桂林
,
钟云波
,
傅小明
,
雷作胜
,
任忠鸣
金属学报
在强磁场下采用共沉淀-相转化法制备出了纳米级的钴铁氧体颗粒，通过SEM，XRD和VSM等分析手段，考察了磁感应强度对纳米钴铁氧体形貌及性能的影响规律。试验结果表明：无磁场及磁感应强度小于2T时，纳米钴铁氧体颗粒为球形形貌；当磁感应强度大于等于4T时，有棒状纳米钴铁氧体形成；随着磁感应强度的增大，棒状纳米颗粒数量增加，纳米钴铁氧体的晶化程度提高，磁性能(Mr、Ms、Mr/Ms)也有大幅度的提高，10T时制备的纳米钴铁氧体颗粒的剩余磁化强度(Mr)比无磁场下制备的钴铁氧体颗粒的剩余磁化强度增加了近15倍，饱和磁化强度(Ms)提高1.44倍。从磁聚合定向生长和临界磁畴角度，分析了强磁场影响共沉淀-相转化法制备的纳米钴铁氧体的形貌、晶化程度及磁性能的机理。
关键词:
钴铁氧体
,
Nanoparticles
,
null
G.X. Cai
材料科学技术（英）
Ion implantation is a powerful method for fabricating nanoparticles in dielectric. For the actual application of nanoparticle composites, a careful control of nanoparticles has to be achieved. In this letter, the size, distribution and morphology of Ag nanoparticles are controlled by controlling the ion current density, ion implantation sequence and ion irradiation dose. Single layer Ag nanoparticles are formed by Ag+ ion implantation at current density of 2.5 μA/cm2. By Ag and Cu ions sequential implantation, the size of single layer Ag nanoparticles increases. While, by Cu and Ag ions sequential implantation, uniform Ag nanoparticles with wide distribution are formed. The morphology of Ag nanoparticles changes to hollow and sandwiched nanoparticles by Cu+ ion irradiation to doses of 3×1016 and 5×1016 ions/cm2. The optical absorption properties of Ag nanoparticles are also tailored by these ways.
关键词:
Nanoparticles
,
null
,
null
Yinxiao DU
,
Ming LEI
,
Hui YANG
材料科学技术（英）
By a facile and efficient solid-state reaction route using an organic reagent cyanamide (CN2H2) as a precursor with another one being metal oxides, we successfully synthesized seven technologically important metal nitrides including cubic VN, CrN, NbN, hexagonal GaN, AlN, BN, and WN at moderate temperatures. The experimental results show that cyanamide (CN2H2) is a powerfully reducing and nitridizing reagent and the metal oxides are completely converted into the corresponding nitride nanoparticles at lower temperatures than that reported in the conventional methods. It is found that CN2H2 can exhibit some interesting condensation processes, and the final products, highly active carbon nitride species, play a crucial role in the reducing and nitridizing processes.
关键词:
Nitride
,
null
,
null
,
null
Chih-Chia HUANG
,
Chen-Sheng YEH
材料科学技术（英）
Porous cube-like crystalline In2O3 nanoparticles with an average diagonal length of 34.8 nm were fabricated by a laser ablation-reflux process to form In(OH)3, followed by a calcination treatment to yield porous In2O3. HRTEM (high-resolution transmission electronic microscopy), XRD (X-ray diffraction), BET (Brunauer-Emmett-Teller), and XPS (X-ray photoelectron spectroscopy) analysis were used to characterize their crystalline structures, grain sizes, surface areas, and surface compositions. The as-prepared porous indium oxides were tested for their sensing properties toward ethanol. Non-porous In2O3 nanopowder (about 40 nm) was also examined in order to compare the results with the as-prepared porous In2O3 nanomaterials. The porous In2O3 exhibited much better performance than that of non-porosus In2O3, and showed enhanced sensitivity with a lower detection limit than other reported In2O3-based materials when exposed to ethanol. Good gas sensitivity and linear behavior as a function of ethanol concentration were observed in the porous In2O3 nanoparticles.
关键词:
In2O3
,
porosity
,
nanoparticles
,
gas
,
senso
徐海峰
,
刘宝林
,
郝保同
,
周国燕
低温物理学报
利用差示扫描量热仪（DSC）研究了羟基磷灰石（HA）纳米微粒对丙三醇溶液冻结过程中水合性质及玻璃化性质的影响．实验结果表明在中高浓度HA纳米颗粒对溶液水合性质影响显著．与未加纳米颗粒的溶液相比，溶液结晶量减少，未冻水含量增大．在较低浓度溶液中，加入纳米颗粒后玻璃化温度变化不明显，但反玻璃化温度明显升高；当溶液浓度达到60％，加入纳米颗粒后玻璃化温度才有明显的升高趋势，并且玻璃化温度与熔融温度的间距缩短幅度很大．种种结果表明纳米颗粒对实现低温保护剂溶液玻璃化是有利的．
关键词:
纳米颗粒
,
水合性质
,
结晶量
,
玻璃化
,
反玻璃化
,
DSC
孙丽娜
,
孙爱民
,
周敏
,
韩佩佩
,
张永福
,
王洁琼
低温物理学报
采用溶胶-凝胶自燃烧法制得了柠檬酸盐络合物,该络合物经960℃煅烧7小时得到了纳米尺寸的Y2BaCuO5 (Y211)细粉.利用XRD对不同pH下的纳米尺寸Y211粉体特性如物相鉴定,晶粒尺寸,晶格常数等进行测量.实验发现干凝胶在空气中点燃后存在自蔓延燃烧.初始溶液中pH值影响了干凝胶自燃烧的过程,决定了自燃烧和煅烧粉体的晶格常数,密度,体积以及粒子尺寸.当pH =7,煅烧粉体的XRD图谱表明煅烧后粉体的平均晶粒尺寸(25nm)远小于自燃烧粉体的平均晶粒尺寸(48nm).此外,pH=5的煅烧粉体的晶格常数有一个最小值,而密度则达到了最大值6.224 g/cm3.
关键词:
pH
,
溶胶-凝胶
,
纳米粒子
,
Y211
