Abstract
Degradation effects in piezoelectric multilayer ceramic (PZT – PML) have been investigated by optical microscopy and Raman spectroscopy. Optical microscopy with dark field revealed that black color points were existed in PZT – PML after conducted by HALT – test. These black color points existed intensively in PZT layer near the negative electrode of PZT – PML. Moreover, we have investigated these black color points by Raman spectroscopy. The Raman spectra of the black color points show some difference compared with Raman spectra at normal colored area. The black color points shows the increase of relative intensity ratio E(2TO)/E+B1 mode and simultaneously the decrease of relative intensity ratio A1(3TO)/E+B1 mode. These changes of peak intensity have discussed with structural change.
