Effect of fired Ag electrodes on electrical properties of a Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 single crystal

The dielectric constants and electromechanical coupling coefficients of Pb[(Zn1/3Nb2/3)(0.91)Ti-0.09]O-3 (PZNT91/9) single crystals with different electrode materials have been investigated. Two types of electrodes, 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 electrodes 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 relatively 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 intrinsic polarization of the rhombohedral system may be reoriented parallel or antiparallel along one particular direction because of the mechanical stress.