Temat: 61.50.-f - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Investigations of Phase Transitions in (NH$\text{}_{4}$)$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ Crystal by Means of Mn$\text{}^{2+}$ EPR Spectra
Autorzy:: Bednarski, W.
Waplak, S.
Tematy:: 61.50.-f
76.30.-v; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1952756.pdf Link otwiera się w nowym oknie
Opis:: EPR of Mn$\text{}^{2+}$ impurity ion in the (NH$\text{}_{4}$)$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ crystal is studied in the temperature range 80-420 K. It is shown that Mn$\text{}^{2+}$ substitutes NH$\text{}_{4}^{+}$(I) ion and is coordinated in deformed oxygen octahedron in which takes two "off-center" positions. Its spin-Hamiltonian parameters and direction cosines of crystal field are determined. The successive EPR line splitting for three phase transitions is discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: EPR Application in the Study of K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ Proton Conductor Doped with Mn$\text{}^{2+}$ or VO$\text{}^{2+}$ Ions
Autorzy:: Waplak, S.
Tematy:: 61.50.-f
76.30.-v; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1931810.pdf Link otwiera się w nowym oknie
Opis:: The EPR of Mn$\text{}^{2+}$- or VO$\text{}^{2+}$-doped superprotonic conductor K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ is studied in the 80-471 K temperature range. VO$\text{}^{2+}$ EPR spectrum reveals diffusion induced merging of proton transferred superhyperfine structure above 380 K. Line width anomaly is observed in Mn$\text{}^{2+}$ EPR spectrum which is attributed to the intrabond and interbond proton motions, these lead to high protonic conductivity. It is shown that paramagnetic centers namely of electronic spin greater than 1, with excess charge compensated by the protonic vacancy, are good probes to monitor the protonic conductivity on molecular level.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: EPR Study of Cu$\text{}^{2+}$ Doped Fast-Proton Conductor K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ in the Temperature Range 100-450 K
Autorzy:: Ostrowski, A.
Bednarski, W.
Waplak, S.
Tematy:: 61.50.-f
76.30.-v; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2037037.pdf Link otwiera się w nowym oknie
Opis:: The K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ doped with Cu$\text{}^{2+}$ ion was studied in detail by X-band CW EPR. Two kinds of Cu$\text{}^{2+}$ complexes (magnetically and structurally nonequivalent) denoted as Cu$\text{}^{2+}$(I) and Cu$\text{}^{2+}$(II) were found. Spin-Hamiltonian parameters, direction cosines, and coordination of Cu$\text{}^{2+}$ ion were determined at room temperature. The superhyperfine structure was observed below 250 K as a result of interacting of Cu$\text{}^{2+}$ ion with four equivalent protons (I=1/2). Temperature studies of K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ crystal show that interbond motion as a precursor of superprotonic phase transition occurs at above≈250 K.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Effects of Doping on the Structural Distortion of $La_{0.7}Dy_{0.3}Mn_{1-x}Zn_xO_3$
Autorzy:: López, J.
Ríos, M.
Mendoza, G.
Tematy:: 75.47.Lx
61.50.-f; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1398317.pdf Link otwiera się w nowym oknie
Opis:: Structural properties were studied in the orthorhombic perovskite $La_{0.7}Dy_{0.3}Mn_{1-x}Zn_{x}O_3$, synthesized in the range 0 ≤ x ≤ 0.4. X-ray diffraction data, refined by the Rietveld analysis, shows for x < 0.1 the presence of stretched octahedra on the Mn-O plane, and, for x > 0.1, the existence of elongated octahedra along the c axis. Increased Zn doping causes a direct structural effect: one Zn atom distorts four neighboring MnO₆ octahedra on the Mn-O plane. It was observed that the unit cell volume containing Dy decreases as x increases, whereas the unit cell volume containing La increases as x decreases.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: EPR Study of VO$\text{}^{2+}$ Center in Fast Proton Conductor K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$
Autorzy:: Ostrowski, A.
Waplak, S.
Bednarski, W.
Tematy:: 61.50.-f
76.30.-v; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2043409.pdf Link otwiera się w nowym oknie
Opis:: The pretransitional phenomena of superprotonic phase transition (T$\text{}_{sp}$=471 K) were studied in detail by X-band continuous wave EPR spectra of K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ crystal doped with VO$\text{}^{2+}$ ions. Three kinds of VO$\text{}^{2+}$ complexes (magnetically equivalent but structurally non-equivalent) denoted as VO$\text{}^{2+}$(I), VO$\text{}^{2+}$(II), and VO$\text{}^{2+}$(III) were found. "Smearing out" of the superhyperfine structure was observed as a result of interbond proton motion. VO$\text{}^{2+}$ impurity replaces K$\text{}^{+}$ ion and experiences the same average crystal field gradient at T$\text{}_{sp}$=471 K for I- and II-type complexes. The increase in interbond proton frequency hopping above 360 K is a reason of significant line broadening.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Detection of "exotic" dopant-related macrodefects in vapour grown CdTe:Cr single crystals
Autorzy:: Popovych, V.
Sagan, P.
Tematy:: 61.50.-f
61.72.-y
61.72.Vv; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1075546.pdf Link otwiera się w nowym oknie
Opis:: SEM observation of non-typical macrodefects in the form of needle-like second phase particles in highly doped CdTe:Cr single crystals, grown by the modified physical vapour transport method, was reported. They form regular network parallel to the {111} and {100} planes. In the combined analyses using energy dispersive X-ray profiling and high-angle annular dark-field elemental mapping, it has been determined that the observed needle-like aggregates are composed of Cr-Te intermetallic compound, most probably cadmium doped Cr₃Te₄.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Magnetic, Thermal and Transport Properties of $YbPt_2Si_2$ and $Yb_2Pt_3Si_5$ Single Crystals
Autorzy:: Fikáček, J.
Prchal, J.
Sechovský, V.
Tematy:: 61.50.-f
75.20.En
75.30.Mb; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1371255.pdf Link otwiera się w nowym oknie
Opis:: Single crystals of $YbPt_{2}Si_{2}$ and $Yb_{2}Pt_{3}Si_{5}$ have been prepared by solvent growth method with Sn flux, characterized by X-ray diffraction and by EDX microprobe analysis and investigated by measurement of magnetization, specific heat and electrical resistivity as functions of temperature and magnetic field. $YbPt_{2}Si_{2} (Yb_{2}Pt_{3}Si_{5})$ crystalizes in the tetragonal $CaBe_{2}Ge_{2}$-type (orthorhombic $U_{2}Co_{3}Si_{5}$-type) structure. Both compounds exhibit metallic resistivity behavior without visible anomaly, which could be connected with onset of magnetic ordering. Neither the specific heat shows any sign of magnetic ordering down to 0.5 K. The corresponding temperature dependences of the magnetic susceptibility of both compounds behave qualitatively similar, which is reminiscent of spin fluctuation behavior: a broad maximum at high temperatures, a shallow minimum at lower temperatures, followed by an upturn with further cooling the crystal, which can be suppressed by applying a sufficient magnetic field. The rather low values of the γ-coefficients of the specific heat (~25÷35 mJ·mol·$K^{-2}$) do not support the mixed valence scenario discussed in literature for $YbPt_{2}Si_{2}$.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Pseudorotational Averaging of EPR Spectrum of Cu(II)O$\text{}_{5}$ Complex in YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ in Low Temperatures
Autorzy:: Stankowski, J.
Kempiński, W.
Trybuła, Z.
Tematy:: 61.50.-f
74.70.Vy
76.30.Fe; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1891644.pdf Link otwiera się w nowym oknie
Opis:: In low temperatures the condensation of oxygen was found to occur at 05 site in an elementary cell of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ being the fifth ligand forming the CuO$\text{}_{5}$ complex around Cul copper in chain. This change of coordinantion from CuO$\text{}_{4}$ to CuO$\text{}_{5}$ is the origin of a pseudorotation related to a strong vibronic coupling of two distorted configurations: a tetragonal pyramid C$\text{}_{4v}$ and a trigonal bipyramid D$\text{}_{3h}$, which yields a pseudocubic EPR spectrum in low temperatures. The averaged spectroscopic splitting coefficient is related to a superposition of vibronically coupled orbital states |x$\text{}^{2}$ - y$\text{}^{2}$〉 and |3z$\text{}^{2}$ - r$\text{}^{2}$〉. The averaged spectrum was for the first time observed in low temperatures since the oxygen condensation in YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ at 05 site of the chain occur only when oxygen undergoing fast diffusion among the chains, gets localized with decreasing temperature. The activation energy of oxygen desorption from the 05 site is 36 K.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: XRD Analysis of Synthetic Diamond Powders Irradiated with Electrons
Autorzy:: Shishonok, E.
Luhin, V.
Koltunowicz, T.
Tematy:: 61.05.-a
61.43.Gt
61.50.-f
61.80.Fe; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1402231.pdf Link otwiera się w nowym oknie
Opis:: Powders of synthetic diamond with low strength were sorted on sets with a different grain size. The synthetic diamond sets had various crushing strengths and morphology. They were irradiated with high energy electrons (6.5 MeV, D=2×10¹⁹ cm¯²) and analyzed using X-ray diffraction (Cu K_α) before and after irradiation. As established from nonlinearity of the a(Θ)=f{R(Θ)} dependences and observed extra splittings in X-ray diffraction patterns (in addition to α₁-α₂ doublets), crystal lattice of synthetic diamond from different sets was variously distorted. Irradiation led to decreasing distortions more significantly, the higher the initial strength of the set was. The made conclusions coincide well with our previous results on synthetic diamond powders which were irradiated under various softer conditions with direct measurements of synthetic diamond crushing strength without X-ray diffraction analysis. X-ray diffraction allows to presort synthetic diamond of critically low relative mechanical strength as well as evaluate resistance of diamond crystal lattice against heavy irradiation and other external impacts.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: On Some Structural and Spectroscopic Aspects of Rare Earth Oxycompounds
Autorzy:: Hölsä, J.
Säilynoja, E.
Porcher, P.
Tematy:: 61.10.-i
61.12.-q
61.50.-f
61.66.Fn; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1952800.pdf Link otwiera się w nowym oknie
Opis:: The aim of this account is to present the use and the advantages of different experimental and theoretical methods in the study of the structural and spectroscopic properties of rare earth (RE) oxyfluorides. The structural characterization was carried out with the X-ray and neutron powder diffraction techniques combined with the analysis of the acquired data with the Rietveld profile refinement method. The detailed spectroscopic studies were also used by employing the optical absorption and luminescence as well as inelastic neutron scattering data. Simple spectroscopic measurements gave, however, only qualitative description of the spectroscopic properties studied. More sophisticated and quantitative means was obtained by the application of the phenomenological crystal field theory to the spectroscopic data. On the other hand, the structural data was also used as initial input to electrostatic point charge calculation in order to extract the spectroscopic information. The structural and spectroscopic studies comprised the verification of the exact crystal and energy level structures and the characterization of the different interactions modifying the spectroscopic properties of the RE$\text{}^{3+}$ ions. Finally, the results from the theoretical model were used to explain the evolution of the crystal field effect on the 4f$\text{}^{N}$ energy level structure of the RE$\text{}^{3+}$ ion in the RE oxyfluorides series.
Dostawca treści:: Biblioteka Nauki

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