Origin of the large piezoelectric activity in (1-x)Ba(Zr0.2Ti0.8)O-3-x(Ba0.7Ca0.3)TiO3 ceramics

The diffusionless pseudobinary phase diagram, monodomain properties, and free energy of (1 - x)Ba(Zr0.2Ti0.8)O-3-x(Ba0.7Ca0.3)TiO3 are computed for comparison with experimental results. Specifically, the variation of the spontaneous polarization, anisotropy energy, and free energy with respect to temperature, composition, and polarization direction are discussed relative to the results of resonant piezoelectric measurements performed over a wide compositional range as a function of temperature. The phase angle, relative permittivity, piezoelectric and coupling coefficients, and elastic compliances were used to investigate relations between the computed and measured pseudobinary phase diagrams and the measured piezoelectric and elastic properties. It was found that d(33) values along the orthorhombic to tetragonal phase boundary are similar to 30% higher than those both along the rhombohedral to orthorhombic phase boundary and in the region where phases converge. It is shown that the reduction in anisotropy energy in these regions of the phase diagram is by itself insufficient to explain the measured properties. The highest small signal piezoelectric activity is found along the orthorhombic to tetragonal phase boundary due to a combination of reduced anisotropy energy, high remanent/spontaneous polarization, and increased elastic softening. The combined computed and experimental results are used to demonstrate that the interdependent behavior of these properties should be considered in the design of engineered piezoelectric ceramicsclose

Effect of temperature distribution on tritium permeation rate to cooling water in JA DEMO condition

The estimation of tritium permeation rate through the plasma facing wall into coolant is required to discuss tritium balance in a D-T fusion plant, to design tritium recovery system and to perform safety assessments. In this work, tritium permeation rates in the blanket first wall and the divertor were estimated by numerical analysis for simplified multi-layer structures with considering the temperature distribution in recent JA DEMO condition. The permeation rate in the blanket first wall, which was a double layer consisting of tungsten and F82H, was estimated to be 0.69 g/day. The permeation rate in the divertor, which was a triple layer consisting of tungsten, copper and copper alloy or F82H, was estimated to be 0.013 g/day. When the permeation rate in tritium breeding region in the blanket can be reduced by three orders of magnitude due to a permeation barrier, total tritium permeation rate in the blanket and the divertor was estimated to be 0.71 g/day

Surface oxidation effect on deuterium permeation in reduced activation ferritic/martensitic steel F82H for DEMO application

Fuel loss and environmental contamination by tritium permeation through structural materials are critical issuesfor the establishment of a fusion DEMO reactor. In this study, the effectivity of a chromium oxide layer formedon reduced activation ferritic/martensitic steel F82H as a tritium permeation barrier and its stability undersimulated solid/liquid breeder blanket conditions have been investigated. A uniform 100-nm-thick chromiumoxide layer was formed by heat treatment at 710 °C for 5 min in 50% argon-50% hydrogen mixed gas with theflow rate of 200 standard cubic centimeter per minute. After exposure to simulated solid breeder blanket con-ditions, an iron oxide layer and a spinel-type iron-chromium oxide layer formed. In the case of a liquid breederblanket condition, the chromium oxide layer partly lost at 500 °C for 100 h. The chromium oxide-formed sampledecreased deuterium permeationflux by a factor of up to 150. The permeation reduction efficiency deterioratedafter exposure to a solid breeder blanket condition due to a change of the chromium oxide layer. However, thechromium oxide formation would play a role to reduce hydrogen isotope permeation even after reduction of theoxide layer

Oxide layer formation in reduced activation ferritic steel F82H under DEMOreactor blanket condition

Tritium permeation through structure materials in fusion blanket systems is a critical issue from the perspectives of fuel loss and radiological hazard. In the previous studies, detailed hydrogen isotope permeation behaviors in reduced activation ferritic/martensitic steels have been investigated; however, oxidation of the steel surface is expected under an actual DEMO reactor condition, and then the tritium permeation behavior will be changed. In this study, deuterium permeation through the steels heat-treated under simulated environment conditions has been investigated for more precise predictions of tritium loss at DEMO reactor blankets. Reduced activation ferritic/martensitic steel F82H substrates were heat-treated in helium gas flow containing 1 vol% hydrogen at 300, 400 and 500 °C for 100 and 200 h to simulate a solid breeder DEMO reactor blanket condition. After surface observation and analysis for the heat-treated samples, gas-driven deuterium permeation measurements were performed. An iron oxide layer was formed on the sample surface, and the thickness of the layer was 50 nm‒12 μm. The oxide layer on the sample surface heat-treated at 500 °C for 100 h decreased deuterium permeation by a factor of 5. After the permeation tests, dissipation of the oxide layers was confirmed

Semi-quantitative RT-PCR analysis.

<p>RT-PCR analysis of the expression of 13 genes, including an internal control: Actin, in fruiting bodies (F) and mycelia (M) of <i>P</i><i>. porrigens</i>. Primer sequences and PCR product sizes are given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069681#tab4" target="_blank">Table 4</a>.</p

The frequency distributions of species having the significantly homologous sequence with <i>P. porrigens</i>.

<p>Species distributions of the top BLASTX hits for unigene sets in (A) fruiting bodies and (B) mycelia.</p