R. Blinc

University of Ljubljana, Ljubljana, Ljubljana, Slovenia

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Publications (970)1564.01 Total impact

  • [Show abstract] [Hide abstract]
    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.
    Physical Review B 02/2013; 71(6). · 3.66 Impact Factor
  • Journal of Molecular Structure 02/2013; 176(1-2):331-335. · 1.40 Impact Factor
  • J. Seliger, V. Žagar, R. Blinc
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    ABSTRACT: The 14N quadrupole coupling constant and asymmetry parameter η have been measured (using a double-resonance technique) as a function of temperature in the smectic A, smectic C, and smectic H phases of achiral TBBA and chiral TBACA, as well as in the smectic VI and the solid phase of TBBA. In the low-temperature smectic H and smectic VI phases of achiral TBBA the results clearly demonstrate the existence of bipolar orientational ordering 〈cos2ϕ〉≠0 whereas they show the existence of polar orientational order 〈cosϕ〉≠0 in the smectic H phase of chiral TBACA. Here 〈cosϕ〉∝(Tc-T)β with β=0.33±0.02. In the smectic C phase of both systems the 14N nuclear-quadrupole-resonance spectrum is mainly determined by anisotropic fluctuations in the long molecular axis and the orientational order parameters can be only roughly estimated.
    Physical Review A 02/2013; 17(3). · 3.04 Impact Factor
  • 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.
    Journal of Magnetic Resonance 02/2013; 58(3):359-369. · 2.30 Impact Factor
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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.
    Zeitschrift für Physik B Condensed Matter 02/2013; 69(2-3):379-384.
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    ABSTRACT: In the presence of external fields or in restricted geometries, the originally continuous helical symmetry of the Sm C* phase is broken by the appearence of field- or geometry-induced soliton-like domain walls. As a result of this symmetry breaking, a crossover between the plane-wave-like and soliton-like regime occurs in both static and dynamic properties which is responsible for some remarkable phenomena such as field-induced optical biaxiality or a field-induced band structure of collective excitations. Whereas we find in the plane-wave-like regime a degenerate soft mode which splits below the Sm A→Sm C* transition into a symmetry recovering Goldstone-phason-mode and an amplitudon mode, we find in the soliton regime a splitting of the phason mode into acoustic and optic-like branches separated by a band gap. Within the same framework we also discuss other remarkable and extraordinary properties such as reentrant phases, Lifshitz points, one dimensional photonic band gaps and thickness dependent phase diagrams.
    International Journal of Modern Physics B 05/2012; 09(18n19). · 0.46 Impact Factor
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    ABSTRACT: We combine a wide variety of experimental techniques to analyze two heretofore mysterious phase transitions in multiferroic bismuth ferrite at low temperature. Raman spectroscopy, resonant ultrasound spectroscopy, EPR, X-ray lattice constant measurements, conductivity and dielectric response, specific heat and pyroelectric data have been collected for two different types of samples: single crystals and, in order to maximize surface/volume ratio to enhance surface phase transition effects, BiFeO3 nanotubes were also studied. The transition at T=140.3K is shown to be a surface phase transition, with an associated sharp change in lattice parameter and charge density at the surface. Meanwhile, the 201K anomaly appears to signal the onset of glassy behaviour.
    Physical review. B, Condensed matter 02/2012; 85(18). · 3.77 Impact Factor
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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.
    International Journal of Modern Physics B 01/2012; 06(23n24). · 0.46 Impact Factor
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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.
    Physical review. B, Condensed matter 01/2012; 85(5):054419. · 3.77 Impact Factor
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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.
    Ferroelectrics. 01/2012; 427(1):56-62.
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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.
    Ferroelectrics 01/2012; 426(1):38-44. · 0.42 Impact Factor
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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.
    Ferroelectrics. 10/2011; 240(1):1473-1478.
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    ABSTRACT: The motionally averaged electric field gradient tensors at the Ti-sites have been evaluated within the 8-site Ti disorder model for the various phases of BaTiO3. The results have been compared with the experimental data and with the observation of a non-zero Ti quadrupole coupling in the cubic phase. The pure 8-site “order-disorder” model does not agree with the experiment. A good agreement is however obtained if in addition to the dynamic Ti disorder the “displacive” soft mode induced deformation of the unit cell shape is taken into account. The presence of the soft mode and the Ti disorder leads to a special type of phase transition with combined “displacive” and “order-disorder” character.
    Integrated Ferroelectrics 10/2011; 2004(Vol. 61):255-260. · 0.38 Impact Factor
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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.
    physica status solidi (b) 09/2011; 248(11):2653 - 2655. · 1.49 Impact Factor
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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.
    Acta Chimica Slovenica 09/2011; 58(3):393-5. · 1.14 Impact Factor
  • Source
    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).
    Journal of Physics Condensed Matter 07/2011; 23(29):299401. · 2.22 Impact Factor
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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.
    Journal of Physics Conference Series 07/2011; 303(1):012065.
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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.
    Journal of Applied Physics 06/2011; · 2.21 Impact Factor
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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.
    Journal of Applied Physics 06/2011; 109:114101. · 2.21 Impact Factor
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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.
    3rd Jožef Stefan International Postgraduate School Students Conference, JSI,; 05/2011

Publication Stats

6k Citations
1,564.01 Total Impact Points

Institutions

  • 1961–2013
    • University of Ljubljana
      • • Department of Physics
      • • Faculty of Mathematics and Physics
      • • Institute of Mathematics, Physics, and Mechanics
      • • Faculty of Medicine
      Ljubljana, Ljubljana, Slovenia
  • 1970–2012
    • Jožef Stefan Institute
      • • Department of Condensed Matter Physics
      • • Solid State Physics
      • • Department of Physics
      Lubliano, Ljubljana, Slovenia
  • 2011
    • EN-FIST Centre of Excellence
      Lubliano, Ljubljana, Slovenia
  • 2009–2011
    • National Academy of Sciences of Ukraine
      • V. E. Lashkaryov Institute of Semiconductor Physics
      Kiev, Misto Kyyiv, Ukraine
    • Jožef Stefan International Postgraduate School
      Lubliano, Ljubljana, Slovenia
    • Université de Picardie Jules Verne
      • LPMC - Laboratoire de physique de la matière condensée
      Amiens, Picardie, France
    • University of Puerto Rico at Rio Piedras
      • Department of Physics
      San Juan, San Juan, Puerto Rico
  • 2006–2011
    • University of Cambridge
      • • Department of Physics: Cavendish Laboratory
      • • Department of Earth Sciences
      Cambridge, ENG, United Kingdom
    • University of Waterloo
      Waterloo, Ontario, Canada
    • Croatian Academy of Sciences and Arts
      Zagrabia, Grad Zagreb, Croatia
  • 2004–2005
    • Università di Pisa
      • Department of Chemistry and Industrial Chemistry
      Pisa, Tuscany, Italy
  • 2003–2004
    • Ioffe Physical Technical Institute
      Sankt-Peterburg, St.-Petersburg, Russia
  • 2000
    • University of Maribor
      Maribor, Maribor, Slovenia
  • 1995
    • University of Leipzig
      Leipzig, Saxony, Germany
  • 1989–1994
    • University of Vienna
      • Basic Experimental Physics Training and Didactics Group
      Vienna, Vienna, Austria
  • 1988
    • Institute of Molecular Physics, Polish Academy of Sciences
      Posen, Greater Poland Voivodeship, Poland
  • 1985
    • Institute of Physics Belgrade
      Beograd, Central Serbia, Serbia
  • 1981
    • Radboud University Nijmegen
      Nymegen, Gelderland, Netherlands
  • 1979
    • Federal University of Minas Gerais
      • Departamento de Física
      Belo Horizonte, Estado de Minas Gerais, Brazil
  • 1971–1977
    • Stockholm University
      • Department of Biochemistry and Biophysics
      Tukholma, Stockholm, Sweden
  • 1976
    • Eawag: Das Wasserforschungs-Institut des ETH-Bereichs
      Duebendorf, Zurich, Switzerland
  • 1969–1976
    • ETH Zurich
      • Laboratory for Solid State Physics
      Zürich, ZH, Switzerland
    • Argonne National Laboratory
      Lemont, Illinois, United States
  • 1974
    • Kent State University
      Kent, Ohio, United States
  • 1968–1969
    • University of Washington Seattle
      Seattle, Washington, United States
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France