GRYSTALLOGRAPHIC EVALUATION OF MESOSCOPIC PARTICLES FORMED BY FGE-TECHNIQUE

FGE 技术形成的介观颗粒的晶体学评估

• 批准号: 08650024
• 负责人: IWAMA Saburo
• 金额: $ 1.54万
• 依托单位: DAIDO INSTITUTE OF TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650024/
• 关键词: Flowing Gas Evaporation technique; Mesoscopic particles; Sb ultrafine particles; Amorphous particles; Crystallization process; Structure reluxation; critical nucleus size; Ge超微粒子; アモルファス粒子; 核生成頻度

(1)Time-dependence of rate constant for crystallization process of amorphous Sb nano-particlesAmorphopus Sb nano-particles are formed by the FGE technique under the following conditions as 6.9m/s of Ar gas velocity and 1.7kPa of the gas pressure. The particles are collected on amorphous carbon films. Two kinds of annealing are carried out in vacuum (a) pre-annealing at 70ﾟC for 6hs followed by the annealing at 150ﾟC for various durations and (b) annealing at 150ﾟC for various durations without preannealing. Time-dependence of crystallization ratio was investigated through the dark field electron microscopic image of annealed specimens. Crystallization ratio Pc can be written by the following equation (1) from the view point of homogeneous reaction of first order,Ln(1-Pc)=Rc・t (1)where Rc represents the rate constant of crystallization. In the case of above (b) Rc does not keep constant and shows a gradual alowing down of crystallization in every particle size. On the other hand, Rc keeps constant for long time in case of (a). Furthermore, Rc decreases with the decrease of the particle size D.The different feature shown in two cases of (a) and (b) can be explained by a reluxation of amorphous structure.(2)Particle size distribution and its control of nano-particles formed by FGE techniqueAntimony was evaporated in the flowing He gas with the velocity of 6m/s. Particle size distribution fits satisfactorily a Gaussian. Mean particle size decreases from 9.5nm to 7.0nm with increasing of evaporation temperature from 850ﾟC to 900ﾟC.This tendency may reflect a critical nucleus size.

(1)非晶锑纳米粒子结晶过程速率常数的时间依赖性采用FGE技术在Ar气速6.9m/s、气压1.7kPa的条件下形成非晶锑纳米粒子。颗粒被收集在无定形碳膜上。在真空中进行两种退火：(a) 在 70°C 下预退火 6 小时，然后在 150°C 下退火不同时间；(b) 在 150°C 下退火不同时间但不进行预退火。通过退火样品的暗场电子显微镜图像研究了结晶率的时间依赖性。从一级均相反应的角度来看，结晶率Pc可以用下式(1)表示： Ln(1-Pc)=Rc·t (1) 其中，Rc表示结晶的速率常数。在上述 (b) 的情况下，Rc 不保持恒定，并且显示出每个粒径的结晶逐渐减弱。另一方面，在(a)的情况下，Rc长时间保持恒定。此外，Rc随着粒径D的减小而减小。(a)和(b)两种情况所表现出的不同特征可以用非晶结构的回流来解释。(2)FGE技术形成的纳米颗粒的粒径分布及其控制锑在流动的He气中以6m/s的速度蒸发。粒度分布令人满意地符合高斯分布。随着蒸发温度从850℃升高到900℃，平均粒径从9.5nm减小到7.0nm。这种趋势可能反映了临界核尺寸。

项目成果

K.Tanaka and S.Iwama: "Size Dependent Crystallization of Nanometer-sized Sb Particles" NanoStructured Materials. 9. 121-124 ((1997))

K.Tanaka 和 S.Iwama：“纳米尺寸锑颗粒的尺寸依赖性结晶”纳米结构材料。

K.Tanaka and S.Iwama: "Size Dependent Crystallization of Nanometer-sized Sb Particles" NanoStructured Materials. Vol.9. 121-124 (1997)

K.Tanaka 和 S.Iwama：“纳米尺寸锑颗粒的尺寸依赖性结晶”纳米结构材料。

Edit.T.Arai et al.: "Mesoscopic Materials and Clusters-Their Physical and Chemical Properties" 講談社(Springer), 500 (1998)

Edit.T.Arai 等人：“介观材料和团簇 - 它们的物理和化学性质”讲谈社 (Springer)，500 (1998)

S.Iwama: "Preparation of Nanometer-sized Composite Particles by Flowing Gas-Enaporation Technique" Mesoscopic Materials and Clusters-Their Physical and Chemical Properties, (Ed.by T.Arai et al., Springer). 275-283 (1998)

S.Iwama：“通过流动气体蒸发技术制备纳米级复合颗粒”介观材料和团簇 - 它们的物理和化学性质，（T.Arai 等人编辑，Springer）。

K.Tanaka and S.Iwama: "Size Dependent Crystallization of Nanometer-saized Sb Particles" NanoStructured Materials. 9. 121-124 (1997)

K.Tanaka 和 S.Iwama：“纳米锑颗粒的尺寸依赖性结晶”纳米结构材料。