Ultra-Thin Al2O3 Formation at Room Temperature

2010 ◽  
Vol 93-94 ◽  
pp. 113-116
Author(s):  
Puenisara Limnonthakul ◽  
Artorn Pokaipisit ◽  
Pichet Limsuwan
Keyword(s):  
Crystal Structure ◽  
Silicon Wafer ◽  
Room Temperature ◽  
Volume Fraction ◽  
Effective Medium Approximation ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
Transmission Electron ◽  
Sputtering Power

Ultra-thin Al films were deposited with different deposition times on silicon wafer and copper grid by dc magnetron sputtering. The sputtering power of 200 watt and Ar flow rate of 20 sccm were used to prepare the films. The deposition times were 40, 120 and 240 second, respectively. The deposited Al films were, then, left in the air under the humidity of 60% for 20 days. The crystal structure of ultra-thin Al films deposited on silicon wafer and copper grid were investigated by glazing x-ray diffraction (GXRD) and transmission electron microscopy (TEM), respectively. The XRD results show that after the ultra thin Al films were exposed to the air, the Al was oxidized and the Al2O3 was formed at room temperature. In addition, Al deposited for 120 and 240 second can form polycrystalline of -Al2O3 with preferred orientations of (110) and (311) planes. The TEM images show that the particle size of -Al2O3 was about 8.5 nm for deposited time of 120 second. Moreover, the spectroscopic ellipsometry (SE) data and simulation model of Bruggemann effective medium approximation (BEMA) was used to determine the volume fraction of Al2O3.

On the Study of PbTe-Based Nanocomposite Thermoelectric Materials

2012 ◽  
Vol 17 ◽  
pp. 165-174 ◽  
Author(s):  
Th. C. Hasapis ◽  
S. N. Girard ◽  
Euripides Hatzikraniotis ◽  
Konstantinos M. Paraskevopoulos ◽  
M. G. Kanatzidis
Keyword(s):  
Volume Fraction ◽  
Vibrational Properties ◽  
Effective Medium Approximation ◽  
Bilayer Thickness ◽  
Phonon Confinement ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Class ◽  
Transmission Electron ◽  
Form Features

We Report on the Structural and Vibrational Properties of the X = 0.11 and X = 0.33 Compositions of a New Class of Nanostructured Thermoelectric System (PbTe)1-X(PbSnS2)x by Means of X-Ray Diffraction, Scanning and Transmission Electron Microscopy and Infrared Reflectivity. both Compositions Are Phase Separated, where Pbsns2 Self-Segregates from Pbte to Form Features with Dimensions Ranging from Tens of Micrometers to Tens of Nanometers. Effective Medium Approximation Was Used in Order to Determine the Volume Fraction and the Dielectric Function of the Nanoscale Pbsns2 Embedded in Pbte. by Comparing the Phonon Parameters of the Nanoscale Pbsns2 and Bulk Pbsns2 Single Crystals, we Concluded that Phonon Confinement Effects and Bilayer Thickness Anisotropy within the Pbsns2 Nanostructures Embedded within Pbte Are Responsible for the Observed Variations in the Frequencies of the Shear and the Compression Modes Not Observed in Pure Crystals of Pbsns2.

Effects of Ho-Doping on Crystal Structure and Microstructure of La0.7Sr0.3MnO3 Ceramics

2013 ◽  
Vol 745-746 ◽  
pp. 96-101 ◽  
Author(s):  
Ben Zhe Sun ◽  
Si Lang Zhou ◽  
Tie Shen
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Perovskite Structure ◽  
Volume Fraction ◽  
Partial Substitution ◽  
X Ray Diffraction ◽  
Doping Amount ◽  
X Ray ◽  
Transmission Electron ◽  
Structure And Microstructure

Crystal structure and microstructure of La0.7-xHoxSr0.3MnO3 (x=0.2,0.6) prepared by usual ceramic techniques and grinding procedure were investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). When doping amount x equals to 0.2, incorporation of Ho atoms contributed to phase separation and coexistence of rhombohedral (La0.7Sr0.3MnO3) and hexagonal (HoMnO3) phases. La0.7Sr0.3MnO3 phase is of typical perovskite structure, whereas, HoMnO3 phase is non-perovskite structure. As x reaches 0.6, the volume fraction of HoMnO3 phase was significantly increasing. Meanwhile, an orthorhombic lattice with perovskite structure and space group Pnma can be observed. It prevented from partial substitution of La 3+ or Sr2+ by Ho3+ and the distortion of Mn-O octahedra.

MICROSTRUCTURE OF FeCo–Cu NANOGRANULAR FILMS WITH GIANT MAGNETORESISTANCE

2007 ◽  
Vol 21 (20) ◽  
pp. 1297-1305
Author(s):  
CHANGZHENG WANG ◽  
PEIMING ZHANG ◽  
YIQING ZHANG ◽  
XIAOGUANG XIAO ◽  
YONGHUA RONG ◽  
...  
Keyword(s):  
Giant Magnetoresistance ◽  
Room Temperature ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Coherent Interface ◽  
X Ray ◽  
Cu Films ◽  
Transmission Electron ◽  
The Relationship ◽  
Fcc Structure

A series of ( Fe 50 Co 50)x Cu 1-x granular films were prepared using a magnetron-controlled sputtering system. The microstructure and giant magnetoresistance of FeCo–Cu films deposited at room temperature and then annealed at various temperatures were investigated through X-ray diffraction, transmission electron microscope and conventional four-probes method under room temperature, respectively. The results revealed that FeCo–Cu films consisted of fine FeCo granules uniformly dispersed in the Cu matrix and formed fcc structure. Meanwhile the Cu (111) interplaner lattice spacing decreased with increasing magnetic volume fraction (x) due to the presence of the metal coherent interface strains and FeCo–Cu alloying. Upon varying the magnetic volume fraction (x), the giant magnetoresistance of as-deposited FeCo–Cu films reached a maximum of about 0.7% at the volume fraction of 31%, corresponding to the fact that the giant magnetoresistance has a non-monotonic relationship with the granule size. In addition, the relationship between the full width at half maximum (FWHM) or the sensitivity of the giant magnetoresistance and the volume fraction are discussed in detail.

Preparation of FeCoZrBCu Thin Films and their Effect of Microstructure on Magnetic Properties

2007 ◽  
Vol 546-549 ◽  
pp. 2163-2166
Author(s):  
Jia Ping Cui ◽  
Li Zhong ◽  
Xiao Fang Bi
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Amorphous State ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
Cu Films ◽  
Si Substrates ◽  
Transmission Electron ◽  
Deposited Films

In this work, (Fe,Co)–Zr–B–Cu films have been deposited on glass and Si substrates by DC magnetron sputtering method. X-ray diffraction analysis was used to identify the structure of the films. A transmission electron microscope (TEM) was employed to observe the microstructure for the films. Magnetic properties at room temperature were investigated by a Vibrating Sample Magnetometer (VSM). It was obtained that the as-deposited films on glass and Si substrates were in an amorphous state. In addition, it has been found that the coercivity is dependent on film thicknesses.

scholarly journals Study on the Electrical, Structural, Chemical and Optical Properties of PVD Ta(N) Films Deposited with Different N2 Flow Rates

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 937
Author(s):  
Yingying Hu ◽  
Md Rasadujjaman ◽  
Yanrong Wang ◽  
Jing Zhang ◽  
Jiang Yan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Photoelectron Spectroscopy ◽  
Crystal Size ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Flow Rates ◽  
X Ray ◽  
N2 Flow Rate

By reactive DC magnetron sputtering from a pure Ta target onto silicon substrates, Ta(N) films were prepared with different N2 flow rates of 0, 12, 17, 25, 38, and 58 sccm. The effects of N2 flow rate on the electrical properties, crystal structure, elemental composition, and optical properties of Ta(N) were studied. These properties were characterized by the four-probe method, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). Results show that the deposition rate decreases with an increase of N2 flows. Furthermore, as resistivity increases, the crystal size decreases, the crystal structure transitions from β-Ta to TaN(111), and finally becomes the N-rich phase Ta3N5(130, 040). Studying the optical properties, it is found that there are differences in the refractive index (n) and extinction coefficient (k) of Ta(N) with different thicknesses and different N2 flow rates, depending on the crystal size and crystal phase structure.

scholarly journals Exploring the Structural Chemistry of Pyrophosphoramides: N,N′,N″,N‴-Tetraisopropylpyrophosphoramide

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 149-163
Author(s):  
Duncan Micallef ◽  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray Diffraction ◽  
X Ray

N,N′,N″,N‴-Tetraisopropylpyrophosphoramide 1 is a pyrophosphoramide with documented butyrylcholinesterase inhibition, a property shared with the more widely studied octamethylphosphoramide (Schradan). Unlike Schradan, 1 is a solid at room temperature making it one of a few known pyrophosphoramide solids. The crystal structure of 1 was determined by single-crystal X-ray diffraction and compared with that of other previously described solid pyrophosphoramides. The pyrophosphoramide discussed in this study was synthesised by reacting iso-propyl amine with pyrophosphoryl tetrachloride under anhydrous conditions. A unique supramolecular motif was observed when compared with previously published pyrophosphoramide structures having two different intermolecular hydrogen bonding synthons. Furthermore, the potential of a wider variety of supramolecular structures in which similar pyrophosphoramides can crystallise was recognised. Proton (1H) and Phosphorus 31 (31P) Nuclear Magnetic Resonance (NMR) spectroscopy, infrared (IR) spectroscopy, mass spectrometry (MS) were carried out to complete the analysis of the compound.

Photoluminescence Enhancement of CdS Nanocrystals Fabricated on Dithiocarbamate Functionalized PET Substrates

2012 ◽  
Vol 512-515 ◽  
pp. 1511-1515
Author(s):  
Chun Lin Zhao ◽  
Li Xing ◽  
Xiao Hong Liang ◽  
Jun Hui Xiang ◽  
Fu Shi Zhang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Hexagonal Structure ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Cds Nanocrystals ◽  
Morphological Studies ◽  
Transmission Electron

Cadmium sulfide (CdS) nanocrystals (NCs) were self-assembled and in-situ immobilized on the dithiocarbamate (DTCs)-functionalized polyethylene glycol terephthalate (PET) substrates between the organic (carbon disulfide diffused in n-hexane) –aqueous (ethylenediamine and Cd2+ dissolved in water) interface at room temperature. Powder X-ray diffraction measurement revealed the hexagonal structure of CdS nanocrystals. Morphological studies performed by scanning electron microscopy (SEM) and high-resolution transmission electron microscope (HRTEM) showed the island-like structure of CdS nanocrystals on PET substrates, as well as energy-dispersive X-ray spectroscopy (EDS) confirmed the stoichiometries of CdS nanocrystals. The optical properties of DTCs modified CdS nanocrystals were thoroughly investigated by ultraviolet-visible absorption spectroscopy (UV-vis) and fluorescence spectroscopy. The as-prepared DTCs present intrinsic hydrophobicity and strong affinity for CdS nanocrystals.

scholarly journals Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1141
Author(s):  
Georgia Basina ◽  
Hafsa Khurshid ◽  
Nikolaos Tzitzios ◽  
George Hadjipanayis ◽  
Vasileios Tzitzios
Keyword(s):  
Room Temperature ◽  
Colloidal Particles ◽  
Iron Pentacarbonyl ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
Organometallic Synthesis ◽  
X Ray ◽  
Transmission Electron ◽  
Hot Injection ◽  
The Stability

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results demonstrated that their stability against complete oxidation related to their size. The crystal structure and the morphology were identified by powder X-ray diffraction and transmission electron microscopy, while the magnetic properties were studied at room temperature with a vibrating sample magnetometer. The injection temperature plays a very crucial role and higher temperatures enhance the stability and the resistance against oxidation. For the case of injection at 315 °C, the nanoparticles had around a 10 nm mean diameter and revealed 132 emu/g. Remarkably, a stable dispersion was created due to the colloids’ surface functionalization in a nonpolar solvent.

Synthesis and Photoluminescence Properties of Novel SnO2 Zigzag Nanoribbons

2010 ◽  
Vol 97-101 ◽  
pp. 4213-4216
Author(s):  
Jian Xiong Liu ◽  
Zheng Yu Wu ◽  
Guo Wen Meng ◽  
Zhao Lin Zhan
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Ceramic Boat

Novel single-crystalline SnO2 zigzag nanoribbons have been successfully synthesized by chemical vapour deposition. Sn powder in a ceramic boat covered with Si plates was heated at 1100°C in a flowing argon atmosphere to get deposits on a Si wafers. The main part of deposits is SnO2 zigzag nanoribbons. They were characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). SEM observations reveal that the SnO2 zigzag nanoribbons are almost uniform, with lengths near to several hundred micrometers and have a good periodically tuned microstructure as the same zigzag angle and growth directions. Possible growth mechanism of these zigzag nanoribbons was discussed. A room temperature PL spectrum of the zigzag nanoribbons shows three peaks at 373nm, 421nm and 477nm.The novel zigzag microstructures will provide a new candidate for potential application.

Magnetic Properties of Sputtered Fe-O and Co-O Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
D. V. Dimitrov ◽  
A. S. Murthy ◽  
G. C. Hadjipanayis ◽  
C. P. SWANN
Keyword(s):  
Grain Size ◽  
Low Temperatures ◽  
Room Temperature ◽  
Oxide Films ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Large Shift ◽  
X Ray ◽  
Grain Size And Shape ◽  
Spherical Grains

AbstractFe-O and Co-O films were prepared by DC magnetron sputtering in a mixture of Ar and O2 gases. By varying the oxygen to argon ratio, oxide films with stoichiometry FeO, Fe3O4, α-Fe2O3, CoO and Co3O4 were produced. TEM studies showed that the Fe – oxide films were polycrystalline consisting of small almost spherical grains, about 10 nm in size. Co-O films had different microstructure with grain size and shape dependent on the amount of oxygen. X-ray diffraction studies showed that the grains in Fe-O films were randomly oriented in contrast to Co-O films in which a <111> texture was observed. Pure FeO and α-Fe2O3 films were found to be superparamagnetic at room temperature but strongly ferromagnetic at low temperatures in contrast to the antiferromagnetic nature of bulk samples. A very large shift in the hysteresis loop, about 3800 Oe, was observed in field cooled Co-CoO films indicating the presence of a large unidirectional exchange anisotropy.

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