Tungsten Trioxide Electric Transport Ⅱ

In the research for electrical transport of BaWO4 in that under high pressure, we use the insulation spacer technology to prevent the introduction of additional impedance of error in the experiment, which in order to obtain more accurate data. We obtain the pressure-induced relaxation phenomena and activation energy by studying the crystal grain boundary effects and measuring high voltage of BaWO4 impedance with spectroscopy with DAC surface use in integrated microcircuit.

 When semi-circular impedance gets together and the resistance is large, the effect of lead inductance is small to BaWO4 polycrystalline powder sample. However, not all the experiments can measure a clear semi-circular, and some will be in the high frequency region, which can show incomplete semi-circular and in the low frequency region is compressed to show semi-circular. With the improvements of measure technology, we can clearly see a semicircular arc in the high frequency region and low frequency.

Grain resistance and grain boundary resistance can be fitted by a semicircle, which intercepts the resistance in size. With the pressure of the grain boundary resistance is different from the pressure-induced changes in grain resistance changes. In fact, most of changing is made from high pressure. Grain resistance and grain boundary resistance with discontinuous change in pressure indicates changes in the electrical transport properties, reflecting the pressure-induced structural phase transition.

In the phase transition, the type Freckle and Scotty defects increase, this is due to atomic thermal process enthalpy fluctuations caused by excitation induced phase transformation. From 6.9 to 8.9GPa, grains have a relaxation frequency increasing trend; this trend with the previous direction of movement of the relaxation peak is consistent. This is due to the different phases within the structure of the grain extraordinary relaxation frequency. Because in this pressure range, there is scheelite, fergusonite and BaWO4-II phase appear, phase has a shorter relaxation time.

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