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Lead-free antiferroelectric AgNbO3 ceramics have garnered extensive attention due to their rapid charge/discharge capabilities and environmentally friendly nature, holding immense potential for energy storage applications. However, the practical utilization of AgNbO3 has been hindered by its low energy storage density. This study employed an A/B-site co-doping strategy, which yielded positive effects on the energy performance of AgNbO3 ceramics. By modifying the A/B-sites with equivalent amounts of Bi3+ and Y3+ ions, enhanced maximum polarization, improved breakdown field, and slimmer hysteresis loops were simultaneously achieved, as the combined effects of refined grain size, wider optical bandgap, and randomly distributed antiferroelectric nanodomains, which were verified through the scanning electron microscope, transmission electron microscope, and ultraviolet–visible spectrum. As a consequence, a high energy storage density of 5.40 J/cm3 accompanied by an energy storage efficiency of 56.5% was achieved in the Ag0.97Bi0.01Nb0.994Y0.01O3 ceramic under a relatively low electric field of 190 kV/cm. This study underscores the effectiveness of A/B-site aliovalent co-doping as a viable strategy for developing high-performance ceramic capacitors for energy storage applications. [ABSTRACT FROM AUTHOR]

The phase stability and mechanical properties of Ti2AC (A=Ga, Cd, Sn, In, and Pb) have close relationship with the behavior of group-A element atoms in these compounds. This letter shows that although the Al, Ga, and In (or Si, Sn, and Pb) are in the same group, the migration energy and vacancy formation energy of group-A atom in Ti2GaC/Ti2InC (or Ti2SnC/Ti2PbC) are noticeable lower than those in Ti2AlC (or Ti3SiC2). The present results are helpful for a better understanding of easy out diffusion and self-extrusion of group-A atoms in these compounds. [ABSTRACT FROM AUTHOR]

In this letter, an oxide heterostructure has been fabricated by successively growing La0.7Sr0.3MnO3 and ZnO layers on a LaAlO3 (100) substrate using pulsed laser deposition. The ZnO/La0.7Sr0.3MnO3 heterostructure exhibits good rectifying behavior and a positive colossal magnetoresistance (MR) effect over a temperature range of 77–280 K. The maximum MR values are determined to be about 53.9% at H=0.5 T and 36.4% at H=0.3 T. A possible explanation is given in terms of the effect of magnetic fields on the depletion layer and the capture carriers effect at the interface. [ABSTRACT FROM AUTHOR]

Substantial improvements in the nanofabrication and characteristics of gold Fresnel zone plates yielded unprecedented resolution levels in hard-x-ray microscopy. Tests performed on a variety of specimens with 8–10 keV photons demonstrated a first-order lateral resolution below 40 nm based on the Rayleigh criterion. Combined with the use of a phase contrast technique, this makes it possible to view features in the 30 nm range; good-quality images can be obtained at video rate, down to 50 ms/frame. The important repercussions on materials science, nanotechnology, and the life sciences are discussed. [ABSTRACT FROM AUTHOR]

Incommensurate modulation structure in uniaxial relaxor ferroelectric Ca0.28Ba0.72Nb2O6 single crystals was investigated using transmission electron microscopy (TEM). The wave-modulation vector can be expressed as q=(1/2)c*+(1+ δ)(a* - b*)/4, where the incommensurability parameter δwas determined to be about 0.09 from [110] diffraction pattern. High-resolution TEM observations along [110] zone provided direct evidence of the incommensurate superstructure. Structural modulation was also evident by high-resolution TEM images through [001] zone, where a sinusoidal variation along [110] and [110] was identified. The incommensurate superlattice structure is caused by the uniform mixing of slabs of two orthorhombic cells. [ABSTRACT FROM AUTHOR]

Polycrystalline Ba0.6Sr0.4TiO3 (BST) films grown on r-plane sapphire exhibit strong variation of in-plane strain over the thickness range of 25–400 nm. At a critical thickness of ∼200 nm, the films are strain relieved; in thinner films, the strain is tensile, while compressive strain was observed in the 400 nm film. Microwave properties of the films were measured from 1 to 20 GHz by the interdigital capacitor method. A capacitance tunability of 64% was observed in the 200 nm film, while thinner films showed improved Q factor. These results demonstrate the possibility of incorporating frequency agile BST-based devices into the silicon on sapphire process. [ABSTRACT FROM AUTHOR]

Ferroelectric domain structure and its evolution in uniaxial relaxor Ca0.28Ba0.72Nb2O6 single crystals were investigated using transmission electron microscopy. It was found that there exists a high density of 180° domain walls in the crystals. The domains appear predominantly spike shaped along the polar axis and have a typical diameter of 50–500 nm. Domain wall motion was occasionally induced by electron beam irradiation. Macrodomains-to-microdomains switching has been observed corresponding to the normal-to-relaxor ferroelectrics transition during an in situ heating experiments. At temperature just below ferroelectric phase transition temperature TC, zero-field-cooled needlelike nanodomains were also observed. [ABSTRACT FROM AUTHOR]

A Raman scattering study of the vibrational modes in K2Al2B2O7 crystals has been performed at room temperature. The vibrational modes are classified by the nuclear site group analysis method and the internal vibrational modes are assigned to vibrations of the BO3 triangle and AlO4 tetrahedron. [ABSTRACT FROM AUTHOR]

High-quality c-axis epitaxial ferroelectric thin films of Bi[sub 4]Ti[sub 3]O[sub 12] (BTO) and Nd-substituted BTO, Bi[sub 3.15]Nd[sub 0.85]Ti[sub 3]O[sub 12] (BNT), were prepared on (001)-LaNiO[sub 3]-coated (001) LaAlO[sub 3] substrates by pulsed-laser deposition. The epitaxial alignments were established by the x-ray diffraction, including θ–2θ and [lowercase_phi_synonym] scans. Compared to the BTO films, the BNT films have significantly improved electrical properties with about 2 times larger remanent polarization, 0.6 times lower coercive field, better fatigue-resisting characteristics, and 1.7 times larger dielectric constant. These results showed experimentally that Nd substitution could enhance the c-axis electrical properties of BTO. The reason for the improved properties of BNT films was discussed. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]