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A. Brilingas

Bio: A. Brilingas is an academic researcher from Vilnius University. The author has contributed to research in topics: Dielectric & Permittivity. The author has an hindex of 13, co-authored 39 publications receiving 672 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the dielectric dispersion of the transparent relaxor ferroelectric ceramics PLZT 8/65/35 and 9.5/35 was determined in a wide frequency range including the microwave and infrared range.
Abstract: The dielectric dispersion of the transparent relaxor ferroelectric ceramics PLZT 8/65/35 and 9.5/65/35 was determined in a wide frequency range including the microwave and infrared range. The number of observed polar phonons in infrared spectra gives evidence about the locally broken cubic symmetry and the presence of polar nanoclusters in the whole investigated temperature range up to 530 K. A single broad and symmetric dispersion that occurs below the polar phonon frequencies was fitted with the Cole-Cole formula and a uniform distribution of Debye relaxations. On decreasing temperature, the distribution of relaxation times becomes extremely broad which indicates increasing correlation among the clusters. The mean relaxation time diverges according to the Vogel-Fulcher law with the same freezing temperature 230±5 K for both ceramics, but different activation energies 1370 K and 1040 K for the 8/65/35 and 9.5/65/35 sample, respectively. The shortest relaxation time is about 10-12 s and remains almost temperature independent. Below room temperature, the loss spectra become essentially frequency independent and the permittivity increases linearly with decreasing logarithm of frequency. The slope of this dependence is proportional to T 4 in the investigated temperature range (above 210 K) which indicates appreciable anharmonicity of the potential for polarization fluctuations.

167 citations

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TL;DR: In this paper, the dielectric properties of asphalt pavement were studied in the process of developing a roller mountable microwave asphalt pavement density sensor as part of the National Cooperative Highway Research Program IDEA project.
Abstract: This paper describes dielectric properties of asphalt pavement that were studied in the process of developing a roller mountable microwave asphalt pavement density sensor as part of the National Cooperative Highway Research Program IDEA project. This new sensor involves simultaneously measuring reflected microwave signals from the asphalt pavement in front of and behind the vibratory roller. As the reflected signal and penetration depth of microwaves depend on the dielectric properties of asphalt pavement, temperature, and frequency dependencies of the permittivity and loss of asphalt, samples of different densities were studied in the frequency range from 100 Hz to 12 GHz. Results show that (1) permittivity and loss depend on frequency and temperature; (ii) the higher the pavement density, the higher the permittivity; (iii) permittivity slightly increases with temperature; (iv) moisture strongly increases permittivity and loss at low frequencies and only slightly at microwave frequencies; and (v) the penetration depth of microwaves in asphalt pavement is about 1214 cm at 8 GHz and only about 4 cm at 30 GHz.

123 citations

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TL;DR: In this paper, a multiferroic composites with the general formula x BaTiO 3 −(1− x ) NiFe 2 O 4 (x = 0.5, 0.7,0.8) were prepared by mixing chemically obtained nickel ferrite and barium titanate powders.

75 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the dielectric and ultrasonic properties of layered CuInP2S6 crystals and found that the high frequency part of the spectra is determined by relaxational soft mode and the critical slowing and Debye-type dispersion show the order-disorder type of the phase transition.
Abstract: Investigation results of dielectric and ultrasonic properties of layered CuInP2S6 crystals are presented. At low frequencies, dielectric spectra are highly influenced by the high ionic conductivity with the activation energy of 7357.4 K (0.635 eV). The high-frequency part of the spectra is determined by relaxational soft mode. The critical slowing down and Debye-type dispersion show the order–disorder type of the phase transition. The temperature dependence of the relaxational soft mode and dielectric contribution show a quasi-one-dimensional behaviour. Ultrasonic velocity exhibits critical slowing down which is accompanied by attenuation peaks in the phase transition region. Layered CuInP2S6 crystals have extremely large elastic nonlinearity in the direction perpendicular to layers. The nonlinear elastic parameters substantially increases at the PT temperature.

67 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the dielectric relaxation of PMN-PSN-PZN relaxor ferroelectrics in a broad frequency range from $20\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}$ up to $100
Abstract: Dielectric spectra of several solid solutions of $\mathrm{Pb}{\mathrm{Mg}}_{1∕3}{\mathrm{Nb}}_{2∕3}{\mathrm{O}}_{3}\text{\ensuremath{-}}\mathrm{Pb}{\mathrm{Sc}}_{1∕2}{\mathrm{Nb}}_{1∕2}{\mathrm{O}}_{3}\text{\ensuremath{-}}\mathrm{Pb}{\mathrm{Zn}}_{1∕3}{\mathrm{Nb}}_{2∕3}{\mathrm{O}}_{3}$ (PMN-PSN-PZN) relaxor ferroelectrics were investigated in a broad frequency range from $20\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}$ up to $100\phantom{\rule{0.3em}{0ex}}\mathrm{THz}$ by a combination of dielectric spectroscopy $(20\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}\char21{}53\phantom{\rule{0.3em}{0ex}}\mathrm{GHz})$, time-domain terahertz spectroscopy $(0.1\char21{}0.9\phantom{\rule{0.3em}{0ex}}\mathrm{THz})$, and infrared reflectivity ($20\char21{}3000\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$, $0.6\char21{}90\phantom{\rule{0.3em}{0ex}}\mathrm{THz}$). The very strong and broad dielectric relaxation observed below phonon frequencies was analyzed in terms of the distribution of relaxation times, using the Tichonov regularization method. This revealed slowing down of the longest and mean relaxation times obeying the Vogel-Fulcher law. The relaxation splits into two components near ${T}_{m}$ and the origin of both components is discussed. The formation of polar clusters below the Burns temperature $(700\char21{}800\phantom{\rule{0.3em}{0ex}}\mathrm{K})$ is manifested by the appearance of dielectric relaxation in the terahertz range and by splitting of the polar modes in the infrared spectra. On heating from low temperatures, the ${A}_{1}$ component of the strongly split ${\mathrm{TO}}_{1}$ mode softens toward the Burns temperature, but the softening ceases near $400\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, which could be a signature of a polar cluster percolation temperature.

64 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the lattice dynamics and the peculiar dielectric relaxation in relaxors are discussed, and theoretical models for the mechanisms of PNR formation and freezing into nonergodic glassy state are also presented.
Abstract: Relaxor ferroelectrics were discovered almost 50 years ago among the complex oxides with perovskite structure. In recent years this field of research has experienced a revival of interest. In this paper we review the progress achieved. We consider the crystal structure including quenched compositional disorder and polar nanoregions (PNR), the phase transitions including compositional order-disorder transition, transition to nonergodic (probably spherical cluster glass) state and to ferroelectric phase. We discuss the lattice dynamics and the peculiar (especially dielectric) relaxation in relaxors. Modern theoretical models for the mechanisms of PNR formation and freezing into nonergodic glassy state are also presented.

1,784 citations

Journal ArticleDOI
R.L. McGreevy1
TL;DR: Reverse Monte Carlo (RMC) is a general method of structural modeling based on experimental data as mentioned in this paper, which can be applied to many different sorts of data, simultaneously if wished.
Abstract: Reverse Monte Carlo (RMC) modelling is a general method of structural modelling based on experimental data. RMC modelling can be applied to many different sorts of data, simultaneously if wished. Powder and single-crystal neutron diffraction (including isotopic substitution), x-ray diffraction (including anomalous scattering) and electron diffraction, extended x-ray absorption fine structure and nuclear magnetic resonance (magic angle spinning and second moment) have already been used to provide data. RMC modelling can also be applied to many different types of system - liquids, glasses, polymers, crystals and magnetic materials. This article outlines the RMC method and discusses some of the common misconceptions about it. It is stressed that RMC models are neither unique nor `correct'. However, they are often useful for aiding our understanding either of the structure itself, or of the relationships between local structure and other physical properties. Examples are given and the possibilities for further development of the RMC method are discussed.

696 citations

Journal ArticleDOI
17 Mar 2005-Nature
TL;DR: Measurements on a simple cubic spinel compound with unusual, and potentially useful, magnetic and electric properties show ferromagnetic order coexisting with relaxor ferroelectricity, and the magnetocapacitive coupling reaches colossal values, approaching 500 per cent.
Abstract: Ferromagnets have been known since ancient times. Ferroelectrics were discovered 80 years ago, and both properties are important in many areas of technology and electronics. Materials displaying both ferroelectricity and ferromagnetism combine the potential applications of both parent phases, with a range of new applications in optics, electronic circuitry and multiple-state memory devices. Such materials are rare, but one described this week, the common sulpho-spinel CdCr2S4, shows promise. It combines reasonable ordering temperatures (the point at which magnetic properties disappear) with sizeable magnetization and polarization well suited for application. Materials in which magnetic and electric order coexist—termed ‘multiferroics’ or ‘magnetoelectrics’—have recently become the focus of much research1,2,3,4. In particular, the simultaneous occurrence of ferromagnetism and ferroelectricity, combined with an intimate coupling of magnetization and polarization via magnetocapacitive effects, holds promise for new generations of electronic devices. Here we present measurements on a simple cubic spinel compound with unusual, and potentially useful, magnetic and electric properties: it shows ferromagnetic order coexisting with relaxor ferroelectricity (a ferroelectric cluster state with a smeared-out phase transition), both having sizable ordering temperatures and moments. Close to the ferromagnetic ordering temperature, the magnetocapacitive coupling (characterized by a variation of the dielectric constant in an external magnetic field) reaches colossal values, approaching 500 per cent. We attribute the relaxor properties to geometric frustration, which is well known for magnetic moments but here is found to impede long-range order of the structural degrees of freedom that drive the formation of the ferroelectric state.

436 citations

Journal ArticleDOI
TL;DR: The existence of stable polarization in a van-der-Waals crystal naturally points toward new strategies for ultimate scaling of polar materials, quasi-2D, and single-layer materials with advanced and nonlinear dielectric properties that are presently not found in any members of the growing "graphene family".
Abstract: We explore ferroelectric properties of cleaved 2-D flakes of copper indium thiophosphate, CuInP2S6 (CITP), and probe size effects along with limits of ferroelectric phase stability, by ambient and ultra high vacuum scanning probe microscopy. CITP belongs to the only material family known to display ferroelectric polarization in a van der Waals, layered crystal at room temperature and above. Our measurements directly reveal stable, ferroelectric polarization as evidenced by domain structures, switchable polarization, and hysteresis loops. We found that at room temperature the domain structure of flakes thicker than 100 nm is similar to the cleaved bulk surfaces, whereas below 50 nm polarization disappears. We ascribe this behavior to a well-known instability of polarization due to depolarization field. Furthermore, polarization switching at high bias is also associated with ionic mobility, as evidenced both by macroscopic measurements and by formation of surface damage under the tip at a bias of 4 V—likely...

278 citations

Journal ArticleDOI
TL;DR: A broad family of layered metal thio(seleno)phosphate materials that are moderate- to wide-bandgap semiconductors with incipient ionic conductivity and a host of ferroic properties are reviewed, arguing that this material class has the potential to merge the sought-after properties of complex oxides with electronic functions of 2D and quasi-2D electronic materials.
Abstract: Since the discovery of Dirac physics in graphene, research in 2D materials has exploded with the aim of finding new materials and harnessing their unique and tunable electronic and optical properties. The follow-on work on 2D dielectrics and semiconductors has led to the emergence and development of hexagonal boron nitride, black phosphorus, and transition metal disulfides. However, the spectrum of good insulating materials is still very narrow. Likewise, 2D materials exhibiting correlated phenomena such as superconductivity, magnetism, and ferroelectricity have yet to be developed or discovered. These properties will significantly enrich the spectrum of functional 2D materials, particularly in the case of high phase-transition temperatures. They will also advance a fascinating fundamental frontier of size and proximity effects on correlated ground states. Here, a broad family of layered metal thio(seleno)phosphate materials that are moderate- to wide-bandgap semiconductors with incipient ionic conductivity and a host of ferroic properties are reviewed. It is argued that this material class has the potential to merge the sought-after properties of complex oxides with electronic functions of 2D and quasi-2D electronic materials, as well as to create new avenues for both applied and fundamental materials research in structural and magnetic correlations.

255 citations