scholarly journals Структура и динамика решетки двухслойных гетероструктур титаната бария-стронция и слоистого титаната висмута разной толщины на подложке окcида магния

2019 ◽  
Vol 61 (11) ◽  
pp. 2178
Author(s):  
А.С. Анохин ◽  
Ю.И. Головко ◽  
В.М. Мухортов ◽  
Д.В. Стрюков
Keyword(s):  
Interface Plane ◽  
Substrate Plane ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
Compression Strain ◽  
Layer Structures ◽  
Monoclinic Distortion ◽  
Plane Direction ◽  
Ceramic Targets ◽  
Mgo Substrate

The results of the structure and lattice dynamics study of Bi4Ti3O12 films with a thickness varying from 4 to 430 nm on a (001) MgO substrate with a preliminarily deposited Ba0.4Sr0.6TiO3 (4 nm) sublayer are presented. Two-layer structures were fabricated by high-frequency sputtering of ceramic targets of the appropriate composition. X-ray diffraction studies at room temperature showed that in such heterostructures the c axis of the Bi4Ti3O12 film is perpendicular to the substrate plane, and the [100] axis makes an angle of ± 45◦ with the [100] MgO axis. Up to ≈ 40 nm of Bi4Ti3O12 film thickness, the unit cell have a compression strain in the normal to the substrate plane direction and tensile strain in the interface plane, for large thicknesses the sign of the deformation changes. The frequency shifts of phonon modes in the Bi4Ti3O12 film and the appearance of additional peaks in the Raman spectra were observed. It is indicating on increasement of monoclinic distortion of the films crystal structure compared to the bulk crystal.

Highly thermally conductive UHMWPE/NG composites with the segregated structure and their application for heat spreader

2020 ◽  
pp. 089270572096564
Author(s):  
Xiao Wang ◽  
Hui Lu ◽  
Jun Chen
Keyword(s):  
Thermal Conductivity ◽  
Laser Flash ◽  
Heating Process ◽  
X Ray Diffraction ◽  
Heat Spreader ◽  
Conductive Composites ◽  
Compression Direction ◽  
Thermal Analyzer ◽  
Thermally Conductive ◽  
Plane Direction

In this work, ultra-high molecular weight polyethylene (UHMWPE)/natural flake graphite (NG) polymer composites with the extraordinary high thermal conductivity were prepared by a facile mixed-heating powder method. Morphology observation and X-ray diffraction (XRD) tests revealed that the NG flakes could be more tightly coated on the surface of UHMWPE granules by mixed-heating process and align horizontally (perpendicular to the hot compression direction of composites). Laser flash thermal analyzer (LFA) demonstrated that the thermal conductivity (TC) of composites with 21.6 vol% of NG reached 19.87 W/(m·K) and 10.67 W/(m·K) in the in-plane and through-plane direction, respectively. Application experiment further demonstrated that UHMWPE/NG composites had strong capability to dissipate the heat as heat spreader. The obtained results provided a valuable basis for fabricating high thermal conductive composites which can act as advanced thermal management materials.

Strain, Stress, and Magnetic Surfaceanisotropy of Epitaxial FE(110)/MO (110) Multilayers

1993 ◽  
Vol 317 ◽  
Author(s):  
R.M. Osgood ◽  
B.M. Clemens ◽  
R.L. White ◽  
S. Brennan
Keyword(s):  
Strain State ◽  
Single Layer ◽  
Grazing Incidence ◽  
Magnetic Surface ◽  
Stress And Strain ◽  
Surface Anisotropy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plane Direction ◽  
Strain Stress

ABSTRACTGrazing incidence and asymmetric X-ray diffraction were used to measure the stress and strain state of Fe(110)/Mo(110) Multilayers. The highest stress in the Fe constituent of the multilayer was along the [110] in-plane direction and was due to interaction with the substrate. The Magnetic anisotropy of the Fe Multilayer constituent was measured and the magnetic surface anisotropy, which favored in-plane [001] magnetization, was deduced. In contrast, the magnetic surface anisotropy of a single layer of Fe on W preferred in-plane [110] magnetization, in agreement with the Néel Model.

scholarly journals Study of Microstructural, Electrical and Dielectric Properties of La0.9Pb0.1MnO3 and La0.8Y0.1Pb0.1MnO3 Ceramics

2019 ◽  
pp. 33-44 ◽  
Keyword(s):  
Transition Temperature ◽  
Frequency Dispersion ◽  
Insulator Transition ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Solid State Route ◽  
Distorted Structure ◽  
Lower Temperature

The present work studies the microstructural and electrical properties of La0.9Pb0.1MnO3 and La0.8Y0.1Pb0.1MnO3 ceramics synthesized by solid-state route method. Microstructure and elemental analysis of both samples were carried out by field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) method, respectively. Phase analysis by X-ray diffraction (XRD) indicated formation of single phase distorted structure. The XRD data were further analyzed by Rietveld refinement technique. Raman analysis reveals that Y atom substitutes La site into the LPMO with shifting of phonon modes. The temperature variation of resistivity of undoped and Y-doped La0.9Pb0.1MnO3 samples have been investigated. The electrical resistivity as a function of temperature showed that all samples undergo an metal-insulator (M-I) transition having a peak at transition temperature TMI. Y-doping increases the resistivity and the metal-insulator transition temperature (TMI) shifts to lower temperature. The temperature-dependent resistivity for temperatures less than metal-insulator transition is explained in terms the quadratic temperature dependence and for T > TMI, thermally activated conduction (TAC) is appropriate. Variation of frequency dispersion in permittivity and loss pattern due to La-site substitution in LPMO was observed in the dielectric response curve.

scholarly journals Переключение поляризации вдоль подложки в тонких пленках Bi-=SUB=-4-=/SUB=-Ti-=SUB=-3-=/SUB=-O-=SUB=-12-=/SUB=- при различных деформационных напряжениях

2020 ◽  
Vol 90 (1) ◽  
pp. 128
Author(s):  
В.М. Мухортов ◽  
Д.В. Стрюков ◽  
С.В. Бирюков ◽  
Ю.И. Головко
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Domain Structure ◽  
Spontaneous Polarization ◽  
Unit Cell ◽  
Interface Plane ◽  
Dielectric Characteristics ◽  
Unit Cells ◽  
Mgo Substrate

A study of epitaxial Bi4Ti3O12 thin films with a pre-deposited 4 nm Ba0.4Sr0.6TiO3 sublay-er on (001) MgO substrates has been performed. In the obtained heterostructures, the rotation of the Bi4Ti3O12 film unit cells by an angle of 45° relative to the MgO substrate unit cell in the inter-face plane has been observed. The Bi4Ti3O12 films contain unit cell deformations depending on the thickness of the film and the sign of the deformation changes at a thickness of ~40 nm. The switchable in-plane spontaneous polarization of Bi4Ti3O12 film at the 180° domain structure oc-curs at a film thickness of 10 nm and increases with a thickness up to 54 µC/cm2. The study of the dielectric characteristics of the films confirmed the existence of properties anisotropy in the interface plane and the effect of deformation of the unit cell on the properties of heterostruc-tures.

Structural and Surface Characteristics of CuO and Pt/CuO Nanostructured Thin Films

2021 ◽  
Vol 14 (5) ◽  
pp. 419-424
Keyword(s):  
Thin Films ◽  
Optical Fibers ◽  
Structural Information ◽  
Surface Characteristics ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
Silar Method ◽  
Nanostructured Thin Films ◽  
Average Grain Size ◽  
Sem Micrograph

Abstract: The most prominent and utilizable platinum-coated copper Oxide nanostructured thin films are prepared using the SILAR method. Their structural properties have been studied using X-ray diffraction (XRD) and Raman spectroscopy. XRD pattern reveals the phase purity and crystallinity of CuO nanostructures. The average grain size estimated from XRD gives diameters in the range of 14 - 27 nm. Raman spectra explain the structural information of CuO and Pt/CuO nanostructured thin films, in which the peaks observed at 328 cm-1, 609.32 cm-1 and 1141.77 cm-1 are the different phonon modes of CuO. The peak at 2136 cm-1 provides strong evidence for the formation of platinum on CuO nanostructures. The SEM micrograph confirms the floral morphology, which is composed of nano petals. From the observed morphology, it is observed that the deposited thin films such as CuO and Pt/CuO will give interesting applications to our society by being self-cleaning agents, photocatalysts, semiconductor devices, optical fibers, … etc. Keywords: CuO, Pt/CuO, Structural analysis, SILAR, Crystallinity.

Investigation of Compound Layer Structures after Nitriding and Nitrocarburizing of Quenched and Tempered Steels

2021 ◽  
Vol 76 (3) ◽  
pp. 219-236
Author(s):  
M. Sommer ◽  
S. Hoja ◽  
M. Steinbacher ◽  
R. Fechte-Heinen
Keyword(s):  
Surface Layer ◽  
Phase Composition ◽  
Bulk Material ◽  
Fatigue Behavior ◽  
Nitrogen Concentration ◽  
Maximum Level ◽  
Compound Layer ◽  
X Ray Diffraction ◽  
Treatment Processes ◽  
Layer Structures

Abstract A compound layer is formed by ingress of nitrogen from an external nitrogen source into the surface layer and the formation of nitrides when the solubility of nitrogen in the bulk material is exceeded. In the surface layer, where the nitrogen concentration is at its maximum level, the nitrides form a closed layer. The compound layer continues to contain alloy nitrides which have formed from the carbides and other precipitates from the bulk material. The properties of the compound layer have a decisive influence on the wear and fatigue behavior of the loaded surfaces. The current investigations deal with the extensive characterization of compound layers that have been produced in heat treatment processes with the aim of producing stress-resistant nitriding layers. The commonly used nitriding and quench and temper (Q&T) steels 31CrMoV9 and 42CrMo4 served as examination material. The structure of the compound layers was varied within the nitriding trials regarding the phase composition, porosity and layer thicknesses. The phase composition of the compound layers was determined by special etching, scanning electron microscopy (SEM), X-ray diffraction and GDOES.

scholarly journals Growth and Structural Characterization of Doped Polymorphic Crystalline MgPc as an Organic Semiconductor

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 495
Author(s):  
Leon Hamui ◽  
María Elena Sánchez-Vergara ◽  
Rocio Sánchez-Ruiz ◽  
Cecilio Álvarez-Toledano ◽  
Jose Luis Reyes-Rodriguez ◽  
...  
Keyword(s):  
High Energy ◽  
X Ray Diffraction ◽  
Energy Peak ◽  
Plane Direction ◽  
Band Transition ◽  
Transparent Region ◽  
Stage Process ◽  
Molecular Semiconductor ◽  
20 Nm ◽  
Optical Behavior

The doping and crystallization of the molecular semiconductor formed from the magnesium phthalocyanine (MgPc) and 1-(4-Methoxyphenyl)-2,2,6,6-tetramethyl-5-phenylhepta-3,4-dienedioic (MTPDA) acid was carried out in this work. The crystals obtained were characterized by using transmission electronic microscopy (TEM), Raman spectroscopy, and X-Ray diffraction (XRD), to later evaluate their optical behavior. Raman, IR, and UV–Vis results indicate that the MgPc has been doped with the MTPDA. A uniform material layer with particles is observed as a result of a two-stage process, nucleation and growth. The polycrystalline films are constituted by a mixture of α and β phases with crystalline sizes of ~7 nm, 14 nm, and 20 nm average sizes. The films exhibit a preferred orientation along the [001]. The MTPDA doping does not have an important effect on the molecule planar distances indicating that the MTPDA molecule is among the equivalent MgPc plane direction. A transparent region with a minimum at 483 nm is observed, also a B-band at 337 nm and a Q-band transition with a high-energy peak around 639 nm, and a low energy peak around 691 nm.

Structural, optical and other spectral studies of transition metal Ti4+-doped Zn-Cd oxide nanomaterials

2020 ◽  
Vol 34 (06) ◽  
pp. 2050033 ◽  
Author(s):  
Mohd Saleem ◽  
S. Tiwari ◽  
M. Soni ◽  
N. Bajpai ◽  
Ashutosh Mishra
Keyword(s):  
Sol Gel ◽  
Relaxation Times ◽  
Hexagonal Structure ◽  
Spectral Studies ◽  
X Rays ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
Spectroscopy Analysis ◽  
Auto Combustion ◽  
High Dielectric

Titanium ([Formula: see text])-doped nanoparticles of the type [Formula: see text] [[Formula: see text], [Formula: see text]] are reported in this study. The samples were synthesized by citric acid assisted sol–gel auto combustion (SGAC) method. The samples are characterized by X-ray diffraction (XRD), Raman, Field emission scanning electron microscopy (FESEM), Energy dispersive analysis of X-rays (EDAX) and Fourier transform infra-red (FTIR) techniques for structural studies. Further, for optical properties, UV-Vis technique has been used. In addition, samples were studied for dielectric properties. Room-temperature XRD data study reveals the sample formation with wurtzite hexagonal structure exhibiting space group [Formula: see text]mc also confirmed from Rietveld refinement of XRD data. Raman spectra displays characteristic active phonon modes in pristine [Formula: see text] and doped [Formula: see text]. UV-Vis diffused reflectance spectroscopy analysis infer bandgap values of 3.14 and 3.12 eV for [Formula: see text] and [Formula: see text], respectively. The dielectric studies confirmed high dielectric constant for [Formula: see text] compared to pristine [Formula: see text]. A non-Debye character with spread of relaxation times was witnessed from impedance study.

CHARACTERIZATION AND MICRO-RAMAN STUDIES OF Bi2−xPbxSr2Ca2Cu3O10+δ (0 ≤ x ≤ 0.6) SUPERCONDUCTOR

1994 ◽  
Vol 08 (10) ◽  
pp. 591-603
Author(s):  
U. SINHA ◽  
S. SATHAIAH ◽  
R. N. SONI ◽  
H. D. BIST ◽  
S. C. MATHUR ◽  
...  
Keyword(s):  
Ac Susceptibility ◽  
Solubility Limit ◽  
Dc Resistivity ◽  
Apical Oxygen ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
X Ray ◽  
Percentage Volume ◽  
Pb Substitution ◽  
Scanning Electron

The X-ray diffraction (XRD), ac susceptibility, dc resistivity, and scanning electron microscopy (SEM) measurements on Bi 2−x Pb x Sr 2 Ca 2 Cu 3 O 10+δ (x = 0.0, 0.2, 0.4, and 0.6) superconductors have been correlated with the Raman scattering studies. Remarkable increases in the transition temperature and percentage volume of high T c phase are found till x = 0.4. Raman spectra also reveal dramatic changes at x = 0.4 in the phonon modes at 625 and 460 cm −1 associated with oxygen vibrations in BiO plane and apical oxygen of CuO 5 pyramid, respectively. The observed changes have been attributed to the phenomenon of oxygen redistribution among various layers. Optimum solubility limit of Pb substitution is found to be x = 0.4.

scholarly journals Partial Reduction/Re-Oxidation Processing of Y-Ba-Cu-O Sputtered Thin Films

1989 ◽  
Vol 169 ◽  
Author(s):  
F.H. Garzon ◽  
J. G. Beery ◽  
D. K. Wilde ◽  
I. D. Raistrick
Keyword(s):  
Thin Films ◽  
Rf Sputtering ◽  
Partial Reduction ◽  
Rf Power ◽  
X Ray Diffraction ◽  
X Ray ◽  
Post Annealing ◽  
Residual Oxygen ◽  
Ceramic Targets ◽  
Substrate Temperatures

AbstractThin films of Y‐Ba‐Cu‐O were produced by RF sputtering of YBa2Cu3O7‐x ceramic targets, using a variety of plasma compositions, RF power levels, and substrate temperatures. Post annealing of these films in oxygen produced superconducting films with Tc values between 40‐60 K, broad transition widths and semiconductor‐like electrical behavior above Tc. Subsequent annealing at 850°C in an inert gas with a residual oxygen partial pressure of ≤10 ppm followed by an oxygen anneal produced high quality thin films: Tc> 85 K with narrow transition widths. The structure and morphology of these films during reduction‐oxidation processing were monitored using X‐ray diffraction and electron microscopy.

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