摘要:

The strength and fracture behaviour of ceramics are considered with particular reference to oxides. Ceramics fracture in a brittle manner and the strength of most materials is about two orders of magnitude less than the theoretical strength. Strength is discussed conveniently in terms of a modified Griffith equation and the important variables are an effective surface energy and an initial crack size. Both these variables can be related to microstructural features. The effective surface energy is relatively insensitive to structure. The Griffith crack size is more dependent on structure but the controlling factors are only partly understood. Further advances require more detailed information about the role of grain and phase boundaries and the relationship to Griffith cracks.

ISSN:0010-7514    

DOI:10.1080/00107516908220103

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The mechanism by which electrons move in crystalline semiconductors is now understood in some detail. The theoretical concepts necessary for the understanding of conductions in non-crystalline materials involve new ideas, which are discussed in this article. These include ‘localized states’ and ‘thermally activated hopping’. Some experiments designed to test the theory are described. Certain switching devices which make use of the electrical properties of non-crystalline materials are described, and theoretical explanations are suggested.

ISSN:0010-7514    

DOI:10.1080/00107516908220104

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

This article reviews some of the experimental work on the Josephson effects. These effectsoccur in both superconductivity and superfluidity. In superconductivity they are found when two superconductors are separated by a thin insulating barrier (∼ 10−9m thick), or connected by a weak link of metal. A supercurrent can flow between the superconductors, and electromagnetic and magnetic fields can interact with this supercurrent. The interactions demonstrate quantum effects in a particularly striking way, have led to a better understanding of the superconducting state, and have also found some interesting applications.

ISSN:0010-7514    

DOI:10.1080/00107516908220105

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Ultrasonic waves injected into a crystal undergo interactions with the crystal lattice and the lattice vibrations, with conduction electrons and electron magnetic moments and with defects in the lattice. The generation of ultrasonic waves at microwave frequencies has allowed the study of such interactions to be extended to above 1 GHz and has provided data which could previously only be estimated from measurements averaged over the whole spectrum of the thermal vibrations of the lattice. At the same time, investigations of the ultrasonic propagation at these frequencies may lead to useful applications in devices.

ISSN:0010-7514    

DOI:10.1080/00107516908220106

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516908220107

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

A simple microscopic deduction of Archimedes' principle as applied to gases is given in terms of the kinetic theory, and some conventional explanations of barometric effects are queried.

ISSN:0010-7514    

DOI:10.1080/00107516908220108

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516908220109

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Les Noyaux Moyens et Lourdes. Colloque de la Société Française de Physique. (Presses Universitaires de la France, 1968.) [Pp. 212.] 35 F.

ISSN:0010-7514    

DOI:10.1080/00107516908220110

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516908220111

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor