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

2013 ◽  
Vol 368-370 ◽  
pp. 760-763
Author(s):  
Chun Huy Wang ◽  
Ming Qiu Wei

(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.

2010 ◽  
Vol 434-435 ◽  
pp. 409-412 ◽  
Author(s):  
Chun Huy Wang

In this paper, the effect of Mn2O3 additions on the electrical and physical properties of 0.98(Na0.5Bi0.5)TiO3 -0.02Ba(Sn0.08Ti0.92)O3 was investigated. X-ray diffraction analysis revealed that, during sintering, all of the Ba(Sn,Ti)O3 diffuse into the lattice of (Na0.5Bi0.5)TiO3 to form a solid solution, in which a hexagonal phase with a perovskite structure was found. The 0.98(Na0.5Bi0.5)TiO3 -0.02Ba(Sn0.08Ti0.92)O3 [0.98NBT-0.02BST] ceramics with the addition of 0~4.0 wt% Mn2O3 have been prepared following the conventional mixed oxide process. For 0.98NBT-0.02BST ceramics by doping 1.0 wt% Mn2O3, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.12 and 0.52, respectively, at the sintering of 1100 oC for 3 h. The 0.98NBT-0.02BST ceramic with 1 wt% Mn2O3 addition exhibit a more homogeneous and grain size of ~3.5 μm. With suitable Mn2O3 doping, a dense microstructure and good piezoelectric properties were obtained.


2010 ◽  
Vol 434-435 ◽  
pp. 413-416 ◽  
Author(s):  
Chun Huy Wang

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.


2010 ◽  
Vol 148-149 ◽  
pp. 232-235 ◽  
Author(s):  
Chun Huy Wang

Extending the investigations on (Bi0.5Na0.5)TiO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Bi0.5Na0.5)TiO3-Ba(Sn,Ti)O3. X-ray diffraction analysis revealed that, during sintering, all of the Ba(Sn,Ti)O3 diffuses into the lattice of (Bi0.5Na0.5)TiO3 to form a solid solution, in which a rhombohedral phase with a perovskite structure was found. It was found that the samples with a low content of Ba(Sn0.06Ti0.94)O3 exhibit relatively good physical and electric properties. For 0.98(Bi0.5Na0.5)TiO3-0.02Ba(Sn0.06Ti0.94)O3 ceramics, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.16 and 0.57, respectively, at the sintering of 1100oC for 3 h. The ratio of thickness coupling coefficient to planar coupling coefficient is 3.56. For 0.98(Bi0.5Na0.5)TiO3-0.02Ba(Sn0.06Ti0.94)O3 ceramics, the relative density and the thickness coupling coefficient kt reach 98.1% and 0.58, respectively, at the sintering of 1100oC for 5 h. With suitable Ba(SnxTi1-x)O3 concentration and sintering condition, a dense microstructure and good electrical properties were obtained.


2011 ◽  
Vol 687 ◽  
pp. 348-353
Author(s):  
Chun Huy Wang

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.


2011 ◽  
Vol 393-395 ◽  
pp. 72-75
Author(s):  
Chun Huy Wang

In this paper, (Na0.5Bi0.5)TiO3 -based solid solutions were studied to improve piezoelectric properties as those found in the PbZrO3-PbTiO3 (PZT)-based ceramics. The 0.98(Na0.5Bi0.5)TiO3 -0.02Ba(Sn0.08Ti0.92)O3 (0.98NBT-0.02BST) ceramics with the addition of 0~2.0 wt.% Nb2O5 have been prepared following the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all of the Ba(Sn0.08Ti0.92)O3 diffuse into the lattice of (Na0.5Bi0.5)TiO3 to form a solid solution, in which a hexagonal phase with a perovskite structure was found. For 0.98NBT-0.02BST ceramics with the addition of 0.5 wt.% Nb2O5, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.12 and 0.28, respectively, at the sintering of 1100oC for 3 h. The ratio of thickness coupling coefficient to planar coupling coefficient is 2.3. It is obvious that 0.98NBT-0.02BST ceramics by adding low quantities of Nb2O5 are one of the promising lead-free ceramics for high frequency electromechanical transducer applications.


2014 ◽  
Vol 1061-1062 ◽  
pp. 83-86
Author(s):  
Hong Wu ◽  
De Yi Zheng

In this paper, the effects of different sintering temperature on the microstructure and piezoelectric properties of Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3(PNZZT) ceramic samples were investigated. The Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3 ceramics materials was prepared by a conventional mixed oxide method. In the period of the experiment, the relationship between crystallographic phase and microstructure were analyzed by X-ray diffraction(XRD) and scanning electron microscopy(SEM) respectively. The XRD patterns shows that all of the ceramic samples are with a tetragonal perovskite structure. Along with sintering temperature increased and the x is 0.03, the grain size gradually become big. Through this experiment, it has been found that when the x is 0.03 and sintered at 1130°C for 2 h, the grains grow well, the grain-boundary intersection of the sample combined well and the porosity of the ceramics decreased, an excellent comprehensive electrical properties of the Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3 samples can be obtained. Its best electrical properties are as follows: dielectric constant (ε) is 1105, dielectric loss(tg) is 0.017, electromechanical coupling coefficient (Kp) is 0.287, piezoelectric constant(d33) is 150PC/N


2013 ◽  
Vol 479-480 ◽  
pp. 3-7
Author(s):  
Chun Huy Wang

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.


2011 ◽  
Vol 130-134 ◽  
pp. 883-886
Author(s):  
Chun Huy Wang

In this paper, the effects of Ta2O5addition on the electrical and physical properties of 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3were investigated. The 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3[0.98NKN-0.02NBT] ceramics with the addition of 0~0.5 wt% Ta2O5have been prepared following the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all of the (Na0.5Bi0.5)TiO3diffuse into the lattice of (Na0.5K0.5)NbO3to form a solid solution, in which a orthorhombic phase with a perovskite structure was found. For 0.98NKN-0.02NBT ceramics by doping 0.1 wt% Ta2O5, the poled dielectric constant (K33T) is 1090. The electromechanical coupling coefficients of the planar modekpand the thickness modektreach 0.39 and 0.48, respectively. Our results show that 0.98NKN-0.02NBT with the addition of 0.1 wt% Ta2O5is a good lead-free piezoelectric ceramic.


2011 ◽  
Vol 415-417 ◽  
pp. 1051-1054
Author(s):  
Chun Huy Wang

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.


2011 ◽  
Vol 687 ◽  
pp. 269-274
Author(s):  
Chun Huy Wang

In this paper, the effects of Nb2O5addition on the electrical and physical properties of 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3were investigated. The 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3[0.98NKN-0.02NBT] ceramics with the addition of 0~1.5 wt% Nb2O5have been prepared following the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all of the (Na0.5Bi0.5)TiO3diffuse into the lattice of (Na0.5K0.5)NbO3to form a solid solution, in which an orthorhombic phase with a perovskite structure was found. For 0.98NKN-0.02NBT ceramics by doping 0.3 wt% Nb2O5, the poled dielectric constant (K33T) is 1180. The electromechanical coupling coefficients of the planar modekpand the thickness modektreach 0.43 and 0.52, respectively. Our results show that 0.98NKN-0.02NBT with the addition of 0.3 wt% Nb2O5is a good lead-free piezoelectric ceramic.


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