Afterglow Properties and Trap-Depth Control in ZrO:Ti, ( = Ca, Y, Nb, W).

Ti-doped ZrO is a chemically stable and persistent luminescence material. Doping and co-doping is an effective approach for improving the afterglow properties of phosphors, but few studies have investigated the co-doping of ZrO:Ti systems. This study aimed to synthesize ZrO:Ti, ( = Ca, Y, Ti single-doped, Nb, W) and evaluate the luminescent properties of the resulting materials, with a specific focus on the relationship between trap depth and the valence state of the co-doped cation.

Development of Measurement Tools for High-Throughput Experiments of Synchrotron Radiation XRD and XAFS on Powder Libraries.

We propose to minimize the sampling time for high-throughput measurements of powder X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) in synchrotron radiation. The conventional synchrotron radiation powder X-ray diffraction method requires filling of a capillary tube, but a structure-refining diffraction pattern could be obtained by transferring the crushed powder to a tape and rotating the cassette-tape tool by ±5° around the sample position. XAFS spectra could also be measured with the sample attached to the tape.

Ethanol Gas Sensing by a Zn-Terminated ZnO(0001) Bulk Single-Crystalline Substrate.

Metal oxide semiconductor gas sensors have been widely studied for the selective detection of various gases with trace concentrations. The identification of the reaction scheme governing the gas sensing response is crucial for further development; however, the mechanism of ethanol (EtOH) gas sensing by ZnO is still controversial despite being one of the most intensively studied target gas and sensing material combinations. In this work, for the first time, the detailed mechanism of EtOH sensing by ZnO is studied by using a bulk single-crystalline substrate, which has a well-defined stoichiometry and atomic arrangement, as the sensing material.

Development of an Automatic, High-Throughput Structural Refinement Method Using Rietveld Analysis.

Automated structural analysis techniques are required to accelerate materials research. In this study, we developed an algorithm to automate Rietveld analysis, which is a method for crystal structure refinement using powder diffraction patterns. This algorithm features the repeated generation of a set of initial values, followed by one-shot refinement.

High-Pressure Synthesis, Crystal Structure, Chemical Bonding, and Ferroelectricity of LiNbO-Type LiSbO.

A polar LiNbO (LN)-type oxide LiSbO was synthesized by a high-temperature heat treatment under a pressure of 7.7 GPa and found to exhibit ferroelectricity. The crystal structural refinement using the data of synchrotron powder X-ray diffraction and neutron diffraction and the electronic structure calculation of LN-type LiSbO suggest a covalent-bonding character between Sb and O.

Low-Temperature Spark Plasma Sintering of ZrWMoO₈ Exhibiting Controllable Negative Thermal Expansion.

Molybdenum-doped zirconium tungstate (ZrWMoO₈) has been widely studied because of its large isotropic coefficient of negative thermal expansion (NTE). However, low density and poor sinterability limit its production and application. In this study, relative density greater than 90% single-phase ZrWMoO₈ (0.

A-Site and B-Site Charge Orderings in an s-d Level Controlled Perovskite Oxide PbCoO.

Perovskite PbCoO synthesized at 12 GPa was found to have an unusual charge distribution of PbPbCoCoO with charge orderings in both the A and B sites of perovskite ABO. Comprehensive studies using density functional theory (DFT) calculation, electron diffraction (ED), synchrotron X-ray diffraction (SXRD), neutron powder diffraction (NPD), hard X-ray photoemission spectroscopy (HAXPES), soft X-ray absorption spectroscopy (XAS), and measurements of specific heat as well as magnetic and electrical properties provide evidence of lead ion and cobalt ion charge ordering leading to PbPbCoCoO quadruple perovskite structure. It is shown that the average valence distribution of PbCoO between PbCrO and PbNiO can be stabilized by tuning the energy levels of Pb 6s and transition metal 3d orbitals.

High-pressure synthesis, crystal structure, and phase stability relations of a LiNbO3-type polar titanate ZnTiO3 and its reinforced polarity by the second-order Jahn-Teller effect.

A polar LiNbO3-type (LN-type) titanate ZnTiO3 has been successfully synthesized using ilmenite-type (IL-type) ZnTiO3 under high pressure and high temperature. The first principles calculation indicates that LN-type ZnTiO3 is a metastable phase obtained by the transformation in the decompression process from the perovskite-type phase, which is stable at high pressure and high temperature. The Rietveld structural refinement using synchrotron powder X-ray diffraction data reveals that LN-type ZnTiO3 crystallizes into a hexagonal structure with a polar space group R3c and exhibits greater intradistortion of the TiO6 octahedron in LN-type ZnTiO3 than that of the SnO6 octahedron in LN-type ZnSnO3.