Exploration of the energy conversion function of actinide compounds by protium probe

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 12480139
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Nuclear engineering
• Research Institution: OSAKA UNIVERSITY
• Principal Investigator: YAMANAKA Shinsuke OSAKA UNIVERSITY, DEPARTMENT OF NUCLEAR ENGINEERING, PROFESSOR, 大学院・工学研究科, 教授 (00166753)
• Co-Investigator(Kenkyū-buntansha): KUROSAKI Ken OSAKA UNIVERSITY, DEPARTMENT OF NUCLEAR ENGINEERING, ASSISTANT PROFESSOR, 大学院・工学研究科, 助手 (90304021) ; UNO Masayoshi OSAKA UNIVERSITY, DEPARTMENT OF NUCLEAR ENGINEERING, ASSOCIATE PROFESSOR, 大学院・工学研究科, 助教授 (00232885)
• Project Period (FY): 2000 – 2001
• Keywords: energy conversion function / Hydrogen absorption properties / photocatalyst / BaUO_3 / UNiAl / SrUO_4 / UCoAl / BaZrO_3

Research Abstract

Relationships between several properties of BaUO_3, BaZrO_3, Ba(U,Zr)O_3 were evaluated. BaZrO_3 shows typical tendencies of perovskite type oxides, while BaUO_3 shows glass-like tendencies. Dimensionless figure of merit for thermoelectric materials (ZT) of BaUO_3 was evaluated from the electrical resistivity, Seebeck coefficient, and thermal conductivity. It is found that BaUO_3 has a potential to be a good thermoelectric material.
Hydrogen absorption properties of UNiAl intermetallic compound are examined at hydrogen pressures up to 2MPa, and temperatures between 298-398 K. From the obtained P-C-isotherms, the standard enthalpy and entropy of hydride formation are estimated. The thermodynamic data are compared with previous ones. It is found that UNiAl is a superior candidate for hydrogen absorption materials.
The amount of evolved H_2 gas of photocatalysts such as ZrO_2 and BaZrO_3 (compound oxide of ZrO_2) was measured. H_2 evolution of ZrO_2 was about 0.07 μmol after 20 hours under the wavelength of irradiation light was 230 nm. But that of BaZrO_3 was not observed in the case of 230 nm but was observed in the case of 200 nm. Photoelectrochemical properties, flat-band potential (V_<fb>) and bandgap energy (E_g) were measured. From these results, it was found that the photocatalytic activity of ZrO_2 was superior to that of BaZrO_3 under the use of solar energy. SrUO_4, CaUO_4, K_2U_2O_7 and Na_2U_2O_7 were formed by the reaction of UO_2 and metal carbonates in air. SrUO_4 is an excellent photocatalyst and the activity of water splitting for this uranium complex oxide doped with Pt was one third of that for P-25 doped with Pt. The activity for this compound doped with NiO was one fifth of that for NaTaO_3 doped with NiO.