Pub Date : 1981-08-16DOI: 10.1107/S0108767381094464
R. Schmelczer, F. Hulliger, D. Schwarzenbach
{"title":"On the crystal chemistry of the rare-earth pnigochalcogenides LnXY","authors":"R. Schmelczer, F. Hulliger, D. Schwarzenbach","doi":"10.1107/S0108767381094464","DOIUrl":"https://doi.org/10.1107/S0108767381094464","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1981-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86480820","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 : 1981-08-16DOI: 10.1107/S0108767381095421
J. Lewis, D. Schwarzenbach
{"title":"Electron density and field gradients in a-Al2O3","authors":"J. Lewis, D. Schwarzenbach","doi":"10.1107/S0108767381095421","DOIUrl":"https://doi.org/10.1107/S0108767381095421","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1981-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87195209","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 : 1981-08-16DOI: 10.1107/S0108767381096463
F. J. Zúñiga, G. Chapuis
{"title":"Phase transitions in (CnH2n+1NH3)2ZnCl4","authors":"F. J. Zúñiga, G. Chapuis","doi":"10.1107/S0108767381096463","DOIUrl":"https://doi.org/10.1107/S0108767381096463","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"39 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"1981-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72562953","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 : 1981-07-01DOI: 10.1107/S0567739481001204
J. Lewis, D. Schwarzenbach
The magnitudes of the electric field gradients at all atomic positions in LiaN are known from NQR experiments. High-temperature NQR data indicate the gradients at Li(1) and Li(2) to be of opposite sign. In this paper, we calculate the field gradients from X-ray data and refine the parameters of the multipole deformation functions together with scale, extinction and temperature factors against X-ray and NQR data simultaneously, assuming various sign combinations for the gradients at Li(1), Li(2) and N. Despite an ill-defined scale factor of the X-ray intensities, negative signs at both Li(2) and N are obtained, and the sign at Li(1) is thus positive. The same signs are obtained from an ionic point-charge model. The extinction correction is important and dependent on the assumed signs. The model deformation map for the signs +, -, - at Li(1), Li(2) and N shows nearly spherical Li ions, whereas N appears to be strongly polarized perpendicular to c. With the assumption of the incorrect negative sign at Li(1), a strongly polarized Li(1) ion but approximately the same reliability indices for the X-ray data are obtained. Inclusion of NQR data in the charge-density refinement results in a better definition of the quadrupolar components of the deformation density close to the atomic centres.
{"title":"Electric Field Gradients and Charge Density in Lithium Nitride","authors":"J. Lewis, D. Schwarzenbach","doi":"10.1107/S0567739481001204","DOIUrl":"https://doi.org/10.1107/S0567739481001204","url":null,"abstract":"The magnitudes of the electric field gradients at all atomic positions in LiaN are known from NQR experiments. High-temperature NQR data indicate the gradients at Li(1) and Li(2) to be of opposite sign. In this paper, we calculate the field gradients from X-ray data and refine the parameters of the multipole deformation functions together with scale, extinction and temperature factors against X-ray and NQR data simultaneously, assuming various sign combinations for the gradients at Li(1), Li(2) and N. Despite an ill-defined scale factor of the X-ray intensities, negative signs at both Li(2) and N are obtained, and the sign at Li(1) is thus positive. The same signs are obtained from an ionic point-charge model. The extinction correction is important and dependent on the assumed signs. The model deformation map for the signs +, -, - at Li(1), Li(2) and N shows nearly spherical Li ions, whereas N appears to be strongly polarized perpendicular to c. With the assumption of the incorrect negative sign at Li(1), a strongly polarized Li(1) ion but approximately the same reliability indices for the X-ray data are obtained. Inclusion of NQR data in the charge-density refinement results in a better definition of the quadrupolar components of the deformation density close to the atomic centres.","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"22 1","pages":"507-510"},"PeriodicalIF":0.0,"publicationDate":"1981-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76933636","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 : 1967-12-10DOI: 10.1107/s0365110x67004347
J M Ohrt, B A Haner, D A Norton
{"title":"Crystal data (3) for some estrone-related compounds.","authors":"J M Ohrt, B A Haner, D A Norton","doi":"10.1107/s0365110x67004347","DOIUrl":"https://doi.org/10.1107/s0365110x67004347","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"23 6","pages":"1100"},"PeriodicalIF":0.0,"publicationDate":"1967-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1107/s0365110x67004347","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"16709480","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 : 1967-12-10DOI: 10.1107/s0365110x67004414
G Falkenberg, H Ringertz
{"title":"Crystallographic data of promazine and chlorpromazine.","authors":"G Falkenberg, H Ringertz","doi":"10.1107/s0365110x67004414","DOIUrl":"https://doi.org/10.1107/s0365110x67004414","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"23 6","pages":"1111"},"PeriodicalIF":0.0,"publicationDate":"1967-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1107/s0365110x67004414","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"16709481","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 : 1967-12-10DOI: 10.1107/S0365110X67004049
S. Chandrasekhar, M. Madhava
The rotatory dispersion of crystals of NaClO3 and NaBrO3 has been measured in the visible and ultraviolet region of the spectrum. Apart from a small infrared contribution, the rotatory dispersion of both crystals can be expressed as a difference of two terms. For NaClO3 the positive term has a greater strength than the negative one, whereas for NaBrO3 the reverse is the case. Thus corresponding configurations of the two crystals have opposite signs of optical rotation. The important point is brought out that calculations of optical activity in terms of atomic refractivities but neglecting rotatory dispersion, such as those carried out recently for these two crystals, arc necessarily inconclusive.
{"title":"Optical rotatory dispersion of crystals of sodium chlorate and sodium bromate","authors":"S. Chandrasekhar, M. Madhava","doi":"10.1107/S0365110X67004049","DOIUrl":"https://doi.org/10.1107/S0365110X67004049","url":null,"abstract":"The rotatory dispersion of crystals of NaClO3 and NaBrO3 has been measured in the visible and ultraviolet region of the spectrum. Apart from a small infrared contribution, the rotatory dispersion of both crystals can be expressed as a difference of two terms. For NaClO3 the positive term has a greater strength than the negative one, whereas for NaBrO3 the reverse is the case. Thus corresponding configurations of the two crystals have opposite signs of optical rotation. The important point is brought out that calculations of optical activity in terms of atomic refractivities but neglecting rotatory dispersion, such as those carried out recently for these two crystals, arc necessarily inconclusive.","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"31 1","pages":"911-913"},"PeriodicalIF":0.0,"publicationDate":"1967-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89970819","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 : 1967-12-10DOI: 10.1107/s0365110x67004232
S S Chu, G A Jeffrey
{"title":"The crystal structure of methyl beta-maltopyranoside.","authors":"S S Chu, G A Jeffrey","doi":"10.1107/s0365110x67004232","DOIUrl":"https://doi.org/10.1107/s0365110x67004232","url":null,"abstract":"","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"23 6","pages":"1038-49"},"PeriodicalIF":0.0,"publicationDate":"1967-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1107/s0365110x67004232","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"16709479","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: 10.1107/S0365110X67004268
G. Stucky, J. Folkers, T. Kistenmacher
The crystal structure of tetraethylammonium tetrachloronickelate(II) has been determined by fullmatrix least-squares refinement of three-dimensional Mo Kct intensity data. The space group is P42/nmc, with Z=2. Cell constants are a=b= 9.05, c= 15"01 A. The corresponding cobalt salt is isomorphous, with a=b=9.00, c= 14.97/~. The tetraethylammonium groups were found to be disordered about intersecting mirror planes. Qualitatively, the distortions of the anion from tetrahedral symmetry are similar to those of the CoC1 lanion in Cs3CoC15.
{"title":"The crystal and molecular structure of tetraethylammonium tetrachloronickelate(II)","authors":"G. Stucky, J. Folkers, T. Kistenmacher","doi":"10.1107/S0365110X67004268","DOIUrl":"https://doi.org/10.1107/S0365110X67004268","url":null,"abstract":"The crystal structure of tetraethylammonium tetrachloronickelate(II) has been determined by fullmatrix least-squares refinement of three-dimensional Mo Kct intensity data. The space group is P42/nmc, with Z=2. Cell constants are a=b= 9.05, c= 15\"01 A. The corresponding cobalt salt is isomorphous, with a=b=9.00, c= 14.97/~. The tetraethylammonium groups were found to be disordered about intersecting mirror planes. Qualitatively, the distortions of the anion from tetrahedral symmetry are similar to those of the CoC1 lanion in Cs3CoC15.","PeriodicalId":7001,"journal":{"name":"Acta Crystallographica","volume":"64 1","pages":"1064-1070"},"PeriodicalIF":0.0,"publicationDate":"1967-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84936014","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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