Epitaxial Growth and Physical Properties of La1-xCaxMnO3-δ Thin Films on MgO(001) Substrates

1995 ◽  
Vol 401 ◽  
Author(s):  
J. Y. Gu ◽  
K. H. Kim ◽  
T. W. NOH ◽  
Jeong Soo Lee ◽  
Young Woo Jeong ◽  
...  
Keyword(s):  
Thin Films ◽  
Physical Properties ◽  
Chemical Compositions ◽  
Magnetic Polaron ◽  
Polaron Model ◽  
X Ray ◽  
Pole Figures ◽  
Wide Range ◽  
Ordering Transitions ◽  
Ferromagnetic Ordering

AbstractPerovskite La1-xCaxMnO3-δ (LCMO) thin films with a wide range of x, i.e., 0.0 ≤ x ≤ 0.6, were deposited on MgO(001) substrates using a pulsed laser deposition (PLD) technique. Epitaxial La0.7Ca0.3MnO3-δ/MgO thin films were able to be grown under a condition such as 1.5 ∼ 2.1 J/cm2 of a laser fluence, 650 ∼ 750 °C of a substrate temperature, and 100 ∼ 300 mtorr of an oxygen pressure. X-ray pole figures and electron diffraction pattern showed that the LCMO films were grown epitaxially on MgO(001). Rutherford Backscattering Spectroscopy measurements investigated that the epitaxial LCMO films have compositions similar to those of targets, demonstrating the PLD is a useful technique to get films with complicated chemical compositions. Various physical properties, including resistance, R, magnetoresistance, ΔR/R(H=0) ≡ (R(H)-R(0))/R(O), and magnetization, M(T), were measured. The LCMO thin films with 0.2 ≤ x ≤ 0.5 had both semiconductor-metal and ferromagnetic ordering transitions, whose temperatures are located close to each other. These physical properties were explained in terms of the magnetic polaron model.

Effect of vacuum annealing on the properties of one step thermally evaporated Sb2S3 thin films for photovoltaic applications

2021 ◽  
Author(s):  
Emna Gnenna ◽  
Naoufel Khemiri ◽  
Minghua Kong ◽  
Maria Isabel Alonso ◽  
Mounir Kanzari
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Vacuum Annealing ◽  
Xrd Analysis ◽  
Band Gap Energy ◽  
Chemical Compositions ◽  
Optical Parameters ◽  
X Ray ◽  
Vis Spectroscopy ◽  
One Step

Sb2S3 powder was successfully synthesized by solid state reaction technique using high-purity elemental antimony and sulfur. Sb2S3 thin films were deposited on unheated glass substrates by one step thermal evaporation and annealed under vacuum atmosphere for 2 hours at different temperatures 150, 200 and 250 °C. Different characterization techniques were used to better understand the behavior of the Sb2S3 material. X-ray diffraction (XRD) and Raman spectroscopy confirmed the formation of pure Sb2S3 powder with lattice parameters a = 11.07 Å, b = 11.08 Å and c = 3.81 Å. The effect of vacuum annealing temperature on the properties of the films was studied. XRD analysis revealed that as-deposited and annealed films at 150ºC were amorphous in nature whereas those annealed at T ≥ 200°C were polycrystalline with a preferred orientation along (201) plane. The crystallite size of the polycrystalline films showed a decrease from 75.8 to 62.9 nm with the increase of the annealing temperature from 200 to 250 °C. The Raman analysis showed several peaks corresponding to the stibnite Sb2S3 phase. The surface morphology of the films was examined by atomic force microscopy (AFM). The surface roughness decreases slightly as the transformation from the amorphous to the crystalline phase occurs. The chemical compositions of Sb2S3 films were analyzed by energy dispersive X-ray spectroscopy (EDS), revealing that all films were Sb-rich. The optical parameters were estimated from the transmittance and reflectance spectra recorded by UV-Vis spectroscopy. A reduction in the direct band gap energy from 2.12 to 1.70 eV with the increase of annealing temperature was also found.

scholarly journals X-ray studies of the structure of hair, wool, and related fibres.- I. General

1931 ◽  
Vol 230 (681-693) ◽  
pp. 75-101 ◽  
Keyword(s):  
Physical Properties ◽  
Crystalline Structure ◽  
Human Hair ◽  
X Rays ◽  
Present Communication ◽  
Cellulose Fibres ◽  
X Ray ◽  
Usual Manner ◽  
Wide Range ◽  
Muscle Nerve

It is now some ten years since it was first realised that, in common with natural and artificial cellulose fibres, animal fibres with a protein basis are in many cases sufficiently crystalline to yield a pronounced interference figure when examined with monochromatic X-rays. Such “ X-ray fibre diagrams ” were reported in 1921 by HERZOG and JANCKE* for muscle, nerve, sinew, and hair, and in 1924 similar photographs from human hair were obtained by one of the present writers. From an X-ray examination of wool it was concluded by THREADGOLD that “ there is no evidence for assuming the wool fibres and yarns examined to have a crystalline structure,” but in 1927 EWLES and SPEAKMAN had already obtained wool interference figures precisely similar to those previously obtained from hair. The two last-named authors endeavoured to interpret their results in the light of certain physical properties, but it has since become clear that the problem of hair structure is sufficiently complex to necessitate an X-ray study of a wide range of materials under as great a variety of conditions as possible. The present communication is an account of the preliminary results of such an investigation. Over a hundred X-ray photographs have been taken, using copper K-radiation filtered of the MATHS FORMULA line by nickel foil about 1/100 mm. thick. The “ slit” was a rectangular aperture, 4 cm. x 0.5mm., the scattered rays from which were screened off in the usual manner by a secondary slit.

Preparation and CO2 Gas Sensitive Properties of CuO-SrTiO3-Based Semiconductor Thin Films

2007 ◽  
Vol 280-283 ◽  
pp. 311-314 ◽  
Author(s):  
Yan Fei Gu ◽  
Hui Ming Ji ◽  
Bin Zhang ◽  
Ting Xian Xu
Keyword(s):  
Thin Films ◽  
Chelating Agents ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Good Resistance ◽  
Gas Sensitivity ◽  
X Ray ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Ft Ir

CuO-SrTiO3-based thin films were prepared by novel sol-gel technology on Al2O3 substrates using Cu(NO3)2, SrCl2 and TiCl4 as the starting materials, critic acid and ethylene glycol as chelating agents. CO2 sensing properties of the films were investigated. Structure characteristics of the sol and asgrown thin films were analyzed by FT-IR spectrum, X-ray diffraction and SEM. The results reveal that the films consisted of CuO phase and SrTiO3 phase have nanocrystalline microstructure at 750°C for 40 min. The modified CuO-SrTiO3 thin films exhibit good resistance-temperature and gas sensitivity properties in a wide range of temperature. The films exposed to 6% CO2 show that sensitivity are 32, and response and recover time are within 2 s at 250 °C operating temperature.

scholarly journals High temperature ferromagnetic ordering in c-axis oriented ZnO:Mn nanoparticle thin films by tailoring substrate temperature

2014 ◽  
Vol 32 ◽  
pp. 1460341 ◽  
Author(s):  
Usman Ilyas ◽  
P. Lee ◽  
T. L. Tan ◽  
R. V. Ramanujan ◽  
Sam Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Magnetic Measurements ◽  
Deep Level ◽  
Growth Conditions ◽  
Optical Quality ◽  
Host Matrix ◽  
X Ray ◽  
Ferromagnetic Ordering ◽  
Substrate Temperatures

This study reports the enhanced ferromagnetic ordering in ZnO:Mn nanoparticle thin films, grown at different substrate temperatures using pulsed laser deposition. The optimum growth conditions were deduced from X-ray, photoemission and magnetic measurements. The X-ray measurements reveal that there was an optimum substrate temperature where the thin films showed relatively stronger texture, better crystallinity and lower strain. Substrate temperature tuned the deep level recombination centers in ZnO:Mn , which changed the optical quality by altering the electronic structure. The M-H curves, in the present study, revealed superior ferromagnetic response of 20-nm sized particles in ZnO:Mn thin film grown at a substrate temperature of 450 °C. Ferromagnetic ordering becomes weaker at higher/lower substrate temperatures due to the activation of native defects in ZnO host matrix.

Multitechnique problem solving using EDS/EPMA and surface analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1782-1783
Author(s):  
Steven J. Simko ◽  
Richard A. Waldo
Keyword(s):  
Thin Films ◽  
Electron Beam ◽  
Integrated Circuits ◽  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
High Surface ◽  
Primary Electron ◽  
Sampling Depth ◽  
X Ray ◽  
Wide Range

Thin films are used in a wide range of modern technologies. Examples include sensors, antiwear coatings, optical coatings, and integrated circuits. A variety of methods have evolved for characterizing thin films in the thickness range of 1 monolayer to several micrometers. Electron probe microanalysis (EPMA) or energy dispersive x-ray spectroscopy (EDS) are two methods for characterizing thicker films (>1 μm). In these techniques, the sampling depth depends on the penetration depth of the primary electron beam which can be controlled by changing the electron beam energy. Thin films can also be characterized using line scans on specimens prepared as polished cross-sections or after angle lapping. For extremely thin films (<3 nm), techniques with high surface sensitivity such as Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) are commonly employed. Sampling depth depends on the attenuation length of the emitted photoelectrons or Auger electrons.Electron spectroscopy techniques are also used to characterize thicker films by adding a microsectioning method to the experiment, most commonly ion sputtering.

Study of the anisotropy of the polycrystal properties based on texture data

2019 ◽  
Vol 85 (9) ◽  
pp. 46-51
Author(s):  
A. V. Stepanenko
Keyword(s):  
Experimental Data ◽  
Physical Properties ◽  
Thermomechanical Processing ◽  
Physical And Mechanical Properties ◽  
Polycrystalline Materials ◽  
X Ray ◽  
Anisotropic Properties ◽  
Pole Figures ◽  
Quantitative Changes ◽  
Crystallographic Orientations

The results of studying correlation between the crystallographic texture of polycrystalline materials and anisotropy of their physical and mechanical properties are considered. The methods for calculating the anisotropic properties of polycrystals based on the data obtained by X-ray methods of direct and inverse pole figures are reviewed. Calculation methods based on the use of the distribution function of crystallite orientations require the use of a large amount of experimental data and, hence, they are not suitable for express estimation of the anisotropy level of the physical properties of samples upon their thermomechanical processing. A method for rapid estimation of the anisotropic properties of the sample based on the use of Д; ("orientation factors") in the calculations, is proposed. Experimental data of X-ray analysis (method of inverse pole figures) are used to calculate the absolute and relative deviations of the physical parameter of textured polycrystal from the same value in the isotropic sample. The contributions of individual crystallographic orientations to the formation of the anisotropy of the properties of the sample are estimated. The dynamics of quantitative changes in the anisotropic properties of a polycrystal in the process of texture formation is studied. To analyze the source of the most rapid changes in the anisotropy of properties, we used the coefficients of the "response" matrix, the calculation of which does not depend on the results of specific diffractometric measurements, but is common for all metals with a hexagonal close-packed (hep) lattice. The anisotropy of the coefficient of thermal conductivity, electrical conductivity, and thermal diffusivity was calculated for the samples of deformed yttrium which underwent cold rolling with a reduction ratio of e = 25%. It is shown that the final physical properties_of the hep polycrystal are largely determined by the pyramidal crystallographic orientations {1015}, {1124}. The results of the study form a basis for analysis of the anisotropy of the physical properties of hep-metal samples upon thermomechanical processing.

scholarly journals Aryl substitution of pentacenes

2014 ◽  
Vol 10 ◽  
pp. 1692-1705 ◽  
Author(s):  
Andreas R Waterloo ◽  
Anna-Chiara Sale ◽  
Dan Lehnherr ◽  
Frank Hampel ◽  
Rik R Tykwinski
Keyword(s):  
Thin Films ◽  
Cyclic Voltammetry ◽  
Solid State ◽  
Physical Properties ◽  
X Ray ◽  
X Ray Crystallography ◽  
Vis Spectroscopy ◽  
Solid State Devices ◽  
Pentacene Derivatives

A series of 11 new pentacene derivatives has been synthesized, with unsymmetrical substitution based on a trialkylsilylethynyl group at the 6-position and various aryl groups appended to the 13-position. The electronic and physical properties of the new pentacene chromophores have been analyzed by UV–vis spectroscopy (solution and thin films), thermoanalytical methods (DSC and TGA), cyclic voltammetry, as well as X-ray crystallography (for 8 derivatives). X-ray crystallography has been specifically used to study the influence of unsymmetrical substitution on the solid-state packing of the pentacene derivatives. The obtained results add to our ability to better predict substitution patterns that might be helpful for designing new semiconductors for use in solid-state devices.

Reactive Coevaporation of SrTiO3 Thin Films for Tunable Microwave Devices

2001 ◽  
Vol 688 ◽  
Author(s):  
Luke S.-J. Peng ◽  
Nina F. Heinig ◽  
Brian H. Moeckly
Keyword(s):  
Thin Films ◽  
Dielectric Property ◽  
Growth Process ◽  
Optimal Growth ◽  
Process Window ◽  
Deposition Technique ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Average Electric Field

AbstractWe have successfully grown SrTiO3 films on LaAlO3 and MgO substrates up to 2” in diameter using the deposition technique of reactive coevaporation. We have explored a wide range of deposition temperatures, oxygen pocket pressures, and compositions in order to determine the optimal growth process window. X-ray diffraction analyses indicate that the process window for growth on MgO substrates is narrower than for LaAlO3 substrates. Dielectric property measurements show that samples near stoichiometry have higher tunability, but their peak loss tangents are also high (∼0.02). The slightly Sr-poor samples (46-48 at.%) show a reduced loss tangent (<0.01) while maintaining an acceptable tunability (∼50%) at an average electric field of 1.7 V/μm.

scholarly journals Pair distribution functions of amorphous organic thin films from synchrotron X-ray scattering in transmission mode

IUCrJ ◽  
2017 ◽  
Vol 4 (5) ◽  
pp. 555-559 ◽  
Author(s):  
Chenyang Shi ◽  
Rattavut Teerakapibal ◽  
Lian Yu ◽  
Geoff G. Z. Zhang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Amorphous State ◽  
Organic Thin Films ◽  
High Energy ◽  
Transmission Mode ◽  
Organic Thin Film ◽  
Total Scattering ◽  
X Ray ◽  
Wide Range

Using high-brilliance high-energy synchrotron X-ray radiation, for the first time the total scattering of a thin organic glass film deposited on a strongly scattering inorganic substrate has been measured in transmission mode. The organic thin film was composed of the weakly scattering pharmaceutical substance indomethacin in the amorphous state. The film was 130 µm thick atop a borosilicate glass substrate of equal thickness. The atomic pair distribution function derived from the thin-film measurement is in excellent agreement with that from bulk measurements. This ability to measure the total scattering of amorphous organic thin films in transmission will enable accuratein situstructural studies for a wide range of materials.

Epitaxial Growth of Cerium Oxide Buffer Layers on MgO, YSZ and Sapphire Substrates

2000 ◽  
Vol 619 ◽  
Author(s):  
A. Thorley ◽  
S. Gnanarajan ◽  
A. Katsaros ◽  
N. Savvides
Keyword(s):  
Thin Films ◽  
Epitaxial Growth ◽  
Buffer Layers ◽  
Metal Target ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
Sapphire Substrates ◽  
Pole Figures ◽  
Biaxial Alignment

ABSTRACTWe studied the epitaxial growth of CeO2 thin films deposited onto MgO(100), YSZ(100) and Al2O3(1102 ) (r-plane sapphire) substrates by reactive dc magnetron sputtering of a Ce metal target in an Ar/O2 plasma. The crystalline quality and biaxial alignment of the films was determined using x-ray diffraction techniques (θ-2θ, ω-scans, pole figures, ø-scans). The CeO2/MgO(100) and CeO2/Al2O3(1102) epitaxy was evident at 600°C and developed to nearly perfect biaxial alignment at 850°C with Δø = 5° and 9° respectively. The CeO2/YSZ (100) epitaxy occurred below 300°C while deposition at ≥ 650°C led to single-crystal quality CeO2 films with Δø = 0.2°.

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