Of Ybco The Redox Reaction And Their Electrical Properties

Both redox reaction and electricity properties of YBa2Cu3O7-x were investigated. The oxygen desorption activation energy of YBaaCusO7-x was obtained by different heating rates and the relationship between resistivity of YBa2Cu3O7-x and oxygen pressure was measured. YBa2Cu3O7-x thick films were also prepared by Sol-gel and PMP methods and their sensitivity for oxygen was studied.The measurement of oxygen desorption activation energy by thermogravimetry (TG) and differential thermogravimetry (DTG) curves with different heating rates shows clear evidences that the behavior of TG, DTG, and desorption activation energy have some relations with the oxygen stoichiometry of the specimeri when temperature changes from 500C to 800C. In the orthorhombic phase, the desorption activation energy has an obvious increase with the increase of temperature, while it varies smoothly in the tetragonal phase as the temperature increases.The resistivity of the high temperature superconducting material YBa2Cu3O7_x as a function of oxygen pressure in the range of 400C-850C for bulk samples was studied. It shows mat YBa2Cu3O7.x has a strong selectivity for oxygen. The resistivity decreases very rapidly with the increasing of oxygen partial pressure and reaches its equilibrium value in a short time. When the oxygen partial pressure decreases, the resistivity of YBa2Cu3O7-x increases slowly and a quite long time is need to keep balance.The sample prepared by Sol-gel way shows higher density than samples achieved by other ways. Measurement of thick film's sensitivity for oxygen in different temperature is also performed. It shows that the sensitivity to oxygen pressure increases with the increase of temperature and reaches a maximum value 62 at 650C. The experiments also show that the responding speed of the thick film is improved and it has better properties than bulk samples and the YBCO film may be as a new oxygen sensor material in practical application.