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Synchrotron X-ray microdiffraction was employed to investigate the inhomogeneous distribution of defect and residual strain in the transitional region between the dendritic and stray grains in a laser-assisted 3D printed Ni-based superalloy. The dendritic region was found to be under tensile strain transversely to the primary dendrite arm directions. The dendrite edges, where high level of strains and geometrically necessary dislocations were detected, were discerned as low angle grain boundaries. High angle grain boundaries were observed in the stray grain region, and the orientation of the strain tensor in this region varied dramatically at the micron scale, in contrast with the more or less homogeneous distribution in the dendritic region.

92%Pb(Mg1/3Nb2/3)O3–8%PbTiO3 (PMNT) thin films have been prepared on Pt/Ti/SiO2/Si substrate with a LaNiO3 (LNO) buffer layer and on sapphire substrate by a chemical solution deposition method, respectively. X-ray diffraction analysis shows that the PMNT thin films on Pt/Ti/SiO2/Si substrate are polycrystalline with (110)-preferential orientation. Pt/PMNT/Pt capacitors have been fabricated and show a ferroelectric character with a spontaneous polarization (Ps) of 25.2 μC/cm2 and a remanent polarization (Pr) of 6.56 μC/cm2. The dielectric constant ([variant_greek_epsilon]r) and the dissipation factor (tan δ) at 1 kHz are 680 and 0.014, respectively. The band-gap energy of the PMNT thin films on the sapphire substrate was found to be about 4.03 eV by the optical transmission spectra measurement. The optical constants (n, k) of the PMNT thin films in the wavelength range of 2.5–12.6 μm were obtained by infrared spectroscopic ellipsometry measurement. [ABSTRACT FROM AUTHOR]

Sodium bismuth titanate (Na0.5Bi0.5)TiO3 (NBT) of perovskite structure is among the best known lead-free piezoelectric/ferroelectric that promises a number of applications in sensors and actuators. However, NBT in thin film form has not been properly investigated, although NBT in bulk ceramic form has been widely studied. In this letter, we report the growth of polycrystalline NBT thin films by radio-frequency magnetron sputtering and their ferroelectric behavior. The NBT thin films exhibit a well-defined hysteresis loop, with a remanent polarization of 11.9 μC/cm2 and coercive field of 37.9 kV/cm when measured at room temperature. There is a steady decrease of dielectric constant in the range of 650–470 over the frequency range of 10–105 Hz. A change in the controlling mechanism of electrical behavior from the grain interior to the grain boundary is observed for the NBT thin film with increasing temperature. Hopping of oxygen vacancies trapped at the grain boundaries is responsible for the high dielectric loss at low frequencies and high dc conductivity observed. [ABSTRACT FROM AUTHOR]

B-site disorder in (PbSc[SUB1/2]Ta[SUB1/2])O[SUB3] (PST) is traditionally tailored by thermal annealing after sintering at elevated temperatures. In this letter, we report B-site disordering in PST triggered by mechanical activation (MA), and the resulting ferroelectric behaviors thus derived. MA induces B-site order-disorder transformation in PST, and more interestingly, the structural disorder can well be retained in sintered PST, leading to a change in ferroelectric transition behavior (e.g., from a normal ferroelectric to relaxor) and a shift in Curie temperature. A designed degree of disorder in PST can therefore be obtained by the effective combination of presinter MA and subsequent sintering, giving rise to the specific ferroelectric properties that are required for certain applications. [ABSTRACT FROM AUTHOR]

With 780-nm, 250-fs laser pulses, ultrafast optical nonlinearity has been observed in a series of thin films containing poly(methyl methacrylate) (PMMA)-TiO[SUB2] nanocomposites, which are synthesized by a simple technique of in-situ sol-gel/polymerization. The best figures of merit are found in one of the films prepared with a 60 wt % of titanium isopropoxide. Transmission electron microscopy shows the presence of 5-nm-diameter particles in the film. The observed optical nonlinearity has a recovery time of ∼1.5 ps. These findings suggest the strong potential of PMMA-TiO[SUB2] nanocomposites for all-optical switching. [ABSTRACT FROM AUTHOR]