ISSN:1042-0150    

DOI:10.1080/10420159108224844

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A brief survey is given of some of the currently unresolved issues in the field of ionic conduction in glassy materials. An outline is then given of a recent microscopic model for ionic transport - the diffusion-controlled relaxation model - which can account for the behaviour of the a. c. conductivity and nuclear magnetic resonance spin-lattice relaxation rate observed experimentally in ionically conducting glasses.

ISSN:1042-0150    

DOI:10.1080/10420159108224845

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The scintillation detector is one of the most widely used radiation detectors. At present there is large interest in the development of new fast inorganic scintillators for application in high-energy physics, medical diagnostics and materials science. A review is presented of the main fast luminescence mechanisms in inorganic crystals and the directions of research.

ISSN:1042-0150    

DOI:10.1080/10420159108224846

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Cooled optically stimulated luminescence (COSL) in CaF2:Mn is an ionizing radiation dosimetry method recently developed at Pacific Northwest Laboratory (1,2,3,4). The new method is thought to be an example of a highly sensitive phototransfer technique that could form the basis for future radiation dosimetry applications.Measurements to date have shown high potential for measuring gamma exposures as low as 10 μR. Along with the potential for a system that is more sensitive than thermoluminescent (TL) dosimetry, multiple COSL readouts may be possible with minimal reduction of the COSL intensity. The multiple readout capability can serve as a possible permanent dosimetry record, thus allowing a questionable reading to be re-analyzed.A new readout system is being developed in an attempt to optimize the sensitivity and to improve the reproducibility of the COSL method. This paper presents details of the new readout system, the COSL process, and recent data obtained with an older manual system.

ISSN:1042-0150    

DOI:10.1080/10420159108224847

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Intrinsic crossluminescence (CRL) of CsBr, CsCl, and of BaF2was investigated with electron-beam and with synchrotron radiation excitation. From the CRL spectra, the excitation spectra and from reflectivity, energy schemes were deduced. Extrinsic CRL was observed changing either the initial (CsCl:Br−) or the final (RbCl:Cs+; KCl: Cs+) state of CRL by doping.

ISSN:1042-0150    

DOI:10.1080/10420159108224848

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

We calculate the excitation energies of the Vkcentre in NaCl by an approach combining an Unrestricted Hartree Fock code with classical potentials to simulate the defect and the distorted lattice around it. This treatment gives better results than previous calculations based on the levels of the Cl−2molecule. Results on the elastic dipole tensor are also discussed.

ISSN:1042-0150    

DOI:10.1080/10420159108224849

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:1042-0150    

DOI:10.1080/10420159108224850

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

We consider the case of localized diffusion of several hydrogen related defects in MgO and CaO. Using the EPR technique we obtain information about the hopping processes, jumping rates and activation energies. Usually the first excited vibrational state is far enough so that the motion takes place by thermally activated jumps between the ground states. This is the case of [OH2-]0and [H-Ca+]0in CaO and Hi0(Li) in MgO. In contrast, for Hi0(Li) in CaO the first vibrational state is close enough to be partially populated at the temperatures of measurement. To explain its dynamical behavior we propose a model in which the reorientation takes place by a tunneling through the first excited vibrational state.

ISSN:1042-0150    

DOI:10.1080/10420159108224851

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The molecular dynamics of the fluorite-phase of bismuth sesquioxide has been investigated using previously-developed interionic potentials. The effect of system size has been examined by using systems containing 270, 640, 1250 and 2160 particles which correspond to a system of n × n × n unit cells of Bi4O6with n = 3, 4, 5 or 6. Phase changes to a superlattice in which there are 3n/2 oxygen planes along one of the cubic axes occurred with n = 4 or 6 but not with n = 5. For n = 3 a phase change to a different structure occurred. However, the diffusion coefficient of D determined from the velocity autocorrelation function does not depend strongly on superlattice formation.

ISSN:1042-0150    

DOI:10.1080/10420159108224852

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The dielectric properties of pure silver bromide and iodobromide crystals, grown using a Bridgman technique, have been investigated in the frequency range 107to 10−4Hz from 683K to 198K. The dielectric information is reported using a normalisation technique. This gave a Maxwell-Wagner response typical of a series resistance charging a barrier layer capacitance, with the capacitance blocking the conductance.Ionic conductivity values have been measured and are reported as functions of both temperature and frequency. These compare favourably with the results of other workers.

ISSN:1042-0150    

DOI:10.1080/10420159108224853

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor