scholarly journals Preparation of Ultrahigh Potential Gradient of ZnO Varistors by Rare-Earth Doping and Low-Temperature Sintering

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Lei Ke ◽  
Ming Hu ◽  
Xueming Ma
Keyword(s):  
Grain Size ◽  
Rare Earth ◽  
Low Temperature ◽  
Potential Gradient ◽  
Schottky Barriers ◽  
Rare Earth Doping ◽  
Low Temperature Sintering ◽  
Experimental Conditions ◽  
Zno Varistors ◽  
The Given

The effects of rare-earth doping and low-temperature sintering on electrical properties of ZnO varistors were investigated. The potential gradient (E1mA) of the ZnO varistors increased significantly to 2247.2 V/mm after doping 0.08 mol% of Y2O3 and sintering at 800°C for 2 h. The notable decrease of the grain size with the given experimental conditions was the origin for the increase in E1mA. During the process of high-temperature sintering, both the oxygen at the grain boundary interface and the neutralisation of the ions on the depletion layer were directly reduced, which caused the weight loss and the internal derangement of double Schottky barriers.

HIGH POTENTIAL GRADIENT OF ZnO VARISTORS PREPARED BY Y2O3-DOPING AND LOW-TEMPERATURE SINTERING

2009 ◽  
Vol 23 (25) ◽  
pp. 3013-3022 ◽  
Author(s):  
LEI KE ◽  
DONG-MEI JIANG ◽  
CHUN-XIA WANG ◽  
XUE-MING MA
Keyword(s):  
Low Temperature ◽  
Sintering Temperature ◽  
Early Period ◽  
Potential Gradient ◽  
High Energy ◽  
High Potential ◽  
Low Temperature Sintering ◽  
Experimental Conditions ◽  
Zno Varistors ◽  
Lower Temperature

A high potential gradient of ZnO varistors were fabricated by Y 2 O 3-doping and low-temperature sintering. The value of the potential gradient increased to 2460.5 V/mm with the Y 2 O 3 content of 0.08 mol% and the sintering temperature of 800°C. The effects of Y 2 O 3-doping and sintering temperature on the electrical properties of ZnO varistors were investigated. Under the given experimental conditions, additive Y 2 O 3 exists in the form of Y 2 O 3 phase after sintering at 800°C. High-energy ball-milling in the early period of the experiment induced the grain refinement and realized the sintering formation at the lower temperature of 800°C. Both Y 2 O 3-doping and low-temperature sintering restrained the ZnO grain growth and increased the potential gradient.

Low-temperature sintering of high potential gradient B2O3-doped ZnO varistors

2015 ◽  
Vol 26 (7) ◽  
pp. 4997-5000 ◽  
Author(s):  
Zhijun Xu ◽  
Shuai Ma ◽  
Ruiqing Chu ◽  
Jigong Hao ◽  
Lihong Cheng ◽  
...  
Keyword(s):  
Low Temperature ◽  
Potential Gradient ◽  
High Potential ◽  
Low Temperature Sintering ◽  
Zno Varistors ◽  
Doped Zno

Low temperature sintering of nano-SiC using a novel Al8B4C7 additive

2010 ◽  
Vol 25 (3) ◽  
pp. 471-475 ◽  
Author(s):  
Sea-Hoon Lee ◽  
Byung-Nam Kim ◽  
Hidehiko Tanaka
Keyword(s):  
Grain Size ◽  
Liquid Phase ◽  
Low Temperature ◽  
Sintering Temperature ◽  
Applied Pressure ◽  
Liquid Phase Sintering ◽  
Low Temperature Sintering ◽  
Densification Rate ◽  
Sintering Additive ◽  
Average Grain Size

Al8B4C7 was used as a sintering additive for the densification of nano-SiC powder. The average grain size was approximately 70 nm after sintering SiC-12.5wt% Al8B4C7 at 1550 °C. The densification rate strongly depended on the sintering temperature and the applied pressure. The rearrangement of SiC particles occurred at the initial shrinkage, while viscous flow and liquid phase sintering became important at the middle and final stage of densification.

Effect of microstructure, grain size, and rare earth doping on the electrorheological performance of nanosized particle materials

2003 ◽  
Vol 13 (12) ◽  
pp. 3096 ◽  
Author(s):  
Shu-Zhen Ma ◽  
Fu-Hui Liao ◽  
Shu-Xin Li ◽  
Ming-Yuan Xu ◽  
Jun-Ran Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Rare Earth ◽  
Rare Earth Doping ◽  
Nanosized Particle ◽  
Effect Of Microstructure

Low-temperature sintering and electrical properties of Co-doped ZnO varistors

2014 ◽  
Vol 25 (9) ◽  
pp. 3878-3884 ◽  
Author(s):  
Shuai Ma ◽  
Zhijun Xu ◽  
Ruiqing Chu ◽  
Jigong Hao ◽  
Lihong Cheng ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Low Temperature ◽  
Low Temperature Sintering ◽  
Zno Varistors ◽  
Doped Zno ◽  
Co Doped

High Temperature Creep Properties of UO2 Fuel Pellets Manufactured by Low Temperature Sintering Technology

2013 ◽  
Author(s):  
Rui Li ◽  
Yuemin Zhou
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Low Temperature ◽  
Uranium Dioxide ◽  
Nitrogen Atmosphere ◽  
Creep Process ◽  
Low Temperature Sintering ◽  
High Temperature Creep ◽  
Creep Properties ◽  
Temperature Creep

In this paper, the low temperature sintering technology to UO2 pellets has been introduced, and we have studied the high temperature creep properties of the pellets which manufactured by low temperature sintering. The sintering temperatures are 1073K, 1273K, 1473K and 1673K, sintering time are 1 hour, 2 hours and 3 hours respectively. We obtained the highest sintering density of pellets at 1673K with 3 hours, which is 10.41g/cm3 (94.98% theoretical density). The grain size of pellets which prepared by low temperature sintering technology and traditional technology are 9.0μm and 23.8μm respectively. So the high temperature creep properties of the two kinds of pellet must be studied. They were performed at 20–50 MPa, 1673K and 1773K respectively, under a nitrogen atmosphere to shorten the experimental time. According to the results, the creep rates of sintered UO2 with the grain sizes of 9.0μm and 23.8μm under the load of 10MPa are almost the same. The creep process is controlled by both Nabarro-Herring creep and Hamper-Dorn creep for uranium dioxide with grain size of 9.0μm; while Hamper-Dorn creep is the dominant mechanism for uranium dioxide with grain size of 23.8μm.

Preferential Orientation of Photochromic Gadolinium Oxyhydrides

2020 ◽  
Author(s):  
Elbruz Murat Baba ◽  
Jose Montero ◽  
Dmitrii Moldarev ◽  
Marcos V. Moro ◽  
Max Wolff ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Rare Earth ◽  
Preferential Orientation ◽  
Reactive Magnetron ◽  
Flow Ratio ◽  
Deposition Pressure ◽  
Step Process ◽  
Oxidation In Air ◽  
Key Parameter

<p>We report preferential orientation control in photochromic gadolinium oxyhydride (GdHO) thin films deposited by a two-step process. Gadolinium hydride (GdH<sub>2-x</sub>) films were grown by reactive magnetron sputtering, followed by oxidation in air. The preferential orientation, grain size, anion concentrations, and photochromic response of the films are strongly dependent on the deposition pressure. GdHO films show preferential orientation along the [100] direction and exhibit photochromism when synthesized at deposition pressures up to 5.8 Pa and. The photochromic contrast is larger than 20 % when the films are deposited below 2.8 Pa with 0.22 H<sub>2</sub>/Ar flow ratio. We argue that the degree of preferential orientation defines the oxygen concentration which is known to be a key parameter for photochromism in rare-earth oxyhydride thin films. The experimental observations described above are explained by the oxidation-induced decrease of the grain size as a result of the increase of the deposition pressure of the sputtering gas. </p>

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