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细晶结构掺杂石墨的抗氧化行为研究
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作者 范壮军 李建刚 +3 位作者 陈峻岭 宋进仁 刘朗 翟更太 《炭素》 2002年第4期15-19,共5页
通过球磨分散方法制备了具有优良热、机械性能的细晶掺杂石墨材料。采用热分析仪考察了掺杂不同粒径陶瓷粒子的复合材料在1500℃温度范围内抗氧化行为;利用扫描电镜分析样品在800℃,1200℃和1400℃恒温氧化后的表面形貌。研究结果表明;... 通过球磨分散方法制备了具有优良热、机械性能的细晶掺杂石墨材料。采用热分析仪考察了掺杂不同粒径陶瓷粒子的复合材料在1500℃温度范围内抗氧化行为;利用扫描电镜分析样品在800℃,1200℃和1400℃恒温氧化后的表面形貌。研究结果表明;细晶掺杂石墨在氧化温度高于800℃时有优良的抗氧化性能。 展开更多
关键词 球磨分散 结晶掺杂 石墨 抗氧化性能 研究
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Sn掺杂Ge-Sb-Te相变薄膜的晶化特性 被引量:1
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作者 顾四朋 侯立松 赵启涛 《材料研究学报》 EI CAS CSCD 北大核心 2004年第2期181-186,共6页
用磁控溅射法制备了掺杂Sn的Ge_2Sb_2Te_5相变材料薄膜,研究了Sn含量对结晶性能的影响.薄膜的X射线衍射(XRD)表明,热处理使薄膜发生了从非晶态到晶态的相变,并出现Sn-Te相.通过示差扫描量热(DSC)实验测出在不同加热速率下非晶态薄膜粉... 用磁控溅射法制备了掺杂Sn的Ge_2Sb_2Te_5相变材料薄膜,研究了Sn含量对结晶性能的影响.薄膜的X射线衍射(XRD)表明,热处理使薄膜发生了从非晶态到晶态的相变,并出现Sn-Te相.通过示差扫描量热(DSC)实验测出在不同加热速率下非晶态薄膜粉末的结晶峰温度,计算了材料的结晶活化能.根据结晶动力学分析和结晶活化能数据,掺杂Sn后的Ge-Sb-Te具有更高的结晶速率,用于光存储时将具有更高的擦除速度. 展开更多
关键词 无机非金属材料 Ge2Sb2Te5 Sn掺杂 热致相变 结晶活化能
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铁掺杂高结晶氮化碳光催化降解萘普生协同产氢的研究
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作者 王盈霏 李传浩 刘国光 《环境科学学报》 CAS CSCD 北大核心 2024年第12期78-90,共13页
以二聚氰胺为前驱体,采用金属氯盐辅助熔盐处理策略制备出铁掺杂高结晶氮化碳光催化剂(CCN/Fe),并通过高分辨透视电子显微镜(HR-TEM)、X射线衍射(XRD)、氮气吸脱附测试(BET)、傅里叶变换红外光谱(FT-IR)、光电子能谱(XPS)对其形貌、组... 以二聚氰胺为前驱体,采用金属氯盐辅助熔盐处理策略制备出铁掺杂高结晶氮化碳光催化剂(CCN/Fe),并通过高分辨透视电子显微镜(HR-TEM)、X射线衍射(XRD)、氮气吸脱附测试(BET)、傅里叶变换红外光谱(FT-IR)、光电子能谱(XPS)对其形貌、组成和结构进行表征.结果显示,CCN/Fe具有合适的能带结构,能够同时满足水体污染物氧化降解和水还原制氢的热力学需求.同时,Fe元素的引入有效提高了光生载流子的分离和迁移效率.以萘普生(NPX)为目标污染物,研究该体系的光催化反应性能.实验发现,经过40 min的可见光照,CCN/Fe对NPX的去除率可达90.2%.此外,光催化产氢反应结果表明,在三乙醇胺和甲醇两种牺牲剂存在下,CCN/Fe均表现出优异的产氢性能.基于此,本文构筑了光催化NPX降解协同产氢反应体系,结果表明,CCN/Fe光催化剂在可见光照下能够同步实现NPX高效降解与协同产氢,产氢效率和NPX的降解率分别达820.5μmol·g^(-1)·h^(-1)和78.9%.实验和理论计算结果表明,CCN/Fe体系产生的光生电子将水分子还原成H_(2),而光生空穴则将水氧化成H_(2)O_(2).原位产生的H_(2)O_(2)随后被分解成·OH,并进攻NPX分子导致其降解.循环稳定性实验和表征表明,CCN/Fe通过4次循环利用后仍能保持良好的光催化性能.值得注意的是,CCN/Fe光催化体系在多种自然水体中均能表现出优异的光催化降解协同制氢性能,表明其具有较好的应用前景. 展开更多
关键词 萘普生 掺杂结晶氮化碳 光催化产氢 降解机理
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Improvement of crystal structure and electrical performance of NASICON-type NaTi_(2)(PO_(4))_(3) solid electrolyte by doping Cr^(3+)ions
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作者 Cheng-jian WEN Zhi-wei LUO +3 位作者 Xin-yu LIU Ju-xia TONG Pan HE An-xian LU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2024年第12期4020-4031,共12页
A series of Cr^(3+)-substituted Na_(1+x)Ti_(2−x)Cr_(x)P_(3)O_(12)(x=0.1,0.2,0.3,0.4,0.5,molar fraction)solid electrolytes were prepared by the solid-phase reaction method.The effects of Cr^(3+)ions on the phase compos... A series of Cr^(3+)-substituted Na_(1+x)Ti_(2−x)Cr_(x)P_(3)O_(12)(x=0.1,0.2,0.3,0.4,0.5,molar fraction)solid electrolytes were prepared by the solid-phase reaction method.The effects of Cr^(3+)ions on the phase composition,microstructure,and electrochemical ion conductivity of Na-based conductors were studied using X-ray powder diffraction,field emission scanning electron microscopy,and AC impedance measurement.The results show that the main crystal phase of NaTi_(2)(PO_(4))_(3) is formed in the solid electrolytes.The substitution of Ti4+sites by 15 at.%Cr^(3+)ions contributes to the enhancement of electrical conductivity,which is attributed to the combined effect of suppressing the formation of impurity phases,broadening ion channels,and improving the bonding degree of grains.Na_(1.3)Ti_(1.7)Cr_(0.3)P_(3)O_(12) electrolyte can obtain the best ionic conductivity of 6.13×10^(−6)S/cm at room temperature,which is 8 times that of the undoped NaTi_(2)(PO_(4))_(3) electrolyte. 展开更多
关键词 NaTi_(2)(PO_(4))_(3) solid electrolyte crystal structure ionic conductivity Cr-doping
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Formation mechanism and crystal simulation of Na_2O-doped calcium aluminate compounds 被引量:2
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作者 田勇攀 潘晓林 +1 位作者 于海燕 涂赣峰 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第3期849-858,共10页
Calcium aluminate clinkers doped with Na2O were synthesized using analytically pure reagents CaCO3, Al2O3, SiO2 and Na2CO3. The effects of Na2O-doping on the formation mechanism of calcium aluminate compounds and the ... Calcium aluminate clinkers doped with Na2O were synthesized using analytically pure reagents CaCO3, Al2O3, SiO2 and Na2CO3. The effects of Na2O-doping on the formation mechanism of calcium aluminate compounds and the crystal property of 12CaO·7Al2O3 (C12A7) cell were studied. The results show that the minerals containing Na2O mainly include 2Na2O·3CaO·5Al2O3 and Na2O·Al2O3, when the Na2O content in clinkers is less than 4.26% (mass fraction). The rest of Na2O is mainly doped in 12CaO·7Al2O3, which results in the decrease of the crystallinity of 12CaO·7Al2O3. The crystallinity of 2Na2O·3CaO·5Al2O3 is also inversely proportional to the Na2O content in clinkers. The formation processes of 2Na2O·3CaO·5Al2O3 and 12CaO·7Al2O3 can be divided into two ways, which are the direct reactions of raw materials and the transformation of CaO·Al2O3, respectively. The simulation shows that the covalency of O-Na bond in Na2O-doped 12CaO·7Al2O3 cell is weaker than those of O-Ca and O-Al bonds. The free energy of the unit cell increases because of Na2O doping, which results in the improvement of chemical activity of 12CaO·7Al2O3. The leaching efficiency of Al2O3 in clinker is improved from 34.81% to 88.17% when the Na2O content in clinkers increases from 0 to 4.26%. 展开更多
关键词 calcium aluminate Na_2O-doping formation mechanism crystal structure SINTERING computer simulation
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Study of transport behavior for Fe-doping La0.67Ca0.33MnO3 perovskite manganese
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作者 崔玉建 葛洪良 +4 位作者 韩雁冰 贾广强 王新燕 曹义刚 张金仓 《Journal of Zhejiang University Science》 EI CSCD 2004年第5期603-608,共6页
Systematic studies of the transport properties of La0.67Ca0.33Mn1- FexO3 (x=0?0.3) systems showed that with x increasing Fe-doping content x the resistance increases and the insulator-metal transition temperature move... Systematic studies of the transport properties of La0.67Ca0.33Mn1- FexO3 (x=0?0.3) systems showed that with x increasing Fe-doping content x the resistance increases and the insulator-metal transition temperature moves to lower temperature. For small doping content, the transport property satisfies metal transport behavior below the transition tem- perature, and above the transition temperature it satisfies the small polaron model. This behavior can be explained by Fe3+ doping, which easily forms Fe3+-O2 -Mn4+channel, suppressing the double exchange Mn3+-O2 -Mn4+ channel and enhancing ? ? the spin scattering of Mn ions induced by antiferromagnetic clusters of Fe ions. 展开更多
关键词 LA2/3CA1/3MNO3 FE-DOPING Crystal structure Transport properties
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Structural and Dielectric Properties of Y_2O_3-Doped Ba_(0.92)Sr_(0.08)Ti_(0.95)Sn_(0.05)O_3 Ceramics
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作者 王晓凤 曲远方 李远亮 《Transactions of Tianjin University》 EI CAS 2009年第6期428-433,共6页
The structural and dielectric properties of Ba0.92Sr0.08Ti0.95Sn0.0503 (BSTS) +x(molar ratio, %) Y^3+ceramics are investigated. Combining the lattice parameters and the distortion of crystal lattice, an alternat... The structural and dielectric properties of Ba0.92Sr0.08Ti0.95Sn0.0503 (BSTS) +x(molar ratio, %) Y^3+ceramics are investigated. Combining the lattice parameters and the distortion of crystal lattice, an alternation of substitution preference of Y^3+ ion for the host cations in perovskite lattice is found. Owing to Y^3- ion entering the A site, the maximum dielectric constant is 5 627 for 1.25% Y^3+-doped samples; when Y^3- ion is more than 1.25%, it tends to occupy the B site in perovskite lattice, causing a drop in the dielectric constant. Owing to the appearance of oxygen vacancy, the optimized dielectric loss is 0.004 for 1.25% Y^3+-doped samples. The thermal stability of BSTS ceramics is significantly improved and the Curie temperature shifts to lower value with the amount of Y2O3 increased, making it a superior candidate for capacitor applications. 展开更多
关键词 dielectric ceramics Y^3+-doping microstructure dielectric properties
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Hollow spherical rare-earth-doped yttrium oxysulfate: A novel structure for upconversion 被引量:7
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作者 Gen Chen Fashen Chen +5 位作者 Xiaohe Liu Wei Ma Hongmei Luo Junhui Li Renzhi Ma Guanzhou Qiu 《Nano Research》 SCIE EI CAS CSCD 2014年第8期1093-1102,共10页
A facile biomolecule-assisted hydrothermal route followed by calcination has been employed for the preparation of monoclinic yttrium oxysulfate hollow spheres doped with other rare-earth ions (Yb3+ and Eu3+ or Er3... A facile biomolecule-assisted hydrothermal route followed by calcination has been employed for the preparation of monoclinic yttrium oxysulfate hollow spheres doped with other rare-earth ions (Yb3+ and Eu3+ or Er3+). The formation of hollow spheres may involve Ostwald ripening. The resulting hybrid materials were used for upconversion applications. The host crystal structure allows the easy co-doping of two different rare-earth metal ions without significantly changing the host lattice. The luminescent properties were affected by the ratio and concentration of dopant rare-earth metal ions due to energy transfer and the symmetry of the crystal field. The type of luminescent center and the crystallinity of samples were also shown to have a significant influence on the optical properties of the as-prepared products. 展开更多
关键词 Y202SO4 Hollow sphere HYDROTHERMAL Ostwald ripening UPCONVERSION
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A facile strategy for ultrasmall Pt NPs being partiallyembedded in N-doped carbon nanosheet structure for efficient electrocatalysis 被引量:6
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作者 Liming Zeng Xiangzhi Cui Jianlin Shi 《Science China Materials》 SCIE EI CSCD 2018年第12期1557-1566,共10页
A facile strategy is established for constructing composite nanostructure with ultrasmall Pt nanoparticles(NPs) of ~2 nm in diameter being homogeneously embedded in N-doped carbon nanosheets. The strong coordination b... A facile strategy is established for constructing composite nanostructure with ultrasmall Pt nanoparticles(NPs) of ~2 nm in diameter being homogeneously embedded in N-doped carbon nanosheets. The strong coordination between Pt atoms in cisplatin and N atoms in pyrrole contributes to the robust embedding of Pt NP into the N-doped carbon nanosheets after annealing. Such a unique partially-embedding structure facilitates the active site exposure while stabilizing the ultrasmall Pt NPs, leading to the comparable electrochemical activities for hydrogen evolution and oxygen reduction reactions, and substantially improves durability performance compared to that of the state-of-the-art Pt/C(20 wt%). 展开更多
关键词 ultrasmaU Pt nanoparticles in situ embedding N-doped carbon nanosheet ELECTROCATALYSIS
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Simultaneous structure and luminescence property control of barium carbonate nanocrystals through small amount of lanthanide doping
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作者 Jianmin Gu Zhenpan Bian +7 位作者 Baipeng Yin Cuihong Jin Xin Liu Yahui Gao Jingxiao Wu Shoufeng Tang Faming Gao Yong Sheng Zhao 《Science Bulletin》 SCIE EI CAS CSCD 2017年第18期1239-1244,共6页
Rare earth doping has been widely applied in many functional nanomaterials with desirable properties and functions,which would have a significant effect on the growth process of the materials.However,the controlling s... Rare earth doping has been widely applied in many functional nanomaterials with desirable properties and functions,which would have a significant effect on the growth process of the materials.However,the controlling strategy is limited into high concentration of lanthanide doping,which produces concentration quenching of the lanthanide ion luminescence with an increase in the Ln^(3+)concentration,resulting in lowering the fluorescence quantum yield of lanthanide ion.Herein,for the first time,we demonstrate simultaneous control of the structures and luminescence properties of BaCO_3nanocrystals via a small amount of Tb^(3+)doping strategy.In fact,Tb^(3+)would partially occupy Ba^(2+)sites,resulting in the changes to the structures of the BaCO_3nanocrystals,which is primarily determined by charge modulation,including the contributions from the surfaces of crystal nuclei and building blocks.These structurally modified nanocrystals exhibit tunable luminescence properties,thus emerging as potential candidates for photonic devices such as light-emitting diodes and color displays. 展开更多
关键词 Lanthanide doping Small amount of doping Structure control Luminescence property Barium carbonate nanocrystals
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