Ryo Hirasawa

Features of policy-making processes in Japan's Council for Science and Technology

Abstract The aim of this paper is to elucidate the features of the policy-making mechanism of Japans Council for Science and Technology (CST) focusing on the policy-making processes of comprehensive recommendations. The CST is the highest decision-making organization in Japans science and technology administrative process and the recommendations have a great influence on the direction of national science and technology policy. The main results are as follows: In the CST, the organizations are never static but very flexible. The dynamic creation of deliberating groups occur in accordance with the development of the policy plan. Thereupon, the incessant negotiations between internal groups of the related ministries are very essential, and the policy-making process is achieved in this interactive way among the policy-makers in participating organizations. In this process, the dual-post holdings (DPH) in the vertical direction of the hierarchy can be seen frequently within the CST. This plays an important role in communication and is a very effective method of information transfer and consensus-building in policy formation requiring a high degree of expertise such as science and technology.

Analysis of role of oxygen deficiency in crystal structure and conduction mechanism of BaBi0.25Pb0.75O3 − δ

Abstract The dependence of oxygen deficiency, δ, of BaBi 0.25 Pb 0.75 O 3 − δ on temperature, T , and oxygen partial pressure, po 2 , was analyzed by thermogravimetry. A linear relationship with proportionality constant about − 1 2 between log δ and log po 2 was observed, suggesting that the chemical potential of the electrons, i.e., effective concentration of electron carrier for conduction, is independent of the concentration of oxygen deficiency, δ. Based on the determined δ - T - po 2 relationships, the dependence of electric conductivity at high temperature on δ was calculated. Also, the samples with various oxygen deficiencies were systematically prepared, based on the data of thermogravimetry. Variations of crystal structure and the electric conduction behavior at low temperature with δ were investigated by the measurements of X-ray diffraction, resistivity and Seebeck coefficient. As δ increased, the crystal system of BaBi 0.25 Pb 0.75 O 3 − δ changed from orthorhombic through tetragonal to pseudo-cubic. Increase of resistivity at room temperature by an order of about four was observed as δ increased, suggesting that the mobility of electron carriers decreased drastically with oxygen deficiency. This decrease of electron mobility was consistent with the relationship between the oxygen content and electrical conductivity of the sample at high temperature. Also consistent with the decrease of electron mobility was the decrease of overlapping of wave function with introduction of oxygen deficiency, assuming variable range hopping conduction at low temperature. Decrease of Fermi level with δ, observed by Seebeck coefficient measurement, also agreed with the decrease of electron mobility.

Characterization of crystal system of BaPb1-xBixO3 with X-ray diffraction for synchrotron radiation

Abstract Crystal symmetry and lattice constants of BaPb1−xBixO3 were analyzed by X-ray diffraction using synchrotron radiation as a light source. Measurements with high resolution could be carried out and crystal system of BaPb1−xBixO3 could be determined clearly. Monoclinic and orthorhombic symmetry were observed in the x range 0.5 ≦ x ≦ 1.0 and 0.0 ≦ x ≦ 0.5, respectively, showing agreement with the electrical conduction behavior and optical reflection property of BaPb1−xBixO3.

Oxygen nonstoichiometry of BaBiO3−δ

Dependence of oxygen deficiency of BaBiO 3-δ on temperature and oxygen partial pressure at a state of equilibrium was investigated by thermogravimetry. Two phases, one with 0.00 ≤ δ < 0.03 (phase I) and the other with 0.43 < δ ≤ 0.50 (phase II). and the first order phase transition between them was observed below 700°C, Besides the two phases, another phase (phase III) with 0.10 < δ < 0.20, which could be regarded as stable at high temperatures, appeared at 750°C. It was observed that the phase transitions of I⇔III and II⇔III are also first order. By increasing the temperature up to 800°C, the δ range of phase III increased to 0.06<δ<0.25. The eutectoid point, at which the three phases coexisted. was observed at a temperature of ∼710°C and an oxygen partial pressure of ∼10 -3 atm in the relationship between the temperature and the oxygen partial pressure at the two phase region. From the relationship. variations of enthalpy of phase transitions were calculated to be 170±35 kJ mol -1 , 190±20 kJ mol -1 and 80±5 kJ mol -1 for I→II, I→III and III→II, respectively.

The effect of oxygen nonstoichiometry of BaBi1 − xPbxO3 − δ on electrical conduction behaviour

Abstract The dependence of oxygen deficiency, δ, of BaBi 1 − x Pb x O 3 − δ on temperature, T , and oxygen partial pressure, P o 2 , was investigated by thermogravimetry. A linear relationship with proportionality constant about − 1 2 between log δ and log pO 2 observed for the specimens with x = 0.25, 0.5 and 0.75 suggested that effective concentration of electron carrier was independent of δ. The decrease of electrical conductivity with δ could be attributed to the decrease of electron mobility. From our thermogravimetry data, deduced were the decrease of valence state of Bi as δ increased and the localization of electrons generated from oxygen vacancy around Bi site, which agreed with the band diagrams which was proposed based on the results of photoelectron spectroscopy and X-ray absorption.

Reversible structural phase transition of BaPb0.75Bi0.25O3.00 around 360°C

Abstract The structural phase transition of superconducting BaPb 0.75 Bi 0.25 O 3.00 with stoichiometric oxygen composition was revealed by X-ray diffraction measurement and differential scanning calorimetry. X-ray diffraction revealed that the crystal symmetry of BaPb 0.75 Bi 0.25 O 3.00 was orthorhombic in the temperature range of 25°C ∼ 350°C while it was pseudo-cubic in the temperature range of 400°C ∼ 500°C. The volume expansion coefficient was calculated from the dependence of the lattice constants on temperature, which was 3.12 × 10 −5 K −1 between 25°C and 350°C and 3.75 × 10 −5 K −1 between 400°C and 500°C. Differential scanning calorimetry showed that the transition was reversible with a heat of transition of ∼200 J/mol which took place at 360 ± 3°C.