R. Blinc

University of Ljubljana, Lubliano, Ljubljana, Slovenia

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Publications (847)2441.28 Total impact

  • K. J. Schenk · G. Chapuis · R. Kind · R. Blinc · J Seliger

    No preview · Article · Feb 2013 · Journal of Molecular Structure
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    ABSTRACT: The structural phase transitions between the intercalated and the non-intercalated phases of the layer structure compound n-decylammoniumchloride and n-hexylammoniumchloride have been studied via proton-14N and proton-35Cl nuclear quadrupole double resonance. The results have been related to an order-disorder model of the alkylammonium chains. The temperature dependence of the order parameters of the -NH3 head groups has been determined.
    No preview · Article · Feb 2013 · Zeitschrift für Physik B Condensed Matter
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    ABSTRACT: The observation of first order satellites in the NMR spectra of 47Ti and 49Ti in the cubic phases of BaTiO3 and SrTiO3 as well as 18O enriched SrTi18O3 demonstrates the presence of nonzero quadrupole coupling at the Ti sites in all these systems. This is incompatible with the central position of Ti in the oxygen octahedron and requires the presence of off-center Ti sites and dynamic disorder even in the paraelectric cubic phase. The Ti potential surface does not seem to change significantly at the cubic-tetragonal transitions. The pure 8-site “order-disorder” model however does not agree with the experiment. A good agreement with the experimental data is obtained if in addition to the dynamic Ti disorder the “displacive” soft mode induced deformation of the unit cell shape in the dynamic tetragonal nanodomains, existing in the cubic phase, is taken into account. The simultaneous presence of the Ti disorder and the soft mode leads to a special type of phase transition with combined “displacive” and “order-disorder” character.
    No preview · Article · Feb 2013 · Physical Review B
  • J Seliger · V Žagar · R Blinc
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    ABSTRACT: The temperature dependence of the 17O nuclear quadrupole double-resonance spectra of squaric acid has been measured and the electric field gradient tensors at the 17OH--O and 17O---HO sites have been determined from −5 to 144°C. The phase transition is connected with a dynamic order-disorder transition of the protons moving between two potential minima in the H bonds. Local in-plane short-range order along the OH--O-bonded chains was found to persist far above Tc. From the proton-17O magnetic dipolar coupling an 17OH--O length of 2.47 Å and a distance between the two proton equilibrium sites of 0.41 Å has been deduced.
    No preview · Article · Feb 2013 · Journal of Magnetic Resonance
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    ABSTRACT: We report on the first observation of a magnetic transition in multiferroic Pb5Cr3F19. The system undergoes a ferroelectric transition at TC = 545 K and probably an antiferromagnetic transition around TN = 11 K. Between 50 K and TN, the system is not paramagnetic but shows the presence of correlated spin clusters, indicating a superparamagnetic or spin glass state. The observable changes of the magnetic properties ongoing through ferroelectric phase transition show a magnetoelectric coupling that may be important for new devices.
    No preview · Article · Feb 2012 · Physical review. B, Condensed matter
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    ABSTRACT: The ESR and NMR lines in powder samples of TDAE-C60 do not show the expected frequency shifts due to long range ordering in the low temperature magnetic phase, but instead show only a relatively small line broadening below Tc=16 K. The temperature dependence of the lineshapes in ESR, the absence of a spontaneous magnetization as well as other magnetic properties suggest that the magnetic ordering below Tc=16 K is local and random, i.e. spin-glass like, rather than ferromagnetic. The possible finite-particle-size effects and possible microscopic mechanisms for the observed magnetic behavior are discussed.
    No preview · Article · Jan 2012 · International Journal of Modern Physics B
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    ABSTRACT: The electrocaloric (EC) effect in normal ferroelectric copolymer P(VDF-TrFE) and in relaxor terpolymer P(VDF-TrFE-CFE) is described in the framework of a phenomenological appoach. The change of the dipolar entropy in the copolymer, derived earlier from dielectric measurements by means of the Maxwell relation, is analyzed in terms of the mean field expression for entropy, and is shown to be consistent with the dielectric data. In the terpolymer case, the entropy change determined recently by direct (EC) measurements is found to be in qualitative agreement with the predictions of the mesoscopic spherical model of relaxor ferroelectrics.
    Full-text · Article · Jan 2012 · Ferroelectrics
  • Yoshihiro Ishibashi · Makoto Iwata · Robert Blinc
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    ABSTRACT: The new eight pseudo-spin model recently introduced to discuss in a unified fashion the ferroelectric and antiferroelectric phase transitions in the hydrogen-bonded crystals of the KH2PO4 family is reviewed. The dielectric susceptibilities along the unique ferroelectric c-axis, and the a (b)-axis, perpendicular to the unique axis, are calculated. The application to the mixed crystals is suggested.
    No preview · Article · Jan 2012 · Ferroelectrics
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    ABSTRACT: 93Nb  → − NMR line shape and spin–lattice measurements show that microcrystalline PbMg1/3Nb2/3O3 (PMN) powder is dynamically disordered at room temperature, whereas nanocrystalline PMN powder is orientationally frozen out and long-range ordered at room temperature. The dynamical disorder of the microcrystalline powder results in a motional averaging of the anisotropic part of the 93Nb chemical shift tensor and second order quadrupole shift, whereas this averaging is absent in the nanocrystalline powder, resulting in a broader central line and a longer spin–lattice relaxation time. This seems to be the first observation of such size effects in a relaxor.
    No preview · Article · Nov 2011 · physica status solidi (b)
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    ABSTRACT: The narrow components in the 93Nb(I = 9/2) and 45Sc(I = 7/2) NMR spectra of single crystalline PMN and disordered single crystalline PST are due to the 1/2 → -1/2 NMR transition whereas the broad background components are due to satellite transitions.The macroscopic cubic symmetry is locally broken on the NMR time scale. From the NMR point of view, the structure is homogeneous and there is no need to invoke the existence of “pinned” chemical clusters. The observed NMR spectra in PMN and PST can be described in terms of reorientable dynamic polar nanoclusters-mainly due to Pb2+ site disorder-as invoked by the spherical random bond-random field model.
    No preview · Article · Oct 2011
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    ABSTRACT: The electrocaloric effect (ECE), i.e., the conversion of electric energy into heat, is of great importance for application in new generation cooling or heating devices that would be friendlier to the environment. Here, utilizing direct measurements of the ECE change of the temperature (delta T) via a high resolution calorimeter, we study the ECE as a function of the magnitude of the electric-field step E in the vicinity of the critical point in several bulk relaxor ferroelectric ceramic systems.Relatively large change of temperature of 2 to 3K were obtained at modest fields of 90 kV/cm, even in the case of ceramic materials. The effective responsivity deltaT/E as a functio of the electric field shows a characteristic peak near the critical point, which demonstrates the importance of proximity to the critical point for the enhancement of the electrocaloric effect. Experimental results are in good agreement with the theoretical calculations based on the spherical random-bond random-field model.
    Full-text · Article · Sep 2011 · Journal of Applied Physics
  • Robert Blinc · Gojmir Lahajnar · Anton Potočnik
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    ABSTRACT: Muon spin rotation (µSR) and relaxation has been used to study the local magnetic structure of K3Fe5F15. A collinear F-µ+-F "hydrogen bond-like" symmetric double minimum type complex with a F...F distance of 2.8 Å and a separation between the two minima of 0.8 Å has been found in the paramagnetic phase. The apparent central position of the muon seems to be the result of fast muon tunneling between two equivalent minima in the F-µ+-F bond.
    No preview · Article · Sep 2011 · Acta Chimica Slovenica
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    J F Scott · R Blinc
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    ABSTRACT: An additional eight or ten fluorides with multiferroic phases are listed as an addendum to our recent review 'Multiferroic Fluorides' (Scott J F and Blinc R 2011 J. Phys.: Condens. Matter 23 113202).
    Preview · Article · Jul 2011 · Journal of Physics Condensed Matter
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    ABSTRACT: Combining the ferroelectric and magnetic components into the solid solution, it is expected to obtain the magneto-electric multiferroic material. Novel bulk ceramic compounds xPZT+(1 − x)PFW, where PZT = Pb(Zr0.575Ti0.425)O3 and PFW = Pb(Fe2/3W1/3)O3, for x = 0.15, 0.20, 0.25, 0.50, 0.70, 0.80 were synthesized and their magnetic investigation was performed, including the measurement of zero-field cooled (ZFC) and field-cooled (FC) magnetization curves, magnetic hysteresis loops and AC susceptibility. In the low temperature region (below 20 K) splitting between the ZFC and FC curves together with the frequency dependent peaks in AC susceptibility point to the glassy freezing/blocking of magnetic moments and magnetic relaxor-like behaviour.
    No preview · Article · Jul 2011 · Journal of Physics Conference Series
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    ABSTRACT: The dielectric response of Rb0.5(ND4)0.5D2PO4 (DRADP-50) dipolar glass has been studied at low temperatures. From the experimental results, the distribution of the relaxation times and of the local polarization at various temperatures is calculated. It is shown that the local-polarization distribution function obtained from the dielectric response e*(�,T) is consistent with that obtained from NMR results. The results also show that the dielectric dispersion is due to diffusion, creation, and annihilation of Takagi groups.
    Full-text · Article · Jun 2011 · Journal of Applied Physics
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    ABSTRACT: We predict that undoped nanoparticles (size ≤ 10–100 nm) of incipient ferroelectrics without any magnetic ions can become ferromagnetic even at room temperatures due to the inherent presence of a new type of magnetic defects with spin S = 1, namely oxygen vacancies, where the magnetic triplet state is the ground state in the vicinity of the surface (magnetic shell), while the nonmagnetic singlet is the ground state in the bulk material (nonmagnetic core). In particular, for a particle radii R less than the critical radius R c (T) ferromagnetic long-range order appears in a shell region of thickness 5–50 nm once the concentration of magnetic defects N exceeds the magnetic percolation threshold N<sup>p</sup>. At vacancy concentrations N < N<sup>p</sup> and radii R < R c (T), short-range ferromagnetic order and consequently a spin glass state may appear. For particle radii R > R c (T), only the paramagnetic phase is possible.
    Full-text · Article · Jun 2011 · Journal of Applied Physics
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    ABSTRACT: In recent years, a pronounced interest in materials that are perspective in applications for everyday life has start to grow. Our interest has been focused on different conversions of energies in such advanced materials. We have studied a giant conversion of thermal to mechanical energy, i.e., thermomechanical effect in nematic liquid crystal elastomers, a giant conversion of electrical to thermal energy, i.e., electrocaloric effect in PLZT thin films, and an electric control of magnetization, i.e.,magnetoelectric effect, in soft multiferroics such as mixtures of SCE9 ferroelectric liquid crystal and magnetic nanoparticles.
    No preview · Conference Paper · May 2011
  • Yoshihiro Ishibashi · Makoto Iwata · Robert Blinc
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    ABSTRACT: The phase transitions in ferroelectric KH2PO4 (KDP) and antiferroelectric NH4H2PO4 (ADP) crystals are discussed on the basis of the eight-pseudospin model of KH2PO4-type crystals previously proposed, where eight pseudospins represent protons on hydrogen bonds connecting PO4 radicals in a unit cell. The dielectric susceptibilities along the c-axis, which is the unique ferroelectric axis, and a (b)-axis, which is perpendicular to the unique axis, are calculated.
    No preview · Article · May 2011 · Journal of the Physical Society of Japan
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    ABSTRACT: The 1H–17O nuclear quadrupole double resonance spectrum and the 13C CP/MAS NMR spectrum of polycrystalline croconic acid, H2C5O5, have been studied at room temperature. Croconic acid has been recently shown to have the highest switchable spontaneous polarization of all organic ferroelectrics and stays polarized up to the decomposition point at around 450 K. Both the 13C NMR and the 17O nuclear quadrupole resonance (NQR) spectra show that there are five crystallorgaphically non-equivalent carbon and oxygen positions for a given molecule and that therefore the two O–H. . .O bonds are non-equivalent. From the dipolar structure of the 17O quadrupole resonance spectra the O–H distance is determined as being 0.099�0.001 nm in both hydrogen bonds. The large 17Oquadrupole coupling constant at the C–O–H as well as at the C–– O. . .H oxygen position and the short O–H distance demonstrate that the O–H. . .O hydrogen bonds are strongly asymmetric. A correlation of the 17O–H. . .O and O–H. . .17O quadrupole coupling constants versus the O. . .O distance has been observed in several organic acids. The data for croconic acid significantly deviate from this correlation, what may be the result of the strong long range ferroelectric ordering which influences the electron distribution in the hydrogen bonds.
    No preview · Article · May 2011 · physica status solidi (b)
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    ABSTRACT: Solar power plants positioned in space for terrestrial electricity use have been proposed due to the ever-rising world energy consumption and its environmental impacts. This idea is analysed here in the context of sustainability of such power generation. To that end we have performed some new economic, environmental and social effects analysis of electricity generation by solar space power plants of both photovoltaic and solar thermal types power using the best currently available technology. The plants in the analysis were assumed to be in different Earth orbits, or on the Moon built by a robotised factory. One of our results is that both economically and environmentally the best scenario may be to launch a thermal solar power plant to the geostationary orbit from the Moon. Electricity produced in this way could be economically competitive to that generated by fossil fuels on Earth already for as few as 100 space power plants of about 5–10 GW each. This option is also deemed socially responsible with its capacity to reduce poverty with large amounts of cheap clean energy, and environmentally friendly, because it produces more than a hundred times less emissions than the same amount of electricity produced from fossil fuels on Earth.
    No preview · Article · Apr 2011 · Fuel and Energy Abstracts

Publication Stats

14k Citations
2,441.28 Total Impact Points


  • 1961-2013
    • University of Ljubljana
      • • Department of Physics
      • • Faculty of Mathematics and Physics
      • • Institute of Mathematics, Physics, and Mechanics
      • • Laboratory of Physics
      Lubliano, Ljubljana, Slovenia
  • 1971-2012
    • Jožef Stefan Institute
      • • Department of Condensed Matter Physics
      • • Solid State Physics
      • • Theoretical Physics
      • • Department of Physics
      Lubliano, Ljubljana, Slovenia
  • 2008-2011
    • Nagoya Institute of Technology
      • Department of Engineering Physics, Electronics and Mechanics
      Nagoya, Aichi, Japan
  • 2006-2011
    • Jožef Stefan International Postgraduate School
      Lubliano, Ljubljana, Slovenia
    • University of Waterloo
      Waterloo, Ontario, Canada
  • 2002
    • University of Utah
      Salt Lake City, Utah, United States
  • 1998
    • Max Planck Institute for Medical Research
      Heidelburg, Baden-Württemberg, Germany
  • 1992
    • Radboud University Nijmegen
      • High Field Magnet Laboratory (HFML)
      Nymegen, Gelderland, Netherlands
  • 1991
    • University of Vienna
      Wien, Vienna, Austria
  • 1976
    • Eawag: Das Wasserforschungs-Institut des ETH-Bereichs
      Duebendorf, Zurich, Switzerland
  • 1969
    • Argonne National Laboratory
      • Division of Physics
      Lemont, Illinois, United States