期刊文献+
共找到336篇文章
< 1 2 17 >
每页显示 20 50 100
Plasma induced grain boundaries to boost electrochemical reduction of CO_(2)to formate
1
作者 Guan Wang Shengtao Zhong +9 位作者 Xiaoqian Xiong Jing Li Fangyuan Wang Li Huo Daoxiong Wu Xingqi Han Zhitong Wang Qi Chen Xinlong Tian Peilin Deng 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第8期636-643,I0014,共9页
Bismuth-based catalysts are highly promising for the electrochemical carbon dioxide reduction reaction(eCO_(2)RR)to formate product.However,achieving high activity and selectivity towards formate and ensuring long-ter... Bismuth-based catalysts are highly promising for the electrochemical carbon dioxide reduction reaction(eCO_(2)RR)to formate product.However,achieving high activity and selectivity towards formate and ensuring long-term stability remains challenging.This work reports the oxygen plasma inducing strategy to construct the abundant grain boundaries of Bi/BiO_x on ultrathin two-dimensional Bi nanosheets.The oxygen plasma-treated Bi nanosheet(OP-Bi)exhibits over 90%Faradaic efficiency(FE)for formate at a wide potential range from-0.5 to-1.1 V,and maintains a great stability catalytic performance without significant decay over 30 h in flow cell.Moreover,membrane electrode assembly(MEA)device with OPBi as catalyst sustains the robust current density of 100 mA cm^(-2)over 50 h,maintaining a formate FE above 90%.In addition,rechargeable Zn-CO_(2)battery presents the peak power density of1.22 mW cm^(-2)with OP-Bi as bifunctional catalyst.The mechanism experiments demonstrate that the high-density grain boundaries of OP-Bi provide more exposed active sites,faster electron transfer capacity,and the stronger intrinsic activity of Bi atoms.In situ spectroscopy and theo retical calculations further elucidate that the unsaturated Bi coordination atoms between the grain boundaries can effectively activate CO_(2)molecules through elongating the C-O bond,and reducing the formation energy barrier of the key intermediate(^(*)OCOH),thereby enhancing the catalytic performance of eCO_(2)RR to formate product. 展开更多
关键词 CO_(2)electroreduction Bi nanosheet grain boundary Unsaturation Bi atoms MEA device
下载PDF
The High Surface Ratio Micro-MoS<sub>2</sub>Grain Composed of MoS<sub>2</sub>Nanosheet Prepared with One-Step Hydrothermal Synthesis
2
作者 Guangtong Zhou Xiangbin Zeng +10 位作者 Wenzhao Wang Yishuo Hu Sue Xu Shaoxiong Wu Yang Zeng Wen Jing Tingting Ren Zhenyu Guo Pengfei Xu Haoran Li Yushu Tang 《Journal of Minerals and Materials Characterization and Engineering》 2018年第3期373-381,共9页
Micro molybdenum disulfide was prepared with one-step hydrothermal method;the influence of reactant concentration and temperature on the surface ratio of micro-MoS2 grain was investigated. Raman spectroscopy (Raman), ... Micro molybdenum disulfide was prepared with one-step hydrothermal method;the influence of reactant concentration and temperature on the surface ratio of micro-MoS2 grain was investigated. Raman spectroscopy (Raman), X-ray diffraction (XRD), and Scanning electron microscopy (SEM) were used to characterize the structure, composition and morphology of MoS2. The results show that micro-MoS2 grains were synthesized with one-step hydrothermal synthesis, and the morphology of micro-MoS2 grains is like flower and sphere. The SEM figures indicate that the surface ratio of micro-MoS2 grains is different and also show that the surface ratio of micro-MoS2 grains can be improved by regulating reactant concentration and temperature. This research showed a method to improve the surface ratio of micro-MoS2 grains. 展开更多
关键词 micro-mos2 grain Hydrothermal One-Step Reaction NANOSHEET
下载PDF
TATA-box binding protein-associated factor 2 regulates grain size in rice
3
作者 Ling Jiang Ning Jiang +6 位作者 Zejun Hu Xuejun Sun Xian Xiang Yahui Liu Mingwei Wu Chunming Liu Xiaojin Luo 《The Crop Journal》 SCIE CSCD 2023年第2期438-446,共9页
Grain size,characterized by a combination of grain length,width,and thickness,is one of the major determinants of yield in rice.The present study identified TATA-box binding protein-associated factor 2(TAF2)as an esse... Grain size,characterized by a combination of grain length,width,and thickness,is one of the major determinants of yield in rice.The present study identified TATA-box binding protein-associated factor 2(TAF2)as an essential component regulating transcription and determining grain size in rice.Map-based cloning showed that a G/T substitution in TAF2 resulted in a naturally occurring mutant called reduced grain size and plant height 1(rgh1).The mutants,with weak edited rgh1 alleles,exhibited a small grain phenotype with reduced grain length and width,while the severe knockout mutant(rgh1-2s)was dwarf and completely sterile.Allelic test performed between rgh1 and several edited alleles confirmed that the mutation in TAF2 caused the rgh1 phenotype.GUS staining showed that TAF2 was mainly expressed in the vascular bundles of roots,stems,leaves,and grains.The cytological analysis revealed that reduced cell division in the glumes resulted in the small grain phenotype of rgh1.Further RNA-sequencing detected altered expression of genes involved in the basic biological processes in rgh1 mutant.These findings provide novel insights into the TAF2-mediated genetic mechanism regulating grain size in rice. 展开更多
关键词 grain size TAF2 RGH1 Cell division RICE
下载PDF
外源Fe^(2+)浓度和矿物粒径对生物浸铀的影响
4
作者 辛燕 王世俊 +3 位作者 刘勇 张益硕 李龙祥 周仲魁 《有色金属(冶炼部分)》 CAS 北大核心 2024年第2期64-71,共8页
为改善以往生物浸铀效率不高的缺陷,通过添加外源Fe^(2+)及改变矿物粒径来提高生物对铀的浸出率。研究结果表明:外源Fe^(2+)浓度分别为0、0.5、1.0和2.0 g/L时,铀浸出率分别为87.34%、88.27%、91.23%、89.13%,当浸出体系中Fe^(2+)浓度为... 为改善以往生物浸铀效率不高的缺陷,通过添加外源Fe^(2+)及改变矿物粒径来提高生物对铀的浸出率。研究结果表明:外源Fe^(2+)浓度分别为0、0.5、1.0和2.0 g/L时,铀浸出率分别为87.34%、88.27%、91.23%、89.13%,当浸出体系中Fe^(2+)浓度为1.0 g/L时,铀矿石会产生部分溶解且表面粗糙孔隙明显,有利于铀的浸出,溶浸液中存在适量的Fe^(2+)对生物浸铀的能力具有提升效果。另外,外源Fe^(2+)对铀矿生物浸出符合固体产物层控制模型,浸出过程主要受扩散控制。当粒径<-2 mm和-5 mm时铀浸出率分别为91.23%和83.70%,矿物粒径适当减小可增大颗粒比表面积,同样利于铀的浸出。 展开更多
关键词 生物浸出 外源Fe^(2+) 粒径
下载PDF
Effects of irradiation on superconducting properties of small-grained MgB_(2) thin films
5
作者 刘丽 Jung Min Lee +7 位作者 Yoonseok Han Jaegu Song Chorong Kim Jaekwon Suk Won Nam Kang 刘杰 Soon-Gil Jung Tuson Park 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第12期534-540,共7页
We investigate the effect of ion irradiation on MgB_(2) thin films with small grains of approximately 122 nm and 140 nm.The flux pinning by grain boundaries is insignificant in the pristine MgB_(2) films due to good i... We investigate the effect of ion irradiation on MgB_(2) thin films with small grains of approximately 122 nm and 140 nm.The flux pinning by grain boundaries is insignificant in the pristine MgB_(2) films due to good inter-grain connectivity,but is significantly improved after 120-keV Mn-ion irradiation.The scaling behavior of the flux pinning force density for the ion-irradiated MgB_(2) thin films with nanoscale grains demonstrates the predominance of pinning by grain boundaries,in contrast to the single-crystalline MgB_(2) films where normal point pinning was dominant after low-energy ion irradiation.These results suggest that irradiation-induced defects can accumulate near the grain boundaries in metallic MgB_(2) superconductors. 展开更多
关键词 MgB_(2)films grain boundaries flux pinning low-energy ion irradiation
下载PDF
MoSi_(2)涂层高温富氧火焰冲刷失效机理研究
6
作者 罗靖川 朱昌发 +4 位作者 刘坤 王钺淞 徐向毅 杨冠军 陈林 《中国材料进展》 CAS CSCD 北大核心 2024年第4期355-365,共11页
MoSi_(2)高温氧化时表面可生成保护性SiO_(2),有望用于推力室喷管内表面抗高温氧化涂层材料。然而,在1800℃及以上超高温火焰冲刷考核条件下,MoSi_(2)涂层发生快速损伤失效。为揭示MoSi_(2)涂层超高温冲刷失效机理,系统研究了推力室喷... MoSi_(2)高温氧化时表面可生成保护性SiO_(2),有望用于推力室喷管内表面抗高温氧化涂层材料。然而,在1800℃及以上超高温火焰冲刷考核条件下,MoSi_(2)涂层发生快速损伤失效。为揭示MoSi_(2)涂层超高温冲刷失效机理,系统研究了推力室喷管不同位置涂层的氧化行为和损伤规律。结果表明:涂层损伤分为5个特征区域,分别为前缘、喉部、过渡段、中部和尾部,其中喉部发生整个涂层剥落,尾部涂层仍保持完整。MoSi_(2)涂层的主要失效形式为:超高温下MoSi_(2)涂层晶界快速氧化和氧化膜快速挥发,产生晶界裂纹,晶界裂纹合并形成网状、贯穿性、大尺度的纵向裂纹,将MoSi_(2)涂层分割成岛状区域。在热冲击载荷作用下,岛状区域MoSi_(2)涂层发生剥落失效。指出了MoSi_(2)涂层超高温冲刷腐蚀机理,为发展推力室喷管用长寿命MoSi_(2)超高温抗氧化涂层提供了理论方向。 展开更多
关键词 MoSi_(2)涂层 氧化膜 晶界 纵向裂纹 剥落
下载PDF
大晶粒UO_(2)燃料裂变气体释放行为相场模拟研究
7
作者 刘东昆 王庆宇 +2 位作者 张田 周羽 王翔 《物理学报》 SCIE EI CAS CSCD 北大核心 2024年第6期281-294,共14页
为预测大晶粒UO_(2)燃料中裂变气体的释放行为,从而为事故容错燃料的发展提供支持,本文采用相场模型,对裂变气体在UO_(2)多晶微观结构中的释放行为进行了模拟.该模型采用一组耦合的Cahn-Hilliard方程与Allen-Cahn方程,用守恒场变量表示... 为预测大晶粒UO_(2)燃料中裂变气体的释放行为,从而为事故容错燃料的发展提供支持,本文采用相场模型,对裂变气体在UO_(2)多晶微观结构中的释放行为进行了模拟.该模型采用一组耦合的Cahn-Hilliard方程与Allen-Cahn方程,用守恒场变量表示裂变气体与空位的分布,以及用序参量区分气泡相与基质相.该模型重点考察了不同晶粒尺寸、不同温度条件与扩散系数对裂变气体释放行为产生的影响,展现了气泡的形核、生长、融合等行为,得到了一定程度燃耗深度下燃料的孔隙度、晶界处气泡覆盖率、气泡平均半径等模拟结果.结果表明,温度与扩散系数对孔隙度、晶界处气泡覆盖率的影响较为显著,在扩散系数较大时,晶粒尺寸也会对裂变气体释放行为产生较大影响,扩散系数较小时,晶粒尺寸的影响则不明显.此外,通过该模型得出的高燃耗深度下裂变气体气泡分布状况与实验结果也较为符合,该模型能较好地预测大晶粒UO_(2)裂变气体释放行为. 展开更多
关键词 相场模型 大晶粒UO_(2)燃料 裂变气体释放
下载PDF
基于分子动力学的热化学储能过程中CaO/Ca(OH)_(2)分子扩散机制研究
8
作者 房意 李英杰 +3 位作者 张友浩 任宇 韩奎华 赵建立 《高等学校化学学报》 SCIE EI CAS CSCD 北大核心 2024年第5期71-80,共10页
在CaO/Ca(OH)_(2)热化学储能过程中,CaO晶粒的结构演变会影响材料的储能和机械性能.本文通过分子动力学模拟研究了热化学储能过程中CaO/Ca(OH)_(2)晶粒中分子的扩散强度和晶格结构的变化.结果表明,脱水反应过程中Ca(OH)_(2)分子的运动... 在CaO/Ca(OH)_(2)热化学储能过程中,CaO晶粒的结构演变会影响材料的储能和机械性能.本文通过分子动力学模拟研究了热化学储能过程中CaO/Ca(OH)_(2)晶粒中分子的扩散强度和晶格结构的变化.结果表明,脱水反应过程中Ca(OH)_(2)分子的运动符合体扩散机制.其中,O/H原子的扩散指前因子为7.9×10^(-8)m^(2)/s,而Ca原子的扩散指前因子仅为4.7×10^(-8) m^(2)/s,O/H的快速扩散破坏了材料原有的晶格结构,使得脱水后CaO的结晶度降低.在水合反应过程中,CaO晶粒外层分子的扩散指前因子为3.2×10^(-8) m^(2)/s,为内层分子的2.5倍,CaO分子扩散符合表面扩散机制.由于水合过程中CaO分子的整体扩散强度较弱,因此对CaO晶格结构影响较小.从分子层面揭示了CaO/Ca(OH)_(2)分子在热化学储能过程中的扩散机制. 展开更多
关键词 氧化钙/氢氧化钙热化学储能 氧化钙晶粒 机械性能 分子扩散 分子动力学模拟
下载PDF
Cr_(3)C_(2)添加量对WC-6%Co超细晶硬质合金微结构及力学性能的影响
9
作者 肖雷 尹超 +2 位作者 阳立庚 蒋甘澍 饶承毅 《硬质合金》 CAS 2024年第1期28-36,共9页
本文采用X射线衍射(XRD)、扫描电镜(SEM)和性能检测等研究了Cr_(3)C_(2)添加量对WC-6%Co-(0~1.0%)Cr_(3)C_(2)超细晶硬质合金WC粒度、WC形貌及力学性能的影响。结果表明:WC平均晶粒尺寸随Cr_(3)C_(2)添加量的增加先快速后缓慢减小;添加0... 本文采用X射线衍射(XRD)、扫描电镜(SEM)和性能检测等研究了Cr_(3)C_(2)添加量对WC-6%Co-(0~1.0%)Cr_(3)C_(2)超细晶硬质合金WC粒度、WC形貌及力学性能的影响。结果表明:WC平均晶粒尺寸随Cr_(3)C_(2)添加量的增加先快速后缓慢减小;添加0.25%Cr_(3)C_(2)后,诱发WC晶粒各向异向生长,WC晶粒形貌呈准三棱柱状,随Cr_(3)C_(2)添加量的增加,WC晶粒形貌更规则,最终变成三棱柱状;随Cr_(3)C_(2)添加量的增加,WC-6%CoCr_(3)C_(2)超细晶硬质合金的硬度先快速后缓慢增加,而断裂韧性逐渐降低,抗弯强度先增加后缓慢降低;当添加0.6%Cr_(3)C_(2)时,WC-6%Co硬质合金的综合性能最优,其维氏硬度、抗弯强度和断裂韧性分别为18.42 GPa、3450 MPa和9.32 MPa·m^(1/2)。 展开更多
关键词 Cr_(3)C_(2)添加量 晶粒度分布 WC形貌 力学性能
下载PDF
大气等离子喷涂Y_(3)Al_(5)O_(12)/Al_(2)O_(3)陶瓷涂层的CMAS腐蚀抗力
10
作者 李捷 罗志新 +3 位作者 崔阳 张广珩 孙鲁超 王京阳 《无机材料学报》 SCIE EI CAS CSCD 北大核心 2024年第6期671-680,I0001,I0002,共12页
探索能够有效抵抗1300℃及以上温度钙镁铝硅酸盐(Calcium-Magnesium-Aluminum-Silicate,CMAS)腐蚀的新材料是近年来先进航空发动机用环境障涂层研究的重点任务。本工作围绕具有超强CMAS腐蚀抗力的YAG(Y_(3)Al_(5)O_(12))/Al_(2)O_(3)体... 探索能够有效抵抗1300℃及以上温度钙镁铝硅酸盐(Calcium-Magnesium-Aluminum-Silicate,CMAS)腐蚀的新材料是近年来先进航空发动机用环境障涂层研究的重点任务。本工作围绕具有超强CMAS腐蚀抗力的YAG(Y_(3)Al_(5)O_(12))/Al_(2)O_(3)体系,采用大气等离子喷涂(Atmospheric Plasma Spraying,APS)技术制备了具有共晶成分的YAG/Al_(2)O_(3)涂层。通过在1100、1300和1500℃对制备态涂层进行热处理,获得了具有不同微观结构的YAG/Al_(2)O_(3)涂层。利用不同表征手段研究了YAG/Al_(2)O_(3)涂层抵抗1300℃CMAS腐蚀的性能及微观结构对涂层腐蚀抗性的影响。研究结果发现,经不同温度热处理的YAG/Al_(2)O_(3)涂层与CMAS的反应产物均为石榴石结构固溶体、CaAl_(2)Si_(2)O_(8)和Ca_(2)MgSi_(2)O_(7)。腐蚀机制研究发现,1100℃热处理YAG/Al_(2)O_(3)涂层与CMAS反应界面的近连续分布石榴石固溶体层可有效阻隔CMAS腐蚀元素的扩散;1500℃热处理YAG/Al_(2)O_(3)涂层晶粒尺寸的增加及晶界数量的减少可降低涂层材料在CMAS中的溶解速率,二者均可通过影响腐蚀过程中的离子传输速率而影响各生成物的竞争析出,进而提升涂层的CMAS腐蚀抗力。本工作为YAG/Al_(2)O_(3)涂层热处理工艺优化提供了借鉴,并为通过微观结构优化调控YAG/Al_(2)O_(3)涂层的CMAS腐蚀抗力提供了新思路。 展开更多
关键词 YAG(Y_(3)Al_(5)O_(12))/Al_(2)O_(3) 大气等离子喷涂 环境障涂层 CMAS腐蚀抗力 晶界腐蚀 热处理温度
下载PDF
Enriching Iodine and Regulating Grain Aroma,Appearance Quality,and Yield in Aromatic Rice by Foliar Application of Sodium Iodide
11
作者 HONG Weiyuan DUAN Meiyang +5 位作者 WANG Yifei CHEN Yongjian MO Zhaowen QI Jianying PAN Shenggang TANG Xiangru 《Rice science》 SCIE CSCD 2024年第3期328-342,I0046-I0054,共24页
Applying iodine fertilizers to cultivate iodine-rich crops for daily intake is an effective approach for iodine supplementation,especially for aromatic rice.Field experiments were conducted during the early growing se... Applying iodine fertilizers to cultivate iodine-rich crops for daily intake is an effective approach for iodine supplementation,especially for aromatic rice.Field experiments were conducted during the early growing seasons of 2021 and 2022 to evaluate the impacts of foliar application of iodine fertilizer on aromatic rice and to explore the optimal iodine fertilizer concentration.At the full heading stage,six different concentrations of sodium iodide solutions of 0%(CK),0.010%(T1),0.025%(T2),0.050%(T3),0.075%(T4),and 0.100%(T5)were applied to indica aromatic rice cultivars Meixiangzhan 2 and Xiangyaxiangzhan.The results showed that sodium iodide treatments significantly increased the iodine and sodium contents in both leaves and grains.Compared with the CK,the T1 and T2 treatments increased the 2-acetyl-1-pyrroline(2-AP)content in mature grains by 8.41%-101.66%and 13.58%-74.60%,respectively.Improvements in the contents of 1-pyrroline-5-carboxylic acid,proline,1-pyrroline,and methylglyoxal,as well as the activity of proline dehydrogenase were also detected.Additionally,sodium iodide treatments remarkably decreased the chalky grain rate,chalkiness area,and chalkiness degree of aromatic rice,with the T2 treatment exhibiting a 17.79%-47.42%decrease in chalkiness degree compared with the CK.Meanwhile,T1 and T2 treatments showed beneficial impacts on chlorophyll content,photosynthetic characteristics,and yield components,while T3,T4,and T5 treatments exhibited adverse effects on leaf and grain yields.The linear discriminant analysis revealed significant differences between treatments.The correlation analysis and piecewise structural equation modeling showed that the iodine and sodium influenced the photosynthetic characteristics and chlorophyll content of the leaves,thereby regulating the 2-AP biosynthesis and yield components,ultimately affecting the 2-AP content and yield.Overall,this study suggests that foliar application of 0.025%sodium iodide is an effective method to enrich the iodine content in rice grains,improve the grain aroma and appearance quality of aromatic rice,without detrimental effects on grain yield. 展开更多
关键词 2-acetyl-1-pyrroline appearance quality aromatic rice foliar application grain yield IODINE
下载PDF
Mg掺杂增强CuCrO_(2)陶瓷的电传导及各向异性
12
作者 孟佳源 李毅 +4 位作者 赵裕春 武浩荣 汪雪松 骆婉君 虞澜 《人工晶体学报》 北大核心 2024年第1期163-169,共7页
采用固相反应法制备了具有c轴择优的CuCr_(1-x)Mg_(x)O_(2)(x=0、0.005、0.010、0.020、0.030、0.040、0.050)系列多晶,分别从垂直和平行于压力的宏观面内方向和厚度方向研究Mg掺杂对CuCrO_(2)多晶微结构取向和电性能及各向异性的影响,... 采用固相反应法制备了具有c轴择优的CuCr_(1-x)Mg_(x)O_(2)(x=0、0.005、0.010、0.020、0.030、0.040、0.050)系列多晶,分别从垂直和平行于压力的宏观面内方向和厚度方向研究Mg掺杂对CuCrO_(2)多晶微结构取向和电性能及各向异性的影响,探讨了Mg掺杂增强CuCrO_(2)陶瓷电导率各向异性的机制。当x≤0.030时,多晶为菱方R3m单相结构,随着掺杂量的增加,晶粒在面内充分长大,气孔和晶界减少,致密度逐渐提高,多晶呈现热激活半导体电输运行为;当x=0.030时,面内取向因子F((00l))达到最高值0.912,面内c轴择优取向远优于厚度方向,面内和厚度方向的CuCr_(1-x)Mg_(x)O_(2)多晶室温电阻率分别显著下降至1.80×10^(-3)和3.16×10^(-3)Ω·m,这是由于其结构各向异性的差异,热激活能均减小至0.03 eV,c轴择优取向对热激活能影响并不明显,最大载流子浓度比母相均增加3个量级,晶界缺陷更少,平均自由程增大,输运能力更强,电导率更高。实验表明最优掺杂量为x=0.030,当掺杂量x高于0.030时,出现MgCr_(2)O_(4)尖晶石杂相,样品的微观结构和电输运性能变差。 展开更多
关键词 c轴择优 CuCr_(1-x)Mg_(x)O_(2)多晶 各向异性 电阻率 晶界缺陷 电输运
下载PDF
三元PbBi_(2)S_(4)凝固生长与热电性能研究
13
作者 刘伟 陈彪 肖钰 《铸造技术》 CAS 2024年第4期328-334,共7页
三元PbBi_(2)S_(4)是一种具有本征低晶格热导率的潜力热电材料,但低的电传输性能制约了其热电性能。本工作利用Bridgman法制备了高质量的三元PbBi_(2)S_(4)晶体铸锭,由于减少晶界密度,降低晶界对载流子传输阻碍,电传输性能大幅度提升。... 三元PbBi_(2)S_(4)是一种具有本征低晶格热导率的潜力热电材料,但低的电传输性能制约了其热电性能。本工作利用Bridgman法制备了高质量的三元PbBi_(2)S_(4)晶体铸锭,由于减少晶界密度,降低晶界对载流子传输阻碍,电传输性能大幅度提升。通过优化生长条件获得不同质量的三元PbBi_(2)S_(4)晶体铸锭,最优加权载流子迁移率从多晶中15 cm^(2)/(V·s)提升到56 cm^(2)/(V·s),使三元PbBi_(2)S_(4)晶体铸锭的最大电导率和功率因子分别达到1049 S/cm和4.6μW/(cm·K^(2)),相比多晶PbBi_(2)S_(4)样品分别提高了850%和~64%。最终,PbBi_(2)S_(4)晶体铸锭的最大ZT值在773 K温度下达到0.61。结果表明,通过凝固生长高质量晶体铸锭能显著优化三元PbBi_(2)S_(4)化合物全温区热电性能。 展开更多
关键词 PbBi_(2)S_(4)晶体铸锭 晶界 迁移率 功率因子 ZT值
下载PDF
Fe-44.4%Mo-4.9%B-2.5%Cr-2.9%Ni金属陶瓷烧结阶段晶粒生长机理
14
作者 桂子顺 李延凤 +1 位作者 刘文俊 余海洲 《硬质合金》 CAS 2024年第1期20-27,共8页
Mo_(2)FeB_(2)基金属陶瓷是以Mo、Fe、Cr、Ni、FeB、C为原料,采用反应硼化烧结法制备而成,具有高硬度、高强度和高韧性的特点,并且制造成本相对低廉。本文采用真空液相烧结的方法制备Fe-44.4%Mo-4.9%B-2.5%Cr-2.9%Ni金属陶瓷,研究固相... Mo_(2)FeB_(2)基金属陶瓷是以Mo、Fe、Cr、Ni、FeB、C为原料,采用反应硼化烧结法制备而成,具有高硬度、高强度和高韧性的特点,并且制造成本相对低廉。本文采用真空液相烧结的方法制备Fe-44.4%Mo-4.9%B-2.5%Cr-2.9%Ni金属陶瓷,研究固相、液相烧结阶段金属陶瓷硬质相形貌及生长过程与机理。结果表明:在600℃前,Fe与片状FeB生成Fe_(2)B相,进入固相烧结阶段;随温度升高至900℃,在升温过程中Mo在Fe_(2)B界面上与Fe_(2)B反应形核生成Mo_(2)FeB_(2),生长方式表现为螺旋生长,并且形成生长台阶;温度继续升高至1000℃,Mo_(2)FeB_(2)晶粒继续长大,突破临界半径,开始析出小Mo_(2)FeB_(2)晶粒;温度升高至1050℃,溶解析出一直进行,Mo_(2)FeB_(2)开始长大成截面为正六方形的晶粒。期间经历形核、螺旋生长、溶解析出、形成截面为正六方形晶粒四个阶段,最终由Mo和FeB、Fe_(2)B相形成正六方形的Mo_(2)FeB_(2)晶粒。在1050℃后会进入液相烧结阶段,Mo_(2)FeB_(2)硬质相柱状生长,其长轴、短轴晶粒生长激活能分别为317 kJ/mol和402kJ/mol,因此Mo_(2)FeB_(2)晶粒更易沿长轴生长,最终生长为长条状。 展开更多
关键词 Mo_(2)FeB_(2)基金属陶瓷 固相烧结 液相烧结 晶粒生长机理
下载PDF
La掺杂对(In_(0.5)Nb_(0.5))_(0.10)Ti_(0.90)O_(2)陶瓷微观结构和介电性能的影响
15
作者 张翠玲 陈建宾 《现代化工》 CAS CSCD 北大核心 2024年第3期182-187,共6页
In和Nb共掺杂TiO_(2)(INTO)陶瓷在100 kHz以下的巨大介电常数源于内部势垒层电容效应。根据这种电容效应,通过增加晶界对介电性能的贡献来降低其低频介电损耗。因此,将La掺杂到INTO陶瓷中,通过细化晶粒并增加晶界数量来降低陶瓷制备过... In和Nb共掺杂TiO_(2)(INTO)陶瓷在100 kHz以下的巨大介电常数源于内部势垒层电容效应。根据这种电容效应,通过增加晶界对介电性能的贡献来降低其低频介电损耗。因此,将La掺杂到INTO陶瓷中,通过细化晶粒并增加晶界数量来降低陶瓷制备过程中的能耗。结果表明,La掺杂减小了INTO陶瓷的晶粒尺寸,增加了陶瓷中晶界的数量,并且陶瓷中析出LaNbTiO_(6)二次相,在陶瓷晶粒之间形成高阻态的相界,降低陶瓷的低频介电损耗,优化了陶瓷介电常数的频率稳定性。 展开更多
关键词 共掺杂TiO_(2)陶瓷 内阻挡层电容效应 低频介电损耗 晶界数量 相界
下载PDF
含铬大晶粒UO_(2)芯块制备
16
作者 王博 刘聪 +1 位作者 吴根久 陈煜 《机械研究与应用》 2024年第2期63-66,共4页
大晶粒高热导的UO_(2)芯块为一种理想的高燃耗核燃料芯块。其制备时需在UO_(2)粉末中添加微量Al 2O_(3)和Cr_(2)O_(3),并依照粉末冶金方式来制备。该燃料芯块晶粒尺寸在30μm以上,密度为96.5%~97%T.D,同时为提升芯块导热性,要求Cr含量要... 大晶粒高热导的UO_(2)芯块为一种理想的高燃耗核燃料芯块。其制备时需在UO_(2)粉末中添加微量Al 2O_(3)和Cr_(2)O_(3),并依照粉末冶金方式来制备。该燃料芯块晶粒尺寸在30μm以上,密度为96.5%~97%T.D,同时为提升芯块导热性,要求Cr含量要在0.06wt%~0.1wt%。制备过程中,首先通过单一添加确定了两种物质的最优添加量,再选择合适的粉末预处理技术对两种物质进行混合添加试验。结果表明,分别添加0.008wt%~0.01wt%的Al 2O_(3)粉末和0.2wt%~0.3wt%的Cr_(2)O_(3)粉末并采用制粒粉末包裹Cr_(2)O_(3)的方式制得的芯块晶粒度可达到43.3μm,密度为96.8%T.D,Cr含量为0.0864wt%掺铬大晶粒UO_(2)芯块。 展开更多
关键词 大晶粒 UO_(2)芯块 Al_(2)O_(3) Cr_(2)O_(3)
下载PDF
高压下缺陷对锐钛矿相TiO_(2)多晶电输运性能的影响:交流阻抗测量
17
作者 王月 邵渤淮 +2 位作者 陈双龙 王春杰 高春晓 《物理学报》 SCIE EI CAS CSCD 北大核心 2023年第12期223-232,共10页
采用高压原位阻抗谱测量技术对锐钛矿Ti O_(2)多晶的电输运性质进行了系统研究.在6.4,11.5和24.6 GPa压力处发现了晶粒和晶界的电阻、参数因子和弛豫频率的反常变化行为.研究分析表明:6.4和11.5 GPa压力点分别对应着Ti O_(2)由锐钛矿转... 采用高压原位阻抗谱测量技术对锐钛矿Ti O_(2)多晶的电输运性质进行了系统研究.在6.4,11.5和24.6 GPa压力处发现了晶粒和晶界的电阻、参数因子和弛豫频率的反常变化行为.研究分析表明:6.4和11.5 GPa压力点分别对应着Ti O_(2)由锐钛矿转变为a-Pb O_(2),再转变为斜锆石的结构相变,当压力高于24.6 GPa时,Ti O_(2)完全转变为斜锆石相.通过分析晶粒和晶界电阻在压力作用下的变化行为可知,本征缺陷的存在对Ti O_(2)高压下电输运性质的变化起着关键的作用.在6.4 GPa压力处,相变的发生导致缺陷的作用发生了变化,由作为复合中心的深能级缺陷转变为向导带和价带提供载流子的浅能级缺陷,并且作为浅能级缺陷存在至实验最高压力点38.9 GPa,浅能级缺陷在能带中的位置也随着相变发生而改变.晶粒和晶界的激活能随着压力升高而降低,表明高压下载流子在晶粒和晶界的输运变得更加容易.此外,Ti O_(2)晶粒和晶界的弛豫频率比值随压力的升高而不断减小,高压下的晶界效应不明显. 展开更多
关键词 高压 TiO_(2) 缺陷 晶界
下载PDF
LaAl_(11)O_(18)和Al_(2)O_(3)共同掺杂ZrO_(2)陶瓷的性能研究
18
作者 林信平 陈戈 +2 位作者 陈军超 王步高 邓天有 《中国锰业》 2023年第1期6-10,共5页
在2Y-TZP陶瓷粉中加入总量质量分数50%的不同比例的LaAl_(11)O_(18)和Al_(2)O_(3)粉体,将3种粉体混合均匀、成型并烧结成陶瓷,测试了其力学性能和显微形貌。结果表明,随着LaAl_(11)O_(18)掺杂量增加,烧成陶瓷的力学性能呈现先上升后下... 在2Y-TZP陶瓷粉中加入总量质量分数50%的不同比例的LaAl_(11)O_(18)和Al_(2)O_(3)粉体,将3种粉体混合均匀、成型并烧结成陶瓷,测试了其力学性能和显微形貌。结果表明,随着LaAl_(11)O_(18)掺杂量增加,烧成陶瓷的力学性能呈现先上升后下降的趋势,w(LaAl_(11)O_(18))∶w(Al_(2)O_(3))最佳为1∶1,此时陶瓷强度可到1040 MPa,比50%ZrO_(2)/50%Al_(2)O_(3)样品提升15%。分析测试结果表明,随着LaAl_(11)O_(18)掺杂量的增加,烧成的陶瓷中晶须状晶粒的数量增加,晶须增强效应促使强度提升;但掺杂量继续提升,陶瓷样品中细长颗粒过多导致晶粒分布不均匀,引起相对密度下降和强度降低。 展开更多
关键词 3Y-TZP LaAl_(11)O_(18)和Al_(2)O_(3) 掺杂 晶须状晶粒
下载PDF
Rice-duck co-culture benefits grain 2-acetyl-1-pyrroline accumulation and quality and yield enhancement of fragrant rice 被引量:9
19
作者 Meijuan Li Ronghua Li +3 位作者 Shiwei Liu Jia'en Zhang Hao Luo Shuqing Qiu 《The Crop Journal》 SCIE CAS CSCD 2019年第4期419-430,共12页
Rice-duck co-culture is an integrated farming technology that benefits rice production, grain quality, and ecological sustainability in paddy fields. However, little is known about the effects of rice-duck co-culture ... Rice-duck co-culture is an integrated farming technology that benefits rice production, grain quality, and ecological sustainability in paddy fields. However, little is known about the effects of rice-duck co-culture on enzyme activity involved in the biosynthesis of 2-acetyl-1-pyrroline (2-AP), the volatile that gives fragrant rice its' distinctive and sought-after aroma. The present study aimed to examine the influence of rice-duck co-culture on the photosynthesis, yield, grain quality, rice aroma, and the enzymes involved in 2-acetyl-1-pyrroline biosynthesis in the cultivar Meixiangzhan 2 during the early and late rice growing seasons of 2016 in Guangzhou, China. We compared the rice grown in paddy fields with and without ducks. We found that rice-duck co-culture not only improved the yield and quality of fragrant rice grain, but also promoted the precursors of 2-AP biosynthesis formation and 2-AP accumulation in the grain. Grain 2-AP content in rice-duck co-culture was noticeably increased with 9.60% and 20.81% in early and late seasons, respectively. Proline and pyrroline-5-carboxylic acid (P5C) (precursors of 2-AP biosynthesis) and the activity of enzymes such as proline dehydrogenase (ProDH), ornithine aminotransferase (OAT) and Δ1 pyrroline-5-carboxylic acid synthetase (P5CS) were all improved by 10.15%–12.99%, 32.91%–47.75%, 17.81%–26.71%, 6.25%–21.78%, and 10.58%–38.87% under rice-duck co-culture in both seasons, respectively. Overall, our results suggest that rice-duck co-culture is an environmentally-friendly and sustainable approach to improving rice aroma and grain quality of fragrant rice. 展开更多
关键词 Rice-duck CO-CULTURE 2-AP Proline Yield grain QUALITY FRAGRANT RICE
下载PDF
Fine mapping of GS2, a dominant gene for big grain rice 被引量:7
20
作者 Wuhan Zhang Pingyong Sun +3 位作者 Qiang He Fu Shu Jie Wang Huafeng Deng 《The Crop Journal》 SCIE CAS 2013年第2期160-165,共6页
Grain shape as a major determinant of rice yield and quality is widely believed to be controlled by quantitative trait loci(QTL). We have identified a novel gene 'GS2' to largely regulate grain length and widt... Grain shape as a major determinant of rice yield and quality is widely believed to be controlled by quantitative trait loci(QTL). We have identified a novel gene 'GS2' to largely regulate grain length and width in rice. The GS2 allele in the big-grain rice line ‘CDL’functioned in a dominant manner. In the present study, we employed a chromosome walking strategy in the residual heterozygous lines from recombinant inbred population between cultivar 'R1126' and CDL, and located the GS2 gene in an interval of ~33.2 kb flanked by marker GL2-35-1 and GL2-12 in the long arm of rice chromosome 2. According to genome annotations, three putative gene loci, LOC_Os02g47280, LOC_Os02g47290 and LOC_Os02g47300, exist in this candidate region. In addition, allelic analysis with previously reported genes demonstrated that GS2 was novel for regulating rice grain shape. These results will help promote the cloning and functional characterization of the GS2 gene and further develop linked markers to be used in marker-assisted breeding. 展开更多
关键词 RICE Big-grain FINE mapping GS2 grain SHAPE
下载PDF
上一页 1 2 17 下一页 到第
使用帮助 返回顶部