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La_(0.5)R_(0.5)Ba_(2)Cu_(3)O_(7),Pr_(0.5)R_(0.5)Ba_(2)Cu_(3)O_(7)以及RBa_(2)Cu_(3)O_(7)(R=稀土)的键共价性计算 被引量:2
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作者 武志坚 杨明 张思远 《分子科学学报》 CAS CSCD 2000年第4期202-205,共4页
使用复杂晶体化学键理论计算了La0 .5R0 .5Ba2 Cu3O7(R =Pr,Nd ,Sm ,Eu ,Gd ,Dy ,Y ,Ho,Er,Tm ,Yb ,Lu) (La-R12 3) ,Pr0 .5R0 .5Ba2 Cu3O7(R =La ,Nd ,Sm ,Eu ,Gd ,Dy ,Ho ,Y ,Er,Tm ,Yb ,Lu) (Pr -R12 3)以及RBa2 Cu3O7(R =La ,Pr,Nd ... 使用复杂晶体化学键理论计算了La0 .5R0 .5Ba2 Cu3O7(R =Pr,Nd ,Sm ,Eu ,Gd ,Dy ,Y ,Ho,Er,Tm ,Yb ,Lu) (La-R12 3) ,Pr0 .5R0 .5Ba2 Cu3O7(R =La ,Nd ,Sm ,Eu ,Gd ,Dy ,Ho ,Y ,Er,Tm ,Yb ,Lu) (Pr -R12 3)以及RBa2 Cu3O7(R =La ,Pr,Nd ,Sm ,Eu ,Gd ,Dy ,Ho ,Y ,Er,Tm) (R12 3)中Cu—O键的键共价性 ,结果表明Pr-R12 3,La-R12 3,以及R12 3都应具有超导性 ,而实验结果是La0 .5Pr0 .5Ba2 Cu3O7,R0 .5Pr0 .5Ba2 Cu3O7(R =La,Nd ,Sm ,Eu ,Gd)无超导性 .产生这种矛盾的原因尚不明确 。 展开更多
关键词 键共价 La_(0.5)R_(0.5)Ba_(2)Cu_(3)O_(7) pr_(0.5)R_(0.5)Ba_(2)Cu_(3)O_(7) RBa_(2)Cu_(3)O_(7)
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熔盐法合成Pr_(3)Si_(2)C_(2)粉体及其微观结构表征 被引量:3
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作者 许洁 余腾 +2 位作者 周小兵 代建清 黄庆 《陶瓷学报》 CAS 北大核心 2022年第6期1053-1058,共6页
Pr_(3)Si_(2)C_(2)是一种新型三元层状结构材料,兼具陶瓷和金属的双重特性。由于稀土元素Pr易氧化,如何实现Pr_(3)Si_(2)C_(2)的可控制备是目前研究的重点之一。以SiC和稀土金属Pr为原料,以NaCl-KCl混合熔盐为反应介质,采用熔盐法制备Pr... Pr_(3)Si_(2)C_(2)是一种新型三元层状结构材料,兼具陶瓷和金属的双重特性。由于稀土元素Pr易氧化,如何实现Pr_(3)Si_(2)C_(2)的可控制备是目前研究的重点之一。以SiC和稀土金属Pr为原料,以NaCl-KCl混合熔盐为反应介质,采用熔盐法制备Pr_(3)Si_(2)C_(2)粉体。研究了反应温度对合成产物的物相组成和微观形貌的影响,结果表明,在850℃氩气保护气氛下熔盐反应5 h,可合成出较纯的Pr_(3)Si_(2)C_(2)粉体,其含氧量为~8 wt.%。熔盐法合成Pr_(3)Si_(2)C_(2)粉体为其陶瓷的制备,以及作为SiC陶瓷低温烧结助剂的应用研究奠定了基础。 展开更多
关键词 镨硅碳 熔盐法 微观结构
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还原制备Pr_(2)O_(3)粉体及其结构和光学性能研究
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作者 顾军毅 范武刚 +2 位作者 张兆泉 姚琴 展红全 《无机材料学报》 SCIE EI CAS CSCD 北大核心 2023年第7期771-777,共7页
镨的倍半氧化物(Pr_(2)O_(3))是合成荧光粉和激光增益介质的重要原料,由于其易发生镨的变价并在空气中吸水而受到的关注较少。本研究采用不同表征手段研究在空气和在氩氢混合气氛下Pr6O11还原为Pr_(2)O_(3)的过程机理以及两种粉体的物... 镨的倍半氧化物(Pr_(2)O_(3))是合成荧光粉和激光增益介质的重要原料,由于其易发生镨的变价并在空气中吸水而受到的关注较少。本研究采用不同表征手段研究在空气和在氩氢混合气氛下Pr6O11还原为Pr_(2)O_(3)的过程机理以及两种粉体的物相、微观形貌、粒度及价态等,并进一步分析以上两种氧化镨的发光特性与镨的价态关系。结果表明:两种气氛下氧化镨的相变过程显著不同,还原性的Ar/H_(2)气氛可以加快Pr6O11的还原过程,在800℃即可得到Pr_(2)O_(3)。含Pr^(3+)的Pr_(2)O_(3)除了导带到价带跃迁导致的紫外吸收外,还存在因f→f跃迁引发的可见光波段的吸收,而Pr6O11对波长超过320 nm的紫外–可见光有较强吸收,这与Pr4+和氧之间电荷转移有关。Pr_(2)O_(3)的荧光发射光谱中的宽谱带显示Pr^(3+)的4f5d轨道的最低能级在1S0之下,同时含Pr^(4+)的Pr6O11在404 nm处的荧光强度降低63%,这归因于Pr^(3+)/Pr^(4+)之间的能量耗散。这种荧光性能的差异可用于含谱的高氧离子迁移率陶瓷或晶体中Pr的价态分析。本工作研究的Pr6O11到Pr_(2)O_(3)在不同气氛下的转变过程及相关机理性能,有望推动Pr_(2)O_(3)在不同领域的应用。 展开更多
关键词 pr_(2)O_(3) pr6O11 光学性能 粉体制备
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Pr_(3+)掺杂Sr_(3)Y_(2)TeO_(9)红色荧光粉性能分析
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作者 杨伟斌 杨寅 +3 位作者 罗新 谢岚驰 徐飞翔 熊飞兵 《厦门理工学院学报》 2021年第5期45-50,共6页
通过高温固相法合成Pr_(3+)掺杂Sr_(3)Y_(2)TeO_(9)红色荧光材料,并分析样品的物相与形貌、发光性能、浓度猝灭规律以及荧光衰减寿命等性能。结果表明:合成获得的单一相的Pr_(3+)掺杂Sr_(3)Y_(2)TeO_(9)样品,能够被450~490 nm左右的波... 通过高温固相法合成Pr_(3+)掺杂Sr_(3)Y_(2)TeO_(9)红色荧光材料,并分析样品的物相与形貌、发光性能、浓度猝灭规律以及荧光衰减寿命等性能。结果表明:合成获得的单一相的Pr_(3+)掺杂Sr_(3)Y_(2)TeO_(9)样品,能够被450~490 nm左右的波长有效激发,发射出波长为612 nm的红光;不同物质量浓度的Pr_(3+)掺杂会影响荧光强度,最佳Pr_(3+)掺杂浓度为x=0.003;Pr_(3+)之间的电偶极-电偶极作用是导致荧光浓度猝灭发生的原因;x=0.003 Pr_(3+)掺杂Sr_(3)Y_(2)TeO_(9)的衰减寿命约为7.676μs。因此Pr_(3+)掺杂的Sr_(3)Y_(2)TeO_(9)红色荧光粉有望用于白光LED。 展开更多
关键词 红色荧光粉 pr_(3+) Sr_(3)Y_(2)TeO_(9) 发光性能 物相结构 光致发光 荧光寿命
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助剂Pr6O11掺杂对CeO_(2)-ZrO_(2)-Al_(2)O_(3)材料及其负载单Pd三效催化剂性能的影响研究
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作者 张俊杰 王大军 +5 位作者 李珊珊 李洁 陈耀壮 韩太宇 杨禛祯 王光永 《低碳化学与化工》 CAS 北大核心 2024年第10期72-80,共9页
助剂表面改性是提高铈基材料热稳定性、还原性能及其负载单Pd三效催化剂低温活性的经典方法之一。揭示助剂表面改性的作用机制,对于研发高性能CeO_(2)-ZrO_(2)-Al_(2)O_(3)(CZA)材料,满足日趋严格的汽油车尾气污染物排放标准,解决尾气... 助剂表面改性是提高铈基材料热稳定性、还原性能及其负载单Pd三效催化剂低温活性的经典方法之一。揭示助剂表面改性的作用机制,对于研发高性能CeO_(2)-ZrO_(2)-Al_(2)O_(3)(CZA)材料,满足日趋严格的汽油车尾气污染物排放标准,解决尾气污染具有现实意义。基于引入助剂Pr_(6)O_(11)可以提升CZA的低温还原性能,进一步研究了不同Pr_(6)O_(11)含量(0、3%、5%、7%和9%,质量分数)对其氧化还原性能和热稳定性的影响。N_(2)吸/脱附、X射线衍射(XRD)、H_(2)-程序升温还原(H_(2)-TPR)和储氧量等表征结果表明,Pr_(6)O_(11)的表面改性可在一定程度上降低CeO_(2)-ZrO_(2)(CZ)纳米晶的烧结驱动力,抑制CZ晶粒烧结。同时,引入Pr_(6)O_(11)促进材料产生了更多氧空位,从而提高了其还原性能和储氧性能。其中,Pr_(6)O_(11)含量为5%时,改性CZA表现出最佳的热稳定性、还原性能和储氧性能,1000℃下老化4 h后比表面积和孔容最大(85 m^(2)/g和0.33 mL/g),CZ晶粒尺寸最小(6.9 nm),还原峰温低至532℃,400℃储氧量增至109μmol/g。因此,该改性CZA负载的单Pd三效催化剂表现出最优的催化活性,其CO、NO、C3H8和C3H6的t50(污染物转化率为50%时所需温度)较未改性催化剂分别降低了6℃、15℃、18℃和6℃。综上,在CZA材料中添加适量的Pr_(6)O_(11),可有效提高其负载单Pd三效催化剂的低温活性。该方法简单经济,具有较好的应用前景。 展开更多
关键词 尾气净化 表面改性 CeO_(2)-ZrO_(2)-Al_(2)O_(3) pr_(6)O_(11)
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Electrochemical Characterization and Performance Evaluation of Pr_(0.7)Sr_(0.3)Co_(1-y)Cu_yO_(3-δ) as Cathode Material for IT-SOFCs
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作者 朱成军 刘晓梅 +3 位作者 徐丹 严端廷 裴力 苏文辉 《Journal of Rare Earths》 SCIE EI CAS CSCD 2007年第S1期377-381,共5页
The cathode material Pr0.7Sr0.3Co1-yCuyO3-δ (y=0.05~0.3) was synthesized by a sol-gel method. X-ray diffraction indicated that the samples with y≤0.2 were single phase orthorhombic perovskite structure, but in the ... The cathode material Pr0.7Sr0.3Co1-yCuyO3-δ (y=0.05~0.3) was synthesized by a sol-gel method. X-ray diffraction indicated that the samples with y≤0.2 were single phase orthorhombic perovskite structure, but in the case of y=0.3, traces of a second phase were observed. The unit cell volumes increased with increasing copper content. The electrical conductivity decreased gradually with increasing Cu addition. The investigation of the electrochemical performance suggested that the sample with y=0.1 exhibited the lowest overpotential in all prepared Pr0.7Sr0.3Co1-yCuyO3-δ. With Pr0.7Sr0.3Co0.9Cu0.1O3-δ cathode and porous NiO/Ce0.8Sm0.2O1.9 anode, the single cell based on SDC thin film electrolyte was obtained by a simple dry pressing process. Maximum power densities of the cell were 406 and 481 mW·cm-2 at 700 and 750 ℃, respectively. 展开更多
关键词 IT-SOFC cathode pr_(0.7)Sr_(0.3)Co_(1-y)Cu_yO_(3-δ) catalytic activity rare earths
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Bi_(1-x)Pr_(x)Fe_(1-x)Ti_(x)O_(3)多铁陶瓷的结构与电磁性能研究
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作者 代兴华 王旭昊 代海洋 《兵器材料科学与工程》 CAS CSCD 北大核心 2022年第1期23-27,共5页
采用快速液相烧结法制备Bi_(1-x)Pr_(x)Fe_(1-x)Ti_(x)O_(3)(x=0.00、0.03、0.06、0.12)系列多铁陶瓷样品,研究Pr-Ti共掺杂对BiFe O_(3)结构、缺陷、电学和磁学特性的影响。XRD分析结果表明:所有样品均为菱方钙钛矿结构,Pr-Ti共掺杂可... 采用快速液相烧结法制备Bi_(1-x)Pr_(x)Fe_(1-x)Ti_(x)O_(3)(x=0.00、0.03、0.06、0.12)系列多铁陶瓷样品,研究Pr-Ti共掺杂对BiFe O_(3)结构、缺陷、电学和磁学特性的影响。XRD分析结果表明:所有样品均为菱方钙钛矿结构,Pr-Ti共掺杂可有效抑制杂相生成,当掺杂量高于0.06时杂相基本消失,共掺杂引起结构畸变。正电子湮没寿命谱测试结果表明:所有样品中均存在阳离子空位型缺陷,空位尺寸和浓度均随Pr-Ti掺杂量增加而增大。电学和磁学性能测试结果表明:适量Pr-Ti共掺杂可有效提高Bi Fe O_(3)的介电、铁电和磁学性能。综合上述结果,认为BiFeO_(3)多铁性能的改善可能是由于Pr-Ti共掺杂引起晶格畸变、减少氧空位浓度、改变阳离子空位浓度等多种原因引起。 展开更多
关键词 Bi_(1-x)pr_(x)Fe_(1-x)Ti_(x)O_(3)陶瓷 共掺杂 结构 电磁性能
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Ferroelectric BaTiO_(3) /Pr_(2)O_(3) heterojunction harvesting roomtemperature cold–hot alternation energy for efficiently pyrocatalytic dye decomposition
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作者 Zheng Wu Taosheng Xu +4 位作者 Luohong Zhang Tingting Liu Zhansheng Wu Gangqiang Zhu Yanmin Jia 《Journal of Advanced Ceramics》 SCIE EI CAS CSCD 2024年第1期44-52,共9页
The strong pyrocatalytic dye decomposition of the BaTiO_(3)/Pr_(2)O_(3) heterojunction catalyst under cold–hot alternation conditions has been demonstrated in this work.For pure BaTiO_(3) nanofibers,~54%rhodamine B(R... The strong pyrocatalytic dye decomposition of the BaTiO_(3)/Pr_(2)O_(3) heterojunction catalyst under cold–hot alternation conditions has been demonstrated in this work.For pure BaTiO_(3) nanofibers,~54%rhodamine B(RhB)dye is decomposed under the cold–hot alternation of 29–57℃.With the loading content of Pr_(2)O_(3) increases from 0 to 4 wt%,the pyrocatalytic decomposition ratio of RhB solution increases first and then decreases,eventually achieving a maximum of 91%at 3 wt%.The enhanced pyrocatalytic performance after loading Pr_(2)O_(3) can be attributed to an internal electric field of the heterojunction,which effectively separates positive and negative charges.The strongly pyrocatalytic performance of BaTiO_(3)/Pr_(2)O_(3) makes it hopeful for applications in the dye wastewater treatment through harvesting the environmental cold–hot temperature alternation thermal energy in future. 展开更多
关键词 pyroelectric materials BaTiO_(3) pyrocatalysis BaTiO_(3)/pr_(2)O_(3)heterojunction dye decomposition
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Comparative study on the hydrogen storage performance of as-milled MgRENi rapid quenched alloy catalyzed by metal sulfides
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作者 Xiaoping Dong Zhaoqing Zhang +3 位作者 Liying Yang Shenghai Xin Dandan Su Zhiyuan Li 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第5期2010-2023,共14页
The composites of Mg_(20)Pr_(1)Sm_(3)Y_(1)Ni_(10)as-quenched alloy and 3 wt.%M(M=CoS,CoS_(2),MoS_(2))catalyst were prepared by high-speed vibration ball mill.The effects of metal sulfides on the hydrogenation and dehy... The composites of Mg_(20)Pr_(1)Sm_(3)Y_(1)Ni_(10)as-quenched alloy and 3 wt.%M(M=CoS,CoS_(2),MoS_(2))catalyst were prepared by high-speed vibration ball mill.The effects of metal sulfides on the hydrogenation and dehydrogenation dynamics of alloys were compared.The results show that the as-milled composites contain a large number of amorphous embedded by a small amount of nanocrystals,and there are many point defects.After ball milling,the crystal grain size in the composites containing CoS is relatively larger,followed by CoS_(2)and MoS_(2)again.After hydrogenation,the amorphous phase is crystallized to form Mg_(2)NiH_(4),YH_(3),Pr_(8)H_(18.96),Sm_(3)H_7,Mg,Co or Mo phases,however,Mg_(2)Ni,YH_(2),PrH_(2)and Ni_(3)Y phases appeared after dehydrogenation.The maximum hydrogenation capacity of the composites containing CoS,CoS_(2)and MoS_(2)are 3.939,4.265 and 4.507 wt.%,respectively.The hydrogenation saturation ratio of composite containing MoS_(2)is higher than that of the composites containing CoS and CoS_(2).The dehydrogenation activation energy of the composites containing CoS,CoS_(2)and MoS_(2)is 107.76,68.43 and 63.28 kJ.mol^(-1).H_(2).On the improvement of hydrogen storage performance of Mg_(20)Pr_(1)Sm_(3)Y_(1)Ni_(10)alloy,the catalytic effect of MoS_(2)sulfide is better than that of CoS_(2)sulfide,and which is better than CoS sulfide. 展开更多
关键词 Mg_(20)pr_(1)Sm_(3)Y_(1)Ni_(10)as-quenched alloy COS CoS_(2)and MoS_(2)sulfide MILLING Activation energy Hydrogen storage dynamics
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Pr_(2)O_(3)/RuO_(2)和Gd_(2)O_(3)/RuO_(2)对甲醇的选择性电催化氧化性能研究
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作者 李蒙南 韩洁 +1 位作者 张大峰 刘宝忠 《稀土》 CAS CSCD 北大核心 2022年第5期1-10,共10页
由于电解水阳极析氧反应(Oxygen Evolution Reaction, OER)过电位较高,增加了电解水制氢的整体能耗。故本实验采用热力学上有利的甲醇氧化反应(Methanol Oxidation Reaction, MOR)替代OER,尝试缓解OER对酸性电解水制氢的能耗制约。通过... 由于电解水阳极析氧反应(Oxygen Evolution Reaction, OER)过电位较高,增加了电解水制氢的整体能耗。故本实验采用热力学上有利的甲醇氧化反应(Methanol Oxidation Reaction, MOR)替代OER,尝试缓解OER对酸性电解水制氢的能耗制约。通过热解法制备了Pr_(2)O_(3)/RuO_(2)和Gd_(2)O_(3)/RuO_(2)催化剂,不仅能催化甲醇生成增值的甲酸(HCOOH),而且可以使MOR过程与析氢反应耦合,生成高纯的H2。电化学分析测试表明,在含CH3OH(2.5 mol·L-1)的H2SO4(0.5 mol·L-1)电解质溶液中,电流密度达到10 mA·cm^(-2)时,Pr_(2)O_(3)/RuO_(2)和Gd_(2)O_(3)/RuO_(2)的极化电位分别为1.208 V和1.191 V,远低于纯RuO_(2)的1.40 V。对产物分析发现,在转移电子数约为200 C时,Pr_(2)O_(3)/RuO_(2)和Gd_(2)O_(3)/RuO_(2)产生甲酸的电流效率分别为51.4%和54.7%。上述结果表明,甲醇选择性氧化制甲酸反应对酸性OER过程展现出了极具潜力的替代价值,能够显著降低电解水制氢的成本。 展开更多
关键词 电催化 甲醇氧化 pr_(2)O_(3) Gd_(2)O_(3) RuO_(2)
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Preparation of PSFO and LPSFO nanofibers by electrospinning and their electronic transport and magnetic properties
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作者 Ying Su Dong-Yang Zhu +5 位作者 Ting-Ting Zhang Yu-Rui Zhang Wen-Peng Han Jun Zhang Seeram Ramakrishna Yun-Ze Long 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第5期629-635,共7页
Pr_(0.5)Sr_(0.5)FeO_(3)(PSFO)and La_(0.25)Pr_(0.25)Sr_(0.5)FeO_(3)(LPSFO)nanofibers are prepared by electrospinning followed by calcination,and their morphologies,microstructures,electronic transports,and magnetic pro... Pr_(0.5)Sr_(0.5)FeO_(3)(PSFO)and La_(0.25)Pr_(0.25)Sr_(0.5)FeO_(3)(LPSFO)nanofibers are prepared by electrospinning followed by calcination,and their morphologies,microstructures,electronic transports,and magnetic properties are studied systematically.The temperature-dependent resistance curves of PSFO and LPSFO nanofibers are measured in a temperature range from 300 K to 10 K.With the temperature lowering,the resistance increases gradually and then decreases sharply due to the occurrence of ferromagnetic metal phase.The metal-insulator transition temperatures are about 110 K and 180 K for PSFO and LPSFO nanofibers,respectively.The electronic conduction behavior above the transition temperature can be described by one-dimensional Mott’s variable-range hopping(VRH)model.The hysteresis loops and the field-cooled(FC)and zero-field-cooled(ZFC)curves show that both PSFO nanofiber and LPSFO nanofiber exhibit ferromagnetism.Although the doping of La reduces the overall magnetization intensity of the material,it increases the ferromagnetic ratio of the system,which may improve the performance of LPSFO in solid oxide fuel cell. 展开更多
关键词 pr_(0.5)Sr_(0.5)FeO_(3) La_(0.25)pr_(0.25)Sr_(0.5)FeO_(3) ELECTROSPINNING electronic transport magnetic properties
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Preparation, structure, magnetic properties and special magnetoresistance effect of La_(0.67)Sr_(0.33)MnO_(3+δ) /Pr_(0.7)Ca_(0.3)MnO_(3+δ)/La_(0.67)Sr_(0.33)MnO_(3+δ) trilayered thin films
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作者 熊曹水 皮雳 +6 位作者 汤业庆 朱弘 宗登刚 张骏峰 邓云飞 朱警生 张裕恒 《Science China Mathematics》 SCIE 1999年第1期106-112,共7页
The La0.67Sr0.33MnO3 +δ/Pr0.7Ca0.3MnO3 +δ/La0.67Sr0.33MnO3 +δ(LPL) trilayered films on (100)LaA-1O3 substrates are prepared by using direct current (DC) magnetron sputtering method. The results obtained by means of... The La0.67Sr0.33MnO3 +δ/Pr0.7Ca0.3MnO3 +δ/La0.67Sr0.33MnO3 +δ(LPL) trilayered films on (100)LaA-1O3 substrates are prepared by using direct current (DC) magnetron sputtering method. The results obtained by means of X-ray powder diffractometer show that all films are the high quality epitaxial films. The results gained by SQUID magnetometer indicate that there is a magnetic coupling in the LPL trilayered films. The resistivities of LSMO, PC-MO and LPL films are measured using standard four-probe method and analyzed log ρ/T curve. From the results it is concluded that the middle-layered PCMO which is ferromagnetic may play a role of intra-magnetic field, which weakens the paramagnetism of LSMO film, lowers ρmax and enlarges Tp which is the transition temperature from metal to insulator, just as the applied magnetic field does. And the middle-layered PCMO may induce the change of the density of states in the LSMO' s gap. The two reasons above make the resistivity and Tp of the samples in zero field change with the thickness of PCMO layers. 展开更多
关键词 MAGNETORESISTANCE La_(0.67)Sr_(0.33)MnO_(3+δ) /pr_(0.7)Ca_(0.3)MnO_(3+δ)/La_(0.67)Sr_(0.33)MnO_(3+δ)
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