Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/305
H. Parfitt, D. S. Robertson
Various types of domain structure are described and their relationship to growth conditions recorded. Possible causes of the effects observed are discussed.
描述了各种类型的畴结构，并记录了它们与生长条件的关系。讨论了所观察到的效应的可能原因。
{"title":"Domain structures in lithium niobate crystals","authors":"H. Parfitt, D. S. Robertson","doi":"10.1088/0508-3443/18/12/305","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/305","url":null,"abstract":"Various types of domain structure are described and their relationship to growth conditions recorded. Possible causes of the effects observed are discussed.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"548 1","pages":"1709-1836"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77200132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/308
C. Wronski
The size dependence of the melting point of tin has been studied by means of transmission electron diffraction and microscopy. In accordance with the observations of other workers, it has been found that the melting point of a spherical particle of tin decreases as the radius Rm of the particle decreases. However, the decrease does not depend linearly on 1/Rm. The experimental results are explained in terms of a thermodynamic treatment which allows for the fact that a liquid cannot be subdivided indefinitely. The theory ceases to give correct results for the melting point of particles with radii less than about 50 ?, the calculated temperatures being less than those observed. For particles to which the theory is applicable it is found that the surface tension at the interface between solid and liquid tin is ?1 = 62?2 ? 10 dyn cm-1.
{"title":"The size dependence of the melting point of small particles of tin","authors":"C. Wronski","doi":"10.1088/0508-3443/18/12/308","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/308","url":null,"abstract":"The size dependence of the melting point of tin has been studied by means of transmission electron diffraction and microscopy. In accordance with the observations of other workers, it has been found that the melting point of a spherical particle of tin decreases as the radius Rm of the particle decreases. However, the decrease does not depend linearly on 1/Rm. The experimental results are explained in terms of a thermodynamic treatment which allows for the fact that a liquid cannot be subdivided indefinitely. The theory ceases to give correct results for the melting point of particles with radii less than about 50 ?, the calculated temperatures being less than those observed. For particles to which the theory is applicable it is found that the surface tension at the interface between solid and liquid tin is ?1 = 62?2 ? 10 dyn cm-1.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"1 1","pages":"1731-1737"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74846601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/315
A. Melvin
Temperature distributions were measured during the unsteady-state cooling of hydrogen-air explosions in a cylindrical vessel. From these measurements it was concluded that the rates of heat transfer from the explosions were controlled by the boundary conditions rather than by the relatively high rates of convection occurring in the bulk of the gas.
{"title":"Transient convective heat transfer from gaseous explosions","authors":"A. Melvin","doi":"10.1088/0508-3443/18/12/315","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/315","url":null,"abstract":"Temperature distributions were measured during the unsteady-state cooling of hydrogen-air explosions in a cylindrical vessel. From these measurements it was concluded that the rates of heat transfer from the explosions were controlled by the boundary conditions rather than by the relatively high rates of convection occurring in the bulk of the gas.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"27 1","pages":"1783-1786"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84764898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/318
P. Felsenthal, B. Vonnegut
The motion of conducting particles in electrically stressed dielectric fluids has been examined with the intention of explaining enhanced charge transfer between electrodes in the fluid-particle system. The motion of the particles is due to induction charging and the consequent forces exerted on the particles by an electric field. It is shown that the usual assumptions relating to the velocity of such particles are not substantiated by experiments. The dependence of the enhanced charge transfer on the applied field is derived for one particular case. For this case the study of particle motion shows that particles of different sizes move with a charge equivalent to a maximum voltage on the particle of the order of 16 v. If it is assumed that the particles initially become charged when in contact with one of the electrodes, and on leaving the electrodes are shielded so that the effective charge is reduced, it is possible to show that the current is proportional to the square of the applied voltage, which is in agreement with experimental results.
为了解释流体-粒子系统中电极间电荷转移的增强，研究了带电介质流体中导电粒子的运动。粒子的运动是由于感应电荷和由此产生的电场施加在粒子上的力。结果表明，关于这类粒子的速度的通常假设是不能被实验证实的。在一个特殊情况下，导出了增强电荷转移与外加电场的关系。对这种情况下粒子运动的研究表明,粒子大小不同的移动费用相当于一个粒子的最大电压的顺序16 v .如果假设粒子最初成为带电时接触的一个电极,和离开电极屏蔽的有效电荷减少,可以显示当前正比于电压的平方,这与实验结果一致。
{"title":"Enhanced charge transfer in dielectric fluids containing conducting particles","authors":"P. Felsenthal, B. Vonnegut","doi":"10.1088/0508-3443/18/12/318","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/318","url":null,"abstract":"The motion of conducting particles in electrically stressed dielectric fluids has been examined with the intention of explaining enhanced charge transfer between electrodes in the fluid-particle system. The motion of the particles is due to induction charging and the consequent forces exerted on the particles by an electric field. It is shown that the usual assumptions relating to the velocity of such particles are not substantiated by experiments. The dependence of the enhanced charge transfer on the applied field is derived for one particular case. For this case the study of particle motion shows that particles of different sizes move with a charge equivalent to a maximum voltage on the particle of the order of 16 v. If it is assumed that the particles initially become charged when in contact with one of the electrodes, and on leaving the electrodes are shielded so that the effective charge is reduced, it is possible to show that the current is proportional to the square of the applied voltage, which is in agreement with experimental results.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"44 1","pages":"1801-1806"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82771351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/316
C. Davies
Air containing particles is sucked into an orifice in the underside of a bulky sampling head which is idealized for analysis in two dimensions as a horizontal cylinder with a line sink. Equations are given for the motion of particles around and into the sink when a wind blows past in a horizontal direction; the fluid motion is ideal and the inertia of the particles, which are settling under gravity, is neglected. Particle trajectories are calculated when the wind velocity is of the same magnitude as the rate of fall of the particles.
{"title":"The effect of a cross wind when sampling dust particles through an orifice in the base of a horizontal cylinder","authors":"C. Davies","doi":"10.1088/0508-3443/18/12/316","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/316","url":null,"abstract":"Air containing particles is sucked into an orifice in the underside of a bulky sampling head which is idealized for analysis in two dimensions as a horizontal cylinder with a line sink. Equations are given for the motion of particles around and into the sink when a wind blows past in a horizontal direction; the fluid motion is ideal and the inertia of the particles, which are settling under gravity, is neglected. Particle trajectories are calculated when the wind velocity is of the same magnitude as the rate of fall of the particles.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"9 1","pages":"1787-1792"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83643999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/309
M. Martín, E. Thomas
Focusing the output of a Q-switched ND3+: glass laser (frequency 9441 cm-1) into a high-pressure hydrogen cell (hydrogen molecular vibration frequency 4155 cm-1) produces second Stokes stimulated Raman emission at 9441 - (2 × 4155) = 1131 cm-1 or 884 μm. The dependence of this emission on hydrogen pressure has been investigated, the maximum power of 180 w being reached when the gas pressure was 250 lb in-2, the laser power 30 MW, and the first Stokes power (at 189 μm) 2 MW. At laser powers above 30 MW evidence for plasma formation is presented, and this is put forward as the reason why the output at 884 μm cannot be increased beyond 180 w.
{"title":"Stimulated Raman emission at 8·84 μm","authors":"M. Martín, E. Thomas","doi":"10.1088/0508-3443/18/12/309","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/309","url":null,"abstract":"Focusing the output of a Q-switched ND3+: glass laser (frequency 9441 cm-1) into a high-pressure hydrogen cell (hydrogen molecular vibration frequency 4155 cm-1) produces second Stokes stimulated Raman emission at 9441 - (2 × 4155) = 1131 cm-1 or 884 μm. The dependence of this emission on hydrogen pressure has been investigated, the maximum power of 180 w being reached when the gas pressure was 250 lb in-2, the laser power 30 MW, and the first Stokes power (at 189 μm) 2 MW. At laser powers above 30 MW evidence for plasma formation is presented, and this is put forward as the reason why the output at 884 μm cannot be increased beyond 180 w.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"38 1 1","pages":"1739-1742"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75552868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/304
J. Williams
The effects of anisotropic stress on the current-voltage and noise characteristics of emitter-base junctions of silicon planar transistors have been investigated. Stress was applied to the emitter surface by means of a steel probe having a point radius of 50 μm. The noise measurements were made at frequencies of 1, 10 and 100 kc/s. The experimental results show that the application of stress to the device results in an increase in the base current and in the measured equivalent-noise current. The effects are reversible up to a maximum compression of 9·2 × 1010 dyn cm-2. At a frequency of 100 kc/s it was found that the ratio of the measured equivalent-noise current to the d.c. bias current is approximately unity over the measured region of the diode forward-bias characteristic. The ratio is greater than unity at lower frequencies. The experimental data are interpreted in terms of the model developed by Wortman and his co-workers based upon stress-induced variations in the band-gap energy of the semiconductor and their effect on minority-carrier densities. It is shown that the experimental results are consistent with a stress-induced change in carrier concentration and a recombination-generation rate independent of stress.
{"title":"Effects of anisotropic stress on silicon planar junctions","authors":"J. Williams","doi":"10.1088/0508-3443/18/12/304","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/304","url":null,"abstract":"The effects of anisotropic stress on the current-voltage and noise characteristics of emitter-base junctions of silicon planar transistors have been investigated. Stress was applied to the emitter surface by means of a steel probe having a point radius of 50 μm. The noise measurements were made at frequencies of 1, 10 and 100 kc/s. The experimental results show that the application of stress to the device results in an increase in the base current and in the measured equivalent-noise current. The effects are reversible up to a maximum compression of 9·2 × 1010 dyn cm-2. At a frequency of 100 kc/s it was found that the ratio of the measured equivalent-noise current to the d.c. bias current is approximately unity over the measured region of the diode forward-bias characteristic. The ratio is greater than unity at lower frequencies. The experimental data are interpreted in terms of the model developed by Wortman and his co-workers based upon stress-induced variations in the band-gap energy of the semiconductor and their effect on minority-carrier densities. It is shown that the experimental results are consistent with a stress-induced change in carrier concentration and a recombination-generation rate independent of stress.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"1 1","pages":"1699-1708"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83460759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/129
L. Stenflo
It is known that current oscillations can occur in semiconductors in constant electric fields if the collision cross sections for carrier scattering are strongly energy dependent. The growth rate of these oscillations is calculated and a new criterion for their existence is developed.
{"title":"Current oscillations in semiconductors","authors":"L. Stenflo","doi":"10.1088/0508-3443/18/12/129","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/129","url":null,"abstract":"It is known that current oscillations can occur in semiconductors in constant electric fields if the collision cross sections for carrier scattering are strongly energy dependent. The growth rate of these oscillations is calculated and a new criterion for their existence is developed.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"68 1","pages":"1835-1836"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73310618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/423
K. Breuer, G. Haase, E. Schopper
The effects of alpha particles in AgCl crystals which lead to tracks which can be rendered visible by `decoration' techniques have been found to have in some cases a very short lifetime which is a function of the structural properties of the crystals and the doping materials used. The formation of visible tracks therefore depends on the time interval between irradiation and decoration. This property could be made use of for the triggered recording of tracks.
{"title":"Tracks of charged nuclear particles in AgCl crystals","authors":"K. Breuer, G. Haase, E. Schopper","doi":"10.1088/0508-3443/18/12/423","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/423","url":null,"abstract":"The effects of alpha particles in AgCl crystals which lead to tracks which can be rendered visible by `decoration' techniques have been found to have in some cases a very short lifetime which is a function of the structural properties of the crystals and the doping materials used. The formation of visible tracks therefore depends on the time interval between irradiation and decoration. This property could be made use of for the triggered recording of tracks.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"5 1","pages":"1824-1825"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88729724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-12-01DOI: 10.1088/0508-3443/18/12/319
E. Grant, R. Shack
An 8·6 mm microwave bridge has been used to determine the complex permittivity of water over the temperature range 1-60°C to within a standard error of 0·25 in both ' and . These results indicate that the high-frequency dielectric constant [infinity] varies with temperature from 4·9 ± 0·3 at 1°C to 3·1 ± 0·8 at 60°C, which is a new proposal for water. As with previous investigations, it is difficult to discriminate between Debye behaviour and a small distribution of relaxation times, but the present measurements conform to the latter type of process below room temperature with increasing approximation to a single relaxation time as 60°C is approached. Values of the relaxation wavelength λs, with an error of ± 1-2%, are also given and are slightly lower than those published hitherto.
{"title":"Complex permittivity measurements at 8.6 mm wavelength over the temperature range 1-60°C","authors":"E. Grant, R. Shack","doi":"10.1088/0508-3443/18/12/319","DOIUrl":"https://doi.org/10.1088/0508-3443/18/12/319","url":null,"abstract":"An 8·6 mm microwave bridge has been used to determine the complex permittivity of water over the temperature range 1-60°C to within a standard error of 0·25 in both ' and . These results indicate that the high-frequency dielectric constant [infinity] varies with temperature from 4·9 ± 0·3 at 1°C to 3·1 ± 0·8 at 60°C, which is a new proposal for water. As with previous investigations, it is difficult to discriminate between Debye behaviour and a small distribution of relaxation times, but the present measurements conform to the latter type of process below room temperature with increasing approximation to a single relaxation time as 60°C is approached. Values of the relaxation wavelength λs, with an error of ± 1-2%, are also given and are slightly lower than those published hitherto.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"256 1","pages":"1807-1814"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77132881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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