The article describes the approaches for a reliable,quantitative compositional analysis of lead-free perovskite ceramics in powder and bulk forms that contain volatile alkaline compounds.The combination of scanning el...The article describes the approaches for a reliable,quantitative compositional analysis of lead-free perovskite ceramics in powder and bulk forms that contain volatile alkaline compounds.The combination of scanning electron microscopy(SEM)and transmission electron microcopy(TEM)with electron-probe analytical techniques,such as energy-dispersive X-ray spectroscopy(EDS),wavelength-dispersive X-ray spectroscopy(WDS)and electron-energy-loss spectroscopy(EELS)makes it possible to determine the true chemical composition,from precursor powders to synthesized ceramics or single crystals.The microscale(SEM)and nanoscale(TEM)analytical methods also give an insight into the local variations of the chemical composition.展开更多
(K,Na)NbO_(3)(KNN)-based lead-free piezoceramics have been the spotlight in search for practically viable candidates to replace the hazardous but dominating lead-containing counterparts.In this work,BaTiO_(3)(BT)modif...(K,Na)NbO_(3)(KNN)-based lead-free piezoceramics have been the spotlight in search for practically viable candidates to replace the hazardous but dominating lead-containing counterparts.In this work,BaTiO_(3)(BT)modified KNN ceramics were fabricated by spark plasma sintering(SPS)and the influence of BT content as well as sintering temperature on the phase structure,microstructure,and electrical properties were investigated.It was found that the 0.96(Na_(0.5)K_(0.5))NbO_(3)-0.04BaTiO_(3)(BT4)ceramics sintered at 1000℃have the optimal performance.Additionally,in-depth analysis of the electrical hysteresis revealed that the internal bias field originating from accumulation of space charges at grain boundaries is responsible for the asymmetry in the hysteresis loops.展开更多
Domain structure often has significant influences on both piezoelectric properties and piezoelectric temperature stability of a ferroelectric ceramic.In-depth studies on the characters of domain structure should be he...Domain structure often has significant influences on both piezoelectric properties and piezoelectric temperature stability of a ferroelectric ceramic.In-depth studies on the characters of domain structure should be helpful for the better understanding of piezoelectric performance.In this work,the evolution of domain structure in large-d_(33)0.96(K_(0.48)Na_(0.52))(Nb_(0.96)Sb_(0.04))O_(3)-0.04(Bi_(0.50)Na_(0.50))ZrO_(3) ceramics with poling and temperature was systematically investigated via comparing the various domain patterns that are obtained by acid-etching.It was found that domain structure changes greatly upon poling and varies largely with temperature.Complex domain patterns consisting of long narrow parallel stripes or herringbone structure separated by 180°domain boundaries are observed in the unpoled ceramics at room temperature.Domain patterns become less complicated upon poling,due to the collective polarization reversals of parallel-stripe domain clusters and banded fine-stripe domain segments.Parallel stripes and herringbone bands become much wider upon poling,as some narrow stripes and herringbone bands coalesce into broad ones,respectively.Hierarchical domain structure is commonly seen in the domain patterns acid-etched at room temperature,but is less frequently recognized at elevated temperatures.Schematic models of domain configurations were proposed to explain the domain structure and its evolution with poling.展开更多
基金The authors wish to acknowledge the-nancial support of Slovenian Research Agency(P2-105)the Ministry of Higher Education,Science and Technology of Slovenia,the 5 FP project LEAF,the 6FP project IMMEDIATE and the 6FP NoE MIND.
文摘The article describes the approaches for a reliable,quantitative compositional analysis of lead-free perovskite ceramics in powder and bulk forms that contain volatile alkaline compounds.The combination of scanning electron microscopy(SEM)and transmission electron microcopy(TEM)with electron-probe analytical techniques,such as energy-dispersive X-ray spectroscopy(EDS),wavelength-dispersive X-ray spectroscopy(WDS)and electron-energy-loss spectroscopy(EELS)makes it possible to determine the true chemical composition,from precursor powders to synthesized ceramics or single crystals.The microscale(SEM)and nanoscale(TEM)analytical methods also give an insight into the local variations of the chemical composition.
基金National Nature Science Foundation of China(Grants No.51572143,51302144,51332002)the Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20130002120031)the Tsinghua University Initiative Scientific Research Program(Grant No.20131089230).
文摘(K,Na)NbO_(3)(KNN)-based lead-free piezoceramics have been the spotlight in search for practically viable candidates to replace the hazardous but dominating lead-containing counterparts.In this work,BaTiO_(3)(BT)modified KNN ceramics were fabricated by spark plasma sintering(SPS)and the influence of BT content as well as sintering temperature on the phase structure,microstructure,and electrical properties were investigated.It was found that the 0.96(Na_(0.5)K_(0.5))NbO_(3)-0.04BaTiO_(3)(BT4)ceramics sintered at 1000℃have the optimal performance.Additionally,in-depth analysis of the electrical hysteresis revealed that the internal bias field originating from accumulation of space charges at grain boundaries is responsible for the asymmetry in the hysteresis loops.
基金financially supported by the National Natural Science Foundation of China(Grant No.51972196)Shandong Provincial Natural Science Foundation,China(Grants No.ZR2019MEM07).
文摘Domain structure often has significant influences on both piezoelectric properties and piezoelectric temperature stability of a ferroelectric ceramic.In-depth studies on the characters of domain structure should be helpful for the better understanding of piezoelectric performance.In this work,the evolution of domain structure in large-d_(33)0.96(K_(0.48)Na_(0.52))(Nb_(0.96)Sb_(0.04))O_(3)-0.04(Bi_(0.50)Na_(0.50))ZrO_(3) ceramics with poling and temperature was systematically investigated via comparing the various domain patterns that are obtained by acid-etching.It was found that domain structure changes greatly upon poling and varies largely with temperature.Complex domain patterns consisting of long narrow parallel stripes or herringbone structure separated by 180°domain boundaries are observed in the unpoled ceramics at room temperature.Domain patterns become less complicated upon poling,due to the collective polarization reversals of parallel-stripe domain clusters and banded fine-stripe domain segments.Parallel stripes and herringbone bands become much wider upon poling,as some narrow stripes and herringbone bands coalesce into broad ones,respectively.Hierarchical domain structure is commonly seen in the domain patterns acid-etched at room temperature,but is less frequently recognized at elevated temperatures.Schematic models of domain configurations were proposed to explain the domain structure and its evolution with poling.
