A new method for the preparation of transparent Y2O3 nanocrystalline ceramic with an average grain size of 20 nm

2020 ◽  
Vol 182 ◽  
pp. 57-61 ◽  
Author(s):  
Zhangyi Huang ◽  
Jirui Deng ◽  
Haomin Wang ◽  
Yutong Zhang ◽  
Junjing Duan ◽  
...  
Keyword(s):  
Grain Size ◽  
New Method ◽  
Average Grain Size ◽  
20 Nm ◽  
Nanocrystalline Ceramic

ATOMIC FORCE MICROSCOPY AND XRD ANALYSIS OF SILVER FILMS DEPOSITED BY THERMAL EVAPORATION

2006 ◽  
Vol 20 (02) ◽  
pp. 217-231 ◽  
Author(s):  
MUHAMMAD MAQBOOL ◽  
TAHIRZEB KHAN
Keyword(s):  
Atomic Force Microscopy ◽  
Grain Size ◽  
Surface Characterization ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Xrd Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Average Grain Size ◽  
20 Nm

Thin films of pure silver were deposited on glass substrate by thermal evaporation process at room temperature. Surface characterization of the films was performed using X-ray diffraction (XRD) and atomic force microscopy (AFM). Thickness of the films varied between 20 nm and 72.8 nm. XRD analysis provided a sharp peak at 38.75° from silver. These results indicated that the films deposited on glass substrates at room temperature are crystalline. Three-dimension and top view pictures of the films were obtained by AFM to study the grain size and its dependency on various factors. Average grain size increased with the thickness of the deposited films. A minimum grain size of 8 nm was obtained for 20 nm thick films, reaching 41.9 nm when the film size reaches 60 nm. Grain size was calculated from the information provided by the XRD spectrum and averaging method. We could not find any sequential variation in the grain size with the growth rate.

Transport Properties of B-, P-Doped and Undoped 50 kHz PECVD Microcrystalline Silicon

1989 ◽  
Vol 164 ◽  
Author(s):  
M.A. Hachicha ◽  
Etienne Bustarret
Keyword(s):  
Grain Size ◽  
Hall Mobility ◽  
Solid Phase ◽  
Grazing Angle ◽  
Dc Conductivity ◽  
X Ray Diffraction ◽  
Crystalline Fraction ◽  
Average Grain Size ◽  
20 Nm ◽  
Solid Phase Density

AbstractUndoped 500 nm-thick silicon layers with a crystalline fraction around 95% and an average grain size of 20 nm have been deposited at 350°C by 50 kHz triode PECVD in a H2/SiH4 mixture, in the presence of a magnetic field. Their room temperature (rt) dc conductivity μrt is 0.03 Δ−1cm−1 for a Hall mobility of 0.8 cm 2V−1s−1.The study by SIMS, infrared absorption, grazing angle x-ray diffraction and Raman scattering spectroscopies of the doped samples shows how the crystalline fraction and the grain size drop as the B2H6/SiH4 and PH3/SiH4 volumic ratios increase from 10 ppm to 1%.The rt dc conductivity reaches 2 Δ−1 cm−1 (Hall mobility: 15 cm2V−ls−1) for a solid phase density of 1019 cm−3 boron atoms, and 30 Δ−1cm−1 (Hall mobility: 55 cm2V−ls−1) at the maximum P incorporation of 8 × 1020cm−3.

Formation of nanocrystalline surface of a Cu–Zn alloy under electropulsing surface treatment

2007 ◽  
Vol 22 (7) ◽  
pp. 1947-1953 ◽  
Author(s):  
X.N. Du ◽  
B.Q. Wang ◽  
J.D. Guo
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Surface Layer ◽  
Surface Treatment ◽  
Skin Effect ◽  
Structure And Property ◽  
Average Grain Size ◽  
Solid State Phase Transformation ◽  
20 Nm ◽  
Zn Alloy

A nanocrystalline surface layer of a Cu–Zn alloy was developed by electropulsing (ECP) surface treatment. The average grain size was about 20 nm on the top surface layer and was gradually augmented with the increase in depth from the top surface. Nanoindentation measurements showed that the hardness was significantly enhanced on the top surface layer compared with the as-annealed Cu–Zn sample. The mechanism for the evolution of this structure and property was related not only to a solid-state phase transformation, but also to the effect of the enhancement of the nucleation rate and the skin effect during the ECP treatment. Therefore, the ECP surface treatment provides a promising method for obtaining surface self-nanocrystallization materials.

Autothermal Gelation Synthesis of Uniform Titania Nanoparticles

2010 ◽  
Vol 148-149 ◽  
pp. 1188-1191
Author(s):  
Xi Xin Wang ◽  
Jian Ling Zhao ◽  
Zhao Hui Meng ◽  
Jia Wei Yan
Keyword(s):  
Grain Size ◽  
Tio2 Nanoparticles ◽  
Anatase Phase ◽  
Xrd Analysis ◽  
Rutile Phase ◽  
Titania Nanoparticles ◽  
Gelation Process ◽  
Average Grain Size ◽  
Process Effects ◽  
20 Nm

Titania nanoparticles were successfully synthesized through an easily controlled and simple autothermal gelation process. Effects of H2O2 concentrations, solvent quantity and dissolving temperature were investigated in detail. DSC–TGA and XRD analysis showed that the synthesized TiO2 nanoparticles were in anatase phase at 400°C and in rutile phase at 650°C. TEM image indicated that the titania nanoparticles were uniform and approximately spherical, the average grain size of the product was about 20 nm.

Strength and Ductility in Electrodeposited Nanocrystalline Nickel

2009 ◽  
Vol 633-634 ◽  
pp. 411-420 ◽  
Author(s):  
Heather W. Yang ◽  
Farghalli A. Mohamed
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Annealing Treatment ◽  
Average Grain Size ◽  
Annealing Twins ◽  
Grain Distribution ◽  
Small Grains ◽  
20 Nm ◽  
Strength And Ductility

Electrodeposited nanocrystalline (nc) Ni having an average grain size of 20 nm was annealed at 443 K for different holding times. An examination of the microstructure following annealing showed three important features. First, all annealed samples exhibited abnormal grain growth, which was manifested by the presence of large grains that were surrounded by regions of small grains (bimodal grain distributions). Second, annealing twins existed in the large grains of the samples that showed a bimodal grain distribution. Third, by estimating the density of annealing twin, it was found that annealing nc-Ni at 443 K resulted in a maximum twin density after 5h. Following annealing treatment, specimens with different volume fractions of twins were tested under uniaxial tension at 393 K and a strain rate of 10-4 s-1. The results showed that both strength and ductility in nc-Ni attained maximum values after annealing for 5h. The role of both bimodal grain distributions and annealing twins in enhancing ductility and strength was discussed.

Reversible grain size changes in ball-milled nanocrystalline Fe–Cu alloys

1992 ◽  
Vol 7 (8) ◽  
pp. 1980-1983 ◽  
Author(s):  
J. Eckert ◽  
J.C. Holzer ◽  
C.E. Krill ◽  
W.L. Johnson
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Single Phase ◽  
Underlying Mechanism ◽  
Solution Hardening ◽  
Cu Alloys ◽  
Average Grain Size ◽  
20 Nm ◽  
Composition Changes ◽  
Fcc Structure

Nanocrystalline FexCu100−x solid solutions (x < 60) with single-phase fcc structure have been prepared by mechanical alloying. The average grain size of the powders (8–20 nm) depends on the composition of the material. Varying the composition changes the grain size reversibly. This can be explained by the underlying mechanism of plastic deformation and solution hardening during mechanical alloying coupled with the recovery behavior of the material.

SURFACE CHARACTERIZATION AND GRAIN SIZE CALCULATION OF SILVER FILMS DEPOSITED BY THERMAL EVAPORATION

2005 ◽  
Vol 12 (05n06) ◽  
pp. 759-766 ◽  
Author(s):  
MUHAMMAD MAQBOOL ◽  
TAHIRZEB KHAN
Keyword(s):  
Grain Size ◽  
Surface Characterization ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Xrd Analysis ◽  
Force Microscopy ◽  
Glass Substrates ◽  
Atomic Force ◽  
Average Grain Size ◽  
20 Nm

Thin films of pure silver were deposited on glass substrate by thermal evaporation process at room temperature. Surface characterization of the films was performed using X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). Thickness of the films varied between 20 nm and 60 nm. XRD analysis provided a sharp peak at 38.75° from silver. These results indicated that the films deposited on glass substrates at room temperature are crystalline. 3D and top view pictures of the films were obtained by AFM to study the grain size and its dependency on various factors. Grain sizes were calculated using the XRD results and Scherer's formula. Average grain size increased with the thickness of the deposited films. A minimum grain size of 8 nm was obtained for 20 nm thick films, reaching a maximum value of 41.9 nm when the film size reaches 60 nm. We could not find any sequential variation in the grain size with the growth rate.

scholarly journals Processing and Thermal Conductivity of Bulk Nanocrystalline Aluminum Nitride

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5565
Author(s):  
Matthew A. Duarte ◽  
Vivek Mishra ◽  
Chris Dames ◽  
Yasuhiro Kodera ◽  
Javier E. Garay
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
High Energy ◽  
Transition Alumina ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Nanocrystalline Aluminum ◽  
Optical Applications ◽  
Bulk Nanocrystalline ◽  
Nanocrystalline Ceramic

Producing bulk AlN with grain sizes in the nano regime and measuring its thermal conductivity is an important milestone in the development of materials for high energy optical applications. We present the synthesis and subsequent densification of nano-AlN powder to produce bulk nanocrystalline AlN. The nanopowder is synthesized by converting transition alumina (δ-Al2O3) with <40 nm grain size to AlN using a carbon free reduction/nitridation process. We consolidated the nano-AlN powder using current activated pressure assisted densification (CAPAD) and achieved a relative density of 98% at 1300 °C with average grain size, d¯~125 nm. By contrast, high quality commercially available AlN powder yields densities ~75% under the same CAPAD conditions. We used the 3-ω method to measure the thermal conductivity, κ of two nanocrystalline samples, 91% dense, d¯ = 110 nm and 99% dense, d¯ = 220 nm, respectively. The dense sample with 220 nm grains has a measured κ = 43 W/(m·K) at room temperature, which is relatively high for a nanocrystalline ceramic, but still low compared to single crystal and large grain sized polycrystalline AlN which can exceed 300 W/(m·K). The reduction in κ in both samples is understood as a combination of grain boundary scattering and porosity effects. We believe that these are finest d¯ reported in bulk dense AlN and is the first report of thermal conductivity for AlN with ≤220 nm grain size. The obtained κ values are higher than the vast majority of conventional optical materials, demonstrating the advantage of AlN for high-energy optical applications.

Laser Sintering of BaTiO3 Ceramics Obtained from Nanometric Powders

2006 ◽  
Vol 514-516 ◽  
pp. 1216-1220 ◽  
Author(s):  
Ronaldo Santos da Silva ◽  
Antonio Carlos Hernandes
Keyword(s):  
Grain Size ◽  
Relative Density ◽  
Crystallite Size ◽  
Crystalline Phase ◽  
Laser Sintering ◽  
Linear Rate ◽  
Heating Source ◽  
High Relative Density ◽  
Average Grain Size ◽  
20 Nm

We have studied the synthesis and sintering of BaTiO3 (BTO) nanometric powders produced by Pechini technique. A laser sintering procedure was applied to the BTO and its major advantage was the quickness of the processing. We have used the radiation of a CO2 laser (CW – 100 W) as the heating source. A linear rate of irradiation was applied to avoid macroscopic defects. The calcined powder at 800°C presented a single crystalline phase confirmed by the XRD and a crystallite size of 20 nm. BTO ceramics sintered at Pmax = 7.0 W/mm2 for 10 min of irradiation showed a high relative density (98 ± 1) % with an average grain size of 400 nm for a total time of sintering of 40 minutes.

Surface Modification and its Influence on the Microstructure and Creep Resistance of Nickel Based Superalloy René 77 / Modyfikacja Powierzchniowa Oraz Jej Wpływ Na Mikrostrukture I Wytrzymałosc Na Pełzanie Odlewów Z Nadstopu Niklu Ren´E 77

2013 ◽  
Vol 58 (1) ◽  
pp. 95-98 ◽  
Author(s):  
M. Zielinska ◽  
J. Sieniawski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Surface Modification ◽  
Turbine Blades ◽  
Processing Parameters ◽  
Grain Structure ◽  
Creep Tests ◽  
Cobalt Aluminate ◽  
Nickel Based Superalloy ◽  
Average Grain Size

Superalloy René 77 is very wide used for turbine blades, turbine disks of aircraft engines which work up to 1050°C. These elements are generally produced by the investment casting method. Turbine blades produced by conventional precision casting methods have coarse and inhomogeneous grain structure. Such a material often does not fulfil basic requirements, which concern mechanical properties for the stuff used in aeronautical engineering. The incorporation of controlled grain size improved mechanical properties. This control of grain size in the casting operation was accomplished by the control of processing parameters such as casting temperature, mould preheating temperature, and the use of grain nucleates in the face of the mould. For nickel and cobalt based superalloys, it was found that cobalt aluminate (CoAl2O4) has the best nucleating effect. The objective of this work was to determine the influence of the inoculant’s content (cobalt aluminate) in the surface layer of the ceramic mould on the microstructure and mechanical properties at high temperature of nickel based superalloy René 77. For this purpose, the ceramic moulds were made with different concentration of cobalt aluminate in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix ( phase), was determined on the stepped samples. The influence of surface modification on the grain size of up to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of ’ phase and carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form creep tests.

Sign in / Sign up

Export Citation Format

Share Document