• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to project page

1990 Fiscal Year Final Research Report Summary

Synthesis of Mixed Valenced Oxide Minerals

Research Project

Project/Area Number 01470055
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field 鉱物学(含岩石・鉱床学)
Research InstitutionHokkaido University

Principal Investigator

KIKUCHI Takeshi  Hokkaido University, Faculty of Science, Assistant Professor, 理学部, 助教授 (60211190)

Co-Investigator(Kenkyū-buntansha) ISHII Kuninobu  Hokkaido University, Faculty of Engineering, Professor, 工学部, 教授 (00001214)
MIURA Hiroyuki  Hokkaido University, Faculty of Science, Lecturer, 理学部, 講師 (70157436)
HARIYA Yu  Hokkaido University, Faculty of Science, Professor, 理学部, 教授 (50000815)
Project Period (FY) 1989 – 1990
KeywordsSolid solution / Mineral synthesis / Hausmannite / Spinel / Mixed valency / Jacobsite / Cryptomelane / Fluorite structure
Research Abstract

(1) Making of Phase Equilibrium Diagram of the System Jacobsite (MnFe_2O_4) -Hausmannite (Mn_3O_4)
Phase diagram of the system jacobsite-hausmannite was made by solid state reactions under hematite-magnetite oxygen buffers. Compositions of the two phase region where a cubic phase and a tetragonal phase coexisted were determined by electron microprobe analysis. A thermodynamical approach revealed that the equilibrium concentration relations among chemical constituents such as Mn^<2+>, Fe^<2+>, Mn^<3+>, Fe^<3+> and vacancy of metal in the cubic phase.
(2) Observation of Thermal Decompostion Behavior of Pyrolusite by Means of Hihg Temperature Powder X-ray Diffractometer
Two kinds of thermally different pyrolusite (S) and (D) are known ; (S) shows one endothermic peak about 650^゚C and (D) has two endothermic peaks about the same temperature. High temperature X-ray measurements for these showed that (S) decomposed at about 650^゚C and transformed to bixbyite (alpha-Mn_2O^3) exclusively, whereas (D) converted to gamma-Mn_2O_3 and Mn_5O_8 in addition to bixybite. Thermal behavior of (D) was explicable from the oxygen deficiency in (D).
(3) Thermal Transformation of Cryptomelane (A_xMn_8O_<16>. nH_2O, A=K, Na)
Tetragonal cryptomelane was converted to a monoclinic cryptomelane and bixybite by heating at about 700^゚C in air. Alkali ions in the part were concentrated in the tunnel and caused the transformation to monoclinic phase accompanying with simulutaneous formation of bixbyite. Structural study in dicated that the Mn^<3+> ions were ordered in the monoclinic cryptomelane.
(4) Valence State of Tellurium in Bismuthtellurates
Valence state of tellurium in the compounds appeared in the pseudo-ternary system Bi_2O_3-Sro-TeO_2 and Bi_2O_3-Pbo-TeO_2 in air was mostly in the state of Te^<4+>. In a superstructure of fluorite, Bi_2SrTeO_7, tellurium ion existed as Te^<6+>.

  • Research Products

    (8 results)

All Other

All Publications (8 results)

  • [Publications] T.Kikuchi: "Synthesis of new compounds of the pseudoーternary system SrOーBi_2O_3ーTeo_2 in air" J.Materials Sci.25. 1285-1288 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Kikuchi: "Phases with fluorite superstructures in the pseudoternary system PbOーBi_2O_3ーTeo_2" J.Materials Sci.Let.9. 580-582 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.Kudo: "Tetragonalーmonoclinic transformation of cryptomelane at high temperature" Miner.J.15. 50-63 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.Miura: "The crystal structure of ramsdellite from Pirika mine" J.Fac.Sci.,Hokkaido Univ.,Ser.IV. 22. 611-617 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T. KIKUCHI, T. HATANO AND H. SAKAI: ""Synthesis of new compounds of the pseudo-ternary system srO-Bi_2O_3-TeO_2 in air"" J. Materials Sci.25. 1285-1288 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T. KIKUCHI, T. HATANO AND S. HORIUCHI: ""Phases with fluorite superstructures in the pseudo-ternary system PbO-Bi_2O_3-TeO_2"" J. Materials Sci. Let.9. 580-582 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] H. KUDO, H. MIURA AND Y. HARIYA: ""Tetragonal-monoclinic transformation of cryptomelane at high temperature"" MINER. J.15. 50-63 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] H. MIURA, H. KUDO, J. H. CHOI AND Y. HARIYA: ""The crystal structure of ramsdellite from Pirika mine"" J. Fac. Sci., Hokkaido Univ., Ser. IV. 22. 611-617 (1990)

    • Description
      「研究成果報告書概要(欧文)」より

URL: 

Published: 1993-08-12  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi