Abstract
(Na0.8,K0.2)0.5Bi0.497Eu0.003TiO3 (NKBET20) piezoelectric ceramic powders were prepared by the solid-reaction method. The phase structures of the NKBET20 powders under various pressures were investigated by photoluminescence (PL) spectra and X-ray diffraction (XRD). The PL spectra of the doped Eu3+ ions suggest a pressure induced transformation from the tetragonal to rhombohedral phase (R phase), and the phase transformations were confirmed by XRD analyses. Furthermore, the fluorescence intensity ratio of the transition to the transition (FIR21) could be utilized for the quantitative analyses of the phase transformation. The results from the PL method show that as the pressure increases from 0 to 500 MPa, the fractions of the R phase of the NKBET20 powders increase from about 11% to 58%, while the fractions of the tetragonal phase (T phase) decrease from about 89% to 42%, which are consistent with the XRD Rietveld refinement. Unlike the ceramic bulks, the pressure induced phase transformation in the ceramic powders shows no obvious trigger point and is much gentler. This work suggests a different viewpoint to study the pressure induced phase transformation qualitatively and quantitatively, which can be used for more phase analyses.
Highlights
Piezoelectric material has been widely applied in numerous electromechanical devices
Reported that the piezoelectric coefficient decreases with increasing the mechanical pressures in the PbTiO3 -based piezoelectric ceramic, which was further explained by the pressure-induced depolarization [4]
When grinding, the influence of the mechanical pressure upon piezoelectric ceramic powders is vital in the X-ray diffraction analyses, as pressure induced phase transformation often occurs in the piezoelectric material
Summary
Piezoelectric material has been widely applied in numerous electromechanical devices. When grinding, the influence of the mechanical pressure upon piezoelectric ceramic powders is vital in the X-ray diffraction analyses, as pressure induced phase transformation often occurs in the piezoelectric material. As described above, mechanical pressures could induce phase transformations in piezoelectric materials. The PL spectra of Eu3+ ions were utilized for quantitative analyses of the phase structures of the (Na,K)0.5 Bi0.5 TiO3 :Eu piezoelectric materials in our earlier work [27]. We try to use the PL method for phase analyses in the pressure induced phase transformation In this contribution, we fabricated (Na0.8 ,K0.2 )0.5 Bi0.497 Eu0.003 TiO3 (NKBET20) piezoelectric ceramic powders by a solid reaction method, and investigated their phase structures under various pressures by PL spectra and XRD.
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