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Graduate School of Science and Engineering
Applied Chemistry

Laboratory of Inorganic Synthetic Chemistry

Aiming for new materials, new properties and new synthetic processes

Staff

Ken HIROTA [Professor]

Ken HIROTA
[Professor]
MD
Telephone : +81-774-65-6690
hirota
Office : SC-208
Database of Researchers
Masaki KATO [Professor]

Masaki KATO
[Professor]
MD
Telephone : +81-774-65-6686
kato
Office : SC-207
Database of Researchers

Research Topics

  • Production of metal/ceramic composites used for Induction Heating (IH)
  • Development of oxide thermoelectric materials
  • Production of carbon nano fiber dispersed engineering ceramics
  • Production of ceramic micro particles for use in dye-sensitized solar cells
  • Production of antibacterial ceramics
  • Effect of elemental substitution on magnetic interactions in layered copper oxide
  • Effect of elemental substitution on magnetism in indium (In), copper (Cu) oxide with its particularly low-dimensional structure
  • Elemental substitution effect and microscopic electronic properties of pyrochlore oxide
  • Synthesis and physical properties of iron-based superconductive compounds and properties
  • Synthesis and physical properties of titanium oxide as a new transparent electrode

Research Contents (Prof. Ken HIROTA)

<1>
Production and characterization of ultrafine particle (nanometer-sized) powder.
We use new methods of powder production to prepare oxide powders of spinel compounds such as MgFe2O4 and (Mn,Zn)Fe2O4, as well as the semi-conducting perovskite compound CaMnO3 and its related compounds, and examine the powder properties (including particle size, crystalline phase, phase transition, and specific surface area). High density ceramics are produced using various sintering methods, and then the microstructure and electrical, magnetic and thermoelectric properties are evaluated.
<2>
Production and evaluation of high-density ceramics/ceramics composite materials using high-temperature/high-pressure processes.

  • Ultra-high pressure sintering (1,500°C, 500 - 1,000 MPa (5,000 - 10,000 kg/cm2))
  • Hot isostatic pressing (HIP: 2,000°C, 200 MPa (2,000 kg/cm2))
  • Pulsed Electric-Current Pressure Sintering (PECPS, or Spark Plasma Sintering: SPS: 1,800°C, 30 - 50 MPa (300 - 500 kg/cm2))

If a material shows poor sinterability and it is difficult to evaluate its properties or put it to practical use, the material is densified by using the above-mentioned process, and then the properties of the highly dense sintered ceramics and composite material are evaluated.
<3>
Production of inorganic compound powders with high melting points such as nitrides, silicides, borides, and carbides using self-propagating high-temperature synthesis (SHS) and their powder characterization, and production and evaluation of high-density ceramics obtained using process 2 above.
We synthesize the inorganic compound powders with high melting points using SHS, and aim to produce the dense bulk materials with the same composition during the SHS process. Then we characterize these powders and evaluate the mechanical, electrical, and magnetic properties of the bulk materials in relation to their microstructures.
<4>
Nano composites
  • Fabrication and evaluation of nano-composites, in which carbon nano fibers (CNT; one of the novel carbon allotropes that leads the way in a nano technology) or the similar carbon nano fibers (CNF) are dispersed homogeneously into the ceramic matrix.
  • Production and properties-evaluation of magnetic nano-composites consisting of magnetic metals particles and magnetic ferrite materials, that reveal superior electrical and magnetic properties at high frequencies.
  • Production and properties-evaluation of new thermoelectric materials featuring high electrical and low-thermal conductivities of CNF homogeneously dispersed perovskite oxides.
<5>
Production of new/functional materials
  • Production of novel titanium oxide TiO2(B) powders (used as an electrode in lithium batteries and solar cells), zinc oxide ZnO powder (with its sustainable antibacterial properties under dark) using a hydrothermal reaction.
CNF:Carbon Nano Fiber

Research Contents (Associate Prof. Masaki KATO)

Superconductivity is a phenomenon whereby perfect diamagnetism (property which internally cancel the external magnetic field) called Meissner effect occurs with zero electric resistivity. The applications are too numerous to mention (e.g. development of ultra-strong magnetic fields, lossless power transmission, linear-motor trains and other modes of transport that use magnetic levitation, power storage, nuclear fusion), but the development of materials that become superconductive at high temperatures remains a major issue. To this end, a fundamental elucidation of the mechanisms regarding emergence of superconductivity is necessary.

Notably, it is becoming clear that the dimensionality of the crystalline structure are closely linked to superconductivity and magnetism since the recent discovery of high temperature oxide superconductors and their related compounds. This strong association between structure and electron properties (conductivity and magnetism) is particularly noteworthy in inorganic compounds including transition-metals, and this stems from a much stronger correlation (strong electron correlation) in solids than in ordinary materials. This is a major topic in properties research of interest from both an experimental and theoretical viewpoint. For example, it can be said that all unique electric and magnetic phenomena in transition-metal compounds (such as materials that transition from metal to insulator at a certain temperature, itinerant electron magnets in which the electrons responsible for electrical conductivity also display magnetism, and heavy electron systems of compounds including rare metals in which the effective mass of electrons increases up to 100-1,000 times than normal) are based on strong electron correlation.

However, research on strong electron correlation in solids is still in the early stages, and theoretical discussion is extremely difficult; thus a fundamental understanding will require consolidation of more experimental knowledge.

Thus, this laboratory synthesizes such electrically and magnetically unique materials. Specifically, we produce layered inorganic ceramic compounds controlled materially and structurally on a nanoscale by introducing various atoms and molecules between layers in layered transition-metal compounds. We then analyze their structure using X-ray diffraction, electron microscope observation, and the like, and evaluate their physical properties using such measurements as magnetic susceptibility/electrical resistivity measurement, nuclear magnetic resonance (NMR) measurement, and neutron diffraction, in order to come to an understanding on a nanoscale of the various phenomena (or quantum criticality) based on superconductivity or electron correlation or the like. The knowledge gleaned is fed back into the synthesis, with the ultimate aim of producing new functional inorganic compounds.
Synthesis and physical properties of strongly-correlated electronic states in transition-metal oxides

Keywords

  • Carbon nano fibers (CNF)
  • Nano powder, Nano-composites
  • Electronic ceramics
  • Engineering ceramics
  • Quantum critical phenomena

  • Superconductivity
  • Low-dimensional magnetism
  • Strongly-correlated electron system
  • Metal-insulator transition

.