Investigation of Magnetic Order in Iron Oxide-Nickel Oxide Superlattices with Modulation Wavelength Less Than 80 Å

1991 ◽  
Vol 231 ◽  
Author(s):  
S. D. Berry ◽  
D. M. Lind ◽  
G. Chern ◽  
H. Mathias ◽  
L. R. Testardi
Keyword(s):  
Magnetic Order ◽  
Spontaneous Magnetization ◽  
X Ray Diffraction ◽  
High Crystalline Quality ◽  
X Ray ◽  
Long Wavelength ◽  
Saturation Moment ◽  
Very High ◽  
Modulation Wavelength

AbstractWe have investigated the magnetic order, using SQUID magnetometry, for short modulation wavelength Fe3O4/NiO superlattices, grown on single crystal MgO. Ferrimagnetic Fe3O4 has a saturation moment of ~500 emu/cm3 at 0 K and a Curie temperature of 858 K, while bulk NiO is antiferromagnetic with a NMel temperature of 525 K. Very high crystalline quality with little interdiffusion is indicated by X-ray diffraction, SEM, optical microscopy, and in-situ RHEED, and the samples show highly anisotropic electrical conductivity which also indicates the strong modulation present. Long wavelength samples (Amod > 200 Å) have a behavior only slightly different from that expected from bulk Fe3O4, but for Amod<80 Å, spontaneous magnetization is replaced by paramagnetism, with weak temperature dependence (not I/T) from 5 K to 400 K.

Stress in Ag/Ni Multilayers: A Comparison of Specimen-Curvature and X-Ray Diffraction Methods

1997 ◽  
Vol 472 ◽  
Author(s):  
P. Gergaud ◽  
S. Labat ◽  
H. Yang ◽  
A. Bottger ◽  
P. SandstrÖm ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Intrinsic Stress ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Scanning Method ◽  
X Ray ◽  
Integrated Devices ◽  
Curvature Measurement ◽  
Very High

ABSTRACTMultilayers and superlattices are of great industrial interest because of their specific properties (magnetic, electronic, tribological…). Multilayers stacking are often in a very high state of intrinsic stress (some GPa) and for reliable integrated devices to be made it is capital to control and understand these intrinsic as well as extrinsic stresses. The objective of the present work is therefore the understanding of the origin of stresses and strains in multilayered metallic materials. Of course, a comparison of the different techniques which can be used for stress determination is a necessary first step of this study. In this aim, we have studied Ag/Ni multilayers, Ag and Ni thin films and Ag/Ni bilayers obtained by sputtering. The stresses have been determined via curvature measurement using both a laser scanning method and X-ray diffraction rocking curves technique, and via X-ray diffraction measurement of several d-spacings which act as in-situ strain gauges (also called the sin2ψ method and related methods). The obtained results from these different techniques are discussed in terms of accuracy, reproducibility and advantages / drawbacks. The obtained stresses from these methods cannot be directly compared and a specific discussion is developed around the relation between the measured strains and stresses and the microstructure of the materials.

In situ studies of electrodic materials in Li-ion cells upon cycling performed by very-high-energy x-ray diffraction

2001 ◽  
Vol 79 (1) ◽  
pp. 27-29 ◽  
Author(s):  
V. Rossi Albertini ◽  
P. Perfetti ◽  
F. Ronci ◽  
P. Reale ◽  
B. Scrosati
Keyword(s):  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Studies ◽  
Very High Energy ◽  
Li Ion ◽  
Very High

scholarly journals Superflexibility of graphene oxide

2016 ◽  
Vol 113 (40) ◽  
pp. 11088-11093 ◽  
Author(s):  
Philippe Poulin ◽  
Rouhollah Jalili ◽  
Wilfrid Neri ◽  
Frédéric Nallet ◽  
Thibaut Divoux ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Unique Feature ◽  
Bending Rigidity ◽  
X Ray Diffraction ◽  
Synchrotron Source ◽  
X Ray ◽  
Bending Modulus ◽  
Bendable Electronics ◽  
Very High

Graphene oxide (GO), the main precursor of graphene-based materials made by solution processing, is known to be very stiff. Indeed, it has a Young’s modulus comparable to steel, on the order of 300 GPa. Despite its very high stiffness, we show here that GO is superflexible. We quantitatively measure the GO bending rigidity by characterizing the flattening of thermal undulations in response to shear forces in solution. Characterizations are performed by the combination of synchrotron X-ray diffraction at small angles and in situ rheology (rheo-SAXS) experiments using the high X-ray flux of a synchrotron source. The bending modulus is found to be 1kT, which is about two orders of magnitude lower than the bending rigidity of neat graphene. This superflexibility compares with the fluidity of self-assembled liquid bilayers. This behavior is discussed by considering the mechanisms at play in bending and stretching deformations of atomic monolayers. The superflexibility of GO is a unique feature to develop bendable electronics after reduction, films, coatings, and fibers. This unique combination of properties of GO allows for flexibility in processing and fabrication coupled with a robustness in the fabricated structure.

Influence of the N/Al Ratio in the Gas Phase on the Growth of AlN by High Temperature Chemical Vapor Deposition (HTCVD)

2009 ◽  
Vol 615-617 ◽  
pp. 987-990 ◽  
Author(s):  
Arnaud Claudel ◽  
Elisabeth Blanquet ◽  
Didier Chaussende ◽  
D. Pique ◽  
Michel Pons
Keyword(s):  
Growth Rate ◽  
Gas Phase ◽  
Chemical Vapor ◽  
High Growth ◽  
High Growth Rate ◽  
X Ray Diffraction ◽  
High Crystalline Quality ◽  
X Ray ◽  
Bulk Growth

In order to achieve AlN bulk growth, HTCVD chlorinated process is investigated. High growth rate and high crystalline quality are targeted for AlN films grown on (0001) 4H SiC at 1750°C. The precursors used are ammonia NH3 and aluminium chlorides AlClx species formed in situ by action of Cl2 on high purity Al wire. Influences of N/Al ratio in the gas phase on growth rate, crystalline state and microstructure are presented. Growth rates of up to 200 µm/h have been reached for polycrystalline layers. Thermodynamic calculations were carried out and correlated to the experimental results. As-grown AlN layers were characterized by SEM and X-ray Diffraction. Surface morphology is studied by SEM and FEG-SEM and crystallographic orientations were obtained by X-ray diffraction on θ/2θ.

scholarly journals Effect of Mineral Composition and w/c Ratios to the Growth of AFt during Cement Hydration by In-Situ Powder X-ray Diffraction Analysis

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4963
Author(s):  
Bo Chen ◽  
Yongming Zhang ◽  
Qing Chen ◽  
Fei Yang ◽  
Xianping Liu ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cement Hydration ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
X Ray ◽  
Hardened Cement Pastes ◽  
Maximum Content ◽  
Very High

AFt is one of the major products at the early stage of cement hydration. It is an important product that influences the performance of the fresh and hardened cement pastes such as the setting time. However, there is a lack of detailed investigation on the growth of AFt in the cement pastes with a long-time scale. In this work, we reported a detailed analysis by using in-situ powder X-ray diffraction (XRD) on the growth of AFt in the cement pastes during hydration. Samples of the hydrated ordinary Portland cement (OPC) and another locally produced Portland cement with very high tricalcium silicate (C3S) content with different water–cement (w/c) ratios were investigated continually till they were hydrated for about 270 days by powder XRD. The work shows that during Portland cement hydration, the AFt reaches its maximum content with very high speed within about 24 h, which is influenced by the content of C3S in the raw cement samples and the w/c ratios of the cement pastes. Once the maximum content of AFt was reached, it decreases very fast within the following couple of days, and then decreases slowly and finally reaches a stable level at the late stage of hydration. The results also present that a lower w/c ratio is beneficial to the formation of AFt and the conversion of AFt to AFm as well. While higher w/c ratios are favorable for the AFt to remain stable in the hardened cement pastes.

Synthesis and Properties of Ultra-Thin YBa2Cu3O7 and YBa2Cu3O7/La2-xSrxCuO4 Multilayers

1989 ◽  
Vol 169 ◽  
Author(s):  
C.B. Eom ◽  
S.K. Streiffer ◽  
J.Z. Sun ◽  
K. Yamamoto ◽  
S.S. Laderman ◽  
...  
Keyword(s):  
Single Layer ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Superconducting Thin Film ◽  
Cross Sectional ◽  
X Ray ◽  
Single Target ◽  
Modulation Wavelength

AbstractUsing our standard single target off-axis sputter deposition procedure[1], ultra-thin YBa2Cu3O7 superconducting films were made in-situ. We have studied the thickness dependence of superconducting properties (Tc, Jc) from 20 to 5000Å. Tc starts degrading below 125Å and falls to 50 K for the 30 Å film. Jc drops linearly with decreasing thickness below l000Å. We have grown YBa2Cu3O7/La2-xSrxCuO4 superconducting thin film multilayers in-situ by the same process. The modulation wavelength of the multilayers ranged from 45Å to 2000Å. X-ray diffraction and cross sectional TEM confirm the superlattice periodicity. The superconducting transition temperature drops in much the same way as the single layer ultra-thin films. Both the critical current density and its magnetic field dependence decrease as the modulation wavelength decreases.

Growth of Thick AlN Layers by High Temperature CVD (HTCVD)

2008 ◽  
Vol 600-603 ◽  
pp. 1269-1272 ◽  
Author(s):  
Arnaud Claudel ◽  
Elisabeth Blanquet ◽  
Didier Chaussende ◽  
M. Audier ◽  
D. Pique ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
High Growth Rate ◽  
X Ray Diffraction ◽  
High Crystalline Quality ◽  
X Ray ◽  
Bulk Growth ◽  
Pole Figures ◽  
Α Al2o3

To achieve AlN bulk growth, HTCVD chlorinated process is investigated. High growth rate and high crystalline quality are targeted for AlN films grown on (0001) α-Al2O3 and (0001) 4H or 6H SiC substrates between 1100 °C and 1750 °C. The precursors used are ammonia NH3 and aluminium chlorides AlClx species formed in situ by action of Cl2 on high purity Al wire. Both influences of temperature and carrier gas on microstructure, crystalline state and growth rate are presented. Growth rates higher than 190 μm.h-1 have been reached. Thermodynamic calculations were carried out to understand the chemistry of AlN deposition. AlN layers were characterized by SEM and θ/2θ X-Ray Diffraction. Their epitaxial relationships with substrates were deduced from pole figures obtained by X-Ray diffraction on a texture goniometer.

Development of the Compact Furnace for the In Situ Observation under Ultra-High Temperature by Synchrotron x-Ray Surface Diffraction

2016 ◽  
Vol 858 ◽  
pp. 505-508
Author(s):  
Masahiro Yoshida ◽  
Yasunori Kutsuma ◽  
Daichi Dohjima ◽  
Kenji Ohwada ◽  
Toshiya Inami ◽  
...  
Keyword(s):  
Crystal Growth ◽  
High Temperature ◽  
Room Temperature ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Diffraction ◽  
Very High ◽  
Ultra High Temperature

We have established the grazing-incidence x-ray diffraction (GIXD) method under ultra- high temperature for in-situ crystal growth observation. For this purpose, we have developed the compact furnace which can be mounted on a goniometer used for the GIXD experiment. Using the custom-designed furnace, we have succeeded in controlling very high temperature around 1800°C. Subsequently, we have proved the performance of the furnace through the measurement of the tem- perature dependence of a-lattice constant of 4H-SiC in the range from room temperature to 1500 °C.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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