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.

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.

Removeal of Arsenic(III) from Water by Using a New Class of Zero-Valent Iron Modified Mesoporous Silica Molecular Sieves SBA-15

2011 ◽  
Vol 356-360 ◽  
pp. 423-429
Author(s):  
Meng Ye ◽  
Jin Huang ◽  
Rui Chen ◽  
Qi Zhuang He
Keyword(s):  
Molecular Sieves ◽  
Cost Effective ◽  
Zero Valent Iron ◽  
Preparation Process ◽  
X Ray Diffraction ◽  
Wet Impregnation ◽  
X Ray ◽  
New Class ◽  
Transmission Electron ◽  
Removal Of Arsenic

An elevated arsenic (As) content in groundwater imposes a great threat to people worldwide. Thus, developing new and cost-effective methods to remove As from groundwater and drinking water becomes a priority. Using Zero-Valent iron (ZVI) to remove As from water is a proven technology. In this study, ZVI modified SBA-15 mesoporous silicamolecular sieves (ZVI-SBA-15), was prepared, characterized, and used for removing arsenic from water. Wet impregnation, drying, and calcination steps led to iron inclusion within the mesopores. Iron oxide was reduced to ZVI by NaBH4, and the ZVI modified SBA-15 was obtained. Fourier-transform infrared spectroscopy confirmed the preparation process of the nitrate to oxide forms. The structure of the materials was confirmed by Powder X-ray diffraction. Its data indicated that the structure of ZVI-SBA-15 retained the host SBA-15 structure. Brunauer-Emmett-Teller analysis revealed a decrease in surface area and pore size, indicating ZVI-SBA-15 coating on the inner surfaces. Transmission electron micrographs also confirmed that modified SBA-15 retained the structure of the parent SBA-15 silica.It has a high uptake capability(more than 90 pecent) make it potentially attractive absorbent for the removal of arsenic from water.

scholarly journals TEM Study of High-Temperature Precipitation of Delta Phase in Inconel 718 Alloy

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Moukrane Dehmas ◽  
Jacques Lacaze ◽  
Aliou Niang ◽  
Bernard Viguier
Keyword(s):  
Inconel 718 ◽  
Volume Fraction ◽  
Alloy 718 ◽  
Double Diffraction ◽  
X Ray Diffraction ◽  
Inconel 718 Alloy ◽  
X Ray ◽  
Delta Phase ◽  
Transmission Electron ◽  
Matrix Free

Inconel 718 is widely used because of its ability to retain strength at up to 650∘C for long periods of time through coherent metastable Ni3Nb precipitation associated with a smaller volume fraction of Ni3Al precipitates. At very long ageing times at service temperature, decomposes to the stable Ni3Nb phase. This latter phase is also present above the solvus and is used for grain control during forging of alloy 718. While most works available on precipitation have been performed at temperatures below the solvus, it appeared of interest to also investigate the case where phase precipitates directly from the fcc matrix free of precipitates. This was studied by X-ray diffraction and transmission electron microscopy (TEM). TEM observations confirmed the presence of rotation-ordered domains in plates, and some unexpected contrast could be explained by double diffraction due to overlapping phases.

Preparation and Property of Al87Ce3Ni8.5Mn1.5 Nanophase Amorphous Composites

2011 ◽  
Vol 412 ◽  
pp. 263-266
Author(s):  
Hong Wei Zhang ◽  
Li Li Zhang ◽  
Feng Rui Zhai ◽  
Jia Jin Tian ◽  
Can Bang Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
Volume Fraction ◽  
Material Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures

The higher mechanical strength of Al87Ce3Ni8.5Mn1.5 nanophase amorphous composites has been obtained with two methods. The first nanophase amorphous composites are directly produced by the single roller spin quenching technology. The method taken for the second nanophase amorphous composites is at first to obtain amorphous single-phase alloy, followed by annealed at different temperatures .The formative condition, the microstructure, the particle size, the volume fraction of α-Al phase and microhardness of nanophase amorphous composites etc have been investigated and compared by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The microstructure of composites produced by the second method is higher than the former, the fabricated material structure of the system is more uniform and the process is easier to control.

The Ti-B-N System: Nanocomposite nc-TiN/a-(TiB2, BN) and Nano-Multilayer nc-TiN/a-TiBN Thin Films

2008 ◽  
Vol 8 (5) ◽  
pp. 2713-2718
Author(s):  
Y. H. Lu ◽  
K. Chu ◽  
Y. G. Shen
Keyword(s):  
Thin Films ◽  
Dislocation Motion ◽  
Structural Barriers ◽  
Mechanical Behaviors ◽  
Bilayer Thickness ◽  
Maximum Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
Transmission Electron

The nanostructures and mechanical properties of nanocomposite nc-TiN/a-(TiB2, BN) and nanostructured multilayers nc-TiN/a-TiBN were investigated using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), microindentation, and stress measurements. It was found that the monolayer Ti-B-N thin films consisted of nanometer-sized crystalline (nc-) Ti(N, B) embedded into amorphous (a-) (TiB2, BN) matrix. When B content was below ∼16 at.%, two different-sized nanocrystallites with mean grain sizes of ∼3 and 9 nm respectively were embedded in a-TiB2. With increasing B incorporation (>∼27 at.%), more uniform nanograins was embedded a-(TiB2, BN). Incorporation of B not only decreased the size of nanocrystallites, but also gave rise to twinning deformation in nanocrystallites. A maximum hardness of ∼44 GPa was achieved at B content of 19 at.%. It was also found that the nanostructure and mechanical behaviors of nc-TiN/a-TiBN multilayers was dependent on the modulation length (bilayer thickness Λ). Decrease of Λ made the preferred orientation of nc-TiN gradually transform from (200) to (111). A maximum hardness of ∼30 GPa was achieved at Λ = 1.8 nm. Deflection from this Λ value decreased hardness. By contrast, the residual compressive stress value monotonically increased with decrease of Λ. The enhancement of the hardness was due to the coherent stresses and the structural barriers to dislocation motion in the interface.

Hardness evolution of Al–Cr–N coatings under thermal load

2008 ◽  
Vol 23 (11) ◽  
pp. 2880-2885 ◽  
Author(s):  
Herbert Willmann ◽  
Paul H. Mayrhofer ◽  
Lars Hultman ◽  
Christian Mitterer
Keyword(s):  
Thermal Load ◽  
Structural Changes ◽  
Single Phase ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Al Content ◽  
Annealing Temperatures ◽  
Transmission Electron

Microstructure and hardness evolution of arc-evaporated single-phase cubic Al0.56Cr0.44N and Al0.68Cr0.32N coatings have been investigated after thermal treatment in Ar atmosphere. Based on a combination of differential scanning calorimetry and x-ray diffraction studies, we can conclude that Al0.56Cr0.44N undergoes only small structural changes without any decomposition for annealing temperatures Ta ⩽ 900 °C. Consequently, the hardness decreases only marginally from the as-deposited value of 30.0 ± 1.1 GPa to 29.4 ± 0.9 GPa with Ta increasing to 900 °C, respectively. The film with higher Al content (Al0.68Cr0.32N) exhibits formation of hexagonal (h) AlN at Ta ⩾ 700 °C, which occurs preferably at grain boundaries as identified by analytical transmission electron microscopy. Hence, the hardness increases from the as-deposited value of 30.1 ± 1.3 GPa to 31.6 ± 1.4 GPa with Ta = 725 °C. At higher temperatures, where the size and volume fraction of the h-AlN phase increases, the hardness decreases to 27.5 ± 1.0 GPa with Ta = 900 °C.

Sol-gel derived Ba(Mg1/3Ta2/3)O3 thin films: Preparation and structure

1997 ◽  
Vol 12 (3) ◽  
pp. 596-599 ◽  
Author(s):  
Ji Zhou ◽  
Qing-Xin Su ◽  
K. M. Moulding ◽  
D. J. Barber
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Small Grains

Ba(Mg1/3Ta2/3)O3 thin films were prepared by a sol-gel process involving the reaction of barium isopropoxide, tantalum ethoxide, and magnesium acetate in 2-methoxyethanol and subsequently hydrolysis, spin-coating, and heat treatment. Transmission electron microscopy, x-ray diffraction, and Raman spectroscopy were used for the characterization of the thin films. It was shown that the thin films tend to crystallize with small grains sized below 100 nm. Crystalline phase with cubic (disordered) perovskite structure was formed in the samples annealed at a very low temperature (below 500 °C), and well-crystallized thin films were obtained at 700 °C. Although disordered perovskite is dominant in the thin films annealed below 1000 °C, a low volume fraction of 1 : 2 ordering domains was found in the samples and grows with an increase of annealing temperature.

Structure and Morphology of Epitaxially Intergrown (100)- and (116)-Oriented SrBi2Ta2O9 Ferroelectric Thin Films on SrLaGaO4(110) Substrates

2001 ◽  
Vol 688 ◽  
Author(s):  
H. N. Lee ◽  
D. N. Zakharov ◽  
P. Reiche ◽  
R. Uecker ◽  
D. Hesse
Keyword(s):  
Thin Films ◽  
Volume Fraction ◽  
Scanning Force Microscopy ◽  
Epitaxial Thin Films ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Integrated Intensity ◽  
Scanning Force

AbstractSrBi2Ta2O9 (SBT) epitaxial thin films having a mix of (100) and (116) orientations have been grown on SrLaGaO4(110) by pulsed laser deposition. X-ray diffraction θ2 θ and pole figure scans, and cross-sectional transmission electron microscopy (TEM) analyses revealed the presence of two epitaxial orientations, SBT(100) ∥ SLG(110); SBT[001] ∥ SLG[001] and SBT(116) ∥ SLG(110); SBT [110] ∥ SLG[001]. By calculating the integrated intensity of certain x-ray diffraction peaks, it was established that the crystallinity and the in-plane orientation of the (100) and (116) orientation are best at a substrate temperature of 775 °C and 788 °C, respectively, and that the volume fraction of the (100) orientation at about 770 °C reached about 60%. By scanning force microscopy and cross-sectional TEM investigations we found that the a-axisoriented grains are rounded and protrude out due to the rapid growth along the [110] direction, leading to a distinct difference of the surface morphology between (100)- and (116)-oriented grains.

Research on Solution and Aging Treatment of Mg-7Zn-3Al Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 247-250
Author(s):  
Jing Zhang ◽  
Fu Sheng Pan ◽  
Ru Lin Zuo
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Volume Fraction ◽  
Solution Treatment ◽  
Aging Treatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Quantitative Image ◽  
The Matrix

Effect of solution and aging treatment on the microstructure of Mg-7Zn-3Al alloy is studied by using optical microscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy and quantitative image analysis. The results show that the as-aged microstructure is composed of α-Mg matrix, grain boundary τ (Mg32(Al,Zn)49 ) phase, and fine dispersed τ particles inside the grain. The solution degree has significant effects on the formation, morphology, and size of the grain boundary τ phase. The volume fraction and the size of the undissolved eutectic τ phase decrease with the increase of solution time treated at 325°C. Through sufficient solution treatment, discontinuous eutectic τ phase retains fine strip morphology after aging, in contrast to the microstructure in sample undergone insufficient solution which manifests as-cast feature, while at the same time nano-sized particles precipitate out from the matrix. The precipitates display paralleled short bar, having certain orientation relationship with the matrix.

Nano-Structured TiN/TiBN Multilayer Thin Films

2007 ◽  
Vol 334-335 ◽  
pp. 889-892
Author(s):  
K. Chu ◽  
Yao Gen Shen
Keyword(s):  
Thin Films ◽  
Multilayer Film ◽  
Multilayer Thin Films ◽  
Bilayer Thickness ◽  
Maximum Hardness ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
Significant Relationships ◽  
Transmission Electron

Nano-structured TiN/TiBN multilayer thin films were deposited onto unheated Si(100) substrates by reactive unbalanced dc-magnetron sputtering in an Ar-N2 gas mixture at a pulsed-bias voltage of –60 V. The effects of the bilayer thickness (Λ = 1.8-7.7 nm) on microstructures and mechanical properties have been analyzed using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and microindentation measurements. Microstructure studies revealed that the TiN layers were fcc B1-NaCl structure comprising of (111)- and (200)-oriented grains depending on Λ, while the TiBN layers were amorphous. Significant relationships were found between hardness (H) and Λ. A maximum hardness of ~30 GPa was observed in a multilayer film with = 1.8 nm. The possible hardness enhancement mechanism was also discussed.

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