Thermal Properties of Nanocrystalline Silver

1992 ◽  
Vol 286 ◽  
Author(s):  
Xijun Wu ◽  
Hongfei Zhang ◽  
Xiaoying Qin ◽  
Lifang Chen ◽  
Guanzhong Wang ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Grain Growth ◽  
Room Temperature ◽  
Nanocrystalline State ◽  
Gas Condensation ◽  
Average Grain Size ◽  
Endothermal Peak ◽  
Dsc Curves ◽  
Compacting Pressure

ABSTRACTThe thermal properties of the nanocrystalline metal Ag (n-Ag), with the average grain size of 10 run, synthesized by an inert gas condensation and in situ compacting technique under different pressures of 0.2 to 1.5 GPa were studied. The thermal stable temperature for asprepared state is 373K, above which the grain growth appears at different rates. An exothermal peak and an endothermal peak occur on the DSC curves of the n-Ag. The enthalpy of both peaks are dependent upon the compacting pressure. Tht enhancement of the specific heat in going from the polycrystalline to the nanocrystalline state varies between 5.4% and 3.6% in the temperature range of 380K to 540K. The thermal diffusivity at room temperature increases with grain growth, and approaches to the corresponding value of the polycrystalline Ag.

scholarly journals In Situ Hvem Study of Ion Irradiation-Induced Grain Growth in Au Thin Films

1988 ◽  
Vol 128 ◽  
Author(s):  
Joyce C. Liu ◽  
Jian Li ◽  
J. W. Mayer ◽  
Charles W. Allen ◽  
Lynn E. Rehn
Keyword(s):  
Grain Growth ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Average Grain Size ◽  
In Situ Observations ◽  
Au Thin Films ◽  
Grain Coalescence

ABSTRACTIn situ observations of 1.5 MeV Xe+ ion irradiated Au films at room temperature and at 150°C reveal the evolution of grain growth: the average grain size increases by the mechanisms of grain boundary migration and grain coalescence.

Synthesis and Ionic Conductivity of Nanophase Ca1-xLaxF2+x

1992 ◽  
Vol 286 ◽  
Author(s):  
Xijun Wu ◽  
Fang Su ◽  
Xiaoying Qin ◽  
Bin Xie ◽  
Xiaoli Ji
Keyword(s):  
Ionic Conductivity ◽  
Volume Fraction ◽  
Complex Impedance ◽  
Ionic Conductors ◽  
Gas Condensation ◽  
Large Volume Fraction ◽  
Average Grain Size ◽  
Order Of Magnitude ◽  
Compacting Pressure

ABSTRACTThe nanophase ionic conductors Ca1-xLaxF2+x with x=0 and 0.25 were synthesized by an inert gas condensation and in situ compacting technique. The samples with average grain size of 16 na for nanophase CaF2 and 11 nm for nanophase Ca0.75 La0.25F2.25 were prepared under the compacting pressure of 0.5 GPa. The alternating ionic conductivity was deduced from the temperature dependence of the complex impedance.The results indicated that the logarithm of ionic conductivity obeys Arrhenius relation in the temperature range from 300 °C to 530 °C both for nanophase CaF2 and for nanophase Ca0.75La0.25F2.25. Their activation energies are 1.14 eV and 1.00 eV, respectively. The ionic conductivity of nanophase CaF2 is about one and two orders of magnitude higher than that of polycrystalline and single crystal CaF2, respectively. While the ionic conductivity of nanophase Ca0.75La0.25F2.25 is about one order of magnitude higher than that of nanophase CaF2. Further analysis indicated that the enhanced ionic conductivity of nanophase Ca1-xLaxF2+x is related to the large volume fraction of interfaces.

scholarly journals In Situ Grain Growth of Nanograined Magnetite under Ion Irradiation at Room Temperature and 500 ℃

2021 ◽  
Vol 27 (S1) ◽  
pp. 2640-2643
Author(s):  
Chris McRobie ◽  
Ryan Schoell ◽  
Tiffany Kaspar ◽  
Daniel Schreiber ◽  
Djamel Kaoumi
Keyword(s):  
Grain Growth ◽  
Room Temperature ◽  
Ion Irradiation

scholarly journals Forming pressure effect on microstructure and mechanical properties of nanocrystalline aluminum synthesized by inert gas condensation

2019 ◽  
Vol 79 ◽  
pp. 02002
Author(s):  
Shangshu Wu ◽  
Zhou Yu ◽  
Junjie Wang ◽  
Hanxin Zhang ◽  
Chaoqun Pei ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Vacuum ◽  
Inert Gas ◽  
Helium Atmosphere ◽  
Gas Condensation ◽  
Inert Gas Condensation ◽  
In Situ Forming ◽  
Nanocrystalline Aluminum ◽  
Al Powder

The preparation of nanocrystalline aluminum (NC Al) was conducted in two steps. After the NC Al powder was synthesized by an Inert gas condensation (IGC) method in a helium atmosphere of 500 Pa, the NC Al powder was in-situ compacted into a pellet with a 10 mm diameter and 250 μm-300 μm thickness in a high vacuum (10-6 Pa-10-7 Pa) at room temperature. The NC Al samples were not exposed to air during the entire process. After the pressure reached 6 GPa, the relative density could reach 99.83%. The results showed that the grain size decreased with the increased of in-situ forming pressure. The NC Al samples present obvious ductile fracture, and the tensile properties were greatly changed with the increase of forming pressure.

In-Situ Tem Investigation During Thermal Cycling of thin Copper Films

1996 ◽  
Vol 436 ◽  
Author(s):  
R.-M. Keller ◽  
W. Sigle ◽  
S. P. Baker ◽  
O. Kraft ◽  
E. Arzt
Keyword(s):  
Grain Growth ◽  
Room Temperature ◽  
Dislocation Motion ◽  
In Situ Tem ◽  
Copper Films ◽  
Stress Evolution ◽  
Cu Films ◽  
Transmission Electron ◽  
Insight Into

AbstractIn-situ transmission electron microscopy (TEM) was performed to study grain growth and dislocation motion during temperature cycles of Cu films with and without a cap layer. In addition, the substrate curvature method was employed to determine the corresponding stresstemperature curves from room temperature up to 600°C. The results of the in-situ TEM investigations provide insight into the microstructural evolution which occurs during the stress measurements. Grain growth occurred continuously throughout the first heating cycle in both cases. The evolution of dislocation structure observed in TEM supports an explanation of the stress evolution in both capped and uncapped films in terms of dislocation effects.

In Situ Observation of Grain Growth and Recrystallization of Steel at High Temperature

2010 ◽  
Vol 638-642 ◽  
pp. 1077-1082 ◽  
Author(s):  
Yasuhiro Yogo ◽  
Kouji Tanaka ◽  
Koukichi Nakanishi
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Grain Growth ◽  
In Situ Observation ◽  
Initial Structure ◽  
Grain Sizes ◽  
Dynamic Observation ◽  
Average Grain Size ◽  
Observation Method

An in-situ observation method for structures at high temperature is developed. The new observation device can reveal grain boundaries at high temperature and enables dynamic observation of these boundaries. Grain growth while maintaining microstructure at high temperature is observed by the new observation device with only one specimen for the entire observation, and grain sizes are quantified. The quantifying process reveals two advantages particular to the use of the new observation device: (1) the ability to quantify grain sizes of specified sizes and (2) the results of average grain size for many grains have significantly less errors because the initial structure is the same for the entire observation and the quantifying process. The new observation device has the function to deform a specimen while observing structures at high temperature, so that enables it to observe dynamic recrystallization of steel. The possibility to observe recrystallization is also shown.

scholarly journals Synthesis, Characterization and Mechanical Properties of Nanocrystalline NiAl

1996 ◽  
Vol 457 ◽  
Author(s):  
M. S. Choudry ◽  
J. A. Eastman ◽  
R. J. DiMelfi ◽  
M. Dollar
Keyword(s):  
Room Temperature ◽  
Dark Field ◽  
Inert Gas ◽  
Coarse Grained ◽  
Gas Condensation ◽  
Grain Sizes ◽  
Room Temperature Ductility ◽  
Cast Alloys ◽  
Bend Tests

ABSTRACTNanocrystalline NiAl has been produced from pre-cast alloys using an electron beam inert gas condensation system. In-situ compaction was carried out at 100 to 300°C under vacuum conditions. Energy dispersive spectroscopy was used to determine chemical composition and homogeneity. Average grain sizes in the range of 4 to 10 nm were found from TEM dark field analyses. A compression-cage fixture was designed to perform disk bend tests. These tests revealed substantial room temperature ductility in nanocrystalline NiAl, while coarse grained NiAl showed no measurable room temperature ductility.

Microstructure Evolution in Bulk Nanostructured Copper during Repeated Cold Rolling

2012 ◽  
Vol 248 ◽  
pp. 43-47
Author(s):  
Lei Liu ◽  
Han Zhuo Zhang ◽  
Qin Lan Zhao
Keyword(s):  
Grain Size ◽  
Cold Rolling ◽  
Grain Growth ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Maximum Value ◽  
Deformation Stages ◽  
Average Grain Size ◽  
Dislocation Interactions ◽  
Room Temperature Rolling

Room temperature rolling tests were performed on a bulk nanostructured Cu with an average grain size of 90 nm. The results indicated a high thickness reduction ( ) of 92% without crack and an increased {220} texture as the rolling processes continued. Microstructure evolution of the deformed nanostructured Cu could be characterized by several deformation stages. Grain growth and coalescence was prevalent in the early deformation stage, while grain boundaries were impaired and replaced by dislocation interactions when 24%. Microhardness of the deformed nanostructured Cu increased sharply to a maximum value of 1.61 GPa at 8% and then slightly decreased to 1.58 GPa at 92%.

Synthesis and Detection the Thermal Expansion of CdSe Quantum Dots from Room Temperature to 700°C

2015 ◽  
Vol 35 ◽  
pp. 11-20 ◽  
Author(s):  
Zi Yan Zhao ◽  
Ying Zhou ◽  
Feng Gang Bian ◽  
Kun Hao Zhang
Keyword(s):  
Quantum Dots ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Room Temperature ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
In Situ Xafs

In this paper, we synthesized the CdSe quantum dots (QDs) about 4.5 nm, and using the in-situ XAFS technique to study the thermal expansion of CdSe QDs from room temperature to 700°C. We find that the thermal expansion of the CdSe QDs is about 2.0×10-5/K, which is bigger than the bulk CdSe (3~8×10-6/K). This can demonstrate that the thermal properties of CdSe QDs is related to the size of the dots, which means the thermal expansion is reducing as the size of the nanoparticles increasing. Keywords: CdSe quantum dots, thermal expansion, EXAFS technique

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