崔彦娜
,
王德平
,
黄文旵
,
姚爱华
材料科学与工程学报
以气泡为模板,通过简单的一步水热法合成了尖晶石型MⅡFe2O4（M=Fe,Ni）纳米空心微球,并采用柠檬酸对其表面进行了修饰。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、红外光谱（IR）和振动样品磁强计（VSM）对修饰前后纳米空心微球的形貌、结构和磁性能进行了表征。结果表明,MⅡFe2O4（M=Fe,Ni）纳米空心微球的尺寸在300～600nm,前躯体溶液的pH值大于9或反应时间小于12h都不能生成空心结构。此外,MⅡFe2O4（M=Fe,Ni）纳米空心微球呈现较好的超顺磁性,但与纳米Fe3O4实心微粒相比较,Fe3O4纳米空心微球的饱和磁化强度却有所降低。
关键词:
纳米空心微球
,
结构特性
,
超顺磁性
薛锦红
,
陈敬超
,
冯晶
,
周晓龙
,
潘勇
,
卢雯婷
,
陈蓉
稀有金属材料与工程
综述了La-Rh-O、Bi-Rh-O、Cu-Rh-O、Ca-Rh-O、Zn-Rh-O、Li-Rh-O系列铑基氧化物热电材料的最新研究工作,分析其晶体结构、制备方法、元素掺杂对热电性能的影响,认为铑基氧化物热电材料是目前很有潜能的新型热电材料.
关键词:
铑基氧化物
,
热电材料
,
热电性能
Haibo LI Weitao ZHENG Yudong LIU Ruilin ZHANG Department of Materials Science
,
Jilin University
,
Changchun
,
130023
,
China
材料科学技术（英）
The procedure of preparing specimens of ultrafine particles (UFP) Fe_3O_4 was studied and the measurement and analysis of the Mssbauer spectra at room temperature was made.After the hyperfine field due to iron was analyzed carefully,it is shown that the interaction of the interfaces be- tween grains of UFP Fe_3O_4 has stronger effects (enlarging the quadrupole splitting in Mssbauer spectrum) and it is found that superparamagnetic effects appear,which means that the magnetic property of UFP Fe_3O_4 is different from that of bulk Fe_3O_4.
关键词:
UFP
,
null
,
null
高文元
,
孙俊才
,
刘扬
功能材料
使用金属氧化物La2O3,NiO,CuO和Co2O3作为原料,固相反应法能够合成出具有K2NiF4型结构单一相的、且晶粒尺寸在35～50nm范围的La2Ni0.5M0.5O4+δ(M=Co,Cu)粉料,用XRD、SEM和直流四极探针电导测试法研究了合成La2Ni0.5M0.5O4+δ(M=Co,Cu)粉料的煅烧工艺条件和掺杂元素对电性能的影响以及粉料的颗粒形貌.随着煅烧温度的升高和保温时间的延长,晶粒尺寸在不断长大;合成的粉料在1300℃烧结5h后所有样品的电导率在空气条件下于100～800℃范围内都在增加.掺杂C0或Cu后的材料La2NiO4+δ的电导率均有增加,但掺杂Co后材料电导率要大于掺杂Cu的电导率.为此确定La2Ni0.5M0.5O4+δ(M=Co,Cu)类粉料固相法合成的适宜煅烧条件为1400℃下保温时间14h.
关键词:
K2NiF4型结构
,
LLa2Ni0.5M0.5O4+δ
,
晶粒尺寸
,
掺杂元素
,
电导率
Acta Physica Sinica
Polycrystalline samples of Sr(14)Cu(24)O(41) and Sr(14) (Cu(0.97) M(0.03))(24) O(41) (M = Zn, Ni, Co) were synthesized by standard solid state reaction method. All samples are single phase as identified by X-ray diffraction, no regular shift of lattice parameters a, c is found, but the lattice parameter b increases slightly with doping magnetic ions Ni and Co, and has no change with doping non-magnetic ion Zn, respectively. Selected area electron diffraction experiments show that Zn,Ni and Co ions may substitute for Cu ions in the chain. All the doping compounds are still semiconductors and have a crossover temperature T(p) like the parent phase Sr(14)Cu(24)O(41). The influence of magnetic ion Ni or Co doping on the resistivity is smaller than that of non-magnetic ion Zn doping, while the influence of non-magnetic ion Zn doping on crossover temperature is smaller than that of magnetic ion Ni or Co doping.
关键词:
spin ladder compound;Sr(14)Cu(24)O(41);B-site doping;transport;property;metal-insulator-transition;single-crystals;sr(14-x)a(x)cu(24)o(41);sr14cu24o41;dynamics;charge;la;gap;ca
贺全国
,
刘军
,
胡蓉
稀有金属材料与工程
采用焙烧法制备γ-Fe2O3之后,再利用3-氨丙基三乙氧基硅烷(APTES)对其表面进行功能化修饰,在其溶液体系中加入氯铂酸/氯化钯溶液,使游离的四价铂粒子/二价的钯离子吸附在磁性纳米粒子表面,与氨基化基团形成配位化合物,在超声化学作用下,利用水合肼将铂离子和钯离子还原为单质,制成γ-Fe2O3/M(M=Pt/Pd)复合磁敏催化剂纳米粒子.并采用Bruker Advanced-D8粉末衍射仪,带有选区电子衍射(SAED)的透射电子显微镜(TEM),高分辨透射电子显微镜(HRTEM)和带有超导量子干涉装置(SQUID)功能的磁性测量系统(MPMS)等对γ-Fe2O3粒子和y-Fe2O3/M复合粒子磁性进行表征.结果表明:采用焙烧法制备的γ-Fe2O3磁性纳米粒子粒径在20 nm左右,制备的γ-Fe2O3/Pt和γ-Fe2O3/Pd复合粒子粒径分别在68和36 nm左右,室温下的磁化强度分别为29.4和31.2 (A·m2)/kg,磁响应性能优越,可用于磁敏催化剂反应体系.这为贵金属Pt、Pd催化剂的回收与磁敏催化剂应用提供了新的思路.
关键词:
γ-Fe2O3
,
γ-Fe2O3/Pt复合粒子
,
γ-Fe2O3/Pd复合粒子
,
超声化学
,
磁敏催化剂
徐波
,
王树林
,
李生娟
,
李来强
材料工程
doi:10.3969/j.issn.1001-4381.2011.08.008
通过水解Zn/Fe3O4纳米粒子制备ZnFe2O4纳米结构,采用XRD和TEM检测产品的成分和形貌变化,验证反应过程方程的正确性.结果表明:当反应温度为260℃时,产品中含有ZnO纳米棒,随着反应温度升至300℃,ZnO纳米棒逐渐消失,得到纯度较高的ZnFe2O4纳米颗粒,粒度分布在20～30nm范围内.产品的M(o)ssbauer谱分析,显示样品为磁分裂六线谱,晶体结构为正、反尖晶石混合结构,为磁有序结构,呈反铁磁性.
关键词:
Zn铁氧体
,
Zn/Fe3O4
,
水解反应
,
M(o)ssbauer谱
黄立辉
,
刘行仁
,
王晓君
,
郑著宏
无机材料学报
本文合成了掺Ce3+的M3MgSi2O8（M＝Sr，Ba）荧光粉，这两种荧光粉在UV光激发下发射出较强的蓝紫色光，报道了它们室温下的激发光谱和发射光谱以及77K低温下的荧光光谱．阐述了在这两种焦硅酸盐体系中，Ce3+均形成两个发光中心，且随Sr，Ba顺序，荧光体发射峰稍稍向短波移动．
关键词:
Ce3+离子
,
null
,
null
,
null
Ying LI
材料科学技术（英）
Oxide materials NaCo2O4 and (Na1-yMy)1.6Co2O4 (M=K, 0.05≤y≤0.35; M=Ca, Sr, 0.10≤y≤0.40) were prepared by a sol-gel method. Experimental results indicated that the Seebeck coefficient and the Power-factor of Na Co2O4 were improved by doping Ca and Sr but not by K. The Power-factor of NaCo2O4 is in its maximum, 1.68×10-4 W•m-1•K-2 and 11% bigger than that of the original one when the dopant fraction of Ca was 0.1. Doping Sr makes NaCo2O4 have the biggest Power-factor, 1.68×10-4 W•m-1•K-2 that is 50% bigger than the non-doping oxide. The experimental results indicate that suitable dopants and addition amounts could improve the thermoelectric properties of NaCo2O4 greatly.
关键词:
Thermoelectric materials
,
materials
,
Electric
,
proper
