Effective preparation of the N-dimension spin Greenberger–Horne–Zeilinger state with quantum dots embedded in microcavities

We propose a scheme for preparation of the N-dimension spin Greenberger–Horne–Zeilinger state by exploiting quantum dots (QDs) embedded in microcavities. Numerically analysed results show that with the spin-selective photon reflection from the cavity, we can complete the scheme assisted by one polarized photon with high fidelity and 100% successful probability in principle. Furthermore, the set-up is just composed of simple linear optical elements, delay lines and conventional photon detectors, which are feasible with existing experimental technology. Moreover, QDs have numerous admirable features in weak-coupling regime, which are practicable in realistic cavity quantum electrodynamics system shown by previous numerical simulations and experiments. Therefore, our scheme might be realized in near future.     

High luminescence quantum efficiency of Eu3+-doped SnO2–SiO2 glasses due to excitation energy transfer from nano-sized SnO2 crystals

The strong Eu³⁺ photoluminescence in xSnO₂–(100−x)SiO₂ derived by the sol–gel method was reported. It was shown that Eu³⁺ ions were embedded in SnO₂ nanocrystals (tetragonal, rutile) surrounded by a SiO₂ glass matrix. Time-resolved photoluminescence spectra and excitation spectra revealed that Eu³⁺ ions could receive excitation energy from electron–hole pairs in SnO₂ semiconductor nanocrystal, whose band-gap energy shifted to the higher energy side due to the quantum size effect, and was tuned to an optimum frequency for energy transfer to Eu³⁺ ions. Absolute quantum luminescence efficiencies were found to be 60.5 (internal) and 26.7% (external).     

Study on the interaction between a dislocation and impurities in KCl:Sr<Superscript>2+</Superscript> single crystals by the Blaha effect—Part IV influence of heat treatment on dislocation density

Strain-rate cycling tests associated with ultrasonic oscillation were carried out at 80–239 K for two kinds of KCl:Sr²⁺ (0.05 mol.% in the melt) single crystals: one is a quenched specimen and the other an annealed one. In this study, it was found that the density of moving dislocation is not influenced by the heat treatment. Furthermore, the increase in forest dislocation density for the annealed specimen seemed to be remarkable under the compression test, compared with that for the quenched specimen. As a result, the strain-hardening rate increased and the extent of plastic deformation region became short at a given temperature by annealing the quenched specimens. The investigation concerning forest dislocation density was conducted on the basis of the which will represent the variation of the strain-rate sensitivity due to dislocation cuttings with shear strain.     

Superconductivity and spin correlation study by Fe3+ - ESR in (La1−xSrx)2Cu1−yFeyO4−z

Fe³⁺-ESR measurements are carried out for the samples of (La_1–xSr_x)₂Cu_1–yFe_yO_4–z. Peak-peak width H_pp of the signals decreases with falling temperature until minimum value and rises sharply with further decreasing temperature, which is approximated by H_pp = C₀ +C₁/T + BT. The H_pp behavior at high temperature and at low temperature can be analyzed by Korringa mechanism and slowing down of Fe₃₊ spin fluctuation, respectively. From the analysis of coefficient B's of Korringa terms, C₀ and g-shift, it is revealed that the magnetic interaction of Fe³⁺ with hole carriers and Ce²⁺ spins depends strongly on hole density.     

Correlation between spin–phonon coupling and magneto-electric effects in CoFe2O4/PMN-PT nanocomposite: Raman spectroscopy and XMCD study

We have investigated strain-induced spin lattice coupling in the CoFe₂O₄/0.65Pb (Mg_1/3Nb_2/3)O₃–0.35PbTiO₃(PMN-PT) composite system, evident by temperature-dependent Raman spectroscopy and magnetization measurements. The strain interactions lead to magneto-electric coupling, and the measured magneto-electric voltage coefficient is 40 mV/cm^?1Oe^?1 for the CoFe₂O₄/PMN-PT composite samples. X-ray magnetic circular dichroism (XMCD) analysis establishes modified spin structure in the electrically poled CoFe₂O₄/PMN-PT composite, further validating the coupling between magnetic and electric ordering in the composite. The magneto-electric coupling coefficient α vs dc magnetic field curves revealed hysteretic behavior and enhanced α values after electric poling, which originates from the strain-induced modifications in the magnetic structure of composite in the electrically poled samples. These findings suggest that the existence of spin lattice coupling may lead to the mechanism of strong magneto-electric effects via strain interactions in CoFe₂O₄/PMN-PT composite.

     

Pyrochlore phase in the Bi2O3–Fe2O3–WO3–(H2O) system: Physicochemical and hydrodynamic aspects of its production using a microreactor with intensively swirled flows

The present work deals with a study of physicochemical and hydrodynamic aspects of a new approach to the synthesis of a (Bi, Fe, □)₂(Fe, W)₂O₆O′_δ cubic pyrochlore-structured phase (hereinafter BFWO) in the Bi₂O₃–Fe₂O₃–WO₃–(H₂O) system. The considered approach is based on the use of microreactor technology at the stage of obtaining the amorphous precursor suspension, which is subsequently hydrothermally treated. The amorphous precursor suspension was obtained by co-precipitation method using two techniques of mixing reagent solutions, namely (i) by dropwise supply (traditional laboratory technique), and (ii) by intensive co-precipitation in a microreactor with a continuous supply of swirling flows of reagent solutions (microreactor technology with a suspension output of ∼ 7 L/min). It is shown that the microreactor strategy made it possible to avoid the spatial isolation of components during the amorphous precursor formation, which further ensured the formation of crystals of only the BFWO phase (without impurities). The values of the band gap (E_g) for direct allowed electronic transitions are 2.40 ± 0.03 and 2.35 ± 0.03 eV for the microreactor case and for the dropwise supply, respectively, which permits characterization of the obtained materials as wide bandgap semiconductors.     

KBаY(MoO4)3:Er3+/Yb3+—an Erbium/Ytterbium-Codoped Upconversion Phosphor in the К2MoO4–BaMoO4–Y2(MoO4)3 System

Inorganic Materials - We have investigated phase relations along a number of joins in the subsolidus region of the К2MoO4–BaMoO4–Y2(MoO4)3 system using X-ray diffraction and...     

Redox equilibrium U(IV) + 2Fe(CN) 63? ? U(VI) + 2Fe(CN) 64? in solutions of unsaturated heteropoly anions: Potentials of redox couples, stability of U(IV) complexes, reaction mechanism

The kinetics and equilibria of the reactions UO₂²⁺ + 2L + 2Fe(CN)₆⁴⁻ ⇄ UL₀ + 2Fe(CN)₆³⁻ in 0.1–1.0 M HCl solutions (ionic strength 1.0), where L is heteropoly anion of the composition P₂W₁₇O₆₁¹⁰⁻ or SiW₁₁O₃₉⁸⁻, were studied speelrophotometrically. Measurement of the redox potential of the ferri/rerrocyanide couple in acid solutions allowed estimation of the stability constants of the complxes U^IV(P₂W₁₇O₆₁)₂¹⁶⁻ and U^IV(SiW₁₁O₃₉)₂¹²⁻, equal in 1 M H⁺ solutions to 10^18.6 and 10^21.O, respectively. Accumulation of U^IVL₂ formed by reduction of UO₂²⁺ follows a first-order rate law, i.e., it involves the formation of UO₂⁺ which slowly reacts with L. The arising complex rapidly reacts with UO₂⁺. The loss of UL₂ occurs via formation of the complex of nonoxygenated U(V) with the heleropoly anion. Original Russian Text ? V.P. Shihv, A.B. Yusov. M.N. Sokolova, A.M. Fedoseev, 2008, published in Radiokhimiya, 2008, Vol. 50, No. 3, pp. 209–214.     

Synthesis of Y<Subscript>3</Subscript>Al<Subscript>5</Subscript>O<Subscript>12</Subscript>:Ce<Superscript>3+</Superscript> phosphor in the Y<Subscript>2</Subscript>O<Subscript>3</Subscript>–Al metal–CeO<Subscript>2</Subscript> ternary system

Garnet phosphor Y₃Al₅O₁₂:Ce³⁺ is prepared in the Y₂O₃–Al metal–CeO₂ ternary system by the solid-state reaction method in the air. For the first time, metal Al is used as a source of aluminum for the reaction instead of traditional oxide Al₂O₃. It is shown that the chemical reaction can be realized at lower temperatures and without use of special reducing atmosphere. The structural and spectroscopic properties of the prepared powder phosphor are very close to those earlier reported for the Y₃Al₅O₁₂:Ce³⁺ single crystal.