Large electrostrictive effect in Sn-doped NBT–BT lead-free relaxor ceramics

In this work, we design and adjust the composition in [Formula: see text]–[Formula: see text] lead-free relaxor ferroelectrics by doping SnO2 to introduce a relaxor phase and accordingly obtain prominent lead-free electrostrictors. It was found that all the samples exhibited ideal features of relaxor ferroelectrics and the ferroelectric-relaxor phase transition temperature of the ceramics was adjusted to near or below room temperature after doping with a handful of [Formula: see text]. A relatively high electrostrictive coefficient [Formula: see text] of 0.0293 m4/C2 was achieved for the composition with [Formula: see text], which was attributed to the formation of relaxor pseudocubic phase developed by the [Formula: see text] substitution. These results provide some instructive thoughts for the further development of [Formula: see text]-based electrostrictive materials by B-site doping.

Поведение керамических твердых растворов 33PbYb-=SUB=-1/2-=/SUB=-Nb-=SUB=-1/2-=/SUB=-O-=SUB=-3-=/SUB=--22PbZrO-=SUB=-3-=/SUB=--45PbTiO-=SUB=-3-=/SUB=- в электрическом поле

The temperature dependences of the dielectric parameters were studied, as well as the changes in the dielectric constant with time in ceramic 33PbYb1 / 2Nb1 / 2O3-22PbZrO3-45 PbTiO3 samples in electric fields (0 <E <8 kV / cm). It is shown that in the phase existing below the temperature of the morphotropic phase transition, in addition to the rhombohedral and tetragonal phases, a small fraction of the relaxor pseudocubic phase is present. It was found that, unlike other relaxors, the dielectric constant practically does not change with time when an electric field is applied in the phase below the temperature of the morphotropic phase transition. Possible reasons for this behavior are discussed.

Structure and dielectric properties of NBT-xBT-ST lead-free ceramics for energy storage

([Formula: see text])(Na[Formula: see text]Bi[Formula: see text])TiO3-[Formula: see text]BaTiO3-0.26SrTiO3 ([Formula: see text]) (abbreviated as NBT-[Formula: see text]BT-ST) lead-free ceramics were fabricated by a solid-state reaction method. The effect of Ba doping amount [Formula: see text] on the structure and energy storage properties of NBT-[Formula: see text]BT-ST ceramics were investigated. All the NBT-[Formula: see text]BT-ST ceramics showed single perovskite structure with a pseudocubic phase. Ba doping effectively suppressed grain growth, in favor of forming small and uniform grains. The ceramics with a composition of [Formula: see text], an optimized energy storage density ([Formula: see text][Formula: see text]J/cm3) and efficiency ([Formula: see text]%), under an applied electric field of 50[Formula: see text]kV/cm, should be a candidate for solid-state compact pulsed power capacitor materials.

STABILITY OF HYPOTHETICAL CARBON PHOSPHIDE SOLIDS

Using first-principles calculation, we have investigated the stability of various possible structures for hypothetical carbon phosphide solids with composition C 3 P 4. Unlike C 3 N 4, the calculations predict that pseudocubic-C3P4 is energetically favored relative to α-C3P4 and β-C3P4. The pseudocubic phase has bulk modulus of 230 GPa, highest among the various structures considered.

Preparation of Epitaxial BaTiO3 Thin Films by the Dipping-pyrolysis Process

Epitaxial BaTiO3 thin films were prepared on SrTiO3 (100) substrates by the dipping-pyrolysis process using metal naphthenates as starting materials. Highly oriented BaTiO3 thin films were crystallized by heat treatment at 800 °C and higher, from amorphous precursor films pyrolyzed at 470 °C. XRD pole-figure and reciprocal-space mapping analyses showed that the films were epitaxially grown on SrTiO3substrates and were pseudocubic phase with an a║/aτ ratio of 1.003, smaller than the c0/a0 ratio (=1.011) of bulk tetragonal BaTiO3.

Structure Characteristics of Cubic and Orthorhombic Phases of High Density Scintillator Pbf2 from 4.2–300 K

ABSTRACTAn anomaly of the temperature dependence of the unit cell parameter has been observed for β–PbF2 single crystals at 200 K that is interpreted as a phase transition to a pseudocubic lattice. Such a pseudocubic phase is observable at room temperature after uniaxial plastic deformation of the bulk single crystals. The structural aspects of the β→α transition have been established. The as-grown crystals of α–PbF2 phase are shown to undergo a phase transition at 100 K.