92.
The effects of sintering additives on photostriction properties have been rarely reported and the polarization effect of KNN-based ceramics on the photostriction characteristics remains uncertain. In the present work, a highly feasible approach has been adopted to obtain improved photostrictive coefficient (
α = 2.4 × 10
?9 m
2/W) for KNN-based ceramics by adding appropriate amount (
x = 0.5 wt%) of MnO
2 as sintering additives into 0.97(K
0.5Na
0.5)NbO
3-0.03(La
0.51Na
0.49)(Zr
0.54Ni
0.46)O
3 (97KNN-3LNNZ) ceramics. The appropriate amount of MnO
2 (
x ≤ 0.5 wt%) in the ceramics does not alter the inherent multi-phase structure and results in uniform grain growth of the ceramics. The ferroelectricity and piezoelectricity can be optimized by the “softening” effect of Mn
2+ and Mn
3+ in KNN-based ceramics. The addition of MnO
2 increases energy band gap and also optimizes the optical absorption properties in the near-infrared band. 97KNN-3LNNZ+0.5 wt% MnO
2 ceramics show optimum overall performance. In addition to this, for
x = 0.5 wt% sample, the power-dependent Raman spectra of ceramics measured before and after the electrical poling shows that the prior E-field poling can enhance the red shift corresponding to F
2g bending vibration mode. Subsequently, there are changes in bond angle of elements induced by light in oxygen octahedron. These phenomena play active roles in getting a deep understanding of the underlying mechanisms of photostriction for ferroelectric ceramics.
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