Structure-property relations of co-doped bismuth layer-structured Bi3.25La0.75(Ti1-xMox)3O12 ceramics

In this work, the fabrication and investigation of substituting higher-valence Mo6+ for Ti4+ ion on the B-site of La3+-doped Bi4Ti3O12 [BLT] structure to form Bi3.25La0.75(Ti1-xMox)3O12 [BLTM] (when x = 0, 0.01, 0.03, 0.05 0.07, 0.09, and 0.10) ceramics were carried out. X-ray diffraction patterns of BLTM ceramics indicated an orthorhombic structure with lattice distortion, especially with a higher concentration of a MoO3 dopant. Microstructural investigation showed that all ceramics composed mainly of plate-like grains. An increase in MoO3 doping content increased the length and thickness of the grain but reduced the density of the ceramics. Electrical conductivity was found to decrease, while the dielectric constant increased with Mo6+ doping concentration. Ferroelectric properties were found to be improved with increasing MoO3 content and were optimized at x = 0.1

Crystal structure and electrical properties of bismuth sodium titanate zirconate ceramics

Lead-free bismuth sodium titanate zirconate (Bi0.5Na0.5Ti1-xZrxO3 where x = 0.20, 0.35, 0.40, 0.45, 0.60, and 0.80 mole fraction) [BNTZ] ceramics were successfully prepared using the conventional mixed-oxide method. The samples were sintered for 2 h at temperatures lower than 1,000°C. The density of the BNTZ samples was at least 95% of the theoretical values. The scanning electron microscopy micrographs showed that small grains were embedded between large grains, causing a relatively wide grain size distribution. The density and grain size increased with increasing Zr concentration. A peak shift in X-ray diffraction patterns as well as the disappearance of several hkl reflections indicated some significant crystal-structure changes in these materials. Preliminary crystal-structure analysis indicated the existence of phase transition from a rhombohedral to an orthorhombic structure. The dielectric and ferroelectric properties were also found to correlate well with the observed phase transition

Dimensionally-dependent uncertainty relations, or why we (probably) won't see micro-black holes at the LHC, even if large extra dimensions exist

We present a simple gedanken experiment in which a compact object traverses a spacetime with three macroscopic spatial dimensions and $n$ compact dimensions. The compactification radius is allowed to vary, as a function of the object's position in the four-dimensional space, and we show that the conservation of gravitational self-energy implies the dimensional dependence of the mass-radius relation. In spacetimes with extra dimensions that are compactified at the Planck scale, no deviation from the four-dimensional result is found, but, in spacetimes with extra dimensions that are much larger than the Planck length, energy conservation implies a deviation from the normal Compton wavelength formula. The new relation restores the symmetry between the Compton wavelength and Schwarzschild radius lines on the mass-radius diagram and precludes the formation of black holes at TeV scales, even if large extra dimensions exist. We show how this follows, intuitively, as a direct consequence of the increased gravitational field strength at distances below the compactification scale. Combining these results with the heuristic identification between the Compton wavelength and the minimum value of the position uncertainty, due to the Heisenberg uncertainty principle, suggests the existence of generalised, higher-dimensional uncertainty relations. These relations may be expected to hold for self-gravitating quantum wave packets, in higher-dimensional spacetimes, with interesting implications for particle physics and cosmology in extra-dimensional scenarios.Comment: 14 pages, 2 figures. Matches the version published in Frontiers in Astronomy and Space Sciences (minus typos

The effects of Ba0.85Ca0.15Zr0.1Ti0.9O3 addition on the phase, microstructure, and thermoelectric properties of Ca3Co4O9 ceramics

In this work, the influences of Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) addition on phase, microstructure, and thermoelectric properties of Ca3Co4O9 (CCO) were investigated. (1-x)CCO-(x)BCZT ceramics where x= 0, 0.003, 0.005, and 0.010 were fabricated successfully via a conventional solid-state sintering at 1,223 K for 24 h. The substitution of BCZT introduced the chemical defects ([Formula: see text], [Formula: see text], [Formula: see text]) in CCO ceramic, which increased charge carrier concentration and enhanced the electrical conductivity. The presence of Ca3Co2O6 phase and Co3+ improved the Seebeck coefficients of CCO ceramic. The thermal conductivity of CCO ceramic decreased when BCZT was added. The addition of BCZT at x = 0.010 promoted the highest thermoelectric power factor (PF~235 μW/mK2), and the highest figure of merit (ZT~0.5) at 800 K, which presents this ceramic an alternative p-type oxide thermoelectric for a high-temperature thermoelectric device

ELECTRICAL AND MECHANICAL PROPERTIES OF PZT/PVDF 0–3 COMPOSITES

Granules of in-house prepared PZT ceramic and powder of commercially available PVDF polymer were used as starting materials to form a series of xPZT/(1 - x)PVDF composites (where x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0) with 0–3 connectivity. Densities of the composites tended to increase with increasing PZT ceramic content. Phase and microstructure of the composites revealed homogeneous mixture between PZT and PVDF phases. The composites with higher ceramic content had higher dielectric constant and dielectric loss tangent. Ferroelectric measurement revealed the effect of PZT phase connectivity in 0.9PZT/0.1PVDF ceramic in which a sudden jump in ferroelectric properties was observed. Mechanical properties in terms of hardness, Young's modulus and fracture toughness were also improved when PZT content was increased.PZT/PVDF, composite, 0–3 connectivity, electrical properties, mechanical properties