Mocvd of Polycrystalline and Epitaxial Complex Oxides by Liquid Delivery

1997 ◽  
Vol 474 ◽  
Author(s):  
J. F. Roeder ◽  
S. M. Bilodeau ◽  
R. J. Carl ◽  
T. H. Baum ◽  
P. C. Van Buskirk ◽  
...  
Keyword(s):  
Single Crystal ◽  
Current Density ◽  
Complex Oxides ◽  
The Other ◽  
Charge Storage ◽  
Growth Mechanisms ◽  
X Ray ◽  
Unique Approach ◽  
Bst Films ◽  
Liquid Delivery

ABSTRACTA unique approach to MOCVD of complex oxides enables deposition of a number of materials of technological importance through the use of liquid delivery of metalorganic precursors. Methodologies for control of composition and exploration of. process space are compared for two film systems, one in a relatively mature state of development ((Ba,Sr)Ti03), the other in an early state of development (Ni-ferrite). In both cases, composition was controlled by mixing metalorganic precursors dissolved in solvents using a liquid delivery system. Films with excellent crystalline quality were deposited in both cases. Polycrystalline BST films displayed properties suitable for DRAM applications: charge storage densities > 80 fF/μm2 and leakage current density < 10−8 A/cm2 for films as thin as 15 nm. Growth mechanisms and rates were determined for the single component oxides of the ferrite films. Epitaxial NiFe204 films were deposited on MgO single crystal substrates at 650°C; x-ray rocking curves yielded FWHM values of 0.046°, commensurate with the substrate.

Molecular tapes in the structure of isoguaninium chloride

2017 ◽  
Vol 74 (1) ◽  
pp. 108-112 ◽  
Author(s):  
Urszula Anna Budniak ◽  
Paulina Maria Dominiak
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Charge Density ◽  
Interaction Energy ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Structure

Isoguanine, an analogue of guanine, is of intrinsic interest as a noncanonical nucleobase. The crystal structure of isoguaninium chloride (systematic name: 6-amino-2-oxo-1H,7H-purin-3-ium chloride), C5H6N5O+·Cl−, has been determined by single-crystal X-ray diffraction. Structure analysis was supported by electrostatic interaction energy (E es) calculations based on charge density reconstructed with the UBDB databank. In the structure, two kinds of molecular tapes are observed, one parallel to (010) and the other parallel to (50\overline{4}). The tapes are formed by dimers of isoguaninium cations interacting with chloride anions. E es analysis indicates that cations in one kind of tape are oriented so as to minimize repulsive electrostatic interactions.

Crystal Structure of Calcium Picrate Pentahydrate: A New Eight-Coordinate Stereochemistry for [M(bidentate)2(unidentate)4]

1979 ◽  
Vol 32 (2) ◽  
pp. 301 ◽  
Author(s):  
V Diakiw ◽  
TW Hambley ◽  
DL Kepert ◽  
CL Raston ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Single Crystal ◽  
Title Compound ◽  
Lattice Site ◽  
The Other ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Triangular Face ◽  
X Ray

The crystal structure of the title compound, Ca(C6H2N307)2,5H2O, has been determined by single-crystal X-ray diffraction at 295(1) K and refined by least squares to a residual of 0.049 for 1513 'observed' reflections. Crystals are orthorhombic, Pmab, a 24.169(6), b l0.292(7), c 8.554(2) �, Z 4. The stereochemistry about the calcium has not been observed previously for the system [M(bidentate)2- (unidentate)4]; in the present structure, the calcium is coordinated by a pair of bidentate picrate ligands and the four water molecules in an array in which three of the water molecules occupy a triangular face of a square antiprism, the overall array having m symmetry. The remaining water molecule occupies a lattice site with no close interaction with the other species.

Synthesis and Structure of and Cation Distribution in the Zirconium Cluster Rb[(Zr6C)Cl15]

2008 ◽  
Vol 63 (5) ◽  
pp. 507-512 ◽  
Author(s):  
Henning W. Rohm ◽  
Martin Köckerling
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Cation Distribution ◽  
Type Structure ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coulombic Interactions ◽  
Cluster Network ◽  
Zirconium Cluster

Rb[(Zr6C)Cl15] was prepared by heating ZrCl4, Zr powder, RbCl and Al4C3 at 850 °C for 21 days. The crystal structure was determined by single crystal X-ray diffraction (space group Pmma, a = 18.484(3), b = 18.962(2), c = 9.708(1) Å, V = 2505.4(6) Å3, and Z = 4). Rb[(Zr6C)Cl15] crystallises in the Cs[Nb6Cl15]-type structure. It is built up from two interconnected types of cluster chains, one with linear Zr−Cla−a-Zr bridges, the other one with bent bridges. The rubidium cations are spread over three different sites within the cluster network which differs significantly from the cation distribution in the comparable potassium and caesium phases. The cation distribution can be rationalised considering the size of the cavities and the Coulombic interactions.

Conformational Comparisons Between Phenoxyacetic Acid Derivatives in Adducts and in the Free Form

1999 ◽  
Vol 52 (7) ◽  
pp. 695 ◽  
Author(s):  
Graham Smith ◽  
Catherine J. Cooper ◽  
Veena Chauhan ◽  
Daniel E. Lynch ◽  
Simon Parsons ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Single Crystal ◽  
Free Acid ◽  
Molecular Complexes ◽  
The Other ◽  
Free Form ◽  
Phenoxyacetic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dichlorophenoxy Acetic Acid

Six molecular complexes containing the herbicidally active (2,4-dichlorophenoxy)acetic acid (2,4-d) and (2,4,5-trichlorophenoxy)acetic acid (2,4,5-t) have been prepared and studied by using single-crystal X-ray diffraction techniques. These adduct structures are 2,4-d with 4,4′-dipyridine (2 : 1 complex), and 2,4,5-t with respectively 5-nitroquinoline (1 : 1), 4,4′-dipyridine (2 : 1), 2-amino-2-thiazoline (1 : 1), 2-aminobenzothiazole (1 : 1) and 2-amino-5-ethyl-1,3,4-thiadiazole (1 : 1). The conformations of the phenoxyacetic acid molecules were found to be either synclinal (in three cases) or antiperiplanar (in the other three cases). A general review is also made about the conformational aspects of previously reported adducts of phenoxyacetic acid derivatives and how they compare to their free acid structures.

Structure and Stereochemistry of Adducts of Tris(dipivaloylmethanato)europium(III), Eu(dpm)3, with Some Dipolar Aprotic Unidentate O-Donors

2020 ◽  
Vol 73 (6) ◽  
pp. 455
Author(s):  
Eric J. Chan ◽  
Jack M. Harrowfield ◽  
Brian W. Skelton ◽  
Alexandre N. Sobolev ◽  
Allan H. White
Keyword(s):  
Single Crystal ◽  
Dimethyl Sulfoxide ◽  
The Other ◽  
Asymmetric Unit ◽  
X Ray ◽  
Metal Atoms ◽  
Oxygen Donor ◽  
Trigonal Prismatic

Single crystal X-ray structural characterisations are reported for adducts of the form [(L-O)Eu(O,O′-dpm)3] obtained by the crystallisation of tris(dipivaloylmethanato)europium(iii) (dpm=[HC(C(tBu).CO)2]−) from an array of dipolar aprotic oxygen-donor solvents L (L=N-methylpyrrolidinone (nmp), trimethylphosphate, (MeO)3PO, (tmp), hexamethylphosphoramide (hmpa), dimethylacetamide (dma), dimethyl sulfoxide (dmso), and the bidentate octamethylpyrophosphoramide (ompa). In all adducts, the resulting arrays contain seven-coordinate metal atoms, which adopt two different isomeric forms of the mono-capped trigonal prismatic stereochemistry, the L=dma and dmso adducts corresponding to one type, nmp and tmp the other. The adduct formed with ompa behaves as a pair of discrete metal environments bridged by the O-ompa-O′ ligand, thus; [(dpm-O,O′)3Eu(O-ompa-O′)Eu(O,O′-dpm)3], and is found in two forms, one in which both Eu environments is of the tmp type, the other of the dmso/dma type. In the hmpa adduct, the asymmetric unit of the structure is a disordered composite of both types. In none of the adducts is there any further solvation beyond coordination of a single L.

scholarly journals Diffuse scattering from the lead-based relaxor ferroelectric PbMg1/3Ta2/3O3

2011 ◽  
Vol 44 (3) ◽  
pp. 603-609 ◽  
Author(s):  
Antonio Cervellino ◽  
S. N. Gvasaliya ◽  
O. Zaharko ◽  
B. Roessli ◽  
G. M. Rotaru ◽  
...  
Keyword(s):  
Single Crystal ◽  
Atomic Structure ◽  
Diffuse Scattering ◽  
Relaxor Ferroelectric ◽  
The Other ◽  
X Ray Diffraction ◽  
Correlation Lengths ◽  
X Ray ◽  
Displacement Vectors ◽  
Polar Nanoregions

The relaxor ferroelectric PbMg1/3Ta2/3O3was studied by single-crystal neutron and synchrotron X-ray diffraction, and its detailed atomic structure modelled in terms of static Pb displacements that lead to the formation of polar nanoregions. Similar to the other members of the Pb-based relaxor family like PbMg1/3Nb2/3O3or PbZn1/3Nb2/3O3the diffuse scattering in the [H00]/[0K0] scattering plane has a butterfly shape around theh00 Bragg reflections and is orthogonal to the scattering vector forhh0 peaks. In the [HH0]/[00L] plane the diffuse scattering is elongated along the 〈112〉 directions and is orthogonal to the scattering vector forhhhreflections. It is found that a model consisting of correlated Pb displacements along the 〈111〉 directions reproduces adequately the main features of the diffuse scattering in PbMg1/3Ta2/3O3when the correlation lengths between the Pb-ion displacement vectors are longest along the 〈111〉 and shortest along the 〈11{\overline 2}〉 and 〈1{\overline 1}0〉 directions.

One-dimensional ribbons of solvated Ag sulfonates

1999 ◽  
Vol 77 (3) ◽  
pp. 313-318 ◽  
Author(s):  
George KH Shimizu ◽  
Gary D Enright ◽  
Gabriela S Rego ◽  
John A Ripmeester
Keyword(s):  
Coordination Polymer ◽  
Single Crystal ◽  
The Other ◽  
Monoclinic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
One Dimensional ◽  
X Ray ◽  
Structure Determinations

Single crystal X-ray structure determinations of two solvated silver sulfonates have been obtained and these compounds have been shown to adopt infinite one-dimensional motifs. {AgOTs(MeCN)}[Formula: see text] (OTs = p-toluenesulfonate) crystallizes in the monoclinic space group, P21, a = 8.4278(5) Å, b = 5.7413(3) Å, c = 12.1057(7) Å, β = 109.24(1)°. {Ag(NDSA)(MeCN)2(H3O)(H2O)2}[Formula: see text] (NDSA = 1,5-naphthalenedisulfonate) crystallizes in the triclinic space group, P[Formula: see text], a = 8.3407(4) Å, b = 10.4374(5) Å, c = 12.3399(6) Å, α = 101.941(8)°, β = 109.24(1)°, γ = 102.190(8)°. Despite one compound containing a monosulfonate and the other a disulfonate, both complexes form infinite one-dimensional arrays.Key words: silver, sulfonates, coordination polymer.

Structure of caesium disulfate at 120 and 273 K

2009 ◽  
Vol 65 (5) ◽  
pp. 551-557 ◽  
Author(s):  
Kenny Ståhl ◽  
Rolf W. Berg ◽  
K. Michael Eriksen ◽  
Rasmus Fehrmann
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Crystal Structures ◽  
Metal Structure ◽  
Structure Type ◽  
The Other ◽  
Crystal Data ◽  
Remarkable Similarity ◽  
Disorder Transition ◽  
X Ray

The crystal structures of Cs2S2O7 at 120 and 273 K have been determined from X-ray single-crystal data. Caesium disulfate represents a new structure type with a uniquely high number of independent formula units at 120 K: In one part caesium ions form a tube surrounding the disulfate ions, [Cs8(S2O7)6+] n ; in the other part a disulfate double-sheet sandwiches a zigzagging caesium ion chain, [Cs2(S2O7)6−] n . Caesium disulfate shows an isostructural order–disorder transition between 230 and 250 K, where two disulfate groups become partially disordered above 250 K. The Cs+-ion arrangement shows a remarkable similarity to the high-pressure RbIV metal structure.

Dinuclear oxofluorometallates as a new structural type of d 0 transition metal oxofluoride compound

2012 ◽  
Vol 68 (6) ◽  
pp. 602-609 ◽  
Author(s):  
Anatoly A. Udovenko ◽  
Natalia M. Laptash
Keyword(s):  
Transition Metal ◽  
Single Crystal ◽  
Structural Type ◽  
The Other ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
Orthorhombic Unit Cell ◽  
Fluoride Ions ◽  
X Ray ◽  
Irradiation Process

Five isomorphous d 0 transition metal oxofluoride compounds A 3[M 2O x F11 − x ]·(AF)0.333 (A = K, Rb, NH4; M = Nb, Mo, W; x = 2, 4) have been synthesized from acid fluoride solutions, and their crystal structures have been determined by single-crystal X-ray diffraction. The basic structural building units are dinuclear M 2 X 11 (dimers) formed from NbOF5 or Mo(W)O2F4 octahedra connected by the fluorine bridging atom. In the Nb2O2F9 dimer, the O atoms occupy apical corners. In the M 2O4F7 (M = Mo, W) dimers two O atoms are also apically placed, whereas the other two O atoms are statistically disordered in equatorial planes. The arrangement of dimers is so that the hexagonal tunnels containing `free' fluoride ions are formed. During the irradiation process the orthorhombic structure of K3Nb2O2F9·(KF)0.333 transforms into a pseudo-trigonal one with a = 23.15 Å, which is the [101] diagonal of the orthorhombic unit cell. The other four trigonal crystals are merohedral twins.

scholarly journals Die Kristallstruktur des Cyano-Elpasoliths [N(CH3)4]2CsFe(CN)6 / The Crystal Structure of the Cyano Elpasolite [N(CH3)4]2CsFe(CN)6

1982 ◽  
Vol 37 (12) ◽  
pp. 1534-1539 ◽  
Author(s):  
D. Babel
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
The Other ◽  
Methyl Groups ◽  
Orientational Disorder ◽  
Space Group ◽  
X Ray ◽  
Ray Methods ◽  
The Ideal

The crystal structure of the cubic compound [N(CH3)4]2CsFe(CN)6 was determined by X-ray methods: a = 2527.4(6) pm, space group Fd3c, Z = 32, Rg = 0.028 (260 independent single crystal reflections). The resulting distances within the practically undistorted Fe (CN)63- - octahedron are Fe-C = 193.4(6) and C-N = 115.7(7) pm. Compared to the ideal elpasolite structure of space group Fm3m, Z = 4, the octahedra are rotated by 7.4° through their 3 axis. This is discussed as caused by steric requirements of the tetramethylammonium groups (N-C = 148.4(10) and 149.1(38) pm, resp.). Three quarters of them, of which also the hydrogen positions could be located, are well oriented. The remaining quarter shows orientational disorder to approach similar contact distances as the other N(CH3)4+ ion exhibits between the methyl groups and the nitrogen ends of the anions

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