Water-associated dielectric relaxation in oxide nanoparticles

被引：20

作者：

Fontanella, J. J. ^{[1
]}

Wintersgill, M. C. ^{[1
]}

Edmondson, C. A. ^{[1
]}

Lomax, J. F. ^{[2
]}

机构：

[1] USN Acad, Dept Phys, Annapolis, MD 21402 USA

[2] USN Acad, Dept Chem, Annapolis, MD 21402 USA

来源：

JOURNAL OF PHYSICS D-APPLIED PHYSICS | 2009年 / 42卷 / 04期

关键词：

DYNAMICS; BEHAVIOR; SILICA;

D O I：

10.1088/0022-3727/42/4/042003

中图分类号：

O59 [应用物理学];

学科分类号：

摘要：

Audio frequency dielectric relaxation studies were carried out over the temperature range 120 to 390K on nanoscale mesoporous silica coated with polystyrene and nanoscale. alumina. Two features are observed, both of which are attributed to water. A relaxation is observed at about 150 K and 1000 Hz that is thermally activated. The activation enthalpy is relatively high and the pre-exponential appears to be unusually low and to depend upon the water concentration. A model is presented that accounts for the apparently anomalous behaviour. This relaxation is attributed to water molecules bound at surface hydroxyl groups. A feature is found in the vicinity of 250 K and 1000 Hz that is associated with conductivity that varies omega(n). This response is attributed to hopping conductivity in loosely bound surface water.

引用

页数：6

共 14 条

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