New forms of MSb 2 O 6 (M = Co, Ni, Cu, Zn, and Mg) have been prepared by ion exchange.
We demonstrate that the simultaneous substitution of calcium and aluminum for strontium and iron in strontium hexaferrite results in a significant increase of coercivity up to a record high of 21.3 kOe. We propose that the effect is originated from a crystal structure distortion causing an increase of the magnetocrystalline anisotropy.
The paper reports the relationship between single-walled carbon nanotube (SWNT) doping and capsulate crystal structure in RbxAg1−xI@SWNT composites. The structures of one dimensional (1D) RbI, AgI and RbAg4I5 crystals inside single-walled carbon nanotubes were established by high-resolution transmission electron microscopy (HRTEM) and high-resolution scanning transmission electron microscopy (HAADF HRSTEM), and confirmed by image simulation. Opposite to one-dimensional RbI and AgI, inheriting the structure of bulk analogues, 1D RbAg4I5 forms a new phase within a confined space of the SWNT channel, which differs from the bulk RbAg4I5 structure and can be described by a deformed cubic 1D lattice. X-ray absorption, XPS, optical absorption and Raman spectroscopies were used for comprehensive study of the composites' electronic structures. The study reveals the donor behavior of RbI capsulate and the acceptor behavior of RbAg4I5 and AgI. Quantification of doping levels indicated the prevalence of the effect of the chemical composition of the capsulate on the overall doping efficiency, while a structural effect is mostly prominent in potential distribution on nanotube walls and partial charges on SWNT atoms.
The manganese end member of triplite-triploidite series of compounds, Mn 2 (PO 4 )OH, is synthesized by a hydrothermal method. Its crystal structure is refined in the space group P2 1 /c with a = 12.411(1) Å, b = 13.323(1) Å, c = 10.014(1) Å, β = 108.16(1), V = 1573.3 Å 3 , Z = 8, and R = 0.0375. Evidenced in measurements of magnetization M and specific heat C p , Mn 2 (PO 4 )OH reaches a long range antiferromagnetic order at T N = 4.6 K. As opposed to both triplite Mn 2 (PO 4 )F and triploidite-type Co 2 (PO 4 )F, the title compound is magnetically frustrated being characterized by the ratio of Curie-Weiss temperature Θ to Néel temperature T N of about 20. The large value of frustration strength |Θ|/T N stems from the twisted saw tooth chain geometry of corner sharing triangles of Mn polyhedra, which may be isolated within tubular fragments of a triploidite crystal structure.
The TALYS Evaluated Nuclear Data Library (TENDL) has now 8 releases since 2008. Considerable experience has been acquired for the production of such general-purpose nuclear data library based on the feedback from users, evaluators and processing experts. The backbone of this achievement is simple and robust: completeness, quality and reproducibility. If TENDL is extensively used in many fields of applications, it is necessary to understand its strong points and remaining weaknesses. Alternatively, the essential knowledge is not the TENDL library itself, but rather the necessary method and tools, making the library a side product and focusing the efforts on the evaluation knowledge. The future of such approach will be discussed with the hope of nearby greater success
The JEFF library does not contain fission yield covariances, but simply best estimates and uncertainties. This situation is not unique as all libraries are facing this deficiency, firstly due to the lack of a defined format. An alternative approach is to provide a set of random fission yields, themselves reflecting covariance information. In this work, these random files are obtained combining the information from the JEFF library (fission yields and uncertainties) and the theoretical knowledge from the GEF code. Examples of this method are presented for the main actinides together with their impacts on simple burn-up and decay heat calculations
In the design of a spent nuclear fuel disposal system, one necessary condition is to show that the configuration remains subcritical at time of emplacement but also during long periods covering up to 1,000,000 years. In the context of criticality safety applying burn-up credit, k-eff eigenvalue calculations are affected by nuclear data uncertainty mainly in the burnup calculations simulating reactor operation and in the criticality calculation for the disposal canister loaded with the spent fuel assemblies. The impact of nuclear data uncertainty should be included in the k-eff value estimation to enforce safety. Estimations of the uncertainty in the discharge compositions from the CASMO5 burn-up calculation phase are employed in the final MCNP6 criticality computations for the intact canister configuration; in between, SERPENT2 is employed to get the spent fuel composition along the decay periods. In this paper, nuclear data uncertainty was propagated by Monte Carlo sampling in the burn-up, decay and criticality calculation phases and representative values for fuel operated in a Swiss PWR plant will be presented as an estimation of its impact
This paper presents a Bayesian approach based on integral experiments to create correlations which do not appear with differential data. Some quantities such as the fission cross section (σ), neutron multiplicity (ν̅p), neutron spectra (χ), etc. are usually neither modeled together nor measured in coincidence, thus there is no correlation matrices in evaluated nuclear data libraries. One can nevertheless use the information from integral experiments such as fast criticality-safety benchmarks to correlate such quantities for possible inclusion in nuclear data libraries. A simple Bayesian set of equations is presented with random nuclear data, similarly to the usual methods applied with differential data. An example for 239Pu is proposed
In the production of concrete structures widespread shaking tables of various designs. The effectiveness of vibroforming concrete items largely depends on the choice of rational modes of vibroeffect to the compacting mixture. The article discusses the propagation of a wave packet in the concrete mixture under shock and vibration molding. Studies have shown that the spectrum of a wave packet contains a large number of harmonics. The main parameter influencing the amplitude-frequency spectrum is the stiffness of elastic gaskets between mold and forming machine vibrating table. By varying the stiffness of the elastic gaskets can widely change the spectrum of the oscillations propagating in the concrete mix. Thus, it is possible to adjust the intensity of the process of vibroforming
A class of dual integral equations is analyzed which arises in solution of a wide range of plane and antiplane contact problems of elasticity theory for a half-plane with functionally graded coating. In particular, a similar equation arises in solution of the contact problem on indentation in the presence of tangential stresses on a surface. The solution of the dual integral equation is sought in the form of a sum of even and odd functions. It makes possible to reduce the problem to independent solution of two dual integral equations over odd and even functions. Kernel transform of these equations is approximated by a product of fractional quadratic functions. The solution of dual integral equations is constructed in approximated analytical form by the bilateral asymptotic method. The expressions obtained are asymptotically exact for small and large values of a characteristic geometrical parameter