Weak Ferromagnetism in Chiral 3-Dimensional Oxalato-Bridged Cobalt(II) Compounds. Crystal Structure of [Co(bpy)3][Co2(ox)3]ClO4

1998 ◽  
Vol 37 (16) ◽  
pp. 4131-4135 ◽  
Author(s):  
María Hernández-Molina ◽  
Francesc Lloret ◽  
Catalina Ruiz-Pérez ◽  
Miguel Julve
Keyword(s):  
Crystal Structure ◽  
Weak Ferromagnetism ◽  
3 Dimensional

Crystal structure of KBSi3O8 isostructural with danburite

1993 ◽  
Vol 57 (386) ◽  
pp. 157-164 ◽  
Author(s):  
Mitsuyoshi Kimata
Keyword(s):  
Crystal Structure ◽  
Direct Method ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
3 Dimensional ◽  
Tetrahedral Sites ◽  
Structural Types ◽  
Coupled Substitution ◽  
Insight Into

AbstractThe crystal structure of KBSi3O8 (orthorhombic, Pnam, with a = 8.683(1), b = 9.253(1), c = 8.272(1) Å,, V = 664.4(1) Å3, Z = 4) has been determined by the direct method applied to 3- dimensional rcflection data. The structure of a microcrystal with the dimensions 20 × 29 × 37 μm was refined to an unweightcd residual of R = 0.031 using 386 non-zero structure amplitudes. KBSi3O8 adopts a structure essentially different from recdmergneritc NaBSi3O8, with the low albite (NaAlSi3O8) structure, and isotypic with danburite CaB2Si2Os which has the same topology as paracelsian BaAl2Si2O8. The chenfical relationship between this sample and danburitc gives insight into a new coupled substitution; K+ + Si4+ = Ca2+ + B3+ in the extraframework and tetrahedral sites. The present occupancy refinement revealed partial disordering of B and Si atoms which jointly reside in two kinds of general equivalent points, T(1) and T(2) sites. Thus the expanded crystal-chemical formula can be written in the form K(B0.44Si0.56)2(B0.06Si0.94)2O8The systematic trend among crystalline compounds with the M+T3+T4+3O8 formula suggests that they exist in one of four structural types; the feldspar structures with T3+/T4+ ordered and/or disordered forms, and the paracelsian and the hollandite structures.

scholarly journals Preparation and Crystal Structure of a Platinum(II) Complex of [CH2N(CH2COOH)CH2CONH2]2, the Hydrolysis Product of an Anti-Tumour Bis(3,5-Dioxopiperazin-1-YL)Alkane

1994 ◽  
Vol 1 (4) ◽  
pp. 321-328 ◽  
Author(s):  
Kevin B. Nolan ◽  
Leo P. Ryan ◽  
Colm J. Campbell ◽  
Patrick McArdle ◽  
Desmond Cunningham ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrolysis Product ◽  
Molecular Structures ◽  
3 Dimensional ◽  
Crystal And Molecular Structures ◽  
Dimensional Network ◽  
Square Planar ◽  
Ligand Bond ◽  
Hydrogen Bonded

The synthesis and crystal and molecular structures of the platinum(II) complex Pt(HL)Cl where H2L is the diacid diamide –[CH2N(CH2COOH)CH2CONH2]2, a hydrolytic metabolite of an antitumour active bis(3,5-dioxopiperazin-1-yl)alkane are reported. The complex is square planar and contains HL− as a tridentate 2N (amino), O (carboxylate) donor. The metal to ligand bond distances are Pt-Cl 2.287(1) Å, Pt-O 2.002 (1) Å, Pt-Ntrans Cl 2.014(1) Å and Pt-Ntrans O 2.073 Å. There is extensive hydrogen bonding, each molecule of Pt(HL)Cl being intermolecularly hydrogen bonded to ten others giving a 3-dimensional network. There is also one intramolecular H-bond.

Correlation between Ionic Radius of Substituting Element and Magnetic Properties of Bi1-xAxFeO3-x/2 (A= Ca, Sr, Pb, Ba) Multiferroics

2009 ◽  
Vol 152-153 ◽  
pp. 131-134 ◽  
Author(s):  
V.A. Khomchenko ◽  
Michael Kopcewicz ◽  
Armandina M. Lima Lopes ◽  
Yuri G. Pogorelov ◽  
J.P. Araujo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Spin Structure ◽  
Ionic Radius ◽  
Oxygen Vacancies ◽  
Magnetic State ◽  
Weak Ferromagnetism ◽  
Host Lattice ◽  
A Site ◽  
Spiral Spin

Investigation of crystal structure and magnetic properties of the diamagnetically- substituted Bi1-xAxFeO3-x/2 (A= Ca, Sr, Pb, Ba; x= 0.2, 0.3) polycrystalline samples has been carried out. It has been shown that the heterovalent A2+ substitution result in the formation of oxygen vacancies in the host lattice. The solid solutions have been found to possess a rhombohedrally distorted perovskite structure described by the space group R3c. Magnetization measurements have shown that the magnetic state of these compounds is determined by the ionic radius of the substituting elements. A-site substitution with the biggest ionic radius ions has been found to suppress the spiral spin structure of BiFeO3 giving rise to the appearance of weak ferromagnetism.

scholarly journals Model phonon spectra of Cu7SiS5I and Ag7SiS5I crystals

2020 ◽  
Vol 23 (04) ◽  
pp. 366-371
Author(s):  
I.I. Nebola ◽  
◽  
A.F. Katanytsia ◽  
A.Ya. Shteyfan ◽  
I.M. Shkyrta ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Brillouin Zone ◽  
Vibrational Spectra ◽  
Superionic Conductors ◽  
Model Calculations ◽  
3 Dimensional ◽  
Phonon Spectra

In the concept of superspatial symmetry the crystal structure of Cu7SiS5I and Ag7SiS5I superionic conductors has been analyzed. To calculate the phonon spectra, the model of FCC superlattice (8а, 8а, 0; 8а, 0, 8а; 0, 8а, 8а) in the metric of protocrystal (а, а, 0; а, 0, а; 0, а, а) has been developed. For the developed model, the general (3+3)-dimensional basis, the array of modulation vectors and mass modulation functions have been presented. The model calculations of phonon spectra dispersion for Cu7SiS5I and Ag7SiS5I crystals in schemes with various partial occupation of crystallographic orbits by Cu(Ag) atoms have been performed. The dispersion dependences of phonon spectra for Cu7SiS5I and Ag7SiS5I crystals in the high-symmetric directions of Brillouin zone have been presented. The genesis of phonon branches of vibrational spectra has been analyzed.

A priori crystal structure analysis: layer structure

1987 ◽  
Vol 45 ◽  
pp. 472-475
Author(s):  
Raymond P. Scaringe
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Rational Design ◽  
Layer Structure ◽  
A Priori ◽  
Lattice Energy ◽  
Crystal Structure Analysis ◽  
Molecular Solids ◽  
3 Dimensional ◽  
Potential Applications

Advances in the theoretical prediction of molecular structure based on molecular mechanics and in the calculation of the lattice energy of molecular crystals with the use of atom-atom potentials have prompted us to examine the problem of a priori crystal structure analysis (i.e., the prediction of crystal structure without the use of diffraction data). A practical solution to this problem would not only represent a significant new tool for theoretical crystallography, but would also open the way to the rational design of molecular solids with engineered structural properties. Potential applications in the areas of solid-state chemistry, optics, and electronics are numerous. In this paper we will describe a complete model for predicting the structure of a 2-dimensional crystal (i.e., a layer). Although the prediction of layer structure is important as a preamble to treating the full 3-dimensional case, molecular layers are also of intrinsic interest.

Multiscale 2D Rectangular and 3D Rhombic Gratings Created by Self-Organization of Crystal Structure Defects under Constrained Cyclic Deformation and Fracture

2007 ◽  
Vol 567-568 ◽  
pp. 421-424 ◽  
Author(s):  
Yuri Gordienko ◽  
Pavel V. Kuznetsov ◽  
Elena Zasimchuk ◽  
Rimma Gontareva ◽  
Jürgen Schreiber ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Self Organization ◽  
Ordered Structures ◽  
Structure Defects ◽  
3 Dimensional ◽  
Deformation And Fracture ◽  
Self Similar ◽  
Crystal Structure Defects ◽  
Pattern Formations ◽  
Cooperative Arrangement

The substructure evolution was observed in the range of scales from dozens nanometers to millimeters on the surface of the aluminum single crystalline plates under restricted cyclic tension. The self-similar systems of crossing bands that create the grid-like ordered structures on different scales are assumed to be clear manifestation of their self-organization. The selforganization of these grid-like structures is assumed to be inevitably related to the crystal structure defects (dislocations, point-like defects and their ensembles). The model is proposed for explanation of 2-dimensional rectangular "tweed" and 3-dimensional rhombic "pullover" pattern formations which are related to cooperative arrangement of crystal structure defects.

Weak ferromagnetism in the molecular compound Cu(ta)(3-pic).cntdot.H2O(ta=terephthalato,3-pic=3-picoline). Crystal structure of Cu(ta)(3-pic)2.cntdot.0.5(3-pic).cntdot.0.5CH3OH

1992 ◽  
Vol 31 (4) ◽  
pp. 625-631 ◽  
Author(s):  
Evangelos Bakalbassis ◽  
Pierre Bergerat ◽  
Olivier Kahn ◽  
Suzanne Jeannin ◽  
Yves Jeannin ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Weak Ferromagnetism ◽  
Molecular Compound

PrBa2Cu3Ox Polycrystalline Superconductor Preparation

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3278-3283 ◽  
Author(s):  
W. L. Hults ◽  
J. C. Cooley ◽  
E. J. Peterson ◽  
J. L. Smith ◽  
Howard A. Blackstead ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Partial Pressure ◽  
High Temperatures ◽  
Sintering Temperature ◽  
Weak Ferromagnetism ◽  
Electromagnetic Properties ◽  
Oxygen Level ◽  
Partial Pressure Of Oxygen ◽  
Preparation Conditions

We prepared many samples of nominal PrBa2Cu3O x as ceramic, polycrystalline pellets with an enormous variety of preparation conditions and can confirm its superconductivity at T c = 89 K. We found that the superconductivity is in material with the YBa2Cu3O7 (YBCO) crystal structure. We observed weak ferromagnetism (canted antiferromagnetism) in samples prepared at high temperatures with a low partial pressure of oxygen; these samples also contained the phase PrBaO3 . The electromagnetic properties of the material depend sensitively on preparation conditions, especially the sintering temperature and the oxygen level.

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