The effect of artificial stress on Er³⁺ doped perovskite lead-free piezoceramics

Generally speaking, the change of the composition and temperature would affect the optical properties of rare earth element doped ferroelectric materials. Besides, the factors during the preparation or post-treatment process of materials such as the stress, the external field and so forth could cause influence on the phase structure of rare earth element doped ferroelectric materials and further affect its macroscopic properties. An obvious variation of Up-conversion emission spectra was observed in Er³⁺ doped (Li,K,Na)NbO₃ ceramics by adjusting the cooling down speed of the sintering process. X-ray diffraction analysis evidently indicated the phase structure evolution from tetragonal phase to orthorhombic with the increase of cooling down speed. Meantime, the enhanced Up-conversion emission intensity was closely related with the favored formation of the orthorhombic phase induced by the stress during the cooling down process.