49 research outputs found
CCDC 1567343: Experimental Crystal Structure Determination
No full textRelated Article: Liurukara D. Sanjeewa, Vasile O. Garlea, Michael A. McGuire, Matthias Frontzek, Colin D. McMillen, Kyle Fulle, Joseph W. Kolis|2017|Inorg.Chem.|56|14842|doi:10.1021/acs.inorgchem.7b02024,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
CCDC 1567344: Experimental Crystal Structure Determination
No full textRelated Article: Liurukara D. Sanjeewa, Vasile O. Garlea, Michael A. McGuire, Matthias Frontzek, Colin D. McMillen, Kyle Fulle, Joseph W. Kolis|2017|Inorg.Chem.|56|14842|doi:10.1021/acs.inorgchem.7b02024,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
Low Temperature Phases of Na2Ti3Cl8 Revisited
No full textThe low temperature phases of Na2Ti3Cl8 and their phase transitions were investigated by powder neutron diffraction, heat capacity, and magnetic susceptibility measurements between 1.6 K and room temperature. Aside from the previously known high temperature α‐phase (R3m) and low temperature γ‐phase (R3m), a new intermediate temperature β‐phase was detected. It has a k = (1/4,1/4,0) superstructure and its molar volume and χT product are half way between the α‐ and γ‐phases. The β‐phase is observed between 210 K and 190 K on cooling in powder samples. Its formation is kinetically hindered in crystals. Upon heating the β→α transition occurs at 227 K. From the γ‐phase, a γ→α transitions is observed on heating. Only in heat capacity measurements, a shoulder of the peak indicates an intermediate formation of the β‐phase. Strong antiferromagnetic interactions between the Ti2+ ions result in the formation of triangular trimers (Ti3 clusters). In the γ‐phase all Ti2+ ions are part of trimers. For the β‐phase a structural model is proposed, where half of the Ti2+ ions form trimers. No long‐range magnetic order was observed in Na2Ti3Cl8 down to 1.6 K
Magnetic properties of R2PdSi3 (R = heavy rare earth) compounds
No full textThe R2PdSi3 (R = heavy rare earth) have been synthesized first in 1990 in the search for materials with unusual electronic properties. The availability of single crystals was the starting point for several investigations of the magneto-crystalline anisotropy, also in applied magnetic fields. The results of the observed properties in resistivity, magnetization and susceptibility lead to the summary that these compounds range from interesting to exotic and that their magnetic properties are low dimensional, spin-glass like and altogether “novel”.
The focus of this thesis is the careful analysis of the magnetic properties and magnetic structures of single crystalline R2PdSi3 (R = Gd, Tb, Dy, Ho, Er, Tm). The investigation of macroscopic properties uses magnetization and ac-susceptibility measurements. Resulting from these investigations are magnetic phase diagrams. Neutron and resonant X-ray diffraction measurements elucidate the magnetic structure for the investigated compounds. The phase diagram of Tb2PdSi3 is the starting point of a detailed neutron diffraction study in applied magnetic fields up to 6.5 T and in the temperature range from 0.05 K to 100 K on this compound. Key to the understanding of the R2PdSi3 is the strong coupling of crystallographic structure to the magnetic properties. Thus the established framework of exchange interaction and magneto-crystalline anisotropy allows a collective description instead of a “novel” behavior.Die R2PdSi3 (R = schwere seltene Erde) sind erstmals 1990, im Rahmen der Suche nach Materialien mit ungewöhnlichen elektronischen Eigenschaften, synthetisiert worden. Die Verfügbarkeit von Einkristallen war der Startpunkt für eine Vielzahl von Untersuchungen, auch in angelegten Magnetfeldern, der magneto-kristallinen Anisotropie. Das Ergebnis der untersuchten Eigenschaften Widerstand, Magnetisierung und Suszeptibilität führte zu dem Schluss, dass diese Verbindungen interessant bis exotisch und das ihre magnetischen Eigenschaften niedrig dimensional, spin-glas ähnlich und insgesamt “neuartig“ sind.
Der Schwerpunkt dieser Dissertation ist die genaue Analyse der magnetischen Eigenschaften und Magnetischen Strukturen von einkristallinen R2PdSi3 (R = Gd, Tb, Dy, Ho, Er, Tm). Magnetisierungs- und Suszeptibilitäts-Messungen werden zur Untersuchung der makroskopischen Eigenschaften benutzt. Resultat dieser Untersuchungen sind magnetische Phasendiagramme. Neutronen und resonante Röntgendiffraktrometrie klären die magnetische Struktur der untersuchten Verbindungen auf. Das Phasendiagramm von Tb2PdSi3 ist der Startpunkt einer detaillierten Neutronendiffraktionsuntersuchung dieser Verbindung in Magnetfeldern bis 6.5 T und im Temperaturbereich von 0.05 K und 100 K. Der Schlüssel zum Verständnis der R2PdSi3 ist die starke Kopplung der kristallografischen Struktur und der magnetischen Eigenschaften. Dadurch erlaubt das etablierte System aus Austauschwechselwirkung und magneto-kristalliner Anisotropie eine gemeinsame Beschreibung anstatt „neuartigem“ Verhalten
Magnetic excitations of Er2PdSi3 studied by inelastic neutron scattering in fields up to 12 T
No full textPAND
On the elusive nature of oxygen binding at coordinatively unsaturated 3d transition metal centers in metal–organic frameworks
No full textLow and ambient temperature binding of oxygen, O2, in MOF-74, CPO-27-M (M = Mn, Co, Ni, Cu, Zn) framework materials remains in the physisorption regime, with energetics very similar to that of nitrogen, N2, sorption.</p
Spin-reorientation transitions in the Cairo pentagonal magnet <tex>Bi_{4}Fe_{5}O_{13}F$</tex>
No full textAbstract: We show that interlayer spins play a dual role in the Cairo pentagonal magnet Bi4Fe5O13F, on one hand mediating the three-dimensional magnetic order, and on the other driving spin-reorientation transitions both within and between the planes. The corresponding sequence of magnetic orders unraveled by neutron diffraction and Mossbauer spectroscopy features two orthogonal magnetic structures described by opposite local vector chiralities, and an intermediate, partly disordered phase with nearly collinear spins. A similar collinear phase has been predicted theoretically to be stabilized by quantum fluctuations, but Bi4Fe5O13F is very far from the relevant parameter regime. While the observed in-plane reorientation cannot be explained by any standard frustration mechanism, our ab initio band-structure calculations reveal strong single-ion anisotropy of the interlayer Fe3+ spins that turns out to be instrumental in controlling the local vector chirality and the associated interlayer order
Neutron diffraction from aligned stacks of lipid bilayers using the WAND instrument
No full textNeutron diffraction from aligned stacks of lipid bilayers is examined using the Wide-Angle Neutron Diffractometer (WAND), located at the High Flux Isotope Reactor, Oak Ridge, Tennessee, USA. Data were collected at different levels of hydration and neutron contrast by varying the relative humidity (RH) and H2O/D2O ratio from multi-bilayers of dioleoylphosphatidylcholine and sunflower phosphatidylcholine extract aligned on single-crystal silicon substrates. This work highlights the capabilites of a newly fabricated sample hydration cell, which allows the lipid bilayers to be hydrated with varying H/D ratios from the RH generated by saturated salt solutions, and also demonstrates WAND's capability as an instrument suitable for the study of aligned lipid multi-bilayers.</jats:p
