Papers by Keyword: Y2O3

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Authors: Jun Liu, Jin Liang He, Jun Hu, Wang Chen Long, Feng Chao Luo
Abstract: ZnO varistors are multicomponent polycrystalline ceramics with highly nonlinear current-voltage characteristics and surge energy absorption capabilities. The voltage gradient of the ZnO varistor is inversely proportional to its average grain size. Recently, the rare-earth oxides have been reported as growth inhibitor of ZnO grains to obtain high voltage gradient. Although the dopant of rare-earth oxides can remarkably enhance the voltage gradients of varistor samples, their leakage currents and nonlinear coefficients deteriorate at the same time. In this paper, the sintering effects on electrical characteristics and admittance spectroscopies of ZnO varistor samples doped with yttrium oxides were investigated. Samples were fabricated under different sintering temperatures, including 1000 °C, 1100 °C, 1200 °C and 1300 °C. Then, the electrical characteristics and admittance spectroscopies of these varistor samples were measured. The measured current-voltage results behave special U-type curves related to sintering temperature. Furthermore, the admittance spectroscopy of these samples revealed the sintering effects on the intrinsic defects of ZnO varistors.
Authors: Chang Tian Huan, Jin Feng Xia, Dan Yu Jiang, Qiang Li
Abstract: This paper compares the low-temperature aging performance of 5Y-TZP and 8Y-TZP by coprecipitation and solid-phase synthesis methods in the steam. Analysis the weight changes of samples using analytical balance, and the sample surface microstructure and phase changes with SEM, XRD. The results show that the content of Y2O3 and synthesis method all affect the aging properties of zirconia ceramics; solid-phase synthesis of 8Y-TZP has the best anti-aging performance.
Authors: Kazuyuki Suzuki, Kiyotaka Tanaka, Tatsuo Kimura, Kaori Nishizawa, Takeshi Miki, Kazumi Kato
Abstract: The (Y,Yb)MnO3 films were crystallized on Y2O3 layers using alkoxy-derived precursor solutions. As a result of investigation of the effect of the Y2O3 layer on the dielectric properties of the (Y,Yb)MnO3/Y2O3/Si, the crystallographic properties such as the orientation and surface morphology of the (Y,Yb)MnO3 thin films depended on the crystallographic appearance of the insulator layer. Following that, the dielectric properties of the MFIS structures varied. For the construction of excellent MFIS structure, the improvement of the orientation, crystallinity, and surface smoothness of the (Y,Yb)MnO3 film by the optimization of the microstructure and dielectric property of the insulator is necessary.
Authors: Liang Liang Tian
Abstract: Nano-sized Y2O3 particles were codeposited with nickel by pulse current electroplating from a nickel sulfate bath. The effects of Y2O3 concentration in the plating bath on the deposition behaviors and mechanical properties of Ni-Y2O3 composite coatings were studied. The incorporated Y2O3 increases from 2.6 wt.% to 6.0 wt.% with the increasing of Y2O3 concentration in the plating bath from 20 to 80 g/l. The current efficiency decreases from 81.3% to 45.4% with the Y2O3 concentration increasing from 20 to 80 g/l. SEM images demonstrate that smooth and compact surface can be obtained by the addition of Y2O3. The present study also shows that the codeposited Y2O3 particles in deposits decrease the friction coefficient and reduce the wear weight loss. Ni-Y2O3 composite coating reaches its highest microhardness and best wear resistance at Y2O3 content 6.0 wt.%.
Authors: Kazuyuki Suzuki, Kiyotaka Tanaka, De Sheng Fu, Kaori Nishizawa, Takeshi Miki, Kazumi Kato
Authors: Yuan Liang Li, Yuan Fang Qu, Feng Long Han, Chao Liu, Xiao Yan Li
Abstract: Microstructure and dielectric properties of Ba0.62Sr0.38TiO3 ceramics doped with x mol% (x=0.2~0.6) Y2O3 were investigated. SEM showed that Y3+ can accelerate growth of the grains at first, then turn to inhabit growth of the grains with further addition of Y3+ above 0.8mol%. The experimental results showed that the dielectric constants were improved with the additive amount of Y3+ increasing, if the amount of Y3+ increased continuously, the dielectric constants will drop, whereas the dielectric losses of the samples descended rapidly in the beginning, then went up obviously with further addition of Y3+ above 1.0mol%, the optimal dielectric constant and dielectric loss could reach 6700 and 0.0015 in the room temperature, respectively.
Authors: Shi Min Zhou, Chao Yu, Cheng Ji Deng, Hong Xi Zhu, Wen Jie Yuan
Abstract: The reaction process of synthesis of Al4SiC4 from Al, Si and graphite powders and the effects of Y2O3 on synthesis and microstructure of Al4SiC4 were investigated in this paper. The results show that no substantial changes in the formation of Al4SiC4 content with or without addition of Y2O3. The addition of Y2O3 to Al, Si and carbon powder mixtures was found to be effective for obtaining tabular grains of Al4SiC4. Conversely, Al4SiC4 grains existed as irregular granules without addition of Y2O3.
Authors: Melis Arin, Jef Vleugels, Kim Vanmeensel, Gultekin Goller
Abstract: Fully dense ZrO2-TiN composites containing 1.75-2 mol %Y2O3, 1 mol% Y2O3 and 1 mol% Nd2O3 stabilizers, small amounts of Al2O3, and electrical conductive TiN particles (40-70 vol%) have been produced by hot pressing and spark plasma sintering at 1550°C. Although the intrinsic hardness of TiN (1400 kg/mm²) is higher than that of t-ZrO2 (1200 kg/mm²), the decreasing hardness trend can be attributed to the larger TiN grain size with the higher TiN content. Since TiN is more brittle, the fracture toughness decreases with increasing TiN content. Transformation toughening has been attributed as the main toughening mechanism as a result of fracture toughness decreasing with the transformability. Spark Plasma sintering temperature was too high for mechanical properties and hydrothermal stability of the mixed stabilized composites. The transformability decreases so hydrothermal stability increases linearly with increasing TiN content as a result of smaller volume fraction of t-ZrO2 grains becoming susceptible to hydrothermal transformation due to the shielding effect of the present TiN grains.
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