La Substitution into the Melilite Derivative CaGaO: Prediction, Synthesis and Ionic Conductivity.

Melilite-type gallates of general formula REAEGaO are of interest for their ability to host mobile interstitial oxide ions in [GaO] layers. The crystal structure of CaGaO is closely related to melilite, with [GaO] layers stacked in a more complex way to accommodate an additional 0.5 interlayer cations per formula unit, suggesting the potential for similar oxide ion conduction behavior.

A computationally-guided non-equilibrium synthesis approach to materials discovery in the SrO-AlO-SiO phase field.

Glass-crystallisation synthesis is coupled to probe structure prediction for the guided discovery of new metastable oxides in the SrO-AlO-SiO phase field, yielding a new ternary ribbon-silicate, SrSiO. In principle, this methodology can be applied to a wide range of oxide chemistries by selecting an appropriate non-equilibrium synthesis route.

Stabilization of the Trigonal Langasite Structure in CaGaZnGeO (0 ≤ ≤ 1) with Partial Ordering of Three Isoelectronic Cations Characterized by a Multitechnique Approach.

Crystallization of oxide glasses rich in Zn, Ga, and Ge is of interest for the synthesis of new transparent ceramics. In this context, we report the identification and detailed structural characterization of a new solid solution CaGaZnGeO (0 ≤ ≤ 1). These compounds adopt the trigonal langasite structure type, offering three possible crystallographic sites for the coordination of isoelectronic Zn, Ga, and Ge.

X-ray Diffraction, NMR Studies, and DFT Calculations of the Room and High Temperature Structures of Rubidium Cryolite, RbAlF.

A crystallographic approach incorporating multinuclear high field solid state NMR (SSNMR), X-ray structure determinations, TEM observation, and density functional theory (DFT) was used to characterize two polymorphs of rubidium cryolite, RbAlF. The room temperature phase was found to be ordered and crystallizes in the (no. 70) space group with = 37.

Oxo- and Oxofluoroaluminates in the RbF-AlO System: Synthesis and Structural Characterization.

Precise research on the RbF-AlO system was carried out by means of combining X-ray powder diffraction, high-field solid-state NMR spectroscopy, and thermal analysis methods. α-RbAlF, RbAlO, RbAlO, and new phase, RbAlOF, were identified in the system. The structure of this new rubidium oxofluoroaluminate was determined.

Pressureless glass crystallization of transparent yttrium aluminum garnet-based nanoceramics.

Transparent crystalline yttrium aluminum garnet (YAG; YAlO) is a dominant host material used in phosphors, scintillators, and solid state lasers. However, YAG single crystals and transparent ceramics face several technological limitations including complex, time-consuming, and costly synthetic approaches. Here we report facile elaboration of transparent YAG-based ceramics by pressureless nano-crystallization of YO-AlO bulk glasses.

ZSM-5 Zeolite: Complete Al Bond Connectivity and Implications on Structure Formation from Solid-State NMR and Quantum Chemistry Calculations.

Al site distribution in the structurally complex and industrially important ZSM-5 zeolite is determined by studying the spectroscopic response of Al(OSi) units and using a self-consistent combination of up-to-date solid-state NMR correlations (Si-Al and H-Al D-HMQC) and quantum chemistry methods (DFT-D). To unravel the driving forces behind specific Al sitting positions, our approach focuses on ZSM-5 containing its more efficient OSDA, tetrapropylammonium.

Local Disorder and Tunable Luminescence in SrAlSiO (0.2 ≤ x ≤ 0.5) Transparent Ceramics.

Eu-doped SrAlSiO (x = 0.2, 0.4, and 0.

Structure and Dynamics of Nonionic Surfactant Aggregates in Layered Materials.

The aggregation of surfactants on solid surfaces as they are adsorbed from solution is the basis of numerous technological applications such as colloidal stabilization, ore flotation, and floor cleaning. The understanding of both the structure and the dynamics of surfactant aggregates applies to the development of alternative ways of preparing hybrid layered materials. For this purpose, we study the adsorption of the triethylene glycol mono n-decyl ether (CE) nonionic surfactant onto a synthetic montmorillonite (Mt), an aluminosilicate clay mineral for organoclay preparation with important applications in materials sciences, catalysis, wastewater treatment, or as drug delivery.

Original Synthetic Route To Obtain a SrAl2O4 Phosphor by the Molten Salt Method: Insights into the Reaction Mechanism and Enhancement of the Persistent Luminescence.

SrAl2O4:Eu(2+), Dy(3+) has been extensively studied for industrial applications in the luminescent materials field, because of its excellent persistent luminescence properties and chemical stability. Traditionally, this strontium aluminate material is synthesized in bulk form and/or fine powder by the classic solid-state method. Here, we report an original synthetic route, a molten salt assisted process, to obtain highly crystalline SrAl2O4 powder with nanometer-scale crystals.

Nonstoichiometric control of tunnel-filling order, thermal expansion, and dielectric relaxation in tetragonal tungsten Bronzes Ba0.5-xTaO3-x.

Ordering of interpolated Ba(2+) chains and alternate Ta-O rows (TaO)(3+) in the pentagonal tunnels of tetragonal tungsten bronzes (TTB) is controlled by the nonstoichiometry in the highly nonstoichiometric Ba0.5-xTaO3-x system. In Ba0.

Localization of oxygen interstitials in CeSrGa3O(7+δ) melilite.

The solubility of Ce in the La(1-x)Ce(x)SrGa3O(7+δ) and La(1.54-x)Ce(x)Sr0.46Ga3O(7.

Topological, geometric, and chemical order in materials: insights from solid-state NMR.

Unlike the long-range order of ideal crystalline structures, local order is an intrinsic characteristic of real materials and often serves as the key to the tuning of their properties and their final applications. Although researchers can easily assess local ordering using two-dimensional imaging techniques with resolution that approaches the atomic level, the diagnosis, description, and qualification of local order in three dimensions is much more challenging. Solid-state nuclear magnetic resonance (NMR) and its panel of continually developing instruments and methods enable the local, atom-selective characterization of structures and assemblies ranging from the atomic to the nanometer length scales.

Synthesis and structure determination of CaSi(1/3)B(2/3)O(8/3): a new calcium borosilicate.

This article reports on the identification, synthesis, and in-situ structure determination of a new crystalline calcium borosilicate compound of composition CaSi(1/3)B(2/3)O(8/3). Synthesis was carried out by complete crystallization on annealing from a corresponding glassy composition in the widely studied CaO-SiO2-B2O3 ternary system. The crystallographic structure was determined ab initio using electron diffraction information and the charge flipping algorithm performed on synchrotron and neutron powder diffraction data collected in situ at high temperature.

Effects of the orientation of the 23Na-29Si dipolar vector on the dipolar mediated heteronuclear solid state NMR correlation spectrum of crystalline sodium silicates.

Dipolar-Heteronuclear Multiple Quantum Correlation (D-HMQC) experiment based on SR4(2)(1) recoupling was shown as a very efficient probe of spatial proximities in ordered or disordered materials. As crystalline sodium silicates have been extensively studied using 1D and 2D MAS NMR experiments and DFT calculations, they have been used as candidate model systems to perform this D-HMQC experiment. In this work, we demonstrate that the combination of (29)Si and (23)Na NMR at high magnetic field and DFT calculations makes it possible to revisit the assignment of the NMR signature of the δ-Na(2)Si(2)O(5) polymorph.

Synthesis and structure resolution of RbLaF4.

The synthesis and structure resolution of RbLaF(4) are described. RbLaF(4) is synthesized by solid-state reaction between RbF and LaF(3) at 425 °C under a nonoxidizing atmosphere. Its crystal structure has been resolved by combining neutron and synchrotron powder diffraction data refinements (Pnma,a = 6.

Absence of bacterial imprints on struvite-containing kidney stones: a structural investigation at the mesoscopic and atomic scale.

Objective: Bacterial imprints are always observed on highly carbonated apatite kidney stones but not struvite kidney stones. Struvite and carbonated apatite stones with a high CO(3)(2-)/PO(4)(3-) rate are believed to develop from infections, but their structural differences at the mesoscopic scale lack explanation.

Methods: We investigated 17 urinary calculi composed mainly of struvite or carbonated apatite by Fourier transform infrared, scanning electron microscopy, and powder neutron diffraction techniques.

High temperature NMR study of aluminum metal influence on speciation in molten NaF-AlF3 fluorides.

In situ high temperature NMR spectroscopy has been used to characterize the interactions between aluminum metal and cryolitic melts. (27)Al, (23)Na, and (19)F NMR spectra have been acquired in NaF-AlF(3) and NaF-AlF(3)-Al melts over a wide range of compositions. The evolution of the signals evidence a chemical reaction between the metal and the salt.

Relationships between carbonation rate of carbapatite and morphologic characteristics of calcium phosphate stones and etiology.

Objectives: To examine the significance of the carbonation rate (CR) in carbonated apatite (carbapatite [CA]) stones and its relationships with the morphologic characteristics of CA and etiology. CA stones without struvite can result from metabolic disorders or urinary tract infection, but the latter etiology is still debated. Infection stones caused by urea-splitting bacteria are made of CA admixed with struvite and exhibit a high CO(3)(2-)/PO(4)(3-) ratio (CR).

New routes to mesoporous silica-based spheres with functionalized surfaces.

Mesoporous hybrid silica-based spheres with functionalized surfaces and abundant highly ordered domains are obtained using for the first time a simple synthetic route based on spray-drying processes.