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Host Lattice (host + lattice)

Distribution by Scientific Domains
Chemistry80%

Selected Abstracts

ChemInform Abstract: Chemical Tuning of the Photon Upconversion Properties in Ti2+ -Doped Chloride Host Lattices.

CHEMINFORM, Issue 52 2001
Oliver S. Wenger
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Structural Study of Novel Graphite,Lithium,Calcium Intercalation Compounds

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2004
Sébastien Pruvost
Abstract Three new layered compounds were synthesised by immersing a pyrographite platelet in a molten Ca,Li alloy creating a new graphite intercalation compound family. The samples were studied by X-ray and neutron diffraction, revealing that the intercalated sheets are polylayered. The study of the 00l reflections allowed us to establish the c -axis stacking of these three phases. The ,-phase exhibits a five-layered intercalated sheet which has something in common with a Li,Ca,Li,Ca,Li slice cut in the CaLi2 structure (ThMn2 Laves phase type). The ,-phase, which is richer in metallic elements and with a greater repeat distance, possesses seven-layered intercalated sheets due to the splitting of the middle lithium plane in three. The third phase is a pseudo-binary compound, containing monolayered sheets and with a formula close to CaC6. Electron microdiffraction allowed us to determine the 2D unit cell for each compound, all of which were commensurate with that of graphite. Charge transfer from the intercalate to the host lattice was evaluated for the three phases from hk0 data, leading to high values. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Adduction of amiloride hydrochloride in urea through a modified technique for the dissolution enhancement

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2008
Seema Thakral
Abstract Amiloride hydrochloride is a potassium-sparing diuretic since it favors sodium excretion and potassium reabsorption. In the present study, urea, a well-known adductor for linear compounds was successfully employed for inclusion of amiloride hydrochloride,a substituted cyclic organic compound through a modified technique. Formation of urea inclusion compounds was confirmed by FTIR, DSC and XRD. The minimum amount of rapidly adductible endocyte (RAE) required for adduction of amiloride hydrochloride in urea was estimated by a modified Zimmerschied calorimetric method. Urea,AH,RAE inclusion compounds containing varying proportions of guests were prepared and their thermal behavior studied by DSC. The inclusion compounds were also found to exhibit high content uniformity and markedly improved dissolution profile as demonstrated by increased dissolution efficiency. Studies reveal the possibility of exploiting co-inclusion of the drug in urea host lattice for the dissolution enhancement. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:1191,1201, 2008 [source]

Energy Transfer Enables 1.53 ,m Photoluminescence from Erbium-Doped TiO2 Semiconductor Nanocrystals Synthesized by Ar/O2 Radio-Frequency Thermal Plasma

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008
Ji-Guang Li
Highly crystalline, highly luminescent nanopowders of Er3+ -doped TiO2 have been successfully synthesized via one-step Ar/O2 radio-frequency thermal plasma processing. Energy transfer from the TiO2 host to Er3+ activators has been confirmed by combined means of UV-vis, excitation, and photoluminescence spectroscopies. As a consequence, bright photoluminescence at ,1.53 ,m was observed from the nanopowders either by directly exciting the Er3+ activator or by exciting the TiO2 host lattice. A comparative study shows that the nanopowder of the same system made via coprecipitation lacks the energy transfer. The plasma-generated nanopowders may thus find applications in optoelectronic devices. [source]

The oxygen vacancy in Ga2O3: a double resonance investigation,

MAGNETIC RESONANCE IN CHEMISTRY, Issue S1 2005
H. J. Kümmerer
Abstract When produced under reducing conditions, ,-Ga2O3 is transformed into an n -type semiconductor with delocalized conduction electrons that exhibit a very strong electron spin resonance (ESR) and a strong hyperfine coupling to the gallium nuclei of the host lattice. We apply the Overhauser-shift technique to investigate single crystals of this compound. With extension to the high magnetic field of a W-band spectrometer, we were able to resolve all spectral lines that were recorded and to assign them to their corresponding electronic and nuclear states. This separate analysis was the basis to access additional sample characteristics: the hyperfine coupling that is actually averaged out in the ESR signal, as well as the nuclear relaxation rates could be analyzed. Systematic measurements by varying the microwave power revealed the Overhauser shift in thermal equilibrium. The signal could be tracked to very small microwave saturation parameters, at which the deviation from the usual linear relation between power and shift becomes evident and the shift clearly approaches a constant value. This value in equilibrium was determined directly from a fit to a sequence of measurements, whereas standard X-band experiments only provided indirect conclusions. The probability densities of the electrons at the nuclei in the two nonequivalent crystallographic positions,the lattice sites with octahedral and tetrahedral coordination,could also be determined directly. The enhanced resolution revealed an otherwise hidden substructure in the nuclear resonance signals. On the basis of a microscopic model, this structure could be used to probe the environment of the oxygen vacancy more precisely and to determine the extension of the electronic wave function of the donor electrons. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Tunneling recombination processes in PbWO4 crystals

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2007
P. Fabeni
Abstract Time-resolved emission and excitation spectra and luminescence decay kinetics were studied at 160-300 K for undoped and Mo-doped PbWO4 crystals under XeCl (4.02 eV), N2 (3.67 eV) and KrF (5.0 eV) pulsed excimer laser excitation. The G(II) emission was found to be responsible for the slow (µs-ms) luminescence decay. Under excitation or after irradiation in the exciton region (Eexc = 4.02 eV), this emission accompanies the monomolecular tunneling recombination in genetic pairs of electron and hole centers produced at the photo-thermally stimulated decay of localized excitons, which occurs without release of free charge carriers. Under excitation or after irradiation in the host lattice (Eexc = 5.0 eV) and defect-related (Eexc = 3.67 eV) regions, the bimolecular tunneling recombination takes place in chaotic pairs of the electron and hole centers created at the trapping of optically released free charge carriers. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Electron beam,specimen interactions and their effect on high-angle annular dark-field imaging of dopant atoms within a crystal

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 3 2010
B. G. Mendis
A Bloch wave model based on perturbation theory is used to analyse high-angle annular dark-field (HAADF) imaging of a substitutional and interstitial W atom in [111]-oriented body-centred-cubic Fe. For the substitutional atom the 1s Bloch state is scattered to high angles thereby producing HAADF dopant atom contrast. Intraband scattering of the 1s state is the strongest individual Bloch wave transition but collective interband scattering of the non-1s states to the 1s state leads to variations in the high-angle scattering with depth of the dopant atom. The non-1s states are Coulomb attracted towards the W atom thereby giving rise to an `atom focusing' effect similar to channelling. For the interstitial atom, which in the [111] orientation does not overlap with an atom column of the host lattice, high-angle scattering and Coulomb attraction takes place through the non-1s states. Scattering of the 1s state is, however, negligible. [source]

A host,guest complex of di­aqua­bis­[1-hydroxy-2(1H)-pyridine­thionato- O,S]­magnesium(II) and 2,2,-di­thio­bis­(pyridine N -oxide)

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2000
Andrew Bond
The title compound, [Mg(C5H4NOS)2(H2O)2]·C10H8N2O2S2, is a two-component host,guest material. The 2,2,-di­thio­bis(pyridine N -oxide) molecule has crystallographic twofold symmetry. The metal complex lies on an inversion centre and associates via C,H,S interactions into chains which thread the 2,2,-di­thio­bis­(pyridine N -oxide) lattice in perpendicular directions. Hydro­gen bonds exist between the water mol­ecules of the di­aqua­magnesium units and the N,O groups of the host lattice. [source]

Fullerene-like Mo(W)1,xRexS2 Nanoparticles

CHEMISTRY - AN ASIAN JOURNAL, Issue 8-9 2008
Francis, Leonard Deepak Dr.
Abstract Inorganic fullerene-like (IF) Mo1,xRexS2 and W1,xRexS2 nanoparticles have been synthesized by a gas-phase reaction involving the respective metal halides with H2S. The IF-Mo(W)1,xRexS2 nanoparticles, containing up to 5,% Re, were characterized by a variety of experimental techniques. Analyses of the X-ray powder diffraction and different electron microscopy techniques show that the Re is doped in the MoS2 host lattice. Interestingly, Re-doped MoS2 nanotubes are present as well, although in small quantities (,5,%). XPS results confirm the nanoparticles to be more n-type arising from the effect of Re doping. Additionally, density-functional tight-binding (DFTB) calculations support the observed n-type behavior. [source]

Facile Synthesis of Bastnaesite -Type LaF[CO3] and Its Thermal Decomposition to LaOF for Bulk and Eu3+ -Doped Samples

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2009
Oliver Janka
Abstract Rare-earth metal(III) oxide fluorides with the composition MOF (M = La,Lu) seem to offer promising host lattices for luminescence applications by doping these materials with trivalent lanthanoid cations. Unfortunately, there was no simple and practicable way to synthesize the compounds in phase-pure quality with classical solid-state chemistry reactions. However, by using the rare-earth metal(III) fluoride oxocarbonates, MF[CO3], as solution-born precursor materials that crystallize with a bastnaesite -type structure, easy access is now possible by mild thermal decomposition. Synthetic details, investigations on the phase purity and the presence of the oxocarbonate anion [CO3]2, proved by IR measurements as well as from X-ray powder diffraction data are given in this paper for the example of bulk LaF[CO3] and Eu3+ -doped samples. The latter (LaF[CO3]:Eu3+) shows a bright orange-red luminescence that is stronger than that of the product of its thermal decomposition: trimorphic LaOF:Eu3+.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]