Hokkaido University · Materials Science
Professor Yoshihiro Tsujimoto's research lab specializes in the design, synthesis, and structural characterization of complex oxide and oxyhalide materials with tailored electronic and magnetic properties. The lab focuses on novel perovskite-related structures, including layered Ruddlesden-Popper, Dion-Jacobson, and Aurivillius phases, as well as oxysulfides and oxyfluorides, with an emphasis on anion ordering, crystal engineering, and functional properties such as nonlinear optics and magnetism. Their work often involves high-pressure and high-temperature synthesis techniques to stabilize metastable phases with unique structural and electronic features.
Figures are computed from collected data and may differ slightly.
Reduction without particle growth: Ti2O3 nanoparticles of corundum structure were synthesized by reducing TiO2 nanoparticles of rutile structure with CaH2 powder at a low temperature of 350 °C. The morphology of the reduced oxide was the same as that of the precursor, though the crystal structure was transformed from the tetragonal to the hexagonal system (see picture). Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed,
In this paper, we review recent progress and new challenges in the area of oxyfluoride perovskite, especially layered systems including Ruddlesden-Popper (RP), Dion-Jacobson (DJ) and Aurivillius (AV) type perovskite families. It is difficult to synthesize oxyfluoride perovskite using a conventional solid-state reaction because of the high chemical stability of the simple fluoride starting materials. Nevertheless, persistent efforts made by solid-state chemists have led to a major breakthrough in
Single crystals of a new zinc oxysulfide SrZn2S2O were grown in a eutectic KF–KCl flux, and the structure was determined by single-crystal X-ray diffraction. SrZn2S2O crystallizes in the noncentrosymmetric polar space group Pmn21 with lattice parameters of a = 3.87440(10) Å, b = 9.9847(3) Å, and c = 6.0916(2) Å. In the crystal structure, close-packed corrugated double layers of ZnS3O tetrahedra, which are derived from the wurtzite structure, are vertically separated by Sr2+ ions. In addition, th
Chalcogenide-containing compounds have been widely studied as infrared nonlinear optical (NLO) materials. However, they have never been applied in the ultraviolet (UV) region owing to the high energy levels of chalcogen anions, leading to band gap narrowing. We report the synthesis of a new UV NLO oxysulfide La<sub>3</sub> Ga<sub>3</sub> Ge<sub>2</sub> S<sub>3</sub> O<sub>10</sub> with an exceptionally wide band gap of 4.70 eV due to from the unique anion-ordered frameworks comprising 1D <sup>1<
Extended layered oxyhalide compounds, Sr2NiO3X (X = F, Cl), with the square pyramidal coordination around the trivalent nickel ions in the low spin state (S = 1/2), are successfully synthesized by a high-pressure and high-temperature reaction. Both these compounds crystallize in the n = 1 Ruddlesden–Popper type structure, but the difference of halogen anions incorporated dictate the anion-site ordering patterns and the magnetic ground states. Sr2NiO3F adopts the tetragonal cell in the space grou
The first Ruddlesden-Popper type layered cobalt oxyfluoride, Sr(2)CoO(3)F, has been synthesized under a pressure of 6 GPa at 1700 °C and shown to adopt a K(2)NiF(4)-type structure with distorted square pyramidal coordination around Co and with O/F disorder at the apical sites.
Topotactic reaction of the n = 2 Ruddlesden–Popper phase Sr3Fe2O7−δ (δ ≈ 0.18) with polytetrafluoroethylene (PTFE) yields a highly fluorinated phase Sr3Fe2O5+xF2–x (x ≈ 0.44), compared with Sr3Fe2O6F0.87 prepared by the reaction of Sr3Fe2O6 and F2 gas. Structure analyses based on powder neutron diffraction, synchrotron powder diffraction, and 57Fe Mössbauer spectroscopy measurements demonstrate that the new oxyfluoride perovskite has no anion deficiencies and adopts the tetragonal structure (spa
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