Tungsten Trioxide Electric Transport Ⅲ

In the phase of transition, the pressure reduces the height of the barrier, and it is easier for the electric charge to pass through fergusonite and BaWO4-II,which reduces the relaxation time. Average relaxation time leads to an increase of total relaxation frequency, which also represents an increase of relaxation frequency response characteristic. The pressure ranges from 2.6 to 6.9GPa activate and the grain boundary can be -9.09meV / Pa, which shows active energy with increasing pressure and a decreasing trend for grain boundaries BaWO4 powder sample.

From 6.9 to 8.9GPa, grain boundary activation energy also shows a downward trend, which reduces the rate pressure range is much larger than 2.6-6.9GPa. Activation energy of grain boundaries is described as change of the pressure in the pressure range 2.6-8.9GPa interval. The pressure of activation can play the role of a negative contribution. When the pressure exceeds 8.9GPa, the boundary activation energy conversely grains as the pressure increases. This shows that in the 8.9-13.7GPa pressure range, the pressure on activation energy changes were positive contribution to the role, and the charge carriers conducting are more difficult. More than 13.7GPa, the active energy pass through easily with the pressure decreases.

We can find that impedance spectra arc described grain structure in 7GPa phase transition, which occurs in grains, then the transition to the grain boundaries. Changes in the grain and grain boundary relaxation frequency are caused by a structural phase transition. Within 6.9-8.9GPa pressure range, grain boundary activation energy can play a role in the negative contribution; the charge carries more easily through the grain boundaries. In addition, within 6.9-8.9GPa, rising grain and grain boundary relaxation frequency also shows that the relaxation process takes less time during the phase transition. Therefore, we can obtain the DC resistivity and AC impedance spectroscopy methods combine with synchrotron radiation X-ray diffraction methods .we can analyze the material from hyperbaric and gain nakedness WO3, variation and electrical properties and structure of BaWO4.

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