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J. Przedmojski B. Pura W. Piekarczyk M. Berkowski 《Crystal Research and Technology》1984,19(11):1483-1487
X-ray investigations have been carried out on single crystals of BaLaGa3O7. Debye temperature as well as thermal expansion coefficients were determined, and values of which are respectively 相似文献
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V. P. Dyakonov R. Szymczak A. D. Prokhorov E. Zubov A. A. Prokhorov G. Petrakovskii L. Bezmaternikh M. Berkowski V. Varyukhin H. Szymczak 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,78(3):291-298
Magnetic and electron paramagnetic resonance (EPR) properties of
EuFe3(BO3)4 single crystals have been studied over the
temperature range of 300–4.2 K and in a magnetic field up to 5 T. The
temperature, field and orientation dependences of susceptibility,
magnetization and EPR spectra are presented. An antiferromagnetic ordering
of the Fe subsystem occurs at about 37 K. The easy direction of
magnetization perpendicular to the c axis is determined by magnetic
measurements. Below 10 K, we observe an increase of susceptibility connected
with the polarization of the Eu sublattice by an effective exchange field of
the ordered Fe magnetic subsystem. In a magnetic field perpendicular to the
c axis, we have observed an increase of magnetization at T < 10 K in the
applied magnetic field, which can be attributed to the appearance of the
magnetic moment induced by the magnetic field applied in the basal plane.
According to EPR measurements, the distance between the maximum and minimum
of derivative of absorption line of the Lorentz type is equal to 319 Gs. The
anisotropy of g-factor and linewidth is due to the influence of crystalline
field of trigonal symmetry. The peculiarities of temperature dependence of
both intensity and linewidth are caused by the influence of excited states
of europium ion (Eu3+). It is supposed that the difference between the
g-factors from EPR and the magnetic measurements is caused by exchange
interaction between rare earth and Fe subsystems via anomalous Zeeman
effect. 相似文献
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D.I. Savytskii M. Berkowski L.O. Vasylechko J. Fink‐Finowicki A.O. Matkovskii 《Crystal Research and Technology》2000,35(1):53-63
For La1‐xNdxGaO3 crystals the La‐Nd substitution leads to decrease of spontaneous strains and for composition with x≈0.32 the six possible twin states of orthorhombic phase (m3mFmmm) may be degenerated in three twin states inhered in m3mF4/mmm species when a distorted perovskite pseudocell becomes tetragonal. The {110} and {112} reflection twins and axial twins with compositional planes close to (211) and (21‐1) (S‐walls) were identified in La1‐xNdxGaO3 (x=0.07, 0.12, 0.20) solid solutions crystals. All observed twins are typical for crystals with GdFeO3 type perovskite‐like structure. It has been shown that for x≤0.2 and x≥0.5 orientations of S‐walls weakly depend on La/Nd ratio, whereas in the range of 0.2<x<0.5 they depend strongly on the solid solution composition. The tilt angle between two twin states across twin boundary in La1‐xNdxGaO3 (x<0.6) solid solutions is smaller than that between two twins in pure LaGaO3 or NdGaO3. 相似文献
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L. Vasylechko V. Vashook A. Senyshyn M. Knapp M. Berkowski U. Bismayer 《Journal of solid state chemistry》2003,172(2):396-411
Crystal structure and anisotropy of the thermal expansion of single crystals of La1−xSrxGa1−2xMg2xO3−y (x=0.05 and 0.1) were measured in the temperature range 300-1270 K. High-resolution X-ray powder diffraction data obtained by synchrotron experiments have been used to determine the crystal structure and thermal expansion. The room temperature structure of the crystal with x=0.05 was found to be orthorhombic (Imma, Z=4, a=7.79423(3) Å, b=5.49896(2) Å, c=5.53806(2) Å), whereas the symmetry of the x=0.1 crystal is monoclinic (I2/a, Z=4, a=7.82129(5) Å, b=5.54361(3) Å, c=5.51654(4) Å, β=90.040(1)°). The conductivity in two orthogonal directions of the crystals has been studied. Both, the conductivity and the structural data indicate three phase transitions in La0.95Sr0.05Ga0.9Mg0.1O2.92 at 520-570 K (Imma-I2/a), 770 K (I2/a-R3c) and at 870 K (R3c-R-3c), respectively. Two transitions at 770 K (I2/a-R3c) and in the range 870-970 K (R3c-R-3c) occur in La0.9Sr0.1Ga0.8Mg0.2O2.85. 相似文献
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Growth and recharging processes of chromium ions in SrGdGa3O7 and SrLaGa3O7 single crystals incorporated during growth or doping by diffusion (only for SrLaGa3O7 crystal) were analyzed. The annealing at 1000°C in air and ionizing with gamma rays (doses from 103 to 105 Gy) and protons (1014 cm-2 only for SrGdGa3O7 crystal) were performed. Different kinds of chromium ions valency, from two to four, were found. Electron spin resonance measurements in the temperature range 5-300K with the use of Brucker spectrometer were also done. 相似文献
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Karpinska K Cieplak MZ Guha S Malinowski A Skoskiewicz T Plesiewicz W Berkowski M Boyce B Lemberger TR Lindenfeld P 《Physical review letters》2000,84(1):155-158
Measurements of the resistivity, magnetoresistance, and penetration depth were made on films of La1.85Sr0.15CuO4, with up to 12 at. % of Zn substituted for the Cu. The results show that the quadratic temperature dependence of the inverse square of the penetration depth, indicative of d-wave superconductivity, is not affected by doping. The suppression of superconductivity leads to a metallic nonsuperconducting phase, as expected for a pairing mechanism related to spin fluctuations. The metal-insulator transition occurs in the vicinity of k(F)l approximately 1, and appears to be disorder driven, with the carrier concentration unaffected by doping. 相似文献
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The part of the CdCr2Se4-CdCl2 phase diagram within the range of 75–100 mole% of CdCl2 has been examined. The composition CdCr2Se4 · CdCl2 was found to be stable below 542°C. The crystallisation processes of CdCr2Se4 spinel for two mixture compositions: 88% CdCl2-12% CdCr2Se4 and 80% CdCl2-20% CdCr2Se4 have been carried out and the parameters of CdCr2Se4 crystal growth from the CdCl2 flux were determined. 相似文献