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Microstructure and properties of ultra-fine tungsten heavy alloys prepared by mechanical alloying and electric current activated sintering 被引量:10
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作者 李小强 辛红伟 +1 位作者 胡可 李元元 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第3期443-449,共7页
The microstructure and properties of the 93W-4Ni-2Co-1Fe(mass fraction,%) tungsten heavy alloys prepared by mechanical alloying and electric current activated sintering from mixed elemental powders were investigated.A... The microstructure and properties of the 93W-4Ni-2Co-1Fe(mass fraction,%) tungsten heavy alloys prepared by mechanical alloying and electric current activated sintering from mixed elemental powders were investigated.After 15 h milling,the average W grain size in the powders is decreased to 120 nm.For the powders milled for 15 h,the density,hardness and transverse rupture strength of the alloys sintered only by an intensive pulse electric current are the maximum.When the total sintering time keeps constant,the properties of the sintered alloys can be obviously improved by optimizing the sintering time of pulse-and constant-currents.A bulk ultrafine alloy with an average W grain size of about 340 nm can be obtained by sintering 15 h-milled powders in a total sintering time of 6 min.The corresponding sintered density,hardness and transverse rupture strength reach 16.78 g /cm3,HRA84.3 and 968 MPa,respectively. 展开更多
关键词 93W-4Ni-2Co-1Fe alloy mechanical alloying electric current activated sintering
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Microstructure and Mechanical Performance of Cu-SnO_2-rGO based Composites Prepared by Plasma Activated Sintering 被引量:2
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作者 罗国强 HUANG Jing +4 位作者 JIN Zhipeng LI Meijuan JIANG Xiaojuan SHEN Qiang ZHANG Lianmeng 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2015年第6期1152-1158,共7页
A novel chemical technique combined with unique plasma activated sintering(PAS) was utilized to prepare consolidated copper matrix composites(CMCs) by adding Cu-SnO2-rGO layered micro powders as reinforced fillers... A novel chemical technique combined with unique plasma activated sintering(PAS) was utilized to prepare consolidated copper matrix composites(CMCs) by adding Cu-SnO2-rGO layered micro powders as reinforced fillers into Cu matrix. The repeating Cu-SnO2-rGO structure was composed of inner dispersed reduced graphene oxide(r GO), SnO2 as intermedia and outer Cu coating. SnO2 was introduced to the surface of rGO sheets in order to prevent the graphene aggregation with SnO2 serving as spacer and to provide enough active sites for subsequent Cu deposition. This process can guarantee rGO sheets to suffi ciently disperse and Cu nanoparticles to tightly and uniformly anchor on each layer of rGO by means of the SnO2 active sites as well as strictly control the reduction speed of Cu^2+. The complete cover of Cu nanoparticles on rGO sheets thoroughly avoids direct contact among rGO layers. Hence, the repeating structure can simultaneously solve the wettability problem between rGO and Cu matrix as well as improve the bonding strength between rGO and Cu matrix at the well-bonded Cu-SnO2-rGO interface. The isolated rGO can effectively hinder the glide of dislocation at Cu-rGO interface and support the applied loads. Finally, the compressive strength of CMCs was enhanced when the strengthening effi ciency reached up to 41. 展开更多
关键词 graphene Cu-SnO2-rGO structure copper matrix composites sensitization plasma activated sintering mechanical property
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Effects of Activated Sintering Process on Properties and Microstructure of W-15Cu Alloy
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作者 史晓亮 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第6期909-913,共5页
The effects of activated sintering technology of H2 atmosphere sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying calcining-continuous red... The effects of activated sintering technology of H2 atmosphere sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying calcining-continuous reduction technology were investigated.The experimental results showed that W-15Cu alloy,consolidated by activated sintering technology of H2 atmosphere sintering for 1 h at 1300 ℃,with 98.5 % relative density,transverse rupture strength 1218 MPa,Vickers hardness HV0.5 378,average grain size about 1.2 μm and thermal conductivity 192 W/m·K,was obtained.In comparison to the normal sintering process,activated sintering process to W-15Cu alloy could be achieved at lower sintering temperature.Furthermore,better properties in activated sintered compacts were obtained,and activated sintering process resulted in finer microstructure and excellent properties. 展开更多
关键词 ultrafine composite powder W-15Cu alloy activated sintering process MICROSTRUCTURE PROPERTIES
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Thermal Wave Effect and Sintering Activation Energy at the Initial Stage of Field Assisted Sintering Process for Non-conductive Al_2O_3 Powders
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作者 ZHANG Long 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2018年第6期1416-1421,共6页
The effect of thermal wave at the initial stage for non-conductive Al_2 O_3 powders compact in field assisted sintering technique(FAST) was investigated. The Lord and Shulman type generalized thermoselastic theory was... The effect of thermal wave at the initial stage for non-conductive Al_2 O_3 powders compact in field assisted sintering technique(FAST) was investigated. The Lord and Shulman type generalized thermoselastic theory was introduced to describe the influence of thermal-mechanical interaction, as well as the heat transport and thermal focusing caused by thermal wave propagation. The expression of vacancy concentration difference of the particles was deduced by considering transient thermal stress. Subsequently, the relationship between activation energy and vacancy concentration difference was obtained. The mechanism of surface diffusion, volume diffusion, simultaneous surface and volume diffusion was analyzed. The numerical simulations indicate that low sintering temperature can obtain high local temperature by the superposition effect of thermal wave. Vacancy concentration differences were improved during FAST compared with hot-pressure and pressureless sintering, thereby decreasing the sintering time. By contrast, the activation energy declined with the decrease of vacancy concentration difference in the neck growth process. 展开更多
关键词 field assisted sintering technique generalized thermoelastic theory thermal wave vacancy concentration difference sintering activation energy
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Sintering behaviors of porous 316L stainless steel fiber felt
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作者 冯萍 刘咏 +3 位作者 王岩 李昆 赵秀云 汤慧萍 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第3期793-799,共7页
Isothermal sintering experiments were performed on the 316 L stainless steel fiber felts with fiber diameters of 8 μm and20 μm. Surface morphologies of the sintered specimens were investigated by using scanning elec... Isothermal sintering experiments were performed on the 316 L stainless steel fiber felts with fiber diameters of 8 μm and20 μm. Surface morphologies of the sintered specimens were investigated by using scanning electron microscopy(SEM) and optical microscopy. The results show that the amount of the sintering necks and the relative densities of the fiber felt increase with the increasing of both the sintering temperature and the sintering time. And the activation energies estimated present a decline at high relative densities for both 8 μm and 20 μm fiber felts. Moreover, the sintering densification of the fiber felts is dominated by volume diffusion mechanism at low temperature and relative densities. As more grain boundaries are formed at higher temperature and relative density, grain boundary diffusion will also contribute to the densification of the specimen. 展开更多
关键词 316L stainless steel fiber felt sintering activation energy diffusion
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Improvement of AlN Thermal Conductivity Based on Reductive Compound Additives
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作者 LI Meijuan WANG Chuanyi +2 位作者 WANG Gaoqiang WANG Chuanbin SHEN Qiang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第5期1025-1033,共9页
AlN ceramics were prepared by plasma activation sintering(PAS)with compound additives yttrium acetylacetonate(Y(acac)_(3))and melamine(C_(3)H_(6)N_(6)).The effects of compound additives on the microstructure,density,a... AlN ceramics were prepared by plasma activation sintering(PAS)with compound additives yttrium acetylacetonate(Y(acac)_(3))and melamine(C_(3)H_(6)N_(6)).The effects of compound additives on the microstructure,density,and thermal properties of Al N ceramic were studied.Y(acac)3and C_(3)H_(6)N_(6)can form Y_(2)O_(3),residual organic carbon and reducing gas during the heating process,which improves the Al N sintering performance at a temperature of 1700℃and the bulk thermal conductivity.When the content of Y(acac)_(3)is 10 wt%and C_(3)H_(6)N_(6)is 3 wt%,the thermal conductivity of Al N ceramics is 105.6 W/(m·K),which is much higher than that of Al N ceramics with Y_(2)O_(3)under the same sintering conditions.This work provides theoretical reference for the preparation of high-performance Al N ceramic. 展开更多
关键词 reductive compound additives AlN ceramic thermal conductivity:plasma activated sintering
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Microstructure and mechanical properties of Fe_3Al alloys prepared by MA-PAS and MA-HP 被引量:3
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作者 王建 邢建东 +2 位作者 汤慧萍 杨保军 李亚宁 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第11期2408-2414,共7页
Fe3Al alloys with nearly full density were fabricated by plasma activated sintering(PAS) and hot pressing(HP) from mechanical alloyed Fe-28%Al(mole fraction) powders,respectively.It is found that A2-type Fe3Al a... Fe3Al alloys with nearly full density were fabricated by plasma activated sintering(PAS) and hot pressing(HP) from mechanical alloyed Fe-28%Al(mole fraction) powders,respectively.It is found that A2-type Fe3Al alloys were obtained by PAS,and they had a heterogeneous grain size distribution,most areas had a grain size smaller than 500 nm,and other areas had a grain size of about 1 μm.Different to PAS,D03-type Fe3Al alloys with a grain size of of 1-2 μm were obtained by HP.The compression testing results show that yield strength values of Fe3Al alloys fabricated by PAS and HP are almost equal at an elevated temperature,and the compression yield strength was about 100 MPa for all at 800 ℃.The room temperature compression ductility of Fe3Al alloys by PAS was about 20%,which was superior to that of Fe3Al alloys prepared by HP and casting. 展开更多
关键词 Fe3Al intermetallic plasma activated sintering hot pressing microstructure mechanical properties
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Effect of Rare Earth on Diamond-Tungsten Carbide Super-Hard Composites 被引量:1
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作者 满翠华 赵会友 宁桂峰 《Journal of Rare Earths》 SCIE EI CAS CSCD 2003年第S1期159-161,共3页
A study was undertaken to decrease the sintering temperature and to increase the thermal stability of diamond by adding rare earth elements. The critical factor in the activated sintering is the content of rare earth ... A study was undertaken to decrease the sintering temperature and to increase the thermal stability of diamond by adding rare earth elements. The critical factor in the activated sintering is the content of rare earth element. The results show that adding 0.3% rare earth to the powders makes the composites obtain the properties needed. 展开更多
关键词 diamond-WC/Co activated sintering super-hard composites rare earths
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Mechanical Properties and Friction/Wear Behavior of Copper Alloyed Powder Composites 被引量:1
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作者 DENGChen-hong CHENGuang-zhi GEQi-lu 《Journal of Iron and Steel Research International》 SCIE CAS CSCD 2005年第4期50-53,59,共5页
Copper alloyed powder composites containing nanoparticles were developed by hot pressing. Effects of nanoscale activated sintering aid and fine ceramic particles Al_2O_3 on hardness, working quality, and behaviors of ... Copper alloyed powder composites containing nanoparticles were developed by hot pressing. Effects of nanoscale activated sintering aid and fine ceramic particles Al_2O_3 on hardness, working quality, and behaviors of friction and wear of the composites have been studied, compared with the composites including microscale activated sintering aid and microscale ceramic particles. The microstructures of the samples were analyzed by SEM. The results show that the materials with nanoscale sintering aid and fine ceramic particles have betuer mechanical properties and abrasive resistance than the materials with microscale activated sintering aid and microceramic particles. Moreover, element mutual transfer occurs between samples (strip) and abrasive wheel (ring). 展开更多
关键词 NANOPARTICLE activated sintering aid ceramic particle TRIBOLOGY
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Physico-chemical properties and microstructure of hydroxyapatite-316L stainless steel biomaterials 被引量:5
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作者 邹俭鹏 阮建明 +2 位作者 黄伯云 刘建本 周小霞 《Journal of Central South University of Technology》 2004年第2期113-118,共6页
Sintering shrinkage, compressive strength, bending strength, metallurgical morphology, microstructure and chemical composition diffusion of hydroxyapatite-316L stainless steel(HA-316L SS) composites were investigated.... Sintering shrinkage, compressive strength, bending strength, metallurgical morphology, microstructure and chemical composition diffusion of hydroxyapatite-316L stainless steel(HA-316L SS) composites were investigated. The results show that the sintering shrinkage of HA-316L SS composites decreases from 27.38% to 8.87% for cylinder sample or from 27.18% to 8.62% for cuboid sample with decreasing the volume ratio of HA to 316L SS, which leads to higher sintering activity of HA compared with that of 316L SS. The compressive strength of HA-316L SS composites changes just like parabolic curve (245.3→126.3→202.8 MPa) with reducing the volume ratio of HA to 316L SS. Bending strength increases from 86.3MPa to 124. 2 MPa with increasing the content of 316L SS. Furthermore, comprehensive mechanical properties of 1.0∶3.0 (volume ratio of HA to 316L SS) composite are optimal with compressive strength and bending strength equal to 202.8 MPa and 124.2 MPa, respectively. The (microstructure) and metallurgical structure vary regularly with the volume ratio of HA to 316L SS. Some chemical reaction takes place at the interface of the composites during sintering. 展开更多
关键词 hydroxyapatite-316L stainless steel biomaterial sintering activity mechanical property MICROSTRUCTURE SEM EDXA
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Research on Diamond Enhanced Tungsten Carbide Composite Button 被引量:2
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作者 DUAN Long-chen 1, LIU Xiao-yang 1, MAO Bao-song 2, YANG Kai-hua 1, TANG Fen-lin 1 (1. Engineering Faculty, China University of Geosciences, Wuhan 430074, China 2. Faculty of Engineering and Technology, Jilin University, Changchun 130026, China ) 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期30-31,共2页
At the present, the cutters used in button bits and rock bits are mainly cobalt tungsten carbide in our country. Because of its low abrasive resistance, the bit service life and drilling efficiency was very low when t... At the present, the cutters used in button bits and rock bits are mainly cobalt tungsten carbide in our country. Because of its low abrasive resistance, the bit service life and drilling efficiency was very low when the hard and extremely hard formations were being drilled. Owing to its high abrasive resistance, the diamond composite material is widely used in drilling operations. However, its toughness against impact is too low to be used in percussion drilling, only can it be used in rotary drilling. In order to solve the problems encountered by DTH hammer in hard rock drilling, make bit life longer, increase rate of penetration and decrease drilling cost, a new type diamond enhanced tungsten carbide composite button with high abrasive resistance and high toughness against impact, which may be used in percussion drilling, has been developed. The key problems to make the button are to improve the thermal stability of diamond, to increase the welding strength between diamond and cemented tungsten carbide, and to lower the sintering temperature of tungsten carbide. All these problems have been solved effectively by pretreatment of diamond, low temperature activation hot-press sintering and high sintering pressure. (1) To plate tungsten on the surface of diamond. Diamond suffers easily from erosion in the environment of high temperature containing oxygen and iron family elements. There is very high energy between the interface of diamond and bonding metal and so the metallurgical bond can’t form at the interface between diamond and bond metal. This will lower greatly the bending strength and the toughness against impact of diamond enhanced tungsten carbide composite button. In order to improve thermal stability of diamond and increase the bonding strength of the interface between diamond and bond metal, to plate tungsten on the surface of diamond by vacuum vapor deposit is adopted. (2) To lower the sintering temperature by adding nickel, phosphorus and boron etc into conventional mixed powder. In general, the sintering temperature of cemented tungsten carbide is more than 1 350 ℃ in which diamond will suffer from serious heat erosion, so the sintering temperature must be lowered. To add nickel, phosphorus and boron etc into cobalt-base bond whose melting point is more than 1 350 ℃ will lower the sintering temperature to about 1 050 ℃. To add phosphorus can lower the temperature of liquid phase occurring and promote the densification of matrix alloy in advance because the co-crystallization temperature of Ni-P and Co-P is 880 ℃ and 1 020 ℃ respectively. The proper adding amount of nickel, phosphorus and boron etc is a key problem. To substitute nickel for partial cobalt can improve the toughness against impact of diamond enhanced tungsten carbide composite button and lower the sintering temperature. To add boron is helpful for sintering and improving the toughness against impact of diamond enhanced tungsten carbide composite button. (3) To increase the sintering press. Under the same sintering temperature, to improve the sintering press can improve the density and strength of sintering products. In this study to increase the sintering press 35 MPa in the usual conditions to 50~60 MPa in sintering diamond enhanced tungsten carbide button by adopting ceramic material as pressing rod has improved the sintering quality effectively. The properties of the button have been measured under lab conditions. The testing results show that its hardness is more than HRA86 and that its abrasiveness resistance is 100 times more than conventional cemented tungsten carbide, and its toughness against impact is more than 100J. All these data theoretically show that the button has very good mechanical properties that can meet the need of percussion drilling, and can solve the problems encountered with button bit of conventional cemented tungsten carbide. 展开更多
关键词 DIAMOND tungsten carbide button bit pretreatment of diamond sintering of low temperature activation hot-press
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Effect of current on the microstructure and performance of (Bi_2Te_3)_(0.2)(Sb_2Te_3)_(0.8) thermoelectric material via field activated and pressure assisted sintering
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作者 陈瑞雪 孟庆森 +1 位作者 樊文浩 王忠 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2011年第7期9-13,共5页
(Bi_2Te_3)_(0.2)(Sb_2Te_3)_(0.8) thermoelectric material was sintered via a field activated and pressure assisted sintering(FAPAS) process.By applying different current intensity(0,60,320 A/cm^2) in the si... (Bi_2Te_3)_(0.2)(Sb_2Te_3)_(0.8) thermoelectric material was sintered via a field activated and pressure assisted sintering(FAPAS) process.By applying different current intensity(0,60,320 A/cm^2) in the sintering process,the effects of electric current on the microstructure and thermoelectric performance were investigated.This demonstrated that the application of electric current in the sintering process could significantly improve the uniformity and density of(Bi_2Te_3)_(0.2)(Sb_2Te_3)_(0.8) samples.When the current intensity was raised to 320 A/cm^2,the preferred orientation of grains was observed.Moreover,positive effects on the thermoelectric performance of applying electric current in the sintering process were also confirmed.An increase of 0.02 and 0.11 in the maximum figure of merit ZT value could be acquired by applying current of 60 and 320 A/cm^2,respectively. 展开更多
关键词 thermoelectric material (Bi_2Te_3)_(0.2)(Sb_2Te_3)_(0.8) microstructure performance CURRENT field activated and pressure assisted sintering
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Fe-Mo-B Enhanced Sintering of P/M 316L Stainless Steel 被引量:5
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作者 YANG Xia GUO Shi-ju 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2008年第1期10-14,共5页
Liquid-phase enhanced sintering of powder metallurgy(P/M)316L stainless steel by addition of sintering aids was studied.2%-8% of pre-alloyed Fe-Mo-B powder with two different particle sizes was added as sintering ai... Liquid-phase enhanced sintering of powder metallurgy(P/M)316L stainless steel by addition of sintering aids was studied.2%-8% of pre-alloyed Fe-Mo-B powder with two different particle sizes was added as sintering aids,and the specimens were sintered in vacuum at 1 200-1 350 ℃.The results show that the fine Fe-Mo-B powder(5-10 μm)has stronger activated effect.The sintered density increases with the increase in sintering aid content or sintering temperature.Warm compaction has a better effect on the control of dimensional precision of compacts.The prealloyed Fe-Mo-B powder deviated from Mo2FeB2 component can also be sintering aid of P/M 316L stainless steel. 展开更多
关键词 P/M 316L stainless steel liquid-phase sintering activated sintering Fe-Mo-B sintering aid
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Modified room temperature solid-state synthesis of yttria-stabilized zirconia(YSZ) nano-powders for solid oxide fuel cells 被引量:1
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作者 Xiaoqian Xu Yurun Feng +6 位作者 Zhaoyu Zhong Xue Guo Zhenhao Zhang Jiao Li Shikai Zhao Shigang Wu Haibin Sun 《Journal of Rare Earths》 SCIE EI CAS CSCD 2023年第9期1385-1391,I0004,共8页
High-performance solid oxide fuel cell(SOFC) is in urgent need of high-quality electrolyte powders with high reactivity and chemical uniformity.Here,8 mol% Y_(2)O_(3) doped ZrO_(2)(YSZ) nano-powders were synthesized b... High-performance solid oxide fuel cell(SOFC) is in urgent need of high-quality electrolyte powders with high reactivity and chemical uniformity.Here,8 mol% Y_(2)O_(3) doped ZrO_(2)(YSZ) nano-powders were synthesized by an improved solid-state reaction method at ambient temperature,and were applied to the fabrication of SOFC electrolytes.YSZ nano-powders show average grain sizes of ^(2)0 nm and high dispersibility,which is comparable with or even better than some other chemical methods.Benefitting from their high reactivity,dense YSZ electrolytes(relative density of 97.9%) can be obtained at a relatively low sintering temperature of 1400℃.The optimized electrical conductivity reaches up to a high value of0.034 S/cm at 800 0C in air.The anode supported single cell with the construction of Ni-YSZ/YSZ/Sm_(0.2)Ce_(0.8)O_(2-δ)(SDC)/La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF) exhibits the peak power density of 0.827 W/cm^(2) at800℃ while taking wet H_(2) as fuels and ambient air as oxidants. 展开更多
关键词 Room temperature solid-state reaction YSZ electrolyte High sintering activity High ionic conductivity Rare earths
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