Yuseong gu, South Korea
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Dung D.D.,Sudan University of Science and Technology | Thiet D.V.,University of Ulsan | Quyet N.V.,Hanautech Co. | Bac L.H.,Optics 1 | Cho S.,University of Ulsan
Materials Transactions | Year: 2015

Lead-free ceramics of composition (0.97 - x)Bi0.5Na0.4K0.1TiO3-0.03BiAlO3-xBi0.5Li0.5TiO3 (BNKTBA-xBLTO) were synthesized using solid state technique. The strong enhancements in ferroelectric and electric-field-induced strain were obtained. The electric-field-induced strain values were increased from 410pm/V to 688pm/V for 6 mol% BLTO-added which results from the phase transition from rhombohedral to tetragonal structure. The maximum spontaneous polarization increased from 26.5 μC/cm2 to 30.8 μC/cm2 for 4 mol% BLTO solid solution in BNKTBA and then decreased as BLTO was further added. We expect that this work could be helpful for further understanding the original enhancement in electrical field-induced strain in lead-free BNKT-based ceramics due to comparison between A- and B-site co-modifications. © 2015 The Japan Institute of Metals and Materials.

Quan N.D.,Hanoi University of Science and Technology | Hung V.N.,Hanoi University of Science and Technology | Van Quyet N.,Hanautech Co. | Chung H.V.,Vietnam Academy of Science and Technology | Dung D.D.,Sudan University of Science and Technology
AIP Advances | Year: 2014

We report on the reduction of band gap in Bi0.5(Na 0.82-xLixK0.18)0.5(Ti 0.95Sn0.05)O3 from 2.99 eV to 2.84 eV due to the substitutions of Li+ ions to Na+ sites. In addition, the lithium substitution samples exhibit an increasing of the maximal polarizations from 21.8 to 25.7 μC/cm2. The polarization enhancement of ferroelectric and reduction of the band gaps are strongly related to the Li substitution concentration as evaluated via the electronegative between A-site and oxygen and tolerance factor. The results are promising for photovoltaic and photocatalytic applications. © 2014 Author(s).

Quan N.D.,Sudan University of Science and Technology | Quyet N.V.,Hanautech Co. | Bac L.H.,Sudan University of Science and Technology | Thiet D.V.,Sudan University of Science and Technology | And 2 more authors.
Journal of Physics and Chemistry of Solids | Year: 2015

We reported the role of A-site modification on the structural, ferroelectric, optical and electrical field-induced strain properties of Bi0.5(Na0.78K0.22)0.5Ti0.97Zr0.03O3 lead-free piezoceramics. The Li+ ions with concentration from 0 to 5 mol% were used to substitute at A-site. There was no phase transition when Li+ ions was added up to 5 mol%. The electric field-induced strain (Smax/Emax) values increased from 600 to 643 pm/V for 2 mol% Li+-added which results from distortion both rhombohedral and tetragonal phase structures. The band gap reduced from 2.88 to 2.68 eV and the saturation polarization decreased from 46.2 to 26.1 μC/cm2 when Li+ ions concentration increased from 0 to 5 mol% respectively. We expect that this work could be helpful for further understanding the role of A-site dopants in comparison with B-site modification in lead-free Bi0.5(Na,K)0.5TiO3-based ceramics. © 2014 Elsevier Ltd. All rights reserved.

Dung D.D.,Sudan University of Science and Technology | Van Quyet N.,Hanautech Co. | Bac L.H.,Optics 1
Ferroelectrics | Year: 2015

The effect of sintering temperature on the giant electric field-induced strain was observed in lead-free Bi0.5(Na0.77 Li0.05K0.18)0.5(Ti0.975Ta0.025)O3 ceramics. The grains size and dense structure increased with increasing of the sintering temperature. The growth of polar phases was observed in non-polar phase when sintering temperature increased. The giant electric field-induced strain strongly enhanced up to Smax/Emax = 800 pm/V, resulting from coexistence of polar and non-polar phases. The highest values of Smax/Emax were higher than those were previously reported on non-textured lead-free piezoelectric ceramics. Copyright © Taylor & Francis Group, LLC.

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