On Microstrucitural Evolution in Gas Atomized Ti-50 at.% Al-2 at.% Nb Powder

1988 ◽  
Vol 133 ◽  
Author(s):  
Donald S. Shih ◽  
Gary K. Scarr ◽  
James C. Chesnutt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Powder ◽  
Microstructural Development ◽  
X Ray ◽  
Transmission Electron ◽  
Helium Gas ◽  
Two Phases ◽  
20 Nm

ABSTRACTMicrostructural development in helium gas atomized Ti-50A1-2Nb (at.%) powder has been characterized using x-ray diffractometry and transmission electron microscopy. The structure of the as-atomized powder was a mixture of two phases: an ordered fct (L10)γ TiAl phase and an hcp α Ti phase containing fine (≈ 10–20 nm) D019 α2 domains. Large powder (≈ 250 μm) contained ≈ 14 volume % hcp phase, while fine powder (≈37 μm) contained ≈ 72 volume % hcp phase. However, this α+α2 constituent was metastable and transformed to the γ phase during annealing.

Synthesis of ZnO2 Nanocrystals Produced by Hydrothermal Process

2009 ◽  
Vol 1242 ◽  
Author(s):  
R. Esparza ◽  
A. Aguilar ◽  
A. Escobedo-Morales ◽  
C. Patiño-Carachure ◽  
U. Pal ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Peroxide ◽  
Transmission Electron Microscopy ◽  
Hydrothermal Process ◽  
High Resolution Electron Microscopy ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Zinc Peroxide ◽  
20 Nm

ABSTRACTZinc peroxide (ZnO2) nanocrystals were directly produced by hydrothermal process. The nanocrystals were synthesized using zinc acetate as precursor and hydrogen peroxide as oxidant agent. The ZnO2 powders were characterized by X-ray powder diffraction and transmission electron microscopy. The results of transmission electron microscopy indicated that the ZnO2powders consisted of nanocrystals with diameters below to 20 nm and a faceted morphology. High resolution electron microscopy observations have been used in order to the structural characterization. ZnO2 nanocrystals exhibit a well-crystallized structure.

Effect of Nano-Sized Metal Colloids on Color Change of Photosensitive Glass by Using X-Ray Irradiation

2009 ◽  
Vol 620-622 ◽  
pp. 509-512
Author(s):  
Yong Kap Park ◽  
In Churl Cho ◽  
Y. Choi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Color Change ◽  
Spherical Shape ◽  
Metal Colloids ◽  
X Ray ◽  
Photosensitive Glass ◽  
Transmission Electron ◽  
Ag Colloid ◽  
20 Nm

X-ray irradiation was applied to control the size of metal colloids in a silicate glass to make a high precise photosensitive glass containing K2O, Na2O, ZnO BaO, 0.01-0.05wt.% Au metal as sensitizer, <1.2wt.% Sb2O3 and SnO2 as thermal reducer. Colorimetry showed that X-ray irradiation effectively works to make the color of red system. Transmission electron microscopy revealed that the metal colloids were oxided and had uniform and spherical shape of 10-20 nm. Au colloid made various colors like pink after heating at 400°C, red at 500°C and dark-red at 600°C. Ag colloid made them like yellow-green at 400°C, yellow at 500°C and dark-brown, respectively.

Hydrothermal Synthesis of Luminescent Wollastonite-CePO4 Nanocomposites

2010 ◽  
Vol 92 ◽  
pp. 125-130
Author(s):  
Ming Guo Ma ◽  
Jie Fang Zhu ◽  
Run Cang Sun
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hydrothermal Synthesis ◽  
Electron Diffraction ◽  
Hydrothermal Method ◽  
Powder Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
20 Nm

Luminescent wollastonite-CePO4 nanocomposites have been successfully synthesized using Ca(NO3)2•4H2O, Na2SiO3•9H2O, and CePO4 by hydrothermal method at 200 oC for 24 h. The precursor nanorods with diameters about 20 nm and lengths several micrometers were obtained by hydrothermal treatment, and after calcination at 600 oC for 3h, the precursor nanorods transformed to wollastonite-CePO4 nanocomposites. Considering the experiment result, a possible growth of the precursor nanorods via the rolling mechanism was also proposed. This is the first report about the synthesis of luminescent wollastonite-CePO4 nanocomposites. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDS), and photoluminescence (PL).

Platinum Group Metals Base Refractory Superalloys

1996 ◽  
Vol 460 ◽  
Author(s):  
Y. Yamabe-Mitarai ◽  
Y. Koizumi ◽  
H. Murakami ◽  
Y. Ro ◽  
T. Maruko ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Platinum Group Metals ◽  
Compression Tests ◽  
Two Phase ◽  
X Ray ◽  
Melting Temperatures ◽  
High Temperature Materials ◽  
Transmission Electron ◽  
Two Phases

ABSTRACTIr- and Rh-base refractory superalloys with an fee and Lb two phase structure similar to Ni-base superalloys, yet with considerably higher melting temperatures have been proposed. Fee and Ll2 two phases were observed in these alloys by transmission electron microscopy and X-ray powder diffractometry. The compression tests of these alloys showed that the strengths of several alloys were about 200 MPa at 1800 °C and these alloys have potential to become ultra-high temperature materials for use in power engineering field.

Nanostructured red-emitting MgGa2O4:Eu3+ phosphors

2004 ◽  
Vol 19 (5) ◽  
pp. 1504-1508 ◽  
Author(s):  
Bin-Siang Tsai ◽  
Yen-Hwei Chang ◽  
Yu-Chung Chen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sol Gel ◽  
Photoluminescence Intensity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Gel Technique ◽  
Red Luminescence ◽  
20 Nm

Nano-grained phosphors of Eu3+-doped MgGa2O4 crystallites were prepared by sol-gel technique. The characterization and optical properties of luminescent MgGa2O4:Eu3+ powders have been investigated. The dried sol-gel powders were calcined in air at different temperature from 600 to 1000 °C for 5 h. The x-ray diffraction profiles showed that the MgGa2O4:Eu3+ powders began to crystallize around 600 °C and formed stable MgGa2O4 phase in the temperature range of 600–900 °C. The transmission electron microscopy morphology observations revealed that the fired powders exhibit small grain size less than 20 nm. In the PL studies, under ultraviolet (394 nm) excitation, the calcined powders emitted bright red luminescence (615 nm, 5D0→7F2), and the powders fired at 900 °C were found to have the maximum photoluminescence intensity. The quenching concentration of Eu3+ in MgGa2O4 crystallites was also indicated to be about 5∼6 mol%.

Tem Investigation of Titanium Silicide Thin Films

1998 ◽  
Vol 523 ◽  
Author(s):  
A. F. Myers ◽  
E. B. Steel ◽  
L. M. Struck ◽  
H. I. Liu ◽  
J. A. Burns
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Scanning Transmission Electron Microscopy ◽  
Titanium Silicide ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
20 Nm

AbstractTitanium silicide films grown on silicon were analyzed by transmission electron microscopy (TEM), electron diffraction, scanning transmission electron microscopy (STEM), and energy dispersive x-ray spectroscopy. The films were prepared by sequential rapid thermal annealing (RTA) at 675 °C and 850 °C of 16-nm-thick sputtered Ti on Si (001) wafers. In some cases, a 20-nm-thick TiN capping layer was deposited on the Ti film before the RTA procedure and was removed after annealing. TEM and STEM analyses showed that the silicide films were less than 0.1 μm thick; the capped film was more uniform, ranging in thickness from ∼ 25 – 45 nm, while the uncapped film ranged in thickness from ∼ 15 – 75 nm. Electron diffraction was used to determine that the capped film contained C54-TiSi2, C49-TiSi2, Ti5Si3, and possibly TiSi, and that the uncapped film contained C49-TiSi2, TiSi, Ti5Si3, unreacted Ti, and possibly C54-TiSi2.

scholarly journals Дозовая зависимость формирования нанокристаллов в имплантированных гелием слоях кремния

2018 ◽  
Vol 44 (7) ◽  
pp. 39
Author(s):  
А.А. Ломов ◽  
А.В. Мяконьких ◽  
Ю.М. Чесноков ◽  
В.В. Денисов ◽  
А.Н. Кириченко ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Nanocrystals ◽  
Implantation Dose ◽  
X Ray ◽  
Transmission Electron ◽  
Helium Ion ◽  
Nanocrystal Formation ◽  
20 Nm ◽  
First Time

AbstractThe possibility of nanocrystal formation in silicon layers subjected to plasma-immersion helium-ion implantation at an energy of 5 keV has been proved for the first time. The effect of the implantation dose on the microstructure of the layers has been studied by X-ray reflectometry, transmission electron microscopy and Raman scattering. It has been established that the formation of silicon nanocrystals with dimensions of 10–20 nm is accompanied by a pronounced dependence on the ion flux and occurs at a dose of 5 × 10^17 cm^–2 with subsequent annealing at 700–800°C. The excessive dose has been shown to cause the destruction of the upper protective sublayer and the degradation of the optical properties of nanocrystals.

Síntesis y caracterización de la Perovskita La0,95Sr0,05CrO3. (Synthesis and Characterization of the La0.95Sr0.05CrO3 Perovskite)

2015 ◽  
Vol 6 (1) ◽  
pp. 119 ◽  
Author(s):  
O. C. Vergara Estupiñán ◽  
J. A. Gómez Cuaspud
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Area ◽  
Crystalline Phase ◽  
Synthesis Process ◽  
Synthesis And Characterization ◽  
X Ray ◽  
Transmission Electron ◽  
20 Nm

ResumenEste trabajo investigó la síntesis y la caracterización de un material tipo perovskita basado en el sistema La0,95Sr0,05CrO3, mediante el método de polimerización-combustión, utilizando ácido cítrico para la conformación de especies intermedias de coordinación tipo citrato, que evolucionan en función de la temperatura hasta la consolidación de la fase cristalina buscada. La caracterización del precursor metalorgánico se realizó mediante análisis térmicos (TGA-DTA), con el fin de establecer una temperatura ideal de consolidación de la fase cristalina buscada. Los análisis de difracción de rayos X (XRD), microscopía electrónica de transmisión (TEM), fluorescencia de rayos X por microsonda (EDX) y análisis de área superficial (BET) se realizaron sobre el material cerámico calcinado, y revelaron la obtención de una estructura cristalina ortorrómbica nanoestructurada con grupo espacial Pnma (62), con un tamaño promedio de cristalito de 20 nm. Los análisis derivados de la microscopía electrónica de transmisión revelaron que el material está conformado por agregados del orden nanométrico con una serie de propiedades texturales y morfológicas específicas para eventual aplicación a nivel catalítico, lo que guarda una estrecha relación con los datos derivados de la medida del área superficial, obtenidos por la técnica BET. Finalmente, la valoración de la composición mediante fluorescencia de rayos X permitió determinar que el control en la composición es uno de los parámetros claves en este proceso de síntesis, lo cual permite validar el método utilizado y posibilita el empleo de los materiales obtenidos en potenciales aplicaciones tecnológicas. AbstractThis work investigated the synthesis and characterization of a perovskite material based on theLa0.95Sr0.05CrO3 system, by a wet chemical route that involves the combustion-polymerization method, using citric acid as complexing agent, in order to obtain intermediate coordination species, which evolve depending on the temperature until the desired consolidation crystalline phase is obtained. The metal-organic precursor characterization was performed by thermal analyses (TGA-DTA), in order to evaluate an ideal consolidation temperature of the searched crystalline phase. The analysis by the X-ray diraction (XRD), the transmission electron microscopy (TEM), the X-ray fluorescence microprobe (EDX) and the surface area (BET), were performed over the calcined ceramic material and revealed the obtention of a nanostructured orthorhombic crystal structure with a Pnma (62) space group, and a 20 nm crystallite average size. The analysis derived from the transmission electron microscopy, revealed that the material is composed of aggregates of nanometric range with a series of textural and specific morphological properties for an eventual application at the catalytic level, which is correlated with the data derived from the measurement of the surface area obtained by the BET technique. Finally, the composition by X-ray fluorescence assessment revealed that stoichiometric control in composition is one of the key parameters in this synthesis process, which allows to validate the used method and enables to employ the obtained materials in potential technological applications.

Preparation of Nano-FeXOY by Thermal Decomposition Method and Morphology Research

2010 ◽  
Vol 148-149 ◽  
pp. 1124-1128
Author(s):  
Ru Xin Che ◽  
Shuo Wang ◽  
Bing Yu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thermal Decomposition ◽  
Decomposition Method ◽  
Primary Particle ◽  
X Ray ◽  
Thermal Decomposition Method ◽  
Transmission Electron ◽  
Ray Diffusion ◽  
20 Nm

Nano-FexOy (including γ-Fe2O3, α-Fe2O3 and Fe3O4) particles were prepared by acetylacetonate iron [Fe(C5H7O2)3] thermal decomposition under air condition at low temperature. X-ray diffusion (XRD), transmission electron microscopy (TEM), electron diffraction pattern (EDP), and specific surface area were carried out to characterized these nanoparticles. The influencing factors of experiment were discussed and studied, and the results show that γ-Fe2O3, α-Fe2O3 and Fe3O4 in different morphology can be obtained respectively by controlling the experiment conditions. The primary particle of Fe3O4 is about 16 nm; the primary particle of γ- Fe2O3 is about 20 nm and arranges compact. The second nanoparticle of γ- Fe2O3 presents catenarian and has the tendency to form an close space.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

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