Preliminary Studies on the Dielectric Permittivity in the Isotropic and Mesophase of Cholesteryl Oleyl Carbonate

2002 ◽  
Vol 57 (3-4) ◽  
pp. 126-128 ◽  
Author(s):  
Sebastian Pawlus ◽  
Malgorzata Zasada ◽  
S. J. Rzoska
Keyword(s):  
Phase Transition ◽  
Dielectric Permittivity ◽  
Dielectric Spectroscopy ◽  
Low Frequency ◽  
Broad Temperature Range ◽  
Phase Detection ◽  
Temperature Range ◽  
Simple Detection

The phase detection in cholesteryl oleyl carbonate was studied over a broad temperature range by dielectric spectroscopy. Tests were conducted in the static and the low frequency ionic regions. They point to the possibility of relatively simple detection of phase transition. Some manifestations of pretransitional behaviours were also found. - Pacs: 64.70Md, 77.22Ch, 64.30+t

Precise dielectric spectroscopy of a dual-frequency nematic mixture over a broad temperature range

2012 ◽  
Vol 39 (10) ◽  
pp. 1237-1242 ◽  
Author(s):  
P. Perkowski ◽  
M. Mrukiewicz ◽  
K. Garbat ◽  
M. Laska ◽  
U. Chodorow ◽  
...  
Keyword(s):  
Dielectric Spectroscopy ◽  
Broad Temperature Range ◽  
Dual Frequency ◽  
Temperature Range

scholarly journals Dielectric Properties of Ternary ( ) ( )x ( ) x ZnO MgO PO 30 2 5 70− (x = 5, 8, 13) Glasses

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
S. F. Khor ◽  
Z. A. Talib ◽  
W. M. Daud ◽  
H. A. A. Sidek ◽  
W. M. M. Yunus ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Empirical Data ◽  
Loss Factor ◽  
Low Frequency ◽  
Frequency Range ◽  
Melt Quenching ◽  
Dipolar Relaxation ◽  
Temperature Range

(ZnO)30(MgO)x(P2O5)70-x glasses of the composition x = 5, 8 and 13 mol % have been prepared by melt quenching technique. The dielectric permittivity (89) and loss factor (8:) were measured in the frequency range from 0.01 Hz to 1 MHz and in the temperature range 303 to 573 K . From the results there are evidence of dipolar relaxation occurring between 103 – 106 Hz while at low frequency the spectrum is dominated by dc conduction which manifested by the 1/@ slope of loss factor plot. Value of the relaxing frequency (@p) plotted against 1/T shows one electrical transportation mechanism. The empirical data was sufficiently fitted by using Harviliak-Negami equation.

Permittivity and Microstructure of (Ba,Sr)TiO3 Films: Temperature and Electric Field Response

1999 ◽  
Vol 603 ◽  
Author(s):  
Yu.A. Boikov ◽  
T. Claeson ◽  
Z. Ivanov ◽  
E. Olsson
Keyword(s):  
Phase Transition ◽  
Dielectric Permittivity ◽  
Electric Field ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Transition Point ◽  
Phase Transition Point ◽  
Bulk Single Crystal ◽  
Temperature Range ◽  
Field Response

AbstractEpitaxial heterostructures (001)(Y,Nd)Ba2Cu3O7-δ∥(100)SrTiO3∥(001)(Nd,Y)Ba2Cu3O7-δ,(100)SrRuO3∥(100)Ba0.8Sr0.2TiO3∥(100)SrRuO3, (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 and (100)SrTiO3∥(001)YBa2Cu3O7-δ have been grown by laser ablation. There was only a small difference of the dielectric permittivity, in the temperature range 180-300K, between a bulk single crystal and an epitaxial (100)SrTiO3 layer inserted between either high-Tc superconducting or SrRuO3 electrodes. At T<1 50K, on the other hand, the response of the dielectric permittivity of the SrTiO3 layer on temperature or electric field depended to a large extent upon the materials used as bottom and top electrodes in the heterostructures. The temperature dependence of the dielectric permittivity for the SrTiO3 layer in (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 was well extrapolated by a Curie-Weiss relation in the range of T=80-300K, with about the same Curie constant (C0=7.5 × 104 K) and Curie temperature (TCurie=21K) as in a bulk single crystal. At temperatures higher the phase transition point (65 K), the electric field response of the permittivity of the SrTiO3 layer between high-TC superconducting or metallic oxide electrodes was well extrapolated by the same relation used for a bulk single crystal. The smallest loss factor, tanδ, was measured for the capacitance (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 (T ≈ 50-300K, f=100kHz). The measured conductance G for the SrTiO3 layer in the (001)(Y,Nd)Ba2Cu3O7-δ heterostructure fitted well the relation InG∼-(ED/kT), with ED=0.08-0.09 eV in a temperature range close to 300K. Pronounced hysteresis was observed in the temperature dependence of the dielectric permittivity for the (100)Ba0.8Sr0.2TiO3 layer at temperatures close to the phase transition point, like in the case of a bulk single crystal. The permittivity of the (100)Ba0.8Sr0.2TiO3 layer decreased more than 50% when an electric field of 2.5×106V/m (T ≈ 300K, f=100 kHz ) was applied.

scholarly journals Discovering formation of ice 0 by low-frequency measurement data

2022 ◽  
Vol 962 (1) ◽  
pp. 012028
Author(s):  
A O Orlov ◽  
S V Tsyrenzhapov
Keyword(s):  
Phase Transition ◽  
Dielectric Permittivity ◽  
Measurement Data ◽  
Low Frequency ◽  
Supercooled Water ◽  
Frequency Measurement ◽  
Low Frequencies ◽  
Probing Signal ◽  
Electric Parameters ◽  
Silicate Materials

Abstract In this work, low-frequency characteristics of wetted nanoporous silicate materials were measured, as well as the specimen’s own low-frequency electric fluctuations at the frequencies of 1…100 Hz. The measurements at low frequencies were conducted at different voltages of the probing signal. A capacity cell was used in making the measurements. In the experiments, at the temperatures below –25…–30 °C, non-linearity of the medium was discovered. The experiments on the study of the specimen’s own electric fluctuations at these temperatures revealed their essential increase. These temperatures are below the point of phase transition of supercooled water to recently discovered ferroelectric ice 0. Based on the measurements made, a conclusion was made regarding formation of this modification of ice in the nanosize pores of the wetted materials under study. Ice 0 is a ferroelectric; therefore, its formation from deeply supercooled water may have a significant impact on the electric parameters of wetted bodies at the temperatures below –23 °C. At the interface of such ice with another dielectric, a thin layer with practically metallic conductivity emerges. Such a layer influences not only the non-linear dependence of dielectric permittivity on the electric field but also increases attenuation of electromagnetic radiation in a medium.

Novel KDP-ADP Nanocomposites

2013 ◽  
Vol 200 ◽  
pp. 144-148 ◽  
Author(s):  
A. Ciżman ◽  
Ewa Rysiakiewicz-Pasek ◽  
J. Kutrowska ◽  
R. Poprawski
Keyword(s):  
Phase Transition ◽  
Dielectric Permittivity ◽  
Size Effect ◽  
Pore Size ◽  
Wide Temperature Range ◽  
Dielectric Anomaly ◽  
Average Pore ◽  
Porous Glasses ◽  
Temperature Range ◽  
Pore Sizes

The influence of the size effect on the features of ADP-KDP-porous glasses composites was studied. The dielectric permittivity results of mixed ADP and KDP embedded into porous glasses with different average pore sizes in a wide temperature range are presented. The data obtained indicate that pore size affects the nature of the dielectric anomaly in the vicinity of phase transition regions.

Precursor Nanoscale Textures: from Tweed to Glassy Behaviour

2011 ◽  
Vol 172-174 ◽  
pp. 135-143
Author(s):  
Antoni Planes ◽  
Pol Lloveras ◽  
Teresa Castán ◽  
Marcel Porta ◽  
Avadh Saxena
Keyword(s):  
Phase Transition ◽  
Mechanical Response ◽  
Elastic Anisotropy ◽  
Broad Temperature Range ◽  
Temperature Range ◽  
Spatially Inhomogeneous ◽  
Cluster Phase ◽  
Symmetry Structure ◽  
Nano Cluster ◽  
Low Symmetry

We study spatially inhomogeneous states that occur as precursors of marten-sitic/ferroelastic transitions. We will show that cross-hatched modulations (tweed patterns)arise at temperatures above the phase transition in the limit of high elastic anisotropy or lowdisorder while a nano-cluster phase-separated state occurs at low anisotropy or high disorder.In the latter case, nanoscale inhomogeneities give rise to glassy behaviour while the structuraltransition is inhibited. Interestingly, in this case the ferroelastic system also displays a largethermo-mechanical response so that the low symmetry structure can be easily induced by theapplication of relatively small stresses within a broad temperature range.

Large electrocaloric effect over a wide temperature range in BaTiO3-modified lead-free ceramics

2019 ◽  
Vol 7 (5) ◽  
pp. 1353-1358 ◽  
Author(s):  
Luo Zhao ◽  
Xiaoqin Ke ◽  
Zhijian Zhou ◽  
Xiaoqi Liao ◽  
Junjie Li ◽  
...  
Keyword(s):  
Phase Transition ◽  
Wide Temperature Range ◽  
Diffuse Phase Transition ◽  
Lead Free ◽  
Broad Temperature Range ◽  
Electrocaloric Effect ◽  
Temperature Range ◽  
Lead Free Ceramics ◽  
Diffuse Phase

BT-13CH exhibits a large electrocaloric effect over a broad temperature range because of multiphase coexistence (MPC) with diffuse phase transition (DPT) character.

Dielectric properties of LC mixture with induced antiferroelectric phase

2008 ◽  
Vol 16 (3) ◽  
Author(s):  
M. Wojciechowski ◽  
G. Bąk ◽  
M. Tykarska
Keyword(s):  
Liquid Crystalline ◽  
Low Frequency ◽  
Broad Temperature Range ◽  
Relaxation Mode ◽  
Temperature Range ◽  
Antiferroelectric Phase ◽  
Mode Characteristic ◽  
Low Frequency Mode ◽  
Identification And Characterization

AbstractMixture of two liquid crystalline components exhibits the antiferroelectric phase in a broad temperature range at room temperatures, though the two components separately do not show an antiferroelectric phase in a temperature range applied. The dielectric spectroscopy technique combined with measurements of the selective light reflection was used for identification and characterization of the phases and subphases existing in the mixture. In the SmC*A phase, the low frequency mode characteristic of antiferroelectric phase has been detected. In the broad temperature range between SmC*A and SmA* phases, no relaxation mode has been detected. The soft mode registered near the phase transition to SmA* phase follows the Curie-Weiss law.

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