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Journal of research of the National Bureau of Standards. Section A, Physics and chemistry最新文献

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Reduction of Space Groups to Subgroups by Homogeneous Strain. 通过同质应变将空间群还原为子群。
Journal of research of the National Bureau of Standards. Section A, Physics and chemistry Pub Date : 1963-09-01 Epub Date: 1963-10-01 DOI: 10.6028/jres.067A.042
H S Peiser, J B Wachtman, R W Dickson
{"title":"Reduction of Space Groups to Subgroups by Homogeneous Strain.","authors":"H S Peiser, J B Wachtman, R W Dickson","doi":"10.6028/jres.067A.042","DOIUrl":"10.6028/jres.067A.042","url":null,"abstract":"<p><p>It is assumed that the symmetry elements possessed by a strained crystal will be those common to the unstrained crystal and to the macroscopic state of strain. This principle has been applied to show all of the possible subgroups to which a given space group can be lowered by homogeneous strain for all of the 230 crystallographic space groups.</p>","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319803/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73509156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Resolution Limits of Analyzers and Oscillatory Systems 分析仪和振荡系统的分辨率极限
Journal of research of the National Bureau of Standards. Section A, Physics and chemistry Pub Date : 1963-09-01 DOI: 10.6028/jres.067A.048
E. Corliss
{"title":"Resolution Limits of Analyzers and Oscillatory Systems","authors":"E. Corliss","doi":"10.6028/jres.067A.048","DOIUrl":"https://doi.org/10.6028/jres.067A.048","url":null,"abstract":"This paper considers the resolution limits of those analyzers and oscillatory systems whose performance may be represented by a second-order differential equation. The “signal uncertainty” product Δf·Δt is shown to be controlled by the ability of a system to indicate changes in energy content. The discussion refers the functioning of the system to a signal space whose coordinates are energy, frequency, and time. In this signal space, the product of the resolution limits, U = (ΔE/E0) (Δf/f0) (Δt/T0) is the volume of a region within which no change of state in the system may be observed. Whereas the area element Δf·Δt is freely deformable, no operations upon either Δf or Δt can further the reduction of the energy resolution limit. Thus U is irreducibly fixed by the limiting value of ΔE/E0. By considering the effects of noise upon ΔE/E0, and thus upon U, the paper demonstrates the rise of statistical features as signal-to-noise ratios decrease. Functional relationships derived from ΔE/E0 and U are tabulated. These equations facilitate computation of the limits of observable changes of state in a system, and they provide guidance for the design of experiments to apportion the uncertainties of measurement of transient phenomena as advantageously as possible. A reference bibliography and appendices giving somewhat detailed proofs are included.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74711838","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}
引用次数: 6
Melting Temperature and Change of Lamellar Thickness with Time for Bulk Polyethylene. 块状聚乙烯的熔化温度和层状厚度随时间的变化。
Journal of research of the National Bureau of Standards. Section A, Physics and chemistry Pub Date : 1963-09-01 Epub Date: 1963-10-01 DOI: 10.6028/jres.067A.046
James J Weeks
{"title":"Melting Temperature and Change of Lamellar Thickness with Time for Bulk Polyethylene.","authors":"James J Weeks","doi":"10.6028/jres.067A.046","DOIUrl":"10.6028/jres.067A.046","url":null,"abstract":"<p><p>The melting temperature of linear polyethylene has been obtained as a function of the time and temperature of crystallization. Recrystallization was minimized by a special melting procedure. By interpreting the melting points as characteristic of a given lamellar thickness, it was found that the thickness of crystals of appreciable age increased linearly with the logarithm of their time of existence. The lowest melting (i.e., thinnest) lamellae in a given specimen may be assumed to have either existed for only a short period of time, or to have been impeded in their growth in the chain direction, and they were found to have an estimated thickness close to that predicted by recent kinetic theories of polymer crystal growth with chain folding.</p>","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319807/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81390990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Preparation of Anhydrous Single Crystals of Rare-Earth Halides 稀土卤化物无水单晶的制备
Journal of research of the National Bureau of Standards. Section A, Physics and chemistry Pub Date : 1963-07-01 DOI: 10.6028/jres.067A.036
N. H. Kiess
{"title":"Preparation of Anhydrous Single Crystals of Rare-Earth Halides","authors":"N. H. Kiess","doi":"10.6028/jres.067A.036","DOIUrl":"https://doi.org/10.6028/jres.067A.036","url":null,"abstract":"Anhydrous rare-earth halides are prepared by the conversion of the rare-earth oxide to the halide by means of its reaction with the appropriate ammonium halide. Without transfer from the reaction vessel, the halide is melted, then crystallized by slow cooling. The resulting solid usually contains single crystals large enough to permit spectroscopic studies of the compounds.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82199888","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}
引用次数: 8
Relaxation Modes for Trapped Crystal Point Defects 俘获晶点缺陷的弛豫模式
Journal of research of the National Bureau of Standards. Section A, Physics and chemistry Pub Date : 1963-07-01 DOI: 10.6028/jres.067A.030
A. Franklin
{"title":"Relaxation Modes for Trapped Crystal Point Defects","authors":"A. Franklin","doi":"10.6028/jres.067A.030","DOIUrl":"https://doi.org/10.6028/jres.067A.030","url":null,"abstract":"Group representation theory is applied to the problem of calculating the relaxation modes of a point defect trapped near an impurity atom or other defect in a crystal, where more than one set of neighboring sites is available to the point defect. For illustration, the case of a cation vacancy trapped near a divalent impurity in the sodium chloride lattice is treated, including nearest- and next-nearest-neighbor sites.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90852631","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}
引用次数: 16
A Note on the Galvanomagnetic and Thermoelectric Coefficients of Tetragonal Crystalline Materials 关于四方晶体材料的磁、热电系数的注记
Journal of research of the National Bureau of Standards. Section A, Physics and chemistry Pub Date : 1963-07-01 DOI: 10.6028/jres.067A.031
W. C. Hernandez, A. Kahn
{"title":"A Note on the Galvanomagnetic and Thermoelectric Coefficients of Tetragonal Crystalline Materials","authors":"W. C. Hernandez, A. Kahn","doi":"10.6028/jres.067A.031","DOIUrl":"https://doi.org/10.6028/jres.067A.031","url":null,"abstract":"The independent Hall, magnetoresistive, and thermoelectric coefficients for a tetragonal crystal have been tabulated and geometric configurations for their experimental measurement have been determined. These coefficients have been calculated on assumptions of several simple ellipsoidal models, in the range of nondegenerate statistics. Implications of experimentally observed isotropy or anisotropy of transport properties on the structure of the energy surfaces are noted.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78382998","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}
引用次数: 2
Symmetry Splitting of Equivalent Sites in Oxide Crystals and Related Mechanical Effects 氧化物晶体中等效位的对称分裂及相关力学效应
Journal of research of the National Bureau of Standards. Section A, Physics and chemistry Pub Date : 1963-07-01 DOI: 10.6028/jres.067A.029
J. B. Wachtman, H. Peiser, E. Levine
{"title":"Symmetry Splitting of Equivalent Sites in Oxide Crystals and Related Mechanical Effects","authors":"J. B. Wachtman, H. Peiser, E. Levine","doi":"10.6028/jres.067A.029","DOIUrl":"https://doi.org/10.6028/jres.067A.029","url":null,"abstract":"Changes in the symmetry of a crystal caused by an applied strain have been used to show in what circumstances an internal friction peak can result from the motion of isolated point defects. General rules are given to make the prediction, and these are applied to several structures of common oxides. The prediction for rutile is compared with experimental results which are interpreted by the movement of titanium ions between interstitial positions in the structure.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87288206","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}
引用次数: 15
Photolytic Behavior of Silver Iodide1 碘化银的光解行为
Journal of research of the National Bureau of Standards. Section A, Physics and chemistry Pub Date : 1963-07-01 DOI: 10.6028/jres.067A.032
G. Burley
{"title":"Photolytic Behavior of Silver Iodide1","authors":"G. Burley","doi":"10.6028/jres.067A.032","DOIUrl":"https://doi.org/10.6028/jres.067A.032","url":null,"abstract":"Silver iodide exposed to high intensity radiation in the visible light spectrum was found to yield a powder X-ray diffraction pattern showing marked deviations from ideality. It was found possible to correlate these with a decrease in primary extinction, indicating a constant progress from an ideal to a mosaic type crystallinity. Large single crystals showed pronounced asterism in transmission Laue photographs under similar experimental conditions. Small amounts of colloidal silver were detected. A mechanism for this process in silver iodide is proposed, in general agreement with the theory of the photographic process. The primary difference from the other silver halides appears to be a considerably slower rate, permitting the observation of a two step process in detail.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85710395","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}
引用次数: 10
A Phase Study of the System: Oxalic Acid/Acetic Acid/Water; Its Significance in Oxalic Acid Crystal Growth1 草酸/乙酸/水体系的物相研究其在草酸晶体生长中的意义
Journal of research of the National Bureau of Standards. Section A, Physics and chemistry Pub Date : 1963-07-01 DOI: 10.6028/jres.067A.037
J. Strassburger, John L. Torgesen
{"title":"A Phase Study of the System: Oxalic Acid/Acetic Acid/Water; Its Significance in Oxalic Acid Crystal Growth1","authors":"J. Strassburger, John L. Torgesen","doi":"10.6028/jres.067A.037","DOIUrl":"https://doi.org/10.6028/jres.067A.037","url":null,"abstract":"The presence of limited amounts of water appears to improve the quality of anhydrous oxalic acid single crystals grown from acetic acid solutions. Water concentrations in the saturated solutions which allow crystallization of the anhydrous acid have been determined from the phase study of this ternary system. Near 50 °C the anhydrous acid crystallizes from solutions containing up to 5.2 weight percent water, while the dihydrate appears when water is in excess of this amount. The phase diagram shows a minimum content of oxalic acid in solution at a solvent composition near 83 percent acetic acid, 17 percent water. The solubility increases with increased acetic acid to the isothermal invariant point, found experimentally at a measured temperature of 50.21 °C to have the composition 20.94 percent oxalic acid, 73.89 percent acetic acid, 5.17 percent water. Decreasing solubility occurs at higher acetic acid concentrations. The maximum water content which allows crystallization of anhydrous acid increases with increasing crystallization temperature. The solubility of oxalic acid in acetic acid/water mixtures at 40° and 50 °C is reported.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79952322","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}
引用次数: 5
Wavelength Calibrations in the Far Infrared (30 to 1000 Microns) 远红外线波长校正(30至1000微米)
Journal of research of the National Bureau of Standards. Section A, Physics and chemistry Pub Date : 1963-07-01 DOI: 10.6028/jres.067A.038
K. Rao, R. V. de Vore, E. K. Plyler
{"title":"Wavelength Calibrations in the Far Infrared (30 to 1000 Microns)","authors":"K. Rao, R. V. de Vore, E. K. Plyler","doi":"10.6028/jres.067A.038","DOIUrl":"https://doi.org/10.6028/jres.067A.038","url":null,"abstract":"A discussion is presented of certain calibration procedures employed in the region 30 to 1000 microns. Calculated positions for the pure rotational absorption lines of the CO, HCN, and N2O molecules are given, and a map of the pure rotational absorption lines of the H2O molecule as recorded with a Perkin-Elmer model 301 spectrophotometer is shown.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1963-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81427236","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}
引用次数: 44
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