The electrical transport properties of nanocrystalline tungsten trioxides(WO3)under high pressures have been investigated by various electrical measurements up to36.5Gpa.The discontinuous changes in Direct-current resistivity under high pressures result from two electronic phase transitions at 4.3 and 10.5 GPa and two structural phase transitions at 24.8 and 31.6 GPa. Hall-effect measurement shows that the nanocrystalline W03 is n-type semiconductor within the whole investigated pressure range.The carrier concentration decreases monotonously with increasing pressure,but mobility increase first and then decreases at 10.4 GPa.Through Alternate-current impedance measurement,it can be found that the variation of the ratio of grain boundary resistance to grain resistance synchronizes with that of the mobility under high pressures, indicating that the grain boundary plays morein the carrier resistance and transport relaxation process of nanocrystalline W03.The discontinuous frequency of grain and grain boundary also provide the import role changes of evidence for electronic phase transitions.
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