Critical Behavior of the Dielectric Modulus in Nitrobenzene-Dodecane Mixture

2003 ◽  
Vol 58 (9-10) ◽  
pp. 541-545 ◽  
Author(s):  
P. Malik ◽  
S. J. Rzoska ◽  
A. Drozd-Rzoska ◽  
W. W. Sułkowskia ◽  
J. Jadzynb
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Critical Exponent ◽  
Specific Heat ◽  
Imaginary Part ◽  
Critical Behavior ◽  
Peak Frequency ◽  
Dielectric Modulus ◽  
Static Dielectric Permittivity ◽  
Temperature Dependences

The dielectric properties of a homogenous critical mixture of nitrobenzene-decane were studied in the range 1 Hz< f1 Mz. The temperature dependences of the “static” dielectric permittivity ε’ (1 MHz) and the electric conductivity σ(1 Hz) exhibit pretransitional anomalies which may be associated with the same critical exponent ø = 1−α ≈ 0.88, where α is the critical exponent of the specific heat. The same data were analyzed using the dielectric modulus representation. They show loss curves for the imaginary part of the modulus M ̋( f ). It was found that the temperature evolutions of the peak frequency τ = 1/2π fp and the peak maximum of M ̋ =M ̋( fp) also exhibit critical anomalies. Their forms resemble anomalies obtained for the imaginary part of the dielectric permittivity ε̋( f ), carried out for 40 MHz < f <1 GHz, in an ethanol-dodecane critical mixture [S. J. Rzoska, K. Orzechowski, and A. Drozd-Rzoska, Phys. Rev. E 65, 042501 (2002)]. - PACS: 64.70.Ja, 77.20.+y , 64.60.Fr

CRITICAL BEHAVIOR OF THE SPECIFIC HEAT IN THE VICINITY OF THE TRANSITION TEMPERATURE FOR S-TRIAZINE

2009 ◽  
Vol 23 (09) ◽  
pp. 2253-2259 ◽  
Author(s):  
M. KURT ◽  
H. YURTSEVEN
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
Transition Temperature ◽  
Critical Exponent ◽  
Specific Heat ◽  
Power Law ◽  
Order Phase Transition ◽  
Critical Behavior ◽  
First Order ◽  
Second Order Phase Transition

The critical behavior of the specific heat is studied in s-triazine ( C 3 N 3 H 3). Using the experimental data for the CP, the temperature dependence of the specific heat is analyzed according to a power-law formula and the values of the critical exponent for CP are extracted in the vicinity of the transition temperature (TC=198.07 K ). It is indicated that s-triazine undergoes a weakly first order (quasi-continuous) or second order phase transition.

Theoretical investigation of dielectric properties of rare earth stillwellite compounds

2015 ◽  
Vol 29 (21) ◽  
pp. 1550154
Author(s):  
R. Shaltaf ◽  
J. Khalifeh
Keyword(s):  
Electronic Structure ◽  
Rare Earth ◽  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Density Functional ◽  
Structural Parameters ◽  
The Other ◽  
Static Dielectric Permittivity ◽  
Dielectric Tensors

Ab initio density functional calculations are performed to investigate the dielectric properties of LnBSiO 5 (Ln = Ce, Pr, Nd) with the stillwellite structure. The calculated structural parameters are found to agree well with existing experimental results. The three compounds possess insulating electronic structure with nearly isotropic high frequency dielectric permittivity tensors. On the other hand, the static dielectric permittivity tensors are found to be less isotropic. The anisotropy of static dielectric tensors are found to increase as the atomic number of the lanthanide increases.

The Determination of the Magnetoelectric Coupling Coefficient in Ferroelectric–Ferromagnetic Composite Based on PZT–Ferrite

2013 ◽  
Vol 58 (4) ◽  
pp. 1401-1403 ◽  
Author(s):  
J.A. Bartkowska ◽  
R. Zachariasz ◽  
D. Bochenek ◽  
J. Ilczuk
Keyword(s):  
Dielectric Permittivity ◽  
Coupling Coefficient ◽  
Mean Field ◽  
Field Approximation ◽  
Theoretical Description ◽  
Magnetoelectric Coupling ◽  
Mean Field Approximation ◽  
Dielectric Measurements ◽  
Temperature Dependences ◽  
Multiferroic Composite

Abstract In the present work, the magnetoelectric coupling coefficient, from the temperature dependences of the dielectric permittivity for the multiferroic composite was determined. The research material was ferroelectric-ferromagnetic composite on the based PZT and ferrite. We investigated the temperature dependences of the dielectric permittivity (") for the different frequency of measurement’s field. From the dielectric measurements we determined the temperature of phase transition from ferroelectric to paraelectric phase. For the theoretical description of the temperature dependence of the dielectric constant, the Hamiltonian of Alcantara, Gehring and Janssen was used. To investigate the dielectric properties of the multiferroic composite this Hamiltonian was expressed under the mean-field approximation. Based on dielectric measurements and theoretical considerations, the values of the magnetoelectric coupling coefficient were specified.

scholarly journals Sintering, Microstructure, and Dielectric Properties of Copper Borates for High Frequency LTCC Applications

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4017
Author(s):  
Dorota Szwagierczak ◽  
Beata Synkiewicz-Musialska ◽  
Jan Kulawik ◽  
Norbert Pałka
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Ceramic Materials ◽  
Sintering Behavior ◽  
Terahertz Time Domain Spectroscopy ◽  
Very High Frequency ◽  
X Ray ◽  
Low Dielectric ◽  
Very High

New ceramic materials based on two copper borates, CuB2O4 and Cu3B2O6, were prepared via solid state synthesis and sintering, and characterized as promising candidates for low dielectric permittivity substrates for very high frequency circuits. The sintering behavior, composition, microstructure, and dielectric properties of the ceramics were investigated using a heating microscope, X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy, and terahertz time domain spectroscopy. The studies revealed a low dielectric permittivity of 5.1–6.7 and low dielectric loss in the frequency range 0.14–0.7 THz. The copper borate-based materials, owing to a low sintering temperature of 900–960 °C, are suitable for LTCC (low temperature cofired ceramics) applications.

Influence of smectic order on the static dielectric permittivity of liquid crystals

1974 ◽  
Vol 61 (5) ◽  
pp. 1985-1989 ◽  
Author(s):  
W. H. de Jeu ◽  
W. J. A. Goossens ◽  
P. Bordewijk
Keyword(s):  
Liquid Crystals ◽  
Dielectric Permittivity ◽  
Static Dielectric Permittivity

scholarly journals Polytetrafluoroethylene Films in Rigid Polyurethane Foams’ Dielectric Permittivity Measurements with a One-Side Access Capacitive Sensor

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1173
Author(s):  
Ilze Beverte ◽  
Ugis Cabulis ◽  
Sergejs Gaidukovs
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Low Frequency ◽  
Capacitive Sensor ◽  
Polyurethane Foams ◽  
Active Area ◽  
Ptfe Film ◽  
Practical Applications ◽  
Permittivity Measurements ◽  
The Impact

As a non-metallic composite material, widely applied in industry, rigid polyurethane (PUR) foams require knowledge of their dielectric properties. In experimental determination of PUR foams’ dielectric properties protection of one-side capacitive sensor’s active area from adverse effects caused by the PUR foams’ test objects has to be ensured. In the given study, the impact of polytetrafluoroethylene (PTFE) films, thickness 0.20 mm and 0.04 mm, in covering or simulated coating the active area of one-side access capacitive sensor’ electrodes on the experimentally determined true dielectric permittivity spectra of rigid PUR foams is estimated. Penetration depth of the low frequency excitation field into PTFE and PUR foams is determined experimentally. Experiments are made in order to evaluate the difference between measurements on single PUR foams’ samples and on complex samples “PUR foams + PTFE film” with two calibration modes. A modification factor and a small modification criterion are defined and values of modifications are estimated in numerical calculations. Conclusions about possible practical applications of PTFE films in dielectric permittivity measurements of rigid PUR foams with one-side access capacitive sensor are made.

Anisotropy Energies and Critical Behavior of Ultrathin Ni(111) Films Grown on Smooth and Rough W(110) (invited)

1991 ◽  
Vol 231 ◽  
Author(s):  
Yi Li ◽  
K. Baberschke
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Film Thickness ◽  
Critical Exponent ◽  
Critical Behavior ◽  
Induced Anisotropy ◽  
Effective Anisotropy ◽  
Stress Induced Anisotropy ◽  
Surface Crystal

Abstract6 to 80 Å thin Ni(111) films were prepared on smooth and rough W(110) substrates in UHV and characterized by LEED and Auger spectroscopies. The measurements of the magnetic properties were carried out in situ by ferromagnetic resonance at 9 GHz between 300 and 600 K. We found that the effective anisotropies, which consist of surface, crystal, and stress induced anisotropy, increase with decreasing film thickness and temperature. The roughness of the substrate results in the drastic decrease of the effective anisotropy. This is attributed to the change of the surface structure and the stress within the Ni films. Furthermore we found that the Curie temperature Tc and the critical exponent β of Ni films on the smooth and rough substrates show no change.

scholarly journals Электрофизические и диэлектрические свойства поликристаллов железо-иттриевого феррита-граната, полученных по технологии радиационно-термического спекания

2021 ◽  
Vol 63 (3) ◽  
pp. 356
Author(s):  
В.Г. Костишин ◽  
Р.И. Шакирзянов ◽  
А.Г. Налогин ◽  
С.В. Щербаков ◽  
И.М. Исаев ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Loss Tangent ◽  
Sintering Temperature ◽  
Ceramic Technology ◽  
Complex Dielectric Constant ◽  
Temperature Dependences ◽  
Fast Electron Beam ◽  
Electrical And Dielectric Properties ◽  
Thermal Sintering ◽  
Iron Garnet

In this paper the electrical and dielectric properties of polycrystalline yttrium iron garnet, obtained by the radiation-thermal sintering technology in a fast electron beam were investigated. Spectra of complex dielectric constant, dielectric loss tangent and conductivity were measured in the frequency range 25 – 1∙106 Hz. For comparison, DC resistance measurements were also performed. The temperature dependences of the above parameters were measured at frequencies of 1 kHz, 100 kHz in the range 25 - 300 °C. It is shown, that conduction activations energy, permittivity, loss tangent and resistance vary significantly from sintering temperature in the range of 1300 to 1450 °C. It is found that with an increase in the sintering temperature to 1450 °C, dielectric properties are the same as samples made by the traditional ceramic technology.

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