Non-equilibrium thermodynamical framework for rate- and state-dependent friction

Rate- and state-dependent friction law for velocity-step and healing are analysed from a thermodynamic point of view. Assuming a logarithmic deviation from steady-state a unification of the classical Dieterich and Ruina models of rock friction is proposed.Comment: 12 pages, 5 figure

Phase structure tuned electrocaloric effect and pyroelectric energy harvesting performance of (Pb0.97La0.02)(Zr,Sn,Ti)O3 antiferroelectric thick films

In present work, (100)-oriented (Pb0.97La0.02)(Zr0.95-xSnxTi0.05)O3 antiferroelectric thick films with x=0.08, 0.20 and 0.38, were successfully fabricated. These compositions are located in orthorhombic phase region, the morphotropic phase boundary (MPB), and tetragonal phase region, respectively. The effects of their phase structure on the electrocaloric effect and the pyroelectric energy harvesting behavior were investigated. A considerable temperature reduction of ∆T=13, 33, and 27 oC, due to the ferroelectric-antiferroelectric phase transition, was obtained at 25 oC in these thick films for x=0.08, 0.20, and 0.38, respectively. Moreover, a huge harvested energy density per cycle of W= 3.6, 6.8, and 4.0 J/cm3 was also realized under the experimental condition in the thick films with x=0.08, 0.20, and 0.38, respectively. These results indicated that both the cooling performance and the pyroelectric energy harvesting in antiferroelectrics could be optimized by the proper phase structure control

Influence of rotational instability on the polarization structure of SrTiO3

The k-space polarization structure and its strain response in SrTiO3 with rotational instability are studied using a combination of first-principles density functional calculations, modern theory of polarization, and analytic Wannier-function formulation. (1) As one outcome of this study, we rigorously prove-both numerically and analytically-that folding effect exists in polarization structure. (2) After eliminating the folding effect, we find that the polarization structure for SrTiO3 with rotational instability is still considerably different from that for non-rotational SrTiO3, revealing that polarization structure is sensitive to structure distortion of oxygen-octahedra rotation and promises to be an effective tool for studying material properties. (3) Furthermore, from polarization structure we determine the microscopic Wannier-function interactions in SrTiO3. These interactions are found to vary significantly with and without oxygen-octahedra rotation.Comment: 25 pages, 7 figure

Large-Area Scintillator Hodoscope with 50 ps Timing Resolution Onboard BESS

We describe the design and performance of a large-area scintillator hodoscope onboard the BESS rigidity spectrometer; an instrument with an acceptance of 0.3 m^{2}sr. The hodoscope is configured such that 10 and 12 counters are respectively situated in upper and lower layers. Each counter is viewed from its ends by 2.5 inch fine-mesh photomultiplier tubes placed in a stray magnetic field of 0.2 Tesla. Various beam-test data are presented. Use of cosmic-ray muons at ground-level confirmed 50 ps timing resolution for each layer, giving an overall time-of-flight resolution of 70 ps rms using a pure Gaussian resolution function. Comparison with previous measurements on a similar scintillator hodoscope indicates good agreement with the scaling law that timing resolution is proportional to 1/$\sqrt{N_{\rm pe}}$, where $N_{\rm pe}$ is the effective number of photoelectrons.Comment: 16 pages, 14 figure

GPG-stability of Runge-Kutta methods for generalized delay differential systems

AbstractThe GPG-stability of Runge-Kutta methods for the numerical solutions of the systems of delay differential equations is considered. The stability behaviour of implicit Runge-Kutta methods (IRK) is analyzed for the solution of the system of linear test equations with multiple delay terms. After an establishment of a sufficient condition for asymptotic stability of the solutions of the system, a criterion of numerical stability of IRK with the Lagrange interpolation process is given for any stepsize of the method

Interfacial Magnetoelectric Coupling in Tri-component Superlattices

Using first-principles density functional theory, we investigate the interfacial magnetoelectric coupling in a tri-component superlattice composed of a ferromagnetic metal (FM), ferroelectric (FE), and normal metal (NM). Using Fe/FE/Pt as a model system, we show that a net and cumulative interfacial magnetization is induced in the FM metal near the FM/FE interface. A carefully analysis of the magnetic moments in Fe reveals that the interfacial magnetization is a consequence of a complex interplay of interfacial charge transfer, chemical bonding, and spin dependent electrostatic screening. The last effect is linear in the FE polarization, is switchable upon its reversal, and yields a substantial interfacial magnetoelectric coupling.Comment: 5 pages, 6 figure

Predicting morphotropic phase boundary locations and transition temperatures in Pb- and Bi-based perovskite solid solutions from crystal chemical data and first-principles calculations

Using data obtained from first-principles calculations, we show that the position of the morphotropic phase boundary (MPB) and transition temperature at MPB in ferroelectric perovskite solutions can be predicted with quantitative accuracy from the properties of the constituent cations. We find that the mole fraction of PbTiO$_3$ at MPB in Pb(B$'$B$''$)O$_3$-PbTiO$_3$, BiBO$_3$-PbTiO$_3$ and Bi(B$'$B$''$)O$_3$-PbTiO$_3$ exhibits a linear dependence on the ionic size (tolerance factor) and the ionic displacements of the B-cations as found by density functional theory calculations. This dependence is due to competition between the local repulsion and A-cation displacement alignment interactions. Inclusion of first-principles displacement data also allows accurate prediction of transiton temperatures at the MPB. The obtained structure-property correlations are used to predict morphotropic phase boundaries and transition temperatures in as yet unsynthesized solid solutions.Comment: Accepted for publication in J. Appl. Phy