Pub Date : 1964-05-01DOI: 10.1051/JPHYS:01964002505065301
S. Hautecler, W. V. Dingenen
{"title":"Diffusion des neutrons froids par les phonons dans le nickel","authors":"S. Hautecler, W. V. Dingenen","doi":"10.1051/JPHYS:01964002505065301","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505065301","url":null,"abstract":"","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75246567","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 : 1964-05-01DOI: 10.1051/JPHYS:01964002505061401
G. Felcher, W. Koehler
Des mesures par diffraction neutronique des phases ferromagnetiques et cubiques de Laves Tb Ir2 et Ho Ir2 confirment les faibles moments moleculaires deduits de mesures magnetiques. Un blocage partiel du moment orbital angulaire des atomes de terre rare est probable. L'amplitude de diffusion coherente de Ir a ete determinee. Elle est de (1,00 ± 0,02) × 10^-12 cm.
{"title":"Structure magntique des composs RIr2 Terres rares Iridium","authors":"G. Felcher, W. Koehler","doi":"10.1051/JPHYS:01964002505061401","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505061401","url":null,"abstract":"Des mesures par diffraction neutronique des phases ferromagnetiques et cubiques de Laves Tb Ir2 et Ho Ir2 confirment les faibles moments moleculaires deduits de mesures magnetiques. Un blocage partiel du moment orbital angulaire des atomes de terre rare est probable. L'amplitude de diffusion coherente de Ir a ete determinee. Elle est de (1,00 ± 0,02) × 10^-12 cm.","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81473679","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 : 1964-05-01DOI: 10.1051/JPHYS:01964002505057801
E. Legrand, M. Verschueren
aucun ordre magnétique n’a été trouvé par diffraction neutronique du moins jusqu’aux températures de l’hydrogène liquide. Des résultats préliminaires de Cs2MnCl4 sont présentés. Abstract. 2014 In the tetragonal layer structure K2NiF4, strong magnetic interactions between atoms belonging to the same plane are present, while the interaction between two layers is much weaker. Neutron diffraction work revealed an antiferromagnetic interaction in the planes, the direction of the moments being that of the c-axis. The compounds La0,5Sr1,5MnO4 and La2NiO4 have the same crystal structure. At low tempe- ratures their magnetic susceptibility also deviates from the Curie-Weiss behaviour. Nevertheless no magnetic long range order has been found with neutron diffraction, at least at temperatures down to that of liquid hydrogen. Preliminary results on Cs2MnCl4 are presented.
{"title":"L'interaction magntique dans les structures de K2NiF4","authors":"E. Legrand, M. Verschueren","doi":"10.1051/JPHYS:01964002505057801","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505057801","url":null,"abstract":"aucun ordre magnétique n’a été trouvé par diffraction neutronique du moins jusqu’aux températures de l’hydrogène liquide. Des résultats préliminaires de Cs2MnCl4 sont présentés. Abstract. 2014 In the tetragonal layer structure K2NiF4, strong magnetic interactions between atoms belonging to the same plane are present, while the interaction between two layers is much weaker. Neutron diffraction work revealed an antiferromagnetic interaction in the planes, the direction of the moments being that of the c-axis. The compounds La0,5Sr1,5MnO4 and La2NiO4 have the same crystal structure. At low tempe- ratures their magnetic susceptibility also deviates from the Curie-Weiss behaviour. Nevertheless no magnetic long range order has been found with neutron diffraction, at least at temperatures down to that of liquid hydrogen. Preliminary results on Cs2MnCl4 are presented.","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81329534","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 : 1964-05-01DOI: 10.1051/JPHYS:01964002505044700
E. Stoll, P. Fischer, W. Hälg, G. Maier
2014 The cation distribution of synthetic spinel powder of grain size ~ 50 03BC was redetermined by means of neutron diffraction experiments. The oxygen parameter found by Bacon (1952) has been confirmed, but, in contradiction to Bacon, the degree of inversion amounts to about 10 to 15 %, and depends upon the thermal history of the sample. LE JOURNAL DE PHYSIQUE TOME ‘~5, MAI 196~, Magnesium aluminium oxyde crystallizes in the space group Fd3n?. The unit cell can be described by a nearly close packed cubic oxygen arrangement with built-in cations, which are either tetrahedrally or almost octahedrally surrounded by the oxygen atoms. The lattice parameter of the unit cell amounts to 8.0832 A, and there are eight molecules per cell. The spinel structure is characterized by the fact that, relative to the center of symmetry, the cations are located at fixed positions, while the oxygen positions depend upon a parameter u. The spinel structure is called " normal " if the Mg atoms occupy the tetrahedral A-sites, only. However, on the space average, any fraction of Mg can be replaced by Al atoms. This fraction of replacement is called " degree of inversion " and denoted by i. The knowledge of the degree of inversion, and thus of the cation distribution, is of special interest in connection with possible changes of the structure due to the thermal history of the substance. Thus far, two basically different methods have been employed for the problem in question. One is to use nuclear resonance techniques, as was done by Brun and coworkers [1]. They found that synthetically produced Mg-Al spinels are considerably inverse, while naturally grown Mg-Al spinels exhibit approximately the normal spinel structure, when not annealed beyond about 800 °C. However, once annealed at temperatures higher than 800 OC, natural spinel will be inverse to a large degree. A second, and more reliable method to determine the degree of inversion, and thus the cation distribution, is provided by neutron diffraction. From the equation of the structure factor where and = iiinctions of u, i .--degree of inversion and = inn-lear scattering amplitude, it follows that L can be obtained with accuracy, since the b-values of the two cation constituents differ considerably. Bacon [2] was the first to use the above relationship in order to determine the degree of inversion in synthetic spinel powder samples. He found, in contradiction to Brun and coworkers, a nearly vanishing i-value, i. e. a normal spinel structure with at most a slight tendency towards inversion. Because of this discrepancy, it appeared desirable to repeat the neutron diffraction experiments, and to investigate the effect of annealing the sample on its structure. Since Bacon could, in 1952, perform his diffraction work with low resolution only, the aim in our experiments was to improve the resolution. The investigations were performed with the 20 MW reactor " Diorit " of the Swiss Federal Institute for Reactor Research. Syn
2014利用中子衍射实验重新测定了~ 50 03BC型合成尖晶石粉末的阳离子分布。由Bacon(1952)发现的氧参数已被证实，但与Bacon相反，反演的程度约为10%至15%，并取决于样品的热历史。[j] .物理学报[j] . 5， [m] . 1996，镁铝在空间群中结晶。单晶胞可以用一个几乎紧密排列的立方氧排列来描述，其中含有内嵌的阳离子，它们被氧原子以四面体或几乎八面体的形式包围。单元胞的晶格参数为8.0832 A，每个胞有8个分子。尖晶石结构的特点是，相对于对称中心，阳离子位于固定位置，而氧的位置取决于参数u。只有Mg原子占据四面体a位时，尖晶石结构才被称为“正常”结构。然而，在空间平均上，Mg的任何部分都可以被Al原子取代。这个取代的分数被称为“反转度”，用i表示。反转度的知识，以及阳离子分布的知识，与由于物质的热历史而可能发生的结构变化有关，是特别有趣的。到目前为止，对于所讨论的问题已经采用了两种基本不同的方法。一种是使用核共振技术，如Brun及其同事[1]所做的那样。他们发现，人工合成的Mg-Al尖晶石是相当相反的，而自然生长的Mg-Al尖晶石在不超过800°C退火时，表现出近似正常的尖晶石结构。然而，一旦在高于800℃的温度下退火，天然尖晶石将在很大程度上反转。第二种更可靠的方法是用中子衍射来确定反转的程度，从而确定阳离子的分布。由结构因子式(和= u, i -反演度和= in -lear散射振幅)可知，由于两种阳离子组分的b值相差较大，可以较准确地求出L。Bacon[2]首先利用上述关系来确定合成尖晶石粉末样品中的反转程度。他发现，与布朗和他的同事相反，一个几乎消失的i值，即一个正常的尖晶石结构，最多有轻微的反转趋势。由于这种差异，有必要重复中子衍射实验，并研究退火对样品结构的影响。由于培根在1952年只能在低分辨率下进行衍射工作，所以我们实验的目的是提高分辨率。调查是在瑞士联邦反应堆研究所的20兆瓦“Diorit”反应堆上进行的。采用人工合成和化学计量尖晶石粉末(# 50 tl)，采用AI(ill)和Al(311)反射对中子束进行单色化。图1和图2表示观察到的衍射强度的角度分布。通过比较可以看出，与Al(111)相比，Al(311)单色器产生了更好的分辨率，特别是在高角度下，这与Caglioti的[3]理论很好地吻合。我们的图的评价证实了培根发现的氧参数:u = 0,387 -~0,001。然而，我们的尖晶石样品不能用正常的尖晶石结构来描述。如果假设反转程度大致在10%到15%之间，实验观察到的强度与计算得到的强度最吻合。此外，还发现该值在一定程度上取决于样品的热处理。为了获得关于这种影响的更详细的信息，对同一样品进行了两次退火程序:在第一次实验中，文章发表在EDP科学网站上，并可在http://dx.doi.org/10.1051/jphys:01964002505044700上获得
{"title":"Redetermination of the cation distribution of spinel (MgAl2O4) by means of neutron diffraction","authors":"E. Stoll, P. Fischer, W. Hälg, G. Maier","doi":"10.1051/JPHYS:01964002505044700","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505044700","url":null,"abstract":"2014 The cation distribution of synthetic spinel powder of grain size ~ 50 03BC was redetermined by means of neutron diffraction experiments. The oxygen parameter found by Bacon (1952) has been confirmed, but, in contradiction to Bacon, the degree of inversion amounts to about 10 to 15 %, and depends upon the thermal history of the sample. LE JOURNAL DE PHYSIQUE TOME ‘~5, MAI 196~, Magnesium aluminium oxyde crystallizes in the space group Fd3n?. The unit cell can be described by a nearly close packed cubic oxygen arrangement with built-in cations, which are either tetrahedrally or almost octahedrally surrounded by the oxygen atoms. The lattice parameter of the unit cell amounts to 8.0832 A, and there are eight molecules per cell. The spinel structure is characterized by the fact that, relative to the center of symmetry, the cations are located at fixed positions, while the oxygen positions depend upon a parameter u. The spinel structure is called \" normal \" if the Mg atoms occupy the tetrahedral A-sites, only. However, on the space average, any fraction of Mg can be replaced by Al atoms. This fraction of replacement is called \" degree of inversion \" and denoted by i. The knowledge of the degree of inversion, and thus of the cation distribution, is of special interest in connection with possible changes of the structure due to the thermal history of the substance. Thus far, two basically different methods have been employed for the problem in question. One is to use nuclear resonance techniques, as was done by Brun and coworkers [1]. They found that synthetically produced Mg-Al spinels are considerably inverse, while naturally grown Mg-Al spinels exhibit approximately the normal spinel structure, when not annealed beyond about 800 °C. However, once annealed at temperatures higher than 800 OC, natural spinel will be inverse to a large degree. A second, and more reliable method to determine the degree of inversion, and thus the cation distribution, is provided by neutron diffraction. From the equation of the structure factor where and = iiinctions of u, i .--degree of inversion and = inn-lear scattering amplitude, it follows that L can be obtained with accuracy, since the b-values of the two cation constituents differ considerably. Bacon [2] was the first to use the above relationship in order to determine the degree of inversion in synthetic spinel powder samples. He found, in contradiction to Brun and coworkers, a nearly vanishing i-value, i. e. a normal spinel structure with at most a slight tendency towards inversion. Because of this discrepancy, it appeared desirable to repeat the neutron diffraction experiments, and to investigate the effect of annealing the sample on its structure. Since Bacon could, in 1952, perform his diffraction work with low resolution only, the aim in our experiments was to improve the resolution. The investigations were performed with the 20 MW reactor \" Diorit \" of the Swiss Federal Institute for Reactor Research. Syn","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88704660","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 : 1964-05-01DOI: 10.1051/JPHYS:01964002505045100
S. W. Peterson, V. Sadana, W. L. Korst
Neutron diffraction studies have been carried out on powder samples of NiZrH3 and NiZrD3. The x-ray space group and heavy atom positions are confirmed. Hydrogen atoms are located in 4 fold and 8 fold positions of the orthorhombic space group Cmcm. The 8 fold hydrogen atoms have three Zr and one Ni close neighbor while the 4 fold hydrogen atoms have an approximate five-fold coordination.
{"title":"Neutron diffraction study of nickel zirconium hydride","authors":"S. W. Peterson, V. Sadana, W. L. Korst","doi":"10.1051/JPHYS:01964002505045100","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505045100","url":null,"abstract":"Neutron diffraction studies have been carried out on powder samples of NiZrH3 and NiZrD3. The x-ray space group and heavy atom positions are confirmed. Hydrogen atoms are located in 4 fold and 8 fold positions of the orthorhombic space group Cmcm. The 8 fold hydrogen atoms have three Zr and one Ni close neighbor while the 4 fold hydrogen atoms have an approximate five-fold coordination.","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91145686","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 : 1964-05-01DOI: 10.1051/JPHYS:01964002505054500
E. F. Bertaut, A. Delapalme, G. Bassi
2014 In orthorhombic 03B2-FeNaO2, (a0 = 5.672 ; b0 = 7.136 ; c0 = 5.377 Å ; group Pna) each Fe atom has four near Fe neighbors with antiparallel spins. The axis of antiferromagnetism is Oz. A weak ferromagnetic component is associated along Oy. Structure refinement confirms the tetrahedral coordination of Na, proposed by Bertaut and Blum. LE JOURNAL DE PHYSIQUE TOME :2 5, MAI 1 196~, Introduetion. Le ferrite de sodium FeNa02 existe sous tpois formes. La structure [1] de cx:-FeNa02 est rhomboédrique (a = 5,59 A ; oc = 31°20’) appartient au groupe centrosymétrique .R 3 m (-D’3d) et possède des octaèdres de coordination autour des cations Fe3 v et N a + . La structure [2] de composé découvert par Dodero et Desportes [3] est orthorhombique (a = 5,672 A ; b = 7,136 A ; c = 5,377 A ; Dx = 3,36), pseudo-quadratique (a c), appartient au groupe non centré pna (C’,) et possède des tétraèdres de coordination autour des deux sortes de cations. Enfin une troisième variété, quadratique, y-FeNa02 très proche de g-FeNa02 a été signalée assez récemment [4]. La forme oc, stable à l’ambiante, se transforme en forme B vers 600 °C. La transition p y se situe vers 1 103 °C. La transformation est remarquable par sa considérable expansion de volume moléculaire lequel augmente de V = 42,2 Â3 à V = 54,4 A3, soit de 29 %. L’explication de l’expansion réside en ce que dans la forme oc les octaèdres de coordination ont des arêtes communes tandis que dans la forme ~ les tétraèdres de coordination n’ont que des sommets communs. Dans cette étude nous déterminons d’abord la configuration magnétique des spins dans Nous précisons ensuite les paramètres de position provisoires donnés dans la référence [2]. Un tel raffinement nous a paru d’ailleurs d’autant plus nécessaire qu’une coordination tétraédrique autour d’un cation Na+ est exceptionnelle et demande
2014在orthorhombic 03B2-FeNaO2， (a0 = 5.672;b0 = 7.136;c0 =洛美Å;= =地理= =根据美国人口普查，这个县的面积为。is The axis of antiferromagnetism奥兹。A . ferromagnetic元件is associated long Oy。结构细化证实了Bertaut和Blum提出的Na的四面体配位。《物理学报》卷:2、5、196~，介绍。FeNa02钠铁氧体以两种形式存在。cx:-FeNa02的[1]结构为菱形(a = 5.59 a;oc = 31°20 ')属于中心对称群。r3m (- d ' 3d)，在fe3v和na +阳离子周围有配位八面体。Dodero和Desportes[3]发现的化合物结构[2]是正hombic (a = 5,672 a;b = 7,136 A;c = 5.377 A;伪二次型(a c) Dx = 3.36，属于非中心群pna (c '，)，在两种阳离子周围都有配位四面体。最后，第三种二次型y-FeNa02与g-FeNa02非常接近，最近[4]被报道。形式oc在环境中稳定，在600°C左右转变为形式B。p - y转变在1103°C左右。这种转变是显著的，因为它的分子体积膨胀相当大，从V = 42.2 A3增加到V = 54.4 A3，即29%。膨胀的解释是，在oc形中，配位八面体有共同的边，而在~形中，配位四面体只有共同的顶点。在本研究中，我们首先确定自旋的磁配置，然后指定参考[2]中给出的临时位置参数。在我们看来，这种改进似乎是必要的，因为围绕Na+阳离子的四面体协调是例外的，需要
{"title":"Structure magntique de -FeNao2 et affinement des positions atomiques","authors":"E. F. Bertaut, A. Delapalme, G. Bassi","doi":"10.1051/JPHYS:01964002505054500","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505054500","url":null,"abstract":"2014 In orthorhombic 03B2-FeNaO2, (a0 = 5.672 ; b0 = 7.136 ; c0 = 5.377 Å ; group Pna) each Fe atom has four near Fe neighbors with antiparallel spins. The axis of antiferromagnetism is Oz. A weak ferromagnetic component is associated along Oy. Structure refinement confirms the tetrahedral coordination of Na, proposed by Bertaut and Blum. LE JOURNAL DE PHYSIQUE TOME :2 5, MAI 1 196~, Introduetion. Le ferrite de sodium FeNa02 existe sous tpois formes. La structure [1] de cx:-FeNa02 est rhomboédrique (a = 5,59 A ; oc = 31°20’) appartient au groupe centrosymétrique .R 3 m (-D’3d) et possède des octaèdres de coordination autour des cations Fe3 v et N a + . La structure [2] de composé découvert par Dodero et Desportes [3] est orthorhombique (a = 5,672 A ; b = 7,136 A ; c = 5,377 A ; Dx = 3,36), pseudo-quadratique (a c), appartient au groupe non centré pna (C’,) et possède des tétraèdres de coordination autour des deux sortes de cations. Enfin une troisième variété, quadratique, y-FeNa02 très proche de g-FeNa02 a été signalée assez récemment [4]. La forme oc, stable à l’ambiante, se transforme en forme B vers 600 °C. La transition p y se situe vers 1 103 °C. La transformation est remarquable par sa considérable expansion de volume moléculaire lequel augmente de V = 42,2 Â3 à V = 54,4 A3, soit de 29 %. L’explication de l’expansion réside en ce que dans la forme oc les octaèdres de coordination ont des arêtes communes tandis que dans la forme ~ les tétraèdres de coordination n’ont que des sommets communs. Dans cette étude nous déterminons d’abord la configuration magnétique des spins dans Nous précisons ensuite les paramètres de position provisoires donnés dans la référence [2]. Un tel raffinement nous a paru d’ailleurs d’autant plus nécessaire qu’une coordination tétraédrique autour d’un cation Na+ est exceptionnelle et demande","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74586871","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 : 1964-05-01DOI: 10.1051/JPHYS:01964002505049700
G. Brown, H. A. Levy
{"title":"Problems and procedures in collection of three-dimensional neutron diffraction data for crystal structure determination","authors":"G. Brown, H. A. Levy","doi":"10.1051/JPHYS:01964002505049700","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505049700","url":null,"abstract":"","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"137 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75847497","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 : 1964-05-01DOI: 10.1051/JPHYS:01964002505043100
B. Willis
Single crystals have been examined by neutron diffraction in the range of temperatures 20 °C to 1 100 °C and of compositions UO2 to U4O9. The investigations divide into three groups, relating to UO2, UO2+x (where 0 (for O') and along (for O") from the large interstices in the fluorite structure. The interstices themselves are not occupied. At the composition UO 2.25 the oxygen atoms are ordered to form the new phase U4O9. The " main " neutron reflexions of U4O9, corresponding to the fluorite-type peaks of UO2, are much stronger than the superlattice reflexions, which arise from the ordering of the interstitial oxygen atoms within the fluorite framework. The analysis of the intensities of the main reflexions shows that there are two kinds of interstitial sites, as in UO2+x : the 0' atoms are located 0.85 A along the directions from the centres of the large interstices, and the O" atoms 1.05 A along . Vacancies occur in the fluorite-type oxygen sites (0) but not in the uranium sites, and the chemical formula UO2.25 is expressed more fully as U1.00 O1.77 O'0.29 O"0.19. It is concluded that oxygen atoms cannot enter the fluorite structure individually but are incorporated in small groups containing O' and O" atoms and O vacancies. A complete structure determination of U4O9 must await the analysis of the superlattice reflexions.
{"title":"Structures of UO2, UO2+x andU4O9 by neutron diffraction","authors":"B. Willis","doi":"10.1051/JPHYS:01964002505043100","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505043100","url":null,"abstract":"Single crystals have been examined by neutron diffraction in the range of temperatures 20 °C to 1 100 °C and of compositions UO2 to U4O9. The investigations divide into three groups, relating to UO2, UO2+x (where 0 (for O') and along (for O\") from the large interstices in the fluorite structure. The interstices themselves are not occupied. At the composition UO 2.25 the oxygen atoms are ordered to form the new phase U4O9. The \" main \" neutron reflexions of U4O9, corresponding to the fluorite-type peaks of UO2, are much stronger than the superlattice reflexions, which arise from the ordering of the interstitial oxygen atoms within the fluorite framework. The analysis of the intensities of the main reflexions shows that there are two kinds of interstitial sites, as in UO2+x : the 0' atoms are located 0.85 A along the directions from the centres of the large interstices, and the O\" atoms 1.05 A along . Vacancies occur in the fluorite-type oxygen sites (0) but not in the uranium sites, and the chemical formula UO2.25 is expressed more fully as U1.00 O1.77 O'0.29 O\"0.19. It is concluded that oxygen atoms cannot enter the fluorite structure individually but are incorporated in small groups containing O' and O\" atoms and O vacancies. A complete structure determination of U4O9 must await the analysis of the superlattice reflexions.","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"181 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88443234","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 : 1964-05-01DOI: 10.1051/JPHYS:01964002505059600
M. Collins, G. Low
Measurements of the magnetic disorder scattering of neutrons from dilute ferromagnetic alloys allow the spatial distribution of the magnetic moment disturbance around the solute atoms to be investigated. Results are presented for dilute polycrystalline iron based alloys showing the magnetic moment distribution around manganese, chromium and vanadium atoms. The scattering from manganese impurities indicates that their presence has no appreciable effect on the moment of nearby iron atoms. In the case of chromium and vanadium impurities, the data can only be interpreted in terms of a small increase of moment on iron atoms which are roughly 4 A distant from solute atoms. There appears to be a negative moment on the impurity atoms themselves.
{"title":"Neutron diffraction studies of magnetic moments in dilute transition metal alloys","authors":"M. Collins, G. Low","doi":"10.1051/JPHYS:01964002505059600","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505059600","url":null,"abstract":"Measurements of the magnetic disorder scattering of neutrons from dilute ferromagnetic alloys allow the spatial distribution of the magnetic moment disturbance around the solute atoms to be investigated. Results are presented for dilute polycrystalline iron based alloys showing the magnetic moment distribution around manganese, chromium and vanadium atoms. The scattering from manganese impurities indicates that their presence has no appreciable effect on the moment of nearby iron atoms. In the case of chromium and vanadium impurities, the data can only be interpreted in terms of a small increase of moment on iron atoms which are roughly 4 A distant from solute atoms. There appears to be a negative moment on the impurity atoms themselves.","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83141115","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 : 1964-05-01DOI: 10.1051/JPHYS:01964002505056500
S. Pickart, H. Alperin, R. Nathans
2014 Spin orderings of the binary fluorides with chemical formula XMnF3 (X = Na, Rb, Cs, and NH4) were investigated by neutron diffraction. The antiferromagnetic lattices of the compounds with X = Na, Rb, and NH4 are found to be of the same basic type as found in KMnF3 (G-type). In CsMnF3, which is hexagonal, the Mn2+ layers are arranged in an antiparallel sequence along the c-axis, with the spin direction normal to the axis. LE JOURNAL DE PHYSIQUE TOME 25, MAI 196fit, Introduction. Binary fluorides of the type XMnF (X = Na, Rb, Cs, and NH4), which were investigated previously by means of x-ray [1, 2], electron spin resonance [3, 4] specific heat [5], and magnetization [6, 7] measurements, have been reported to be antiferromagnetic. The present study reports powder neutron diffraction measurements on these compounds undertaken to confirm the antiferromagnetism and to study details of the magnetic ordering. Some information was also obtained concerning the nuclear structures. Experimental. The measurements were taken on powdered samples, which were kindly furnished by M. Shafer. Temperatures intermediate between 4.2 oK and 77 oK were attained by heating the sample holder, which was insulated from the liquid helium bath by thin teflon sheets, or by pumping on liquid nitrogen. In this way the sample could be held at any desired temperature, which was measured by a carbon resistance thermometer in contact with the sample holder. For small temperature changes, the sample came into equilibrium after about one-half hour. Structure information. All of the compounds can be considered as based on perovskite. RbMnF3 and NH4MnF3 are cubic (tolerance ratios 1.00 and 0.97, respectively), while NaMnF3 and CSNInF have tolerance ratios outside the cubic range. The Na compound is orthorhombic [1] and has a pseudomonoclinic cell derived from a (1) Work performed under the auspices of the U. S. Atomic Energy Commission. slight distortion of the cubic cell ; the Cs compound is hexagonal [2], with the ABCABC stacking of the cubic phase altered to ABCACB, in analogy with the hexagonal form of BaTio3’ In the case of RbMnF3 we observe only cubic perovskite reflections, as expected. However, if the tabulated nuclear scattering amplitudes ~ bRb = bF = 0.55) are used, there is a small discrepancy between weak reflections which can be removed only by making bRb > bF. Indications are that bxb should be increased to about 0. 63. The hydrogen positions in NH4IVInF3 should be obtainable from the neutron data. Good agreement ~~ == 0 .044) was obtained by distributing the hydrogen statistically in the twelvefold position 12(1) of Pm3m, i.e., along the direction toward the neighboring F ions. The N-H distance is 1.14 ~., which is slightly larger than that found [8] in NH4Cl and ND4Cl. The nuclear scattering from the CsMnF3 was examined to see if any change in the fluorine parameters might be required. Using the x-ray parameters determined by Zalkin et al. [2], we obtained an R
{"title":"Magnetic structure of binary fluorides containing Mn2","authors":"S. Pickart, H. Alperin, R. Nathans","doi":"10.1051/JPHYS:01964002505056500","DOIUrl":"https://doi.org/10.1051/JPHYS:01964002505056500","url":null,"abstract":"2014 Spin orderings of the binary fluorides with chemical formula XMnF3 (X = Na, Rb, Cs, and NH4) were investigated by neutron diffraction. The antiferromagnetic lattices of the compounds with X = Na, Rb, and NH4 are found to be of the same basic type as found in KMnF3 (G-type). In CsMnF3, which is hexagonal, the Mn2+ layers are arranged in an antiparallel sequence along the c-axis, with the spin direction normal to the axis. LE JOURNAL DE PHYSIQUE TOME 25, MAI 196fit, Introduction. Binary fluorides of the type XMnF (X = Na, Rb, Cs, and NH4), which were investigated previously by means of x-ray [1, 2], electron spin resonance [3, 4] specific heat [5], and magnetization [6, 7] measurements, have been reported to be antiferromagnetic. The present study reports powder neutron diffraction measurements on these compounds undertaken to confirm the antiferromagnetism and to study details of the magnetic ordering. Some information was also obtained concerning the nuclear structures. Experimental. The measurements were taken on powdered samples, which were kindly furnished by M. Shafer. Temperatures intermediate between 4.2 oK and 77 oK were attained by heating the sample holder, which was insulated from the liquid helium bath by thin teflon sheets, or by pumping on liquid nitrogen. In this way the sample could be held at any desired temperature, which was measured by a carbon resistance thermometer in contact with the sample holder. For small temperature changes, the sample came into equilibrium after about one-half hour. Structure information. All of the compounds can be considered as based on perovskite. RbMnF3 and NH4MnF3 are cubic (tolerance ratios 1.00 and 0.97, respectively), while NaMnF3 and CSNInF have tolerance ratios outside the cubic range. The Na compound is orthorhombic [1] and has a pseudomonoclinic cell derived from a (1) Work performed under the auspices of the U. S. Atomic Energy Commission. slight distortion of the cubic cell ; the Cs compound is hexagonal [2], with the ABCABC stacking of the cubic phase altered to ABCACB, in analogy with the hexagonal form of BaTio3’ In the case of RbMnF3 we observe only cubic perovskite reflections, as expected. However, if the tabulated nuclear scattering amplitudes ~ bRb = bF = 0.55) are used, there is a small discrepancy between weak reflections which can be removed only by making bRb > bF. Indications are that bxb should be increased to about 0. 63. The hydrogen positions in NH4IVInF3 should be obtainable from the neutron data. Good agreement ~~ == 0 .044) was obtained by distributing the hydrogen statistically in the twelvefold position 12(1) of Pm3m, i.e., along the direction toward the neighboring F ions. The N-H distance is 1.14 ~., which is slightly larger than that found [8] in NH4Cl and ND4Cl. The nuclear scattering from the CsMnF3 was examined to see if any change in the fluorine parameters might be required. Using the x-ray parameters determined by Zalkin et al. [2], we obtained an R","PeriodicalId":54899,"journal":{"name":"Journal de Physique et le Radium","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1964-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88971490","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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