新型氧离子导体稳定氧化铋的中子衍射

新型氧离子导体稳定氧化铋 (Dy2 O3) 0 .15-x(WO3) x(Bi2 O3) 0 85样品具有很高的电导率 ,当x=0 .7时 ,样品在 650℃经过 12 0 0h老化仍不发生相变。用中子衍射技术研究其结构 ,发现氧离子在 32f晶位占位数随着x的变化有一极大值 ,这时晶体结构趋向于氧离子由 8c晶位向 32f晶位移动。由于这时的 2 4e 32f键长最短 ,结构极其稳定。

Study of the production of Λ_b^0 band ~0 hadrons in pp collisions and first measurement of the Λ_b^0→J/ψpK^- branching fraction

The product of the ∧0/b （-B/0） differential production cross-section and the branching fraction of the decay ∧0/b→ J/ψ pK-（-B/0→ J/ψ-K＊（892）0）is measured as a function of the beauty hadron transverse momentum, PT, and rapidity, y. The kinematic region of the measurements is pT〈20 GeV/c and 2.0 〈g〈4.5.The measurements use a data sample corresponding to an integrated luminosity of 3fb-1 collected by the LHCb detector in pp collisions at centre-of-mass energies √s=7 TeV in 2011 and √s=8 TeV in 2012. Based on previous LHCb results of the fragmentation fraction ratio,f∧0/b/fd,the branching fraction of the decay ∧0/b→ J/ψ pK-is measured to be B（∧0/b→ J/ψ pK-）=（3.17±0.04±0.07±0.34＋0.45/-0.28）×10-4,where the first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay -B/0 →J/ψ-K＊（892）0,and the fourth is due to the knowledge of f∧0/b/fd.The sum of the asymmetries in the production and decay between ∧0/b and ∧0/bis also measured as a function of PT and y.The previously published branching fraction of ∧0/b→ J/ψ pπ-,relative to that of ∧0/b→ J/ψ pK-,is updated. The branching fractions of ∧0/b→P＋c（→ J/ψp）K-are determined.

Contribution of piezoelectric effect,electrostriction and ferroelectric/ferroelastic switching to strain-electric field response of dielectrics

This paper presents a thorough study of the strain response of different types of electroceramics during dynamical electrical loading.It highlights important aspects to take into account in the experimental methodology and outlines general guidelines for the discussion and interpretation of the results.The contributions of piezoelectric effect,electrostriction and ferroelectric/ferroelastic domain switching to the strain produced during the application of an alternating electric field are discussed by describing the strainelectric field(S-E)loops of different dielectric ceramics in which each of these contributions are predominant.In particular,attention is given to the description of the strain evolution in the characteristic"butterfly loops"typically shown by ferroelectric materials.The strain-polarization loop is indicated as a useful means to reveal the interconnection between strain and polarization state during dynamical electrical loading.Strain rate is suggested as a powerful tool to obtain more detailed information regarding the mechanisms of the electric field-induced strain.