Glass transition temperature(Tg) of 20BaO·10Fe2O3·xWO3·(70−x)V2O5 glasses showed a step-by-step increase from 339 to 470°C when x was increased from 0 to 50, together with a concordant increase in crystallization temperature(Tc) from 406 to 531°C. Plot of Tg against quadrupole splitting(Δ) of FeIII in the Mössbauer spectra yielded a straight line with a slope of 680K(mm s−1)−1. This indicates that FeIII atoms constitute distorted FeO4 tetrahedra and play a role of network former in the 3D-glass network. Dissolution of vanadium ions from vanadate glass into boiling water was suppressed from 34 to 2mg L−1 when x was modified from 0 to 50, reflecting that introduction of WO3 into the 3D-network of vanadate glass is effective in the improvement of water resistivity. A gradual decrease of Δ was observed from 0.82 to 0.76mm s−1 after isothermal annealing of vanadate glass(x＝20) at 500°C for 240min, indicating structural relaxation of the glass network, and a marked increase in conductivity (σ) from 3.9×10−6 to 2.1×10−3 S cm−1 was observed at room temperature.
A compact accelerator mass spectrometry(AMS) system was installed at Yamagata University in 2010 with the aim of developing technologies for the radiocarbon dating of environmental samples and microdosing clinical tests using radiocarbon. With the installation of this AMS system, we also installed a new automatic sample preparation system comprising an elemental analyzer(EA), an isotope ratio mass spectrometer(IRMS), and a glass vacuum line(GVL). This automatic system can automatically collect CO2 from samples, measure the stable isotope ratio, quantify the amount of CO2 and H2 introduced for reduction, and treat 20 samples in approximately 12.5hrs, thus enabling the preparation of 60 samples per week.