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Studies on the critical crystallite size of ice and glassy states in mesoporous confinement

介孔约束中冰态和玻璃态临界晶粒尺寸的研究

基本信息

批准号：
17550022
负责人：
KITTAKA Shigeharu
金额：
$ 2.3万
依托单位：
Okayama University of Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

When the water is condensed in fine pores, it is frozen and molten at the temperatures lower than those of bulk water. Effect of pore size on this phenomenon has been explained by classical Gibbs-Thomson relation. Present work has investigated this phenomena in detail through DSC measurements by use of mesoporous silica, MCM-41 and SBA-15, which have well-regulated pore sizes, and suggested the limit of applicability of the relation. Furthermore, thermodynamic analysis of the heat of melting presented an interfacial free energy change indicating a phase change in the supercooled water around at 230 K. It was also confirmed that water molecules does not freeze to crystalline ice in the pores below 2.1 nm, that is, they are frozen as glassy ice.Dynamic property (translational motion) of heavy water confined in the pore of MCM-41 (d=2.1 nm) was investigated by using neutron spin echo measurement. It was found that water molecules are mobile at temperatures down to 200 K. Relaxation times of translational motion analyzed by KWW function changed the mode of temperature dependence around at 229 K, above which it obeys the Vogel Fulcher Tamman relation and below which the Arrhenius relation. This fact suggests that supercooled water in fine pores represents a liquid-liquid transition. The transition has been suggested just by molecular dynamic simulation in the noman's land region of temperatures and has not been realized by experiments with bulk water. And thus, we can conclude that one can prepare the noman's land in water in confinement.Critical minimum size of ice crystallite was estimated to be 2.2 nm in the acetonitrile-water mixture confined in the MCM-41 mesopore of 2.4

当水在细孔中凝结时，它在低于本体水的温度下冻结和熔化。用经典的Gibbs-Thomson关系解释了孔径对这一现象的影响。目前的工作已经详细研究了这一现象，通过DSC测量使用介孔二氧化硅，MCM-41和SBA-15，具有良好的调节孔径，并建议的关系的适用性的限制。此外，熔化热的热力学分析提出了界面自由能的变化，表明在230 K附近的过冷水的相变。实验还证实，水分子在2.1 nm以下的孔隙中不会冻结为结晶冰，即冻结为玻璃冰。采用中子自旋回波测量方法研究了MCM-41（d = 2.1 nm）孔隙中重水的动力学性质（平移运动）。发现水分子在低至200 K的温度下是移动的。用KWW函数分析的平移运动弛豫时间在229 K附近改变了温度依赖模式，在此温度以上，弛豫时间服从Vogel Fulcher Tamman关系，在此温度以下，弛豫时间服从Arrhenius关系。这一事实表明，细孔中的过冷水代表了液-液转变。这种转变仅仅是通过分子动力学模拟在诺曼陆地温度范围内提出的，并没有通过大量水的实验实现。在2.4 μ m的MCM-41介孔中，以乙腈-水混合物为溶剂，冰晶的临界最小粒径为2.2 nm

项目成果

期刊论文数量（33）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Bellissent-Funel, Interlayer Water Molecules in Vanadium Pentoxide Hydrate. 8. Dynamic Properties by Quasi Elastic Neutron Scattering.

Bellissent-Funel，五氧化二钒水合物中的层间水分子。

DOI：
发表时间：
2005
期刊：
Langmuir 21
影响因子：
0
作者：
S.Kittaka;S.Takahara;T.Yamaguchi;M.-C.
通讯作者：
M.-C.

Formation of ultra-thin nanotubular chrysotile particles and their thermal properties

超薄纳米管温石棉颗粒的形成及其热性能

DOI：
发表时间：
2006
期刊：
Ads. Sci. Tech. 24・7
影响因子：
0
作者：
S.Kittaka;S.Kittaka;S.Kittaka;T.Yamaguchi;S.Kittaka
通讯作者：
S.Kittaka

Structure and Dynamic Properties of Liquids Confined in MCM-41 Mesopores

MCM-41介孔内液体的结构和动力学性质

DOI：
发表时间：
2007
期刊：
Eur. Phys. J. Special Topics 141
影响因子：
0
作者：
T. Yamaguchi;K. Yoshida;P. Smironv;T. Takamuku;S. Kittaka;S. Takahara;Y. Kuroda;and M.-C. Bellssent-Funel
通讯作者：
and M.-C. Bellssent-Funel

Neutron Scattering Study on Dynamics of Water Molecules Confined in MCM-41

MCM-41 中水分子动力学的中子散射研究