscope is 1.6 nm and the Koehler illumination system is used for the first time in a TEM. Serial recording of EELS spectra with a resolution < 1 eV is possible. The digital control allows X,Y,Z coordinates and tilt settings to be stored and later recalled.

A Novel TEM Technique for Characterizing As-Grown CVD Diamond Films

1991 ◽  
Vol 49 ◽  
pp. 956-957 ◽  
Author(s):  
Z.L. Wang ◽  
J. Bentley ◽  
R.E. Clausing ◽  
L. Heatherly ◽  
L.L. Horton
Keyword(s):  
Diamond Films ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Dark Field ◽  
Growth Surface ◽  
Specimen Preparation ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
First Time ◽  
Microstructural Studies

Microstructural studies by transmission electron microscopy (TEM) of diamond films grown by chemical vapor deposition (CVD) usually involve tedious specimen preparation. This process has been avoided with a technique that is described in this paper. For the first time, thick as-grown diamond films have been examined directly in a conventional TEM without thinning. With this technique, the important microstructures near the growth surface have been characterized. An as-grown diamond film was fractured on a plane containing the growth direction. It took about 5 min to prepare a sample. For TEM examination, the film was tilted about 30-45° (see Fig. 1). Microstructures of the diamond grains on the top edge of the growth face can be characterized directly by transmitted electron bright-field (BF) and dark-field (DF) images and diffraction patterns.

Anisotropic radiation damage of potassium tetracyano platinate (KCP)

1978 ◽  
Vol 36 (1) ◽  
pp. 392-393
Author(s):  
N. Uyeda ◽  
E. J. Kirkland ◽  
B. M. Siegel
Keyword(s):  
Electron Diffraction ◽  
Radiation Damage ◽  
Structural Changes ◽  
High Resolution Electron Microscopy ◽  
Radiation Sensitivity ◽  
Resolution Electron ◽  
Damage Process ◽  
Diffraction Patterns ◽  
Fading Rate

The direct observation of structural change by high resolution electron microscopy will be essential for the better understanding of the damage process and its mechanism. However, this approach still involves some difficulty in quantitative interpretation mostly being due to the quality of obtained images. Electron diffraction, using crystalline specimens, has been the method most frequently applied to obtain a comparison of radiation sensitivity of various materials on the quantitative base. If a series of single crystal patterns are obtained the fading rate of reflections during the damage process give good comparative measures. The electron diffraction patterns also render useful information concerning the structural changes in the crystal. In the present work, the radiation damage of potassium tetracyano-platinate was dealt with on the basis two dimensional observation of fading rates of diffraction spots. KCP is known as an ionic crystal which possesses “one dimensional” electronic properties and it would be of great interest to know if radiation damage proceeds in a strongly asymmetric manner.

COPPER ALLOY No. 230

Alloy Digest ◽  
1972 ◽  
Vol 21 (3) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Shear Strength ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Copper Alloy ◽  
Single Phase ◽  
Heat Treating ◽  
Temperature Performance

Abstract COPPER ALLOY No. 230 is a single-phase brass containing 15% zinc which is the most widely used of the low zinc brasses. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as fracture toughness and creep. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Cu-252. Producer or source: Brass mills.

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