TiO2-nonstoichiometry dependence on piezoelectric properties and depolarization temperature of (Bi0.5Na0.5)0.94Ba0.06TiO3 lead-free ceramics |
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Authors: | XX Wang SW Or HLW Chan PCK Liu |
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Institution: | a Department of Applied Physics and Materials Research Centre, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong b ASM Assembly Automation Ltd., 4/F., Watson Centre, 16 Kung Yip Street, Kwai Chung, NT, Hong Kong |
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Abstract: | (Bi0.5Na0.5)0.94Ba0.06TixO1+2x lead-free piezoceramics with x varying from 0.97 to 1.03 were fabricated and characterized in order to investigate the effects of TiO2-nonstoichiometry on the piezoelectric properties and depolarization temperature of (Bi0.5Na0.5)0.94Ba0.06TiO3 composition. X-ray diffraction (XRD) analysis showed that all samples have a single phase of perovskite structure with rhombohedral symmetry. Piezoelectric and dielectric measurements revealed that deficiency of TiO2 leads to an increase in the piezoelectric coefficient (d33), free relative permittivity (), and loss tangent (tan δ) besides an increase in the electromechanical coupling coefficient (kp) within a certain amount, while excess of TiO2 results in a decrease in kp, d33, and , but an increase in tan δ. Depolarization temperature (Td) measurement indicated a decrease and an increase in Td as a result of increasing TiO2 deficiency and TiO2 excess, respectively. This TiO2-nonstoichiometry also induced changes in the remanent polarization (Pr) and coercive field (Ec) of the ceramics. |
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Keywords: | 77 22 &minus d 77 80 Bh 77 84 Dy |
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