Journal de Physique et le Radium最新文献

{"title":"Experience with the Oak Ridge automatic three-circle neutron diffractometer","authors":"W. Busing, H. G. Smith, S. W. Peterson, H. A. Levy","doi":"10.1051/JPHYS:01964002505049500","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505049500","url":null,"abstract":"","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79064948","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}

{"title":"Structure magntique du manganite de fer par diffraction neutronique","authors":"A. Murasik, G. Roult","doi":"10.1051/JPHYS:01964002505052200","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505052200","url":null,"abstract":"","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89360554","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}

{"title":"On symmetrical O-H-O hydrogen bonds","authors":"R. E. Rundle","doi":"10.1051/JPHYS:01964002505048700","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505048700","url":null,"abstract":"Several hydrogen bonds with O-H-O bond lengths of about 2.4 A are now known. Some of these have been examined well enough by neutron diffraction and other means to know with reasonable certainty that they are symmetrical hydrogen bonds, with either a single or a symmetrical double distribution peak. Even neutron diffraction results remain ambiguous as to whether the distribution has a single or double maximum. Several investigators have reported crystallographically symmetrical O-H-O hydrogen bonds with distances of about 2.5 — 2.6 A. Thermal amplitudes of some of these have been given careful study, and most of these longer bonds appear to be truly, not statistically, symmetrical. It seems likely that the bonds of about 2.4 A are distributions with single maxima, while the longer, apparently symmetrical hydrogen bonds are cases of double maxima. IR and NMR evidence that there are O-H-O bonds as long as 2.6 A with single maxima should be carefully checked before they are accepted. From some theoretical calculation of hydrogen distributions in double and single wells it can be shown that cases with double maxima have a strong isotope effect with a shorter O-H-O distance than O-D-O distance, while cases with single maxima should show almost no isotope effect. With present accuracy in structure determinations a distinction between the two cases seems possible with or without the use of neutron diffraction. As an example that bond distances reliable to ~ 0.01 A are now obtainable in nearly routine fashion, the structure of 3, 4-furandicarboxylic acid was determined to about this accuracy with data obtained in ten days.","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74779178","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}

{"title":"Diffusion critique des neutrons","authors":"J. Villain","doi":"10.1051/JPHYS:01964002505061800","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505061800","url":null,"abstract":"La diffusion des neutrons par les corps magnetiques presente une intensite particulierement grande a la temperature critique a cause des fluctuations d'aimantation importantes qui se produisent alors. On montre que la section efficace critique est proportionnelle a la susceptibilite dans un champ statique sinusoidal, dont on donne des methodes de calcul approche. Lorsqu'on se rapproche des conditions critiques, la diffusion tend a devenir elastique, car la relaxation des fluctuations est freinee par des effets thermodynamiques, et aussi cinematiques dans le cas des ferromagnetiques. On etudie l'inelasticite de la diffusion critique. Les theories faites jusqu'ici reposent sur des hypotheses difficiles a justifier, et ne paraissent pas en accord avec l'experience.","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"92 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85668219","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}

{"title":"Détermination de la position des atomes d'hydrogène dans l'hydrogrinat Al2O3, 3CaO, 6H2O par résonance magnétique nucléaire et diffraction neutronique","authors":"C. Cohen-Addad, P. Ducros, A. Durif, E. F. Bertaut, A. Delapalme","doi":"10.1051/JPHYS:01964002505047800","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505047800","url":null,"abstract":"","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75398193","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}

{"title":"Localisation d'hydrogne et raffinement des positions atomiques dans KHCO3","authors":"P. Herpin, P. Mériel","doi":"10.1051/JPHYS:01964002505048400","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505048400","url":null,"abstract":"2014 The KHCO3 structure has been resolved by X-rays some years ago, with the exception of the positions of the hydrogen atoms joining two CO3 groups. A single crystal neutron diffraction study has led to precise oxygen parameter values and has allowed us to fix the hydrogen positions. Thé O-H-O bond is asymmetrical and in this structure the linking of the CO3 ions is différent from that observed in sodium bicarbonate : there are (HCO3)2 groups. LE JOURNAL DE PHYSIQUE TOME 25, MAI ’196[1, L’étude aux rayons X [1], [2], [3] ayant conduit à une structure de KHC03 différente des autres sels acides (bicarbonate de sodium, d’ammonium, -sesquicarbonate de sodium), il nous a paru intéressant de déterminer la position des atomes d’hydrogène qui lient les ions CO, par une étude au moyen de la diffraction des neutrons. En même temps, il a été possible de préciser la position des atomes d’oxygène qui, relativement au potassium, diffusent mieux les neutrons que les rayons X. Le bicarbonate de potassium cristallise dans le système monoclinique, sa maille élémentaire a pour dimensions : Elle contient quatre groupements KHC03 et le groupe de symétrie est .P21 ~a. Nous avons utilisé un faisceau de neutrons monocinétiques de longueur d’onde ~ = 1,207 A et nous avons déterminé les intensités de 98 réflexions hk0. Les cristaux étaient taillés en forme de prisme dont la plus grande dimension 10 mm était parallèle à l’axe c. Trois de ces cristaux ont été étudiés ; leurs sections étaient approximativement (1) 4 X 3 mm, (2) 2 X 2 mm et (3) 1 X 1 mm. Sur les courbes de la figure 1 on a porté, en fonction de l’intensité des réflexions mesurées sur le petit cristal (3), les intensités mesurées sur le grand cristal (1) et le cristal moyen (2). Ces courbes montrent que l’effet d’extinction, notable pour le cristal le plus grand, est petit pour le cristal moyen, il doit être négligeable pour le cristal le plus petit. Nous avons pu ainsi nous affranchir de l’extinction. Ilne projection unidimensionnelle (fig. 2) sur Fm. 1. A) Intensités mesurées avec le cristal (1) par rapport au cristal (3). B) Intensités mesurées avec le cristal (2) par rapport ru cristal (3). Frc. 2. -projection unidimensionnelle sur Faxe Ox Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphys:01964002505048400","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89063121","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}

{"title":"The hydrogen atom arrangement in ReH2-9","authors":"S. Abrahams, K. Knox","doi":"10.1051/JPHYS:01964002505046100","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505046100","url":null,"abstract":"","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86626396","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}

{"title":"Ferrimagnetic spiral configurations in cobalt chromite","authors":"N. Menyuk, K. Dwight, A. Wold","doi":"10.1051/JPHYS:01964002505052801","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505052801","url":null,"abstract":"Cobalt chromite, CoCr2O4, is a cubic spinel which is ferrimagnetic at low temperatures with a Curie point Tc ≈ 97 °K. The room temperature powder diffraction pattern on this material, corrected for temperature effects, shows that it is a normal spinel with an oxygen parameter equal to 0.38707 :f: .00005. At 4.2 °K there are, in addition to the magnetic contributions to the fundamental spinel peaks, a large number of magnetic 11 satellite \" peaks. All of the additional peaks can be indexed on the basis of the ferrimagnetic spiral model proposed for normal cubic spinels by Lyons, Kaplan, Dwight and Menyuk, in which the spiraling components of the spins are defined by a single k vector along a face diagonal. The experimental magnitude of |k| is approximately 5 % greater than theoretically predicted. The neutron diffraction pattern predicted on the basis of the spiral model is completely determined upon fixing the exchange ratio JBB/J AB and the cone axis direction. Taking JBB /J AB = 1. 5 on the basis of magnetization measurements previously reported, it is found that the intensities of the various peaks are in excellent agreement with the intensities predicted by the spiral model with the cone axis along an [001] direction. The ferrimagnetic spiral configuration is known to become unstable relative to small deviations for JBB SB /JAB S A > 0.98 (i.e. JBB/JAB > 0.98 in CoCr2O4). However, our results indicate that the true configuration closely approximates that predicted by the model over a range of exchange interaction ratios which extends well beyond the onset of local instability. Upon increasing the temperature above 4,2 °K, the satellite peaks disappeared between 25 °K and 35 °K, apparently degenerating into a broad plateau observed at 50 °K and 77 °K. Despite this disappearance, a self-consistent fit to neither the magnetic contributions to the fundamental peaks nor the observed thermal variation of the magnetization can be obtained from a collinear model. However, the predicted values based on a molecular field treatment of the spiral model are in good agreement with these measurements. These results further corroborate the validity of the spiral model for CoCr2O4, and indicate that the molecular field approximation accurately describes the axial component throughout its ferrimagnetic range, but not the azimuthal component.","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"146 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86841418","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}

{"title":"Un emploi possible de filtres d'absorption en diffraction de neutrons","authors":"M. Doménici","doi":"10.1051/JPHYS:01964002505049300","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505049300","url":null,"abstract":"A filter is described which allows the higher harmonics of a \" monochromatic \" neutron beam to be separated. ’With the aid of this filter one can obtain a very small wavelength which represents the only possibility, with certain apparatus, of exploring the high angle g . LE JOURNAL DE PHYSIQUE TOME 25, MAI 1964, Introduction. -Des filtres d’absorption ont été employés fréquemment en diffraction de neutrons surtout pour éliminer une ou plusieurs composantes d’ordre supérieur dans les études où leur effet de perturbation est particulièrement gênant (ordredésordre, structures magnétiques). Pour des longueurs d’onde principales autour de 1 A, un filtre de plutonium est employé pour éliminer l’harmonique 2. S. C. Abrahams et al. [1], dans une étude sur l’antif erromagnétisme du f er (y), ont employé un filtre de Pu pour éliminer la x J2 et un filtre de Ir pour éliminer À étant de 1,032 À. Dans notre laboratoire, un filtre de Sm, préparé avec 170 mg/cm2 de SM20, en poudre contenue Fie. 1. Section efficace du 149Sm. entre deux feuilles minces d’Al, a été employé pour évaluer exactement le montant de la contamination du second ordre. L’allure [2] de la courbe de la section efficace totale du 149Sm présentée sur la figure 1 est telle, en effet, que les neutrons de longueur d’onde plus grande que 0,9 A peuvent être absorbés tandis que les neutrons de longueur d’onde plus petite que 0,7 A peuvent être transmis. Fie. 2. Comptage sur échantillons de Fe, sans filtres Sm.O.. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphys:01964002505049300","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"80 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83848718","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}

{"title":"Neutron diffraction study on manganese telluride","authors":"N. Kunitomi, Y. Hamaguchi, S. Anzai","doi":"10.1051/JPHYS:01964002505056800","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505056800","url":null,"abstract":"Résumé. 2014 L’étude en diffraction neutronique du tellurure de manganèse, a été faite sur une poudre. L’échantillon soigneusement analysé par rayons X à haute température a été prouvé être exempt de traces de MnO et de MnTe2 qui peuvent contaminer l’échantillon. L’etude a montré que la structure magnétique de MnTe consistait en plans c, ferromagnétiques couplés antiferromagnétiquement suivant l’axe c. La direction des spins est dans le plan c. Le facteur de forme magnétique des ions Mn dans MnTe a été trouvé très proche des valeurs expérimentales déjà données par Corliss et al. La valeur la plus probable du nombre quantique de spin d’après les résultats de la diffraction est 4,6/2 et, d’après les mesures de susceptibilité magnétique 5,05/2. Ceci implique que l’ion manganèse dans MnTe a 5 électrons non appariés. Abstract. 2014 A neutron diffraction study of manganese telluride has been made using powder specimen. The specimen has been carefully checked by high temperature X-ray analysis and has been proved to be free from MnO and MnTe2 which are apt to contaminate the specimen. This investigation has shown that the magnetic structure of MnTe consists of ferromagnetic sheets in c-planes which are coupled antiferromagnetically along the c-axis. The d irection of spins lies within the ferromagnetic sheet. The magnetic form factor of Mn ions in MnTe has been found to be very close to the experimental values obtained by Corliss and others. The most probable value of the spin quantum number is obtained by neutron diffraction data as 4.6/2 and by the measurement of the magnetic susceptibility as 5.05/2. It implies that the maganese ion in MnTe has five unpai- red electrons. Résumé. 2014 Une étude de Fe7Se8 a été entreprise afin de déterminer l’ordre magnétique et les transitions de phase dans ce composé. Sur un échantillon refroidi lentement depuis 600 °C, une surstructure correspondant à la structure 3c trouvée par Okazaki [4] a été mise en évidence. Celle- ci est obtenue à de la maille de en doublant l’axe a et été : Abstract. 2014 An investigation of Fe7Se8 was undertaken to study the magnetic ordering and phase transitions in this compound. On a sample","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91198306","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}