Crystal structure solution and high-temperature thermal expansion in NaZr(PO)-type materials.

The NaZrPO family of materials have shown low and tailorable thermal expansion properties. In this study, SrZrPO (SrO·4ZrO·3PO), CaZrPO (CaO·4ZrO·3PO), MgZrPO (MgO·4ZrO·3PO), NaTiPO [½(NaO·4TiO·3PO)], NaZrPO [½(NaO·4ZrO·3PO)], and related solid solutions were synthesized using the organic-inorganic steric entrapment method. The samples were characterized by in-situ high-temperature X-ray diffraction from 25 to 1500°C at the Advanced Photon Source and National Synchrotron Light Source II.

Erratum: Specimen-displacement correction for powder X-ray diffraction in Debye-Scherrer geometry with a flat area detector. Erratum.

[This corrects the article DOI: 10.1107/S1600576722011360.].

Specimen-displacement correction for powder X-ray diffraction in Debye-Scherrer geometry with a flat area detector.

The effect of small changes in the speci-men-to-detector distance on the unit-cell parameters is examined for synchrotron powder diffraction in Debye-Scherrer (transmission) geometry with a flat area detector. An analytical correction equation is proposed to fix the shift in 2θ values due to speci-men capillary displacement. This equation does not require the use of an internal reference material, is applied during the Rietveld refinement step, and is analogous to the speci-men-displacement correction equations for Bragg-Brentano and curved-detector Debye-Scherrer geometry experiments, but has a different functional form.

Thermal expansion and phase transformation in the rare earth di-titanate (RTiO) system.

Characterization of the thermal expansion in the rare earth di-titanates is important for their use in high-temperature structural and dielectric applications. Powder samples of the rare earth di-titanates RTiO (or RO·2TiO), where R = La, Pr, Nd, Sm, Gd, Dy, Er, Yb, Y, which crystallize in either the monoclinic or cubic phases, were synthesized for the first time by the solution-based steric entrapment method. The three-dimensional thermal expansions of these polycrystalline powder samples were measured by in situ synchrotron powder diffraction from 25°C to 1600°C in air, nearly 600°C higher than other in situ thermal expansion studies.

Development of mechanical properties in dental resin composite: Effect of filler size and filler aggregation state.

The aim of this work was to study the effect of filler size and filler aggregation state on the mechanical properties of dental resin composites evaluated at filler loadings between 20 wt% and up to 76.5 wt%. Non-aggregated silica nanoparticles (SiNP) (80 nm), doughnut-shaped silica nanoclusters obtained by spray drying (SDSiNP) (3.

Crystal structure solution for the ABO (A = Zr, Hf; B = Nb, Ta) superstructure.

ZrTaO, HfNbO and HfTaO crystal structure solutions have been solved using synchrotron X-ray powder diffraction and neutron powder diffraction in conjunction with simulated annealing, charge flipping and Rietveld refinement. These structures have been shown to be isomorphous with the ZrNbO superstructure, leading to the classification of the ABO (A = Zr, Hf; B = Nb, Ta) orthorhombic compound family with symmetry Ima2 (No. 46).

Temperature gradients for thermophysical and thermochemical property measurements to 3000 °C for an aerodynamically levitated spheroid.

This study examines thermal gradients in ceramic oxide spheroids being aerodynamically levitated in a conical nozzle levitator (CNL) system equipped with a CO laser (10.6 µm wavelength). The CNL system is a versatile piece of equipment that can easily be coupled with advanced thermophysical and thermochemical measuring devices, such as diffraction/scattering (X-ray and neutron), nuclear magnetic resonance, and calorimetry, for the analysis of bulk spheroidal solids and liquids.

Predicting failure: acoustic emission of berlinite under compression.

Acoustic emission has been measured and statistical characteristics analyzed during the stress-induced collapse of porous berlinite, AlPO4, containing up to 50 vol% porosity. Stress collapse occurs in a series of individual events (avalanches), and each avalanche leads to a jerk in sample compression with corresponding acoustic emission (AE) signals. The distribution of AE avalanche energies can be approximately described by a power law p(E)dE = E(-ε)dE (ε ~ 1.

Crackling noise during failure of alumina under compression: the effect of porosity.

We study acoustic emission avalanches during the process of failure of porous alumina samples (Al2O3) under compression. Specimens with different porosities ranging from 30% to 59% have been synthesized from a mixture of fine-grained alumina and graphite. The compressive strength as well as the characteristics of the acoustic activity have been determined.

Inorganic delivery vector for intravenous injection.

Uniform, small-sized (100-200 nm), layered double hydroxides (LDH) were prepared by a conventional, wet chemistry method using different aging times of 1 and 3 days as an inorganic drug or gene delivery carrier. The samples prepared had a hexagonal thin, plate-like shape and TEM/SAD electron microscopy of LDH particles indicated that they were single crystals. In vivo testing of empty LDH administered to adult male Sprague Dawley rats was done to evaluate the possibility of using LDH as an injectable drug delivery vehicle.