Abstract Piezoelectric materials are considered an enabling technology generating an annual turno... more Abstract Piezoelectric materials are considered an enabling technology generating an annual turnover of about 20 billion $. At present, lead-based materials dominate the market with the known risk to health and environment. One of the three key competitors for their replacement is the class of sodium bismuth titanate (NBT)-based relaxor ferroelectrics, the use of which is limited by thermal depolarization. An increased thermal stability has recently been experimentally demonstrated for composites of Na 1/2 Bi 1/2 TiO 3 -6BaTiO 3 with ZnO inclusions (NBT-6BT: x ZnO). However, the exact mechanism for this enhancement still remains to be clarified. In this study, piezoresponse force microscopy and 23 Na NMR spectroscopy were used to demonstrate that the incorporation of ZnO leads to a stabilization of the induced ferroelectric state at room temperature. Temperature-dependent measurements of the relative dielectric permittivity e′(T) , the piezoelectric coefficient d 33 and the strain response revealed an increase of the working temperature by 37 °C. A simple mechanics model suggests that thermal deviatoric stresses stabilize the ferroelectric phase and increase, as well as broaden, the temperature range of depolarization. Our results reveal a generally applicable mechanism of enhancing phase stability in relaxor ferroelectric materials, which is also valid for phase diagrams of other ceramic matrix composites.
ABSTRACT In this investigation, a simple compound (1 - x)(Bi0.5Na0.5)TiO3-xKNbO(3) (BNT-xKN, x=0-... more ABSTRACT In this investigation, a simple compound (1 - x)(Bi0.5Na0.5)TiO3-xKNbO(3) (BNT-xKN, x=0-0.08) lead-free ceramics were synthesized successfully by conventional solid state reaction method. The piezoelectric, dielectric and ferroelectric characteristics of the ceramics were investigated and discussed. The results shows that moderate KN addition can enhance the piezoelectric response without an obvious decline of ferroelectric properties. The largest piezoelectric response is obtained in BNT-0.05KN, whereas largest electric-field-induced strain is obtained in BNT-0.06KN. An effective d(33)(eff) of similar to 400 pC/N calculated from electric-field-induced strain is obtained in BNT-0.06KN. The present investigation demonstrates that addition KN effectively reduces the depolarization temperature of the BNT-xKN ceramics. The electrical properties of the ceramics are tightly related to their depolarization temperature.
Abstract Piezoelectric materials are considered an enabling technology generating an annual turno... more Abstract Piezoelectric materials are considered an enabling technology generating an annual turnover of about 20 billion $. At present, lead-based materials dominate the market with the known risk to health and environment. One of the three key competitors for their replacement is the class of sodium bismuth titanate (NBT)-based relaxor ferroelectrics, the use of which is limited by thermal depolarization. An increased thermal stability has recently been experimentally demonstrated for composites of Na 1/2 Bi 1/2 TiO 3 -6BaTiO 3 with ZnO inclusions (NBT-6BT: x ZnO). However, the exact mechanism for this enhancement still remains to be clarified. In this study, piezoresponse force microscopy and 23 Na NMR spectroscopy were used to demonstrate that the incorporation of ZnO leads to a stabilization of the induced ferroelectric state at room temperature. Temperature-dependent measurements of the relative dielectric permittivity e′(T) , the piezoelectric coefficient d 33 and the strain response revealed an increase of the working temperature by 37 °C. A simple mechanics model suggests that thermal deviatoric stresses stabilize the ferroelectric phase and increase, as well as broaden, the temperature range of depolarization. Our results reveal a generally applicable mechanism of enhancing phase stability in relaxor ferroelectric materials, which is also valid for phase diagrams of other ceramic matrix composites.
ABSTRACT In this investigation, a simple compound (1 - x)(Bi0.5Na0.5)TiO3-xKNbO(3) (BNT-xKN, x=0-... more ABSTRACT In this investigation, a simple compound (1 - x)(Bi0.5Na0.5)TiO3-xKNbO(3) (BNT-xKN, x=0-0.08) lead-free ceramics were synthesized successfully by conventional solid state reaction method. The piezoelectric, dielectric and ferroelectric characteristics of the ceramics were investigated and discussed. The results shows that moderate KN addition can enhance the piezoelectric response without an obvious decline of ferroelectric properties. The largest piezoelectric response is obtained in BNT-0.05KN, whereas largest electric-field-induced strain is obtained in BNT-0.06KN. An effective d(33)(eff) of similar to 400 pC/N calculated from electric-field-induced strain is obtained in BNT-0.06KN. The present investigation demonstrates that addition KN effectively reduces the depolarization temperature of the BNT-xKN ceramics. The electrical properties of the ceramics are tightly related to their depolarization temperature.
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Papers by Xijie Jiang