A spin state transition in a square planar coordinated iron was found in SrFeO2 and Sr3Fe2O5 under high pressure. This transition occurs as a consequence of enhanced Fe-Fe direct interactions between adjacent face-to-face FeO4 square planar units. We also found a pressure-induced structural transition in Sr3Fe2O5, which is viewed as a B1(NaCl structure) to B2(CsCl structure) structural transition. Such a B1-B2 structural transition generally occurs in intergrowth system consisting of rock-salt blocks and square-planar blocks, as found in A2MO3 (A=Ca, Sr; M=Cu, Pd). An empirical relation between the structural transition pressure Ps and the ionic radius for the binary system holds well for the intergrowth structure, which indicates that the square-planar block is highly compressible along the out-of-plane direction.
We have determined the crystal structure at 0.48 Å resolution of high-potential iron-sulfur protein, HiPIP, which is a small soluble protein playing as an electron carrier in photosynthetic bacteria. The ultra-high resolution structure of HiPIP enabled us to perform charge-density analyses where distributions of valence electrons were clearly visualized as the first case of metalloproteins. A topological analysis of the charge density provided electronic structure information for the iron-sulfur (Fe4S4) cluster as well as the peptide portion.
In-situ synchrotron diffraction experiments were conducted in order to clarify the formation process of α'-martensite from the γ-phase induced by external strain, combined with Lorentz transmission electron microscopy (TEM) and high-resolution TEM observations. Lorentz TEM observation revealed that α'-martensite exist near the defect structures such as dislocations and stacking faults in the parent γ-phase. In addition, it is clearly demonstrated that ε-martensite with hexagonal symmetry appears as an intermediate phase during the plastic deformation of SUS304 stainless steel. Our experimental results suggested that the interfaces between twin structures of the γ-phase presumably play a crucial role in the formation of ε-martensite.
本誌58巻4号掲載の最近の研究から「新物質A(TiO)Cu4(PO4)4(A=Ba,Sr)における結晶カイラリティの強度とドメイン構造の相関」(pp.174-179)およびクリスタリット(p.195)について,以下の誤りがございました.訂正いたします.
(1)p.174,左欄,下から3行目:
(誤)そのうち実に65種がカイラルな空間群である.
→(正)そのうち実に65種の空間群においてカイラルな結晶構造が許される.
(2)p.175,右欄,7行目:
(誤)正方晶カイラルな空間群→(正)正方晶系の空間群
(3)p.195,右欄,14行目:
(誤)結晶構造の対称性を記述する全230種の空間群のうち,65種が回映軸をもたないカイラルな空間群である.
→(正)結晶構造の対称性を記述する全230種の空間群のうち,65種が回映軸をもたない空間群である.