The effects of alternating current poling(ACP)at 80℃on electrical properties of[001]-oriented 0.72 Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.28PbTiO_(3)(PMN-28PT)single crystals(SCs)have been investigated.The square-wave ACP SCs p...The effects of alternating current poling(ACP)at 80℃on electrical properties of[001]-oriented 0.72 Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.28PbTiO_(3)(PMN-28PT)single crystals(SCs)have been investigated.The square-wave ACP SCs poled at high voltage(HV,5 kV_(rms)/cm)occasionally showed large fluctuations and low opposite values of piezoelectric coefficient(d_(33)=±1370 pC/N)in one plate.This revealed spuriousmode vibrations(SMV)of impedance spectrum.However,after depolarizing and repolarizing the sample with a sine-wave ACP at low voltage(LV,3.5 kV_(rms)/cm),the d_(33) enhanced to be 1720 pC/N(+26%)and did not exhibit large fluctuation or opposite values in one plate any more.The impedance spectrum became clean and the abnormal SMV disappeared.We proposed four possible mechanisms of the SMV,and speculate that the main cause maybe by macro-scale sub-domain structure and/or phase change in the main domain structure and/or phase in the SC plate due to the specific poling conditions not eternal mechanical damage of PMN-PT SCs.This study will be useful to realize a high d_(33) and improve other properties of PMN-PT ACP SC ultrasonic transducers without any SMV for high-frequency medical imaging equipment.展开更多
A morphotropic phase boundary(MPB)with temperature-independent behavior,the so-called vertical MPB was investigated in lead-free(K,Na,Li)NbO_(3)–BaZrO_(3)–(La,Na)TiO_(3)ternary ceramic system.The specimens were synt...A morphotropic phase boundary(MPB)with temperature-independent behavior,the so-called vertical MPB was investigated in lead-free(K,Na,Li)NbO_(3)–BaZrO_(3)–(La,Na)TiO_(3)ternary ceramic system.The specimens were synthesized by a conventional solid-state reaction method,and their crystal structures as well as their MPB were determined from X-ray diffraction patterns measured from room temperature to 300℃.The vertical MPB composition was determined to be 0.9025(K_(0:45)Na0:5Li_(0:05))NbO_(3)–0.09BaZrO_(3)–0.0075(La,Na)TiO_(3)and the Curie temperature was found to be about 195℃.It was successfully confirmed that ceramic samples of this system could be sintered in a reducing atmosphere.For lead-free piezoceramic applications of multilayer actuators using Ni inner electrodes,the results obtained in this work have important practical implications.展开更多
Lead-free piezoelectric thin films of 0.055BaZrO_(3)–0.935(K_(0.45)Na_(0.5)Li_(0.05))NbO_(3)–0.01(Bi_(0.5)Na_(0.5))TiO_(3)(BZ–KNLN–BNT)were fabricated on(100)-LaNiO_(3)/SiO_(2)/Si substrates.The Pechini(polymeric ...Lead-free piezoelectric thin films of 0.055BaZrO_(3)–0.935(K_(0.45)Na_(0.5)Li_(0.05))NbO_(3)–0.01(Bi_(0.5)Na_(0.5))TiO_(3)(BZ–KNLN–BNT)were fabricated on(100)-LaNiO_(3)/SiO_(2)/Si substrates.The Pechini(polymeric precursor)method was carried out to prepare the complicated multi-component precursor solution.This method was suited for controlling the complex components accurately.The films crystallized at 700℃ showed a(100)pc-oriented perovskite structure,whose grain size was about 200 nm and thickness was about 700 nm.The Curie temperature Tc of the films was 292℃ that was near to that of the bulk ceramics.The preparation method used in this work provided a possibility for the application of multi-component lead-free piezoelectric films.展开更多
文摘The effects of alternating current poling(ACP)at 80℃on electrical properties of[001]-oriented 0.72 Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.28PbTiO_(3)(PMN-28PT)single crystals(SCs)have been investigated.The square-wave ACP SCs poled at high voltage(HV,5 kV_(rms)/cm)occasionally showed large fluctuations and low opposite values of piezoelectric coefficient(d_(33)=±1370 pC/N)in one plate.This revealed spuriousmode vibrations(SMV)of impedance spectrum.However,after depolarizing and repolarizing the sample with a sine-wave ACP at low voltage(LV,3.5 kV_(rms)/cm),the d_(33) enhanced to be 1720 pC/N(+26%)and did not exhibit large fluctuation or opposite values in one plate any more.The impedance spectrum became clean and the abnormal SMV disappeared.We proposed four possible mechanisms of the SMV,and speculate that the main cause maybe by macro-scale sub-domain structure and/or phase change in the main domain structure and/or phase in the SC plate due to the specific poling conditions not eternal mechanical damage of PMN-PT SCs.This study will be useful to realize a high d_(33) and improve other properties of PMN-PT ACP SC ultrasonic transducers without any SMV for high-frequency medical imaging equipment.
文摘A morphotropic phase boundary(MPB)with temperature-independent behavior,the so-called vertical MPB was investigated in lead-free(K,Na,Li)NbO_(3)–BaZrO_(3)–(La,Na)TiO_(3)ternary ceramic system.The specimens were synthesized by a conventional solid-state reaction method,and their crystal structures as well as their MPB were determined from X-ray diffraction patterns measured from room temperature to 300℃.The vertical MPB composition was determined to be 0.9025(K_(0:45)Na0:5Li_(0:05))NbO_(3)–0.09BaZrO_(3)–0.0075(La,Na)TiO_(3)and the Curie temperature was found to be about 195℃.It was successfully confirmed that ceramic samples of this system could be sintered in a reducing atmosphere.For lead-free piezoceramic applications of multilayer actuators using Ni inner electrodes,the results obtained in this work have important practical implications.
基金This work was partially supported by a research grant fromAme Hisaharu Foundation,Toyama,Japan.
文摘Lead-free piezoelectric thin films of 0.055BaZrO_(3)–0.935(K_(0.45)Na_(0.5)Li_(0.05))NbO_(3)–0.01(Bi_(0.5)Na_(0.5))TiO_(3)(BZ–KNLN–BNT)were fabricated on(100)-LaNiO_(3)/SiO_(2)/Si substrates.The Pechini(polymeric precursor)method was carried out to prepare the complicated multi-component precursor solution.This method was suited for controlling the complex components accurately.The films crystallized at 700℃ showed a(100)pc-oriented perovskite structure,whose grain size was about 200 nm and thickness was about 700 nm.The Curie temperature Tc of the films was 292℃ that was near to that of the bulk ceramics.The preparation method used in this work provided a possibility for the application of multi-component lead-free piezoelectric films.
