Direct observation of the recovery of an antiferroelectric phase during polarization reversal of an induced ferroelectric phase

Electric fields are generally known to favor the ferroelectric polar state over the antiferroelectric nonpolar state for their Coulomb interactions with dipoles in the crystal. In this paper, we directly image an electric-fieldassisted ferroelectric-to-antiferroelectric phase transition during polarization reversal of the ferroelectric phase in polycrystalline Pb0.99{Nb0.02[(Zr0.57Sn0.43)0.92Ti0.08]0.98}O3.With the electric-field in situ transmission electron microscopy technique, such an unlikely phenomenon is verified to occur by both domain morphology change and electron-diffraction analysis. The slower kinetics of the phase transition, compared with ferroelectric polarization reversal, is suggested to contribute to this unusual behavior

Childhood, children and family lives in China

In this chapter we bring into focus those aspects of family lives in China that are concerned with children’s family relationships, and the ways in which such issues are part and parcel of the broader institutionalisation of childhood. We draw on theoretical frameworks in the sociology of childhood and childhood studies (e.g., Prout, 2004; Qvortrup, 2000; Smith and Greene, 2014). Since these theoretical perspectives have developed predominantly in Anglophone literature, some researchers have considered their relevance to, and utility for, China and Chinese childhoods (Goh, 2011; Miao, 2013; Wang YY, 2011, 2014a, 2014b; Zheng, 2012a, 2012b; Ribbens McCarthy et al., 2017). In engaging with existing theories, and applying them to, Chinese children’s family lives, we seek to go beyond any tendency to just ‘add in the missing children’ to existing discussions (Kesby et al., 2006: 186), and give consideration to a variety of cultural and local contexts that characterise China and illuminate why it is necessary to decentre universalist thinking (Jullien, 2008/2014

Unique single-domain state in a polycrystalline ferroelectric ceramic

Non-180° ferroelectric domains are also ferroelastic domains; their existence in polycrystalline materials is to relieve internal stresses generated during solid-solid phase transitions and minimize the elastic distortion energy. Therefore, grains with random orientations in polycrystalline ceramics are always occupied by many domains, especially in the regions close to grain boundaries. In this Rapid Communication, we report the observation of a single-domain state in a BaTiO3-based polycrystalline ceramic at intermediate poling electric fields with in situ transmission electron microscopy. The grains in the virgin ceramic and under high poling fields are found multidomained. The unique single-domain state is believed to be responsible for the ultrahigh piezoelectric property observed in this lead-free composition and is suggested to be of orthorhombic symmetry for its exceptionally low elastic modulus

Evolution of structure and electrical properties with lanthanum content in [(Bi1/2Na1/2)0.95Ba0.05]1-xLaxTiO3 ceramics

Lead-free perovskite [(Bi1/2Na1/2)0.95Ba0.05]1-xLaxTiO3 (x = 0.00 ~ 0.10) ceramics were fabricated via the solid state reaction method and their crystal structures and electrical properties were systematically studied. Transmission electron microscopy examination reveals a transition from a rhombohedral R3c phase with micron-sized complex domains to a mixture of rhombohedral R3c and tetragonal P4bm phases with nanodomains as La content was increased. X-ray diffraction analysis on bulk samples, however, indicates a pseudocubic structure in La-doped compositions. Electrical poling seems to transform the pseudocubic structure to a rhombohedral phase in compositions with 0.00 \u3c x \u3c 0.03. With La addition, the depolarization temperature (Td) is observed to decrease and the dielectric constant (εr) within 100 ~ 350 oCbecomes more temperature independent, promising for applications in high-temperature capacitors. Electric field-induced polarizations and strains display complex changes with respect to La concentration, with the highest strain of 0.35 % achieved in the composition x = 0.04 under 70 kV/cm at room temperature. The piezoelectric coefficient d33 initially increases with La content, reaching a maximum value of 151 pC/N in the composition x = 0.02, and then diminishes

A New Phase Boundary in (Bi1/2Na1/2)TiO3BaTiO3 Revealed via a Novel Method of Electron Diffraction Analysis

A new phase boundary is revealed in (1-x)(Bi1/2Na1/2)TiO3xBaTiO3, the most extensively studied lead-free piezoelectric solid solution. This discovery results from a novel method of electron diffraction analysis, which allows for the precise determination of oxygen octahedra tilting in multi-domain perovskite ferroelectrics. The study using this method supports the recently proposed Cc symmetry for pure (Bi1/2Na1/2)TiO3, and, more importantly, indicates the crystal structure evolves into the R3c symmetry with the addition of BaTiO3, forming a Cc/R3c phase boundary at x = 3~4%. In the poling field Epol vs. composition x phase diagram for polycrystalline ceramics, this phase boundary exists with Epol below 5.5 kV/mm; the Cc phase is transformed to the R3c phase during poling at higher fields. The results reported here provide the microstructural origin for the previously unexplained strain behavior and clarify the low-BaTiO3-content phase relationship in this popular lead-free piezoelectric system

Countermeasure and Interaction of Common Technoinnovation and New Energy Industry Development

AbstractThere is an endogenous response process between common technology innovation and new energy industrial development. This article proposed the concept of common techno-innovation response to the new energy industrial development and comprehensive response degree model of common techno-innovation response to the new energy industrial development