Dielectric properties of (Ba _0.6Sr _0.4)(Cu _1/3Nb _2/3)O ₃ system

This study reports the mechanism for the enhancement of resistivity in the (Ba _xSr _1-x)(Cu _1/3Nb _2/3)O ₃ system. In previous investigations, it has been found that the resistivity of this system decreases significantly with increasing temperature and applied electric field which inhibits the measurement of dielectric properties. The decrement in the resistivity was associated with the eutectic transformation from cuprous to cupric oxide, which occurs in the vicinity of 1075°C at a partial pressure of 0.21 atm of O ₂ during sintering. It was found that by decreasing the sintering temperature to 975°C by addition of ZnO and B ₂O ₃, the resistivity of the system increases by 2 orders of magnitude. The stability under the applied field and temperature is also enhanced permitting the dielectric measurement. The dielectric constant and loss measurement as a function of temperature confirmed that this system has high Curie temperature of more than 600° C.