Relaxor Phase Evolution of (Bi0.5Na0.5-xKx)TiO3 Ceramics due to K Ion Substitution and Their Corresponding Electrical Properties

We synthesized lead-free piezoelectric (Bi0.5Na0.5-xKx)TiO3 (BNKT) ceramics using a conventional solid-state reaction method. We have investigated the structural and electrical properties of the materials with x = 0.05 to 0.40. The X-ray diffraction (XRD) analysis suggests that the BNKT ceramics sho...

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Published in:Energies (Basel) 2020-01, Vol.13 (2), p.455
Main Authors: Cho, Sam Yeon, Kim, Eun-Young, Kim, Sun Yong, Pham, Thuy Linh, Han, Jin Kyu, Song, Da Som, Jung, Ha-Kyun, Lee, Jong-Sook, An, Ki-Seok, Lim, Jongsun, Bu, Sang Don
Format: Article
Language:English
Subjects:
bnt-based ceramics
Ceramics
Composition effects
Dielectric properties
Dielectric relaxation
Electric fields
Electrical properties
Ferroelectrics
Frequency dependence
Lead free
Phase transitions
piezoelectrics
polar nano-regions
Polyvinyl alcohol
relaxor ferroelectrics
Relaxors
Substitution reactions
Temperature
Thermal energy
X-ray diffraction
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Summary:We synthesized lead-free piezoelectric (Bi0.5Na0.5-xKx)TiO3 (BNKT) ceramics using a conventional solid-state reaction method. We have investigated the structural and electrical properties of the materials with x = 0.05 to 0.40. The X-ray diffraction (XRD) analysis suggests that the BNKT ceramics show the transition from rhombohedral to tetragonal structure. The ratio of the tetragonal structure increased continuously in accordance with the increasing composition of x. The sample of x = 0.10 showed a similar ratio between the tetragonal and rhombohedral structures. Frequency-dependent dielectric measurements showed a sort of relaxor properties emerged with increasing x composition, this effect may be interpreted in terms of the formation of polar nano-regions (PNRs) in samples. The value of remnant polarization (Pr) decreases rapidly as x increases beyond the point of x = 0.10 from 25.3 μC/cm2 to 5.9 μC/cm2. On the contrary, as for inverse piezoelectric coefficient (d33*), a higher value of d33* (336 pm/V) at x = 0.10, was observed when compared with x = 0.05 (d33* = 51 pm/V). These results can be explained by the formation of PNRs and their variations with the external applied field. We here propose a possible mechanism showing the effects of dipolar defects, which can be resulted from the K ion substitution on (Bi,Na)TiO3 (BNT) ceramics.
ISSN:1996-1073
1996-1073
DOI:10.3390/en13020455