EFFECT OF FIRED AG ELECTRODES ON ELECTRICAL-PROPERTIES OF A PB[(ZN1 3NB2/3)(0.91)TI-0.09]O-3 SINGLE-CRYSTAL/

The dielectric constants and electromechanical coupling coefficients o f Pb[(Zn1/3Nb2/3)(0.91)Ti-0.09]O-3 (PZNT91/9) single crystals with dif ferent electrode materials have been investigated. Two types of electr odes, sputtered Au/Ti and fired Ag, were applied to single crystals of PZNT91/9, The dielectric constant K at room temperature was 8000 for samples with Au/Ti electrodes. However, the sample with fired Ag elect rodes had a lower K value of 1000. After electrical poling, the sample with Au/Ti electrodes had an electromechanical coupling coefficient k (t) of 52.7%, while the sample with fired Ag electrodes showed a relat ively high k(t) value of 61.4%, This could be the result of the large amount of mechanical stress in the fired Ag electrode, Spontaneous int rinsic polarization of the rhombohedral system may be reoriented paral lel or antiparallel along one particular direction because of the mech anical stress.