Structure and Electrical Properties of Lead-Free (Bi0.5Na0.5)TiO3-Ba(Sn,Ti)O3 Ceramics

Hexagonal Phase ◽

Lead Free ◽

Coupling Coefficients ◽

X Ray Diffraction ◽

Dense Microstructure ◽

Lead Free Ceramics

Lead-free (1-x)(Bi0.5Na0.5)TiO3–x(Na0.5K0.5)NbO3(x<0.1) ceramics have been prepared by the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all of the (Na0.5K0.5)NbO3diffuse into the lattice of (Bi0.5Na0.5)TiO3to form a solid solution and the hexagonal phase with a perovskite structure. The samples with a low content of (Na0.5K0.5) NbO3exhibit relatively good physical and electrical properties. For 0.96(Bi0.5Na0.5) TiO3–0.04 (Na0.5K0.5) NbO3ceramics, the electromechanical coupling coefficients of the planar modekpand the thickness modektreach 0.25 and 0.52, respectively, after sintering at 1100 °C for 5 h. The ratio of the thickness coupling coefficient to the planar coupling coefficient is 2.08. With suitable (Na0.5K0.5)NbO3concentration and sintering conditions, a dense microstructure and good electrical properties are obtained. Our results show that 0.96(Bi0.5Na0.5)TiO3–0.04(Na0.5K0.5)NbO3solid solution ceramics are promising lead-free ceramics for high-frequency electromechanical transducer applications.

Microstructure and Electrical Properties of Lead-Free (Na0.5K0.5)NbO3 - Bi0.5(Na0.97K0.03)0.5TiO3 Ceramics

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.368-370.760 ◽

2013 ◽

Vol 368-370 ◽

pp. 760-763

Author(s):

Chun Huy Wang ◽

Ming Qiu Wei

Keyword(s):

Electrical Properties ◽

Coupling Coefficient ◽

Coupling Coefficients ◽

X Ray Diffraction ◽

X Ray ◽

Dense Microstructure ◽

Dielectric And Piezoelectric Properties ◽

Thickness Mode

(Na0.5K0.5)NbO3 with Bi0.5(Na0.97K0.03)0.5TiO3 with x≤0.05 has been prepared by the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all the Bi(Na0.97K0.03)TiO3 diffuses into the lattice of (Na0.5K0.5)NbO3 to form a solid solution with a perovskite structure. A morphotropic phase boundary (MPB) between orthorhombic (O) and rhombohedral (R) was found at the composition 0.98(Na0.5K0.5)NbO3-0.02Bi0.5(Na0.97K0.03)0.5TiO3 [abbreviated as 0.98NKN-0.02BNKT] with correspondingly enhanced dielectric and piezoelectric properties. For 0.98NKN-0.02BNKT ceramics, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.33 and 0.49, respectively, after sintering at 1100 oC for 3 h. The ratio of the thickness coupling coefficient to the planar coupling coefficient is 1.48. With suitable Bi0.5(Na0.97K0.03)0.5TiO3 concentration, a dense microstructure and good electrical properties are obtained.

Physical and Electrical Properties of Lead-Free (Na0.5K0.5)NbO3-(Bi0.5Na0.5)TiO3 Ceramics

10.4028/www.scientific.net/amr.201-203.2772 ◽

2011 ◽

Vol 201-203 ◽

pp. 2772-2775

Author(s):

Chun Huy Wang

Keyword(s):

Solid Solution ◽

Electrical Properties ◽

Coupling Coefficient ◽

High Frequency ◽

Lead Free ◽

Coupling Coefficients ◽

Lead Free Ceramics ◽

Thickness Mode ◽

Lead-free (1-x)(Na0.5K0.5)NbO3-x(Na0.5Bi0.5)TiO3(x=0.02, 0.04, 0.06, 0.08, and 0.10) ceramics have been prepared by the conventional mixed oxide process. For 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3ceramics, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.33 and 0.62, respectively, after sintering at 1100°C for 5 h. The ratio of the thickness coupling coefficient to the planar coupling coefficient is 1.88. Our results show that 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3solid solution ceramics are promising lead-free ceramics for high-frequency electromechanical transducer applications.

Electrical and Physical Properties of Lead-Free (Na0.5K0.5)NbO3- Bi0.5(Na0.90K0.10)0.5TiO3 Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.602-603.791 ◽

2014 ◽

Vol 602-603 ◽

pp. 791-794

Author(s):

Chun Huy Wang

Keyword(s):

Solid Solution ◽

Dielectric Constant ◽

Coupling Coefficient ◽

Rhombohedral Phase ◽

Coupling Factor ◽

Lead Free ◽

Structure Changes ◽

Solid Solution System

Extending the investigations on (Na0.5K0.5)NbO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Na0.5K0.5)NbO3Bi0.5(Na0.90K0.10)0.5TiO3 [NKN-BNK. (Na0.5K0.5)NbO3 with 1 ~ 5 mol% Bi0.5(Na0.90K0.10)0.5TiO3 has been prepared following the conventional mixed oxide process. It can be concluded that the NKN-BNKT ceramics have orthorhombic structures in the case x 0.03. With increasing BNKT content (x=0.04 to 0.05), however, the structure changes from orthorhombic to rhombohedral phase. Above results demonstrated that the MPB between orthorhombic and rhombohedral phases exits in the solid solution with the BNKT content of x=0.03. At the MPB composition, the cryctalline structure of ceramics is considered to be a coexistence of orthorhombic and rhombohedral phase. Owing to the phase coexistence at the phase boundary, there exists a different symmetry regions (DSR) near the MPB. The DSR boundary motion increases the dielectric permittivity and piezoelectric coefficients. The electromechanical coupling factor and dielectric constant are higher for compositions near the MPB. The dielectric constant (KT33), planar coupling coefficient (kp), thickness coupling coefficient (kt) and piezoelectric constant (d33)of 0.98NKN-0.02BNKT ceramics were 1180, 30%, 58%, and 180, respectively.

Effect of Bi2O3 Addition on the Microstructure and Electrical Properties of Lead-Free (Na0.5K0.5)NbO3-Bi0.5(Na0.93K0.07)0.5TiO3 Ceramics

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.479-480.3 ◽

2013 ◽

Vol 479-480 ◽

pp. 3-7

Author(s):

Chun Huy Wang

Keyword(s):

Solid Solution ◽

Electrical Properties ◽

Lead Free ◽

Coupling Coefficients ◽

Electromechanical Transducer ◽

Lead Free Ceramics ◽

Thickness Mode ◽

In the present study, various quantities of Bi2O3were added into 0.98(Na0.5K0.5)NbO3-0.02Bi(Na0.93K0.07)TiO3(0.98NKN-0.02BNKT) ceramics. It was found that 0.98NKN-0.02BNKTwith the addition of 0~0.5 wt.% Bi2O3exhibit relatively good piezoelectric properties. For 0.98NKN-0.02BNKT ceramics, the electromechanical coupling coefficients of the planar modekpand the thickness modektreach 0.40 and 0.47,respectively. For 0.98NKN-0.02BNKT ceramics with the addition of 0.3 wt.% Bi2O3, the electromechanical coupling coefficients ofthe planar modekpand the thickness modektreach 0.50 and 0.53, respectively. It is obvious that 0.98NKN-0.02BNKT solid solution ceramics by adding low quantities of Bi2O3is one of the promising lead-free ceramics for electromechanical transducer applications.

Effect of Bi2O3 Addition on the Electrical and Physical Properties of Lead-Free 0.98(Na0.5K0.5)NbO3-0.02 Ba(Zr0.04Ti0.96)O3 Piezoelectric Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.434-435.413 ◽

2010 ◽

Vol 434-435 ◽

pp. 413-416 ◽

Cited By ~ 1

Author(s):

Chun Huy Wang

Keyword(s):

Coupling Coefficient ◽

Orthorhombic Phase ◽

Lead Free ◽

Coupling Coefficients ◽

X Ray Diffraction ◽

Sintering Aid ◽

X Ray ◽

Thickness Mode ◽

The 0.98(Na0.5K0.5)NbO3–0.02Ba(Zr0.04Ti0.96)O3 ceramics have been prepared following the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all of the Ba(Zr0.04Ti0.96)O3 diffuses into the lattice of (Na0.5K0.5)NbO3 to form a solid solution, in which a orthorhombic phase with a perovskite structure was found In order to improve the sinterability of the ceramics, Bi2O3 additions were used as a sintering aid. The electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.3 and 0.55, respectively, at the sintering of 1100oC for 5 h. For 0.98NKN-0.02BZT ceramics by doping 0.5 wt.% Bi2O3, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.21 and 0.57, respectively. The ratio of thickness coupling coefficient to planar coupling coefficient is 2.7.

Effect of Bi2O3 Addition on the Physical and Electrical Properties of Lead-Free (Na0.5Bi0.5)TiO3-Ba(Sn0.08Ti0.92)O3 Ceramics

10.4028/www.scientific.net/amr.415-417.1051 ◽

2011 ◽

Vol 415-417 ◽

pp. 1051-1054

Author(s):

Chun Huy Wang

Keyword(s):

Solid Solution ◽

Coupling Coefficient ◽

High Frequency ◽

Lead Free ◽

Coupling Coefficients ◽

Lead Free Ceramics ◽

Thickness Mode ◽

In the present study, various quantities of Bi2O3were added into 0.98(Na0.5Bi0.5)TiO3-0.02Ba(Sn0.08Ti0.92)O3(0.98NBT-0.02BST) ceramics. High-density samples were obtained through the addition of Bi2O3into 0.98NBT-0.02BST ceramic. It was found that 0.98NBT-0.02BST with the addition of 0~3.0 wt.% Bi2O3exhibit relatively good piezoelectric properties. For 0.98NBT-0.02BST ceramic with the addition of 2 wt.% Bi2O3, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.12 and 0.61, respectively, at the sintering of 1100oC for 3 h. The ratio of thickness coupling coefficient to planar coupling coefficient is 5.1. It is obvious that 0.98NBT-0.02BST solid solution ceramic by adding low quantities of Bi2O3is one of the promising lead-free ceramics for high frequency electromechanical transducer applications.

Dielectric and Piezoelectric Properties of Lead-Free (Na0.5K0.5)NbO3- Bi0.5(Na0.85K0.15)0.5TiO3 Ceramics

10.4028/www.scientific.net/amr.211-212.152 ◽

2011 ◽

Vol 211-212 ◽

pp. 152-155

Author(s):

Chun Huy Wang

Keyword(s):

Solid Solution ◽

Dielectric Constant ◽

Coupling Coefficient ◽

Dielectric And Piezoelectric Properties

Coupling Factor ◽

Lead Free ◽

Solid Solution System ◽

Extending the investigations on (Na0.5K0.5)NbO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Na0.5K0.5)NbO3–Bi0.5(Na0.85K0.15)0.5TiO3[NKN-BNKT]. (Na0.5K0.5)NbO3with 2 ~ 6 mol% Bi0.5(Na0.85K0.15)0.5TiO3has been prepared following the conventional mixed oxide process. A morphotropic phase boundary (MPB) between orthorhombic (O) and hexagonal (H) was found at the composition 0.96NKN-0.04BNKT with correspondingly enhanced dielectric and piezoelectric properties. The electromechanical coupling factor and dielectric constant are higher for compositions near the MPB. The dielectric constant (KT33), planar coupling coefficient (kp) and thickness coupling coefficient (kt)of 0.96NKN-0.04BNKT ceramics were 1273, 34% and 38%, respectively.

Electrical and Physical Properties of Lead-Free (Na0.5K0.5)NbO3- Bi0.5(Na0.93K0.07)0.5TiO3 Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.512-515.1351 ◽

2012 ◽

Vol 512-515 ◽

pp. 1351-1354

Author(s):

Chun Huy Wang

Keyword(s):

Solid Solution ◽

Dielectric Constant ◽

Coupling Coefficient ◽

Dielectric And Piezoelectric Properties

Coupling Factor ◽

Lead Free ◽

Solution System ◽

Solid Solution System ◽

Extending the investigations on (Na0.5K0.5)NbO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Na0.5K0.5)NbO3–Bi0.5(Na0.93K0.07)0.5TiO3 [NKN-BNKT]. (Na0.5K0.5)NbO3 with 2 ~ 6 mol% Bi0.5(Na0.93K0.07)0.5TiO3 has been prepared following the conventional mixed oxide process. A morphotropic phase boundary (MPB) between orthorhombic (O) and rhombohedral (R) was found at the composition 0.98NKN-0.02BNKT with correspondingly enhanced dielectric and piezoelectric properties. The electromechanical coupling factor and dielectric constant are higher for compositions near the MPB. The dielectric constant (KT33), planar coupling coefficient (kp) and thickness coupling coefficient (kt)of 0.98NKN-0.02BNKT ceramics were 1040, 47% and 48%, respectively.

Piezoelectric and Electrical Properties of Lead-Free (Na0.5K0.5)NbO3- Bi0.5(Na0.80K0.20)0.5TiO3 Ceramics

10.4028/www.scientific.net/amr.230-232.12 ◽

2011 ◽

Vol 230-232 ◽

pp. 12-15

Author(s):

Chun Huy Wang

Keyword(s):

Solid Solution ◽

Dielectric Constant ◽

Coupling Coefficient ◽

Dielectric And Piezoelectric Properties

Coupling Factor ◽

Lead Free ◽

Solution System ◽

Solid Solution System ◽

Extending the investigations on (Na0.5K0.5)NbO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Na0.5K0.5)NbO3–Bi0.5(Na0.80K0.20)0.5TiO3[NKN-BNKT]. (Na0.5K0.5)NbO3with 2 ~ 6 mol% Bi0.5(Na0.80K0.20)0.5TiO3has been prepared following the conventional mixed oxide process. A morphotropic phase boundary (MPB) between orthorhombic (O) and tetragonal (T) was found at the composition 0.97NKN-0.03BNKT with correspondingly enhanced dielectric and piezoelectric properties. The electromechanical coupling factor and dielectric constant are higher for compositions near the MPB. The dielectric constant (εr), planar coupling coefficient (kp) and thickness coupling coefficient (kt)of 0.97NKN-0.03BNKT ceramics were 1483, 32% and 31%, respectively.