Studies of Dielectric Permittivity of Y2NiMnO6 Ceramics for DC Bias at Various Temperatures

2017 ◽  
Vol 866 ◽  
pp. 272-276
Author(s):  
Naphat Albutt ◽  
Suejit Pechprasarn ◽  
Phimonkhae Chobdee ◽  
Thanapong Sareein
Keyword(s):  
Dielectric Permittivity ◽  
Thermal Effect ◽  
Charge Ordering ◽  
Sharp Transition ◽  
Low Frequencies ◽  
Dc Bias ◽  
Lower Frequencies

The dielectric permittivity (ε) of Y2NiMnO6 ceramics prepared by sintering at 1400 °C over 6 to 24 hours was investigated. The response of the ceramics was measured from 1 kHz to 3 MHz, with the influence of a fixed dc bias from 0 to 1.5 V and temperature from 40 °C to -60 oC. Increasing dc bias was found to reduce ε' at low frequencies, while at higher frequencies the dc bias had less influence on ε'. At 40 °C a sharp transition from high to low ε' occurred starting at ~100 kHz, as the temperature of the ceramic was lowered, the transition shifted to lower frequencies. This behaviour is attributed to the charge ordering of Ni2+ and Mn4+ ions and the thermal effect on the ions energy.

Charge ordering and ferroelectric states in organic quasi-one-dimensional conductors

2002 ◽  
Vol 12 (9) ◽  
pp. 133-138
Author(s):  
F. Nad ◽  
P. Monceau
Keyword(s):  
Phase Transitions ◽  
Charge Ordering ◽  
Electron Interaction ◽  
Charge Symmetry ◽  
Low Frequencies ◽  
One Dimensional ◽  
Thermally Activated ◽  
Correlated Electron ◽  
Temperature Dependences ◽  
New Phase

In quasi-one-dimensional (TMTTF)2X conductors [1], where X are the various centro-symmetrical and non-centrosymmetrical anions, by study of temperature dependences of conductance G and dielectric permittivity $\varepsilon '$ at low frequencies we have found anomalies which are characteristic for phase transitions: an abrupt bend on the G(l/T) dependences with thermally activated decrease of G and sharp maxima of the E' near the charge ordering temperature corresponding to the E' divergence according to the Curie law. A number of evidences have been obtained in favor that driving force of these phase transitions is the long range correlated electron interaction yielding the charge ordering along the molecular chains (a lattice version of the Wigner crystal). The anion chains, electrically balanced with molecular chains, are of very importance in the formation and the stabilization of these new phase states. It appears that the form of charge symmetry of the anions determines to a great extent the types of the occurring transitions and the developing ground states.

Realization of Tunable Varactors Using Bi1.5Zn1.0Nb1.5O7 Thin Films

2009 ◽  
Vol 421-422 ◽  
pp. 153-156
Author(s):  
K. Sudheendran ◽  
K.C. James Raju
Keyword(s):  
Thin Films ◽  
Ground Plane ◽  
Silicon Substrates ◽  
Low Frequencies ◽  
Microwave Frequencies ◽  
Inner Radius ◽  
Voltage Dependent ◽  
Dc Bias ◽  
Fabrication And Characterization

Cubic pyrochlore bismuth zinc niobate thin films are known to exhibit voltage dependent dielectric properties. In this paper, we are demonstrating the fabrication and characterization of interdigital (IDC) and circular patch (CPC) capacitors using the pulsed laser deposited Bi1.5Zn1.0Nb1.5O7 (BZN) thin films on sapphire and platinised silicon substrates respectively. The IDCs fabricated are having 12 fingers of width 12 m each and separated by a gap of 8 m. The CPC are having circular patches with inner radius of 100 m and concentric ground plane with a radius of 300m. The electrical properties of these capacitors were characterized both at low frequencies and at microwave frequencies. The CPC varactors were having a tunability of 25% at 15 Volts. The calculated capacitance of the IDC varactor at 5.3 GHz with 0 V dc bias was 1.1 pF, which has got changed to 0.99 pF by the application of 30 Volts exhibiting a tunability of 10%.

scholarly journals Dielectric Permittivity of Rigid Rapeseed Oil Polyol Polyurethane Biofoams and Petrochemical Foams at Low Frequencies

2020 ◽  
Vol 8 (9) ◽  
pp. 1151-1170
Author(s):  
Ilze Beverte ◽  
Vairis Shtrauss ◽  
Aldis Kalpinsh ◽  
Uldis Lomanovskis ◽  
Ugis Cabulis ◽  
...  
Keyword(s):  
Dielectric Permittivity ◽  
Rapeseed Oil ◽  
Low Frequencies

scholarly journals Dielectric Permittivity Enhancement By Charged Domain Walls Formation In Stoichiometric Lithium Niobate

2016 ◽  
Vol 1 (1) ◽  
pp. 57 ◽  
Author(s):  
A.A. Esin ◽  
A.R. Akhmatkhanov ◽  
V.Ya. Shur
Keyword(s):  
Experimental Study ◽  
Dielectric Permittivity ◽  
Lithium Niobate ◽  
Domain Walls ◽  
Dense Structure ◽  
Decrease Rate ◽  
Order Of Magnitude ◽  
Dc Bias ◽  
Magnitude Increase

<p>We present an experimental study of contribution of charged domain walls into dielectric permittivity of lithium niobate. It has been shown that formation of dense structure with spike-like domains leads to order of magnitude increase of permittivity, which gradually decreases with time. The decrease rate accelerates under DC bias. Dielectric permittivity decreases linearly with a logarithm of frequency. The obtained results were explained considering vibration of the steps on the charged domain walls.</p>

scholarly journals Maintenance of Constant Wave Parameters by Sperm Flagella at Reduced Frequencies of Beat

1973 ◽  
Vol 59 (3) ◽  
pp. 617-629
Author(s):  
C. J. BROKAW ◽  
R. JOSSLIN
Keyword(s):  
Bend Angle ◽  
Satisfactory Explanation ◽  
Low Frequencies ◽  
Bending Waves ◽  
Wave Parameters ◽  
Low Concentrations ◽  
Bending Resistance ◽  
Wide Range ◽  
Triton X ◽  
Lower Frequencies

1. Treatment of Ciona spermatozoa with low concentrations of Triton X-100 (less than 0·01 %) causes them to beat at lower than normal frequencies. The wavelength of the flagellar bending waves remains constant over the range from 10 to 40 Hz. There is a small increase in wavelength at lower frequencies; in the range of 1·5-6·2 Hz, the wavelength averaged 114% of the normal value for Ciona spermatozoa. The angle of bend of the bent regions of the flagellar bending waves remained constant within ± 10% over this range of frequencies. 2. Decapitated sperm flagella from Lytechinus beat at a continually declining frequency as they exhaust their content of ATP. Both wavelength and bend angle retain normal values until the frequency falls below about 8 Hz. Both parameters increase at lower frequencies, with a sharp increase below 3 Hz. 3. ATP-reactivated spermatozoa from Lytechinus show relatively small changes in wavelength and bend angle as the frequency is varied over the range from 5 to 25 Hz by varying the ATP concentration. 4. Constancy of wavelength over a wide range of frequencies is consistent with the hypothesis that wavelength is determined by the relative values of viscous bending resistance within a flagellum and external viscosity. 5. No satisfactory explanation is available at present for the constancy of bend angle over a wide range of frequencies nor for the changes in wave parameters which are observed at low frequencies.

scholarly journals A Study on the Dielectric Behaviour of Epoxy/Hafnium Oxide Nanopowder Composites

2011 ◽  
Vol 20 (5) ◽  
pp. 096369351102000 ◽  
Author(s):  
S.N. Georga
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Permittivity ◽  
High Temperatures ◽  
High Frequency ◽  
Dielectric Response ◽  
Hafnium Oxide ◽  
Filler Concentration ◽  
High Frequency Range ◽  
Frequency Range ◽  
Low Frequencies

The dielectric response of 10 and 15phr epoxy/HfO2 nanocomposite systems has been studied in a wide frequency and temperature range. The experimental results show an enhancement of the dielectric permittivity with increasing filler concentration. The dielectric spectra reveal the presence of α-relaxation and a weak MWS effect. In the high frequency range the real part of the electrical conductivity obeys the Universal Dielectric Response (UDR), whereas at low frequencies and high temperatures DC conductivity is observed. VFT (Vogel-Fulcher-Tamann) parameters are calculated for all measured specimens.

Dynamic Mechanical Properties of Cross-Linked Rubbers. II. Effects of Crosslink Spacing and Initial Molecular Weight in Polybutadiene

1966 ◽  
Vol 39 (4) ◽  
pp. 905-914
Author(s):  
Etsuji Maekawa ◽  
Ralph G. Mancke ◽  
John D. Ferry
Keyword(s):  
Molecular Weight ◽  
Crosslink Density ◽  
Low Frequency ◽  
Dynamic Mechanical Properties ◽  
Cross Linking ◽  
Loss Mechanism ◽  
Low Frequencies ◽  
Molecular Weights ◽  
Monomeric Friction Coefficient ◽  
Lower Frequencies

Abstract The complex shear compliances of eight samples of polybutadiene crosslinked by cumyl peroxide and four samples crosslinked by sulfur have been measured over a frequency range from 0.2 to 2 cps at temperatures from − 6 to 45° C by a torsion pendulum. On four of the samples, measurements were extended by the Fitzgerald transducer from 45 to 600 cps at temperatures from − 71 to 55°. The vulcanizates had been prepared from polymers of two different molecular weights (180,000 and 510,000) with sharp molecular weight distribution; the physical crosslink density ranged from 0.57 to 2.68×10−4 mole/cm3, and the chemical crosslink density calculated following Kraus ranged from 0.22 to 1.49×10−4 mole/cm3. The mechanical data were all reduced to T0=298° K by shift factors calculated from the equation log aT=−3.64(T−T0)/(186.5+T−T0). In the transition zone of frequencies, the viscoelastic functions of the cumyl peroxide vulcanizates were closely similar, except for a shift toward lower frequencies with increasing crosslinking, corresponding to a small but unexpected increase in the monomeric friction coefficient. Cross-linking by sulfur caused a somewhat larger shift toward lower frequencies at a comparable crosslink density. In the rubbery zone, the sample with least cross-linking exhibited a substantial secondary loss mechanism at very low frequencies. The low-frequency losses are evident in all the samples, but their magnitude falls rapidly with increasing crosslink density as previously found for natural rubber. It also falls somewhat with increasing initial molecular weight, indicating a contribution from network strands with loose ends. The possible relation of the low-frequency losses to trapped entanglements is discussed.

scholarly journals Dielectric anisotropy in ice Ih at 9.7 GHz

1993 ◽  
Vol 17 ◽  
pp. 276-280 ◽  
Author(s):  
Shuji Fujita ◽  
Shinji Mae ◽  
Takeshi Matsuoka
Keyword(s):  
Dielectric Permittivity ◽  
Reflection Coefficient ◽  
Microwave Frequency ◽  
Relaxation Dispersion ◽  
Dielectric Anisotropy ◽  
Debye Relaxation ◽  
Low Frequencies ◽  
The Real ◽  
Power Reflection Coefficient ◽  
Radio Echo Sounding

Dielectric anisotropy in ice Ih was investigated at 9.7 GHz with the waveguide method. The measurement of dielectric permittivity was made using single crystals collected from Mendenhall Glacier, Alaska. The result of the measurement shows that ϵ′‖c, the real part of dielectric permittivity parallel to the c axis, is larger than ϵ′⊥c the real part of dielectric permittivity perpendicular to the c axis. This tendency is similar to that at low frequencies in the region of the Debye relaxation dispersion. It can be proposed that ϵ′‖c>ϵ′⊥c in the HF, VHF and microwave frequency range. ϵ′‖c and ϵ′‖c depend slightly upon temperature but the dielectric anisotropy, ∆ϵ′=ϵ′‖c-ϵ′⊥c, is constant and becomes 0.037 (±0.007). Based on the present results, a simple caculation indicates that the maximum power reflection coefficient caused by the dielectric anisotropy is about −50 ∼ −80 dB, which is significantly larger than the power reflection coefficient observed in the ice sheet by radio-echo sounding, about −70 ∼ −80 dB. This leads to a conclusion that dielectric anisotropy is one of the dominant causes of internal reflections.

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.

Electrical Properties in Large Frequency and Temperature Ranges of Sr0.6Ca0.4TiO3 Ceramics

2020 ◽  
Vol 13 (3) ◽  
pp. 201-210
Keyword(s):  
Dielectric Permittivity ◽  
High Temperatures ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Conductivity Measurement ◽  
Calcium Titanate ◽  
Lead Free ◽  
Dielectric Losses ◽  
Low Frequencies ◽  
Wide Range

Abstract: Lead-free Sr0.6Ca0.4TiO3 (SCT) ceramic was prepared by the solid state reaction route. X-Ray diffraction technique showed the phase purity and identified the orthorhombic perovskite structure of the material. Scanning Electronic Microscopy observation evidenced homogeneous morphology and dense microstructure for the ceramic. The dielectric and conductivity properties of the sample were studied using complex impedance measurement technique in a wide range of frequencies and temperatures: from 100 Hz to 1.8 GHz and from 25°C to 550°C. The ceramic exhibits a stable dielectric permittivity and low dielectric losses in frequency and temperature up to 200°C. This is very interesting in view of developing high-quality lead-free ceramic capacitors for applications requiring high temperatures; for example, in cars. The increase in dielectric permittivity for temperatures higher than 200°C may be related to oxygen vacancies that are heat-activated in the material. Dielectric losses show the existence of a dielectric relaxation at low temperatures and low frequencies. Conductivity measurement investigated at high temperatures show on one hand high AC conductivity values attributed to the high temperature jumping process and on the other hand two electrical conductivity mechanisms above 400° C in the material. Keywords: Strontium calcium titanate, Ceramic, Structure, Dielectric properties, Conductivity.

Sign in / Sign up

Export Citation Format

Share Document