1,719 research outputs found

    Nanosized Sodium-Doped Lanthanum Manganites: Role of the Synthetic Route on their Physical Properties

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    In this paper we present the results of the synthesis and characterisation of nanocrystalline La1-xNaxMnO3+delta samples. Two synthetic routes were employed: polyacrylamide-based sol-gel and propellant synthesis. Pure, single phase materials were obtained with grain size around 35 nm for the sol-gel samples and around 55 nm for the propellant ones, which moreover present a more broaden grain size distribution. For both series a superparamagnetic behaviour was evidenced by means of magnetisation and EPR measurements with peculiar features ascribable to the different grain sizes and morphology. Preliminary magnetoresistivity measurements show enhanced low-field (< 1 T) magnetoresistance values which suggest an interesting applicative use of these manganites.Comment: 31 Pages 10 Figures to appear in Chem. Mate

    Потрійна система Er-Cr-Ge

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    The isothermal section of the phase diagram of the Er–Cr–Ge ternary system was constructed at 1070 K over the whole concentration range using X-ray diffractometry, metallography and electron microprobe (EPM) analysis. The interaction between the elements in the Er−Cr−Ge system results in the formation of two ternary compounds: ErCr6Ge6 (MgFe6Ge6-type, space group P6/mmm, Pearson symbol hP13; a = 5.15149(3), c = 8.26250(7) Ǻ; RBragg = 0.0493, RF = 0.0574) and ErCr1-хGe2 (CeNiSi2-type, space group Cmcm, Pearson symbol oS16, a = 4.10271(5), b = 15.66525(17), c = 3.99017(4) Ǻ; RBragg = 0.0473, RF = 0.0433) at investigated temperature. For the ErCr1-xGe2 compound, the homogeneity region was determined (ErCr0.28-0.38Ge2; a = 4.10271(5)-4.1418(9), b = 15.6652(1)-15.7581(4), c = 3.99017(4)-3.9291(1) Ǻ).Ізотермічний переріз діаграми стану потрійної системи Er–Cr–Ge побудований за температури 1070&nbsp;K в повному концентраційному інтервалі методами рентгенофазового, рентгеноструктурного і мікроструктурного аналізів. Взаємодія компонентів у системі Er–Cr–Ge за температури дослідження характеризується утворенням двох тернарних сполук ErCr6Ge6 (структурний тип MgFe6Ge6, просторова група P6/mmm, символ Пірсона hP13; a = 5,15149(3), c = 8,26250(7) Ǻ; RBragg = 0,0493, RF = 0,0574) іErCr1-хGe2 (структурний тип CeNiSi2, просторова група Cmcm, символ Пірсона oS16, a = 4,10271(5), b = 15,6652(1), c = 3,99017(4) Ǻ; RBragg = 0,0473, RF = 0,0433). Для сполуки ErCr1-хGe2 визначена область гомогенності (ErСr0,28-0,38Ge2; a&nbsp;=&nbsp;4,10271(5)-4,1418(9), b&nbsp;=&nbsp;15,6652(1)-15,7581(4), c&nbsp;=&nbsp;3,99017(4)-3,9291(1)&nbsp;Ǻ)

    Ізотермічний переріз потрійної системи Ho–Cu–Sn при 670 K

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    The interaction of the components in the Ho-Cu-Sn ternary system was investigated at 670 K over the whole concentration range using X-ray diffraction and EPM analyses. Four ternary compounds were formed in the Ho–Cu–Sn system at 670 K: HoCuSn (LiGaGe type, space group P63mc), Ho3Cu4Sn4 (Gd3Cu4Ge4-type, space group Immm), HoCu5Sn (CeCu5Au-type, space group Pnma), and Ho1.9Cu9.2Sn2.8 (Dy1.9Cu9.2Sn2.8-type, space group P63/mmc). The formation of the interstitial solid solution based on HoSn2 (ZrSi2-type) binary compound up to 5 at. % Cu was found.Взаємодія компонентів у потрійній системі Ho-Cu-Sn досліджена за температури 670 K в повномуконцентраційному інтервалі методами рентгенівської дифракції і рентгеноспектрального аналізу. При 670K в системі утворюються чотири тернарні сполуки: HoCuSn (структурний тип LiGaGe, просторова групаP63mc), Ho3Cu4Sn4 (структурний тип Gd3Cu4Ge4, просторова група Immm), HoCu5Sn (структурний типCeCu5Au, просторова група Pnma) і Ho1.9Cu9.2Sn2.8 (структурний тип Dy1.9Cu9.2Sn2.8, просторова групаP63/mmc). Встановлено утворення твердого розчину включення на основі бінарної сполуки HoSn2(структурний тип ZrSi2) до вмісту 5 aт. % Cu

    Дослідження структурних, кінетичних та енергетичних властивостей напівпровідникового твердого розчину Zr1-xVxNiSn

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    Structural, electrokinetic and energy state characteristics of the Zr1-xVxNiSn semiconductive solid solution (х=0–0.10) were investigated in the temperature interval 80–400 К. It was shown that doping of the ZrNiSn compound by V atoms (rV=0.134 nm) due to substitution of Zr (rZr=0.160 nm) results in increase of lattice parameter&nbsp;а(х) of Zr1-xVxNiSn indicating unforecast structural change. Based on analysis of the motion rate of the Fermi level ΔεF/Δх&nbsp;for Zr1-xVxNiSn in direction of the conduction band it was concluded about simultaneous generation of the structural defects of the donor and acceptor nature (donor-acceptor pairs) by unknown mechanism and creation of the corresponding energy levels in the band gap of the semiconductor.Досліджено особливості структурних, кінетичних та енергетичних характеристик напівпровідникового твердого розчину Zr1-xVxNiSn (х=0–0.10) в інтервалі температур 80–400 К. Показано, що уведення атомів V (rV=0.134 нм) у структуру сполуки ZrNiSn шляхом заміщення Zr (rZr=0.160 нм) супроводжується неочікуваним збільшенням значень періоду елементарної комірки&nbsp;а(х) Zr1-xVxNiSn, вказуючи на непрогнозовані структурні зміни. На основі аналізу швидкості руху рівня Фермі ΔεF/Δх&nbsp;Zr1-xVxNiSn у напрямі зони провідності зроблено висновок про одночасне генерування у кристалі структурних дефектів донорної та акцепторної природи (донорно-акцепторні пари) за невідомим механізмом, які породжують відповідні енергетичні рівні у забороненій зоні напівпровідник

    Peculiarities of structural, electrokinetic, energetic, and magnetic properties semiconductive solid solution Lu1-xVxNiSb

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    The structural, electrokinetic, energetic, and magnetic properties of the new semiconductive solid solution Lu1-xVxNiSb, х=0–0.10, were studied. It was shown that V atoms could simultaneously occupy different crystallographic positions in different ratios, generating structural defects of acceptor and donor nature. This creates corresponding acceptor and donor bands in the bandgap εg of Lu1-xVxNiSb. The mechanism of the formation of two acceptor bands with different depths of occurrence has been established: a small acceptor band εА2, formed by defects due to the substitution of Ni atoms by V ones in the 4c position, and band εА1, generated by vacancies in the LuNiSb structure. The ratio of the concentrations of generated defects determines the position of the Fermi level εF and the conduction mechanisms. The investigated solid solution Lu1-xVxNiSb is a promising thermoelectric material

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector