Structural Investigations on Ba_xPb_1-x(Mg_1/3Nb_2/3)O₃Solid Solutions Using the X-Ray Rietveld Method

Abstract

We conduct a series of numerical experiments into the nature of three-dimensional (3D) hydrodynamics in the postbounce stalled-shock phase of core-collapse supernovae using 3D general-relativistic hydrodynamic simulations of a 27 M e progenitor star with a neutrino leakage/heating scheme. We vary the strength of neutrino heating and find three cases of 3D dynamics: (1) neutrino-driven convection, (2) initially neutrino-driven convection and subsequent development of the standing accretion shock instability (SASI), and (3) SASIdominated evolution. This confirms previous 3D results of Hanke et al. and Couch & Connor. We carry out simulations with resolutions differing by up to a factor of ∼4 and demonstrate that low resolution is artificially favorable for explosion in the 3D convection-dominated case since it decreases the efficiency of energy transport to small scales. Low resolution results in higher radial convective fluxes of energy and enthalpy, more fully buoyant mass, and stronger neutrino heating. In the SASI-dominated case, lower resolution damps SASI oscillations. In the convection-dominated case, a quasi-stationary angular kinetic energy spectrum E(ℓ) develops in the heating layer. Like other 3D studies, we find E(ℓ) ∝ℓ −1 in the "inertial range," while theory and local simulations argue for E(ℓ) ∝ ℓ −5/3 . We argue that current 3D simulations do not resolve the inertial range of turbulence and are affected by numerical viscosity up to the energy-containing scale, creating a "bottleneck" that prevents an efficient turbulent cascade.

Direct processing of PbZr0.53Ti0.47O3 films on glass and polymeric substrates

“…Perovskite [21] Flourite [22,13] Pyrochlore [23] Other Low the temperature is higher in the film. The majority of the light emitted from…”

“…and are matched to 101 and 110 perovskite PZT planes. [21] d -spacings of 0.268 and 0.313 nm are also extracted from the FFT images and correlate well with the corresponding pyrochlore values (less than 3% variation) compared to a number of literature reports (Table 1)) , [23,21,31,23,13,22,24] PZT films on polymeric substrates were processed with pulse voltages of 200 V, 225 V, and 250 V and pulse counts of 10 and 25, in order to further limit the provided energy, based on the substrate susceptibility to temperature increase.…”

Lead‐reduced Bi(Ni2/3Ta1/3)O3‐PbTiO3 perovskite ceramics with high Curie temperature and performance

“…The XRD patterns of the x BNT‐(1− x )PT ceramics with x = 0.10, 0.20, 0.25, 0.3, 0.35, 0.36, 0.37, 0.38, 0.39, and 0.40 are shown in Figure A. It can be seen that the 0.10BNT‐0.90PT ceramic crystallizes in a tetragonal perovskite structure, which is similar to the structure of pure PT ( P 4mm ) . With increasing the BNT content, the crystal structure of BNT‐PT gradually evolves to a rhombohedral (R) symmetry .…”

Crystal Structure and Compressibility of Pb(Zr1−xTix)O3 Ceramics Under High Pressure

“…The computer program TOPAS 8 was used not only to perform Rietveld analysis at 0 GPa for both Pb(Zr 0.3 Ti 0.7 )O 3 1,9 and Pb(Zr 0.7 Ti 0.3 )O 3 10–15 to refine the ambient‐pressure structures but also to refine the lattice parameters and unit‐cell volumes at high pressures for Pb(Zr 0.3 Ti 0.7 )O 3 and Pb(Zr 0.7 Ti 0.3 )O 3 .…”