DIELECTRIC PROPERTIES OF Li-Sb FERRITES

2005 ◽  
Vol 19 (18) ◽  
pp. 899-905 ◽  
Author(s):  
SHIVAJI CHONGTHAM ◽  
SUMITRA PHANJOUBAM ◽  
H. N. K. SARMA ◽  
RADHAPIYARI LAISHRAM ◽  
CHANDRA PRAKASH
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Room Temperature ◽  
Substitution Level ◽  
Higher Temperature ◽  
Tan Δ ◽  
Almost All ◽  
Frequency Curves

Dielectric properties such as dielectric constant (ε′) and dielectric loss tangent ( tan δ) of Li 0.5+x Fe 2.5-2x Sb x O 4 ferrites, 0.10≤ x ≤0.30 in steps of 0.05 have been investigated as a function of composition, frequency and temperature. The dielectric constant showed dispersion with frequency in the range of 100 Hz–1 MHz. Peaks were observed in the tan δ versus frequency curves for almost all the samples. The temperature variation of dielectric constant for the different samples was studied at 10 kHz in the temperature range from room temperature to 433 K. Peaks were observed for some of the samples. The peaks were seen to shift towards higher temperature region as the substitution level increases. The mechanisms involved in the processes are discussed in this paper.

scholarly journals Dielectric properties and conductivity of PVdF-co-HFP/LiClO4 polymer electrolytes

2018 ◽  
Vol 96 (7) ◽  
pp. 786-791 ◽  
Author(s):  
Kemal Ulutaş ◽  
Ugur Yahsi ◽  
Hüseyin Deligöz ◽  
Cumali Tav ◽  
Serpil Yılmaztürk ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Polymer Electrolytes ◽  
Room Temperature ◽  
Solid Polymer Electrolytes ◽  
Solid Polymer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Maximum Conductivity

In this study, it was aimed to prepare a series of PVdF-co-HFP based electrolytes with different LiClO4 loadings and to investigate their chemical and electrical properties in detail. For this purpose, PVdF-co-HFP based electrolytes with different LiClO4 loadings (1–20 weight %) were prepared using solution casting method. X-ray diffraction (XRD), differential scanning calorimetry, and thermogravimetric (TGA) –differential thermal and dielectric spectroscopy analysis of PVdF-co-HFP/LiClO4 were performed to characterize their structural, thermal, and dielectric properties, respectively. XRD results showed that the diffraction peaks of PVdF-co-HFP/LiClO4 electrolytes broadened and decreased with LiClO4. TGA patterns exhibited that PVdF-co-HFP/LiClO4 electrolytes with 20 wt % of LiClO4 had the lowest thermal stability and it degraded above 473 K, which is highly applicable for solid polymer electrolytes. Dielectric constant, dielectric loss, and conductivities were calculated by measuring capacitance and dielectric loss factor of PVdF-co-HFP/LiClO4 in the range from 10 mHz to 20 MHz frequencies at room temperature. In consequence, conductivities of PVdF-co-HFP/LiClO4 increased significantly with frequency for low loading of LiClO4 while they only slightly changed with higher LiClO4 addition. On the other hand, dielectric constant values of PVdF-co-HFP/LiClO4 films decreased with frequency whereas they rose with LiClO4 addition. The dielectric studies showed an increase in dielectric constant and dielectric loss with decreasing frequency. This result was attributed to high contribution of charge accumulation at the electrode–electrolyte interface. The electrolyte showed the maximum conductivity of 8 × 10−2 S/cm at room temperature.

scholarly journals Effect of TeO2 addition on the dielectric properties of CaCu3Ti4O12 ceramics derived from the oxalate precursor route

2013 ◽  
Vol 03 (04) ◽  
pp. 1350028 ◽  
Author(s):  
P. Thomas ◽  
K. B. R. Varma
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Oxalate Precursor ◽  
X Ray ◽  
Practical Applications ◽  
Low Dielectric ◽  
Precursor Route ◽  
Tan Δ

CaCu 3 Ti 4 O 12 (CCTO) ceramics which has perovskite structure gained considerable attention due to its giant permittivity. But it has high tan δ (0.1 at 1 kHz) at room temperature, which needs to be minimized to the level of practical applications. Hence, TeO 2 which is a good glass former has been deliberately added to CCTO nanoceramic (derived from the oxalate precursor route) to explore the possibility of reducing the dielectric loss while maintaining the high permittivity. The structural, morphological and dielectric properties of the pure CCTO and TeO 2 added ceramics were studied using X-ray diffraction, Scanning Electron Microscope along with Energy Dispersive X-ray Analysis (EDX), spectroscopy and Impedance analyzer. For the 2.0 wt.% TeO 2 added ceramics, there is a remarkable difference in the microstructural features as compared to that of pure CCTO ceramics. This sample exhibited permittivity values as high as 7387 at 10 KHz and low dielectric loss value of 0.037 at 10 kHz, which can be exploited for the high frequency capacitors application.

Dielectric Properties of Li-Doped CaCu3Ti4O12 Ceramics

2011 ◽  
Vol 687 ◽  
pp. 251-256 ◽  
Author(s):  
Ying He ◽  
Huai Wu Zhang ◽  
Yuan Xun Li ◽  
Wei Wei Ling ◽  
Yun Yan Wang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Secondary Phase ◽  
Doping Amount ◽  
Spectroscopy Analysis ◽  
Low Dielectric ◽  
Tan Δ ◽  
High Dielectric ◽  
Impedance Spectroscopy Analysis

CaCu3Ti4O12 ceramics doped with 0-2.0 wt% Li2CO3 were prepared by the solid-state reaction, and their electric and dielectric properties were investigated. It is found that these ceramics had the properties of high dielectric constant and comparatively low dielectric loss. At the doping amount of 0.5 wt%, the dielectric constant is kept to be 105 with weak frequency dependence below 105 Hz, and its loss tangent (tan δ) is suppressed below 0.1 between 300 Hz-5 kHz (with the minimum value of 0.06 at 1 kHz from 218 K to 338 K). The impedance spectroscopy analysis confirms that the decrease of dielectric loss is mainly due to the increase of resistance in the grain boundary, which may be related to the influence of Ti4O7 secondary phase. Our result indicates that doping Li2CO3 is an efficient method to optimize the dielectric properties of CaCu3Ti4O12.

Effect of Platinum Substitution on the Microstructures and Dielectric Relaxation of CaCu3Ti4O12 Ceramics

2013 ◽  
Vol 802 ◽  
pp. 134-138 ◽  
Author(s):  
Worawut Makcharoen
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Loss Tangent ◽  
Room Temperature ◽  
High Dielectric Constant ◽  
Ferroelectric Materials ◽  
X Ray Diffraction ◽  
High Loss ◽  
Internal Barrier Layer Capacitor ◽  
High Dielectric

The CaCu3Ti4O12(CCTO) has the advantage for the various applications especially for capacitive elements in microelectronic devices over the ferroelectric materials including BaTiO3. CCTO is a ceramic compound with a high dielectric constant but it has a high loss tangent at room temperature. In this work, the Influences of PtO2doping on the dielectric properties of CaCu3Ti4O12(CCTO) ceramics were investigate. The ceramics CCTO and PtO2doping CCTO were studied by X- ray diffraction, scanning electron microscopy. The dielectric properties have been measured as a function of temperature and frequency range 0.1 - 500 kHz. The XRD shows the CCTO structure does not changes after doping with platinum. The results show that PtO2doped can reduce the mean grain sizes of CCTO, but the dielectric constant still remained a height. The samples of 2.0 mol% Pt-doped have exhibited high dielectric constant of about 22,000 and the loss tangent about 0.7 at room temperature and frequency at 10 kHz. The reduced of the loss tangent could be interpreted with the internal barrier layer capacitor model (IBLC)

Study of Ac Conductivity and Dielectric Properties of PMMA with Fe2O3+ Al2O3 Composite Films

2013 ◽  
Vol 209 ◽  
pp. 14-17
Author(s):  
Basavaraja Sannakki ◽  
Anita Gandhe ◽  
V.H. Doddamani
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Polymer Composite ◽  
Composite Films ◽  
Weight Percent ◽  
X Ray ◽  
Morphological Studies ◽  
Tan Δ ◽  
Al2o3 Films

Abstract. The PMMA with Fe2O3+ Al2O3 films at different weight percent have been used for measurement of dielectric properties such as dielectric constant, dielectric loss and a. c. conductivity as a function of frequency over the range 50 Hz – 5 MHz at room temperature. The dielectric constant and the dielectric loss (tan δ) of the polymer composite films decreases exponentially at lower frequencies over the range 100 Hz-1 kHz, where as above 1 kHz the values of dielectric constant remains same. But, it has been observed that the value of dielectric constant of PMMA composite films with Fe2O3+ Al2O3 increases as weight percent of Fe2O3+ Al2O3 increases. The a c conductivity of the polymer composite films remains constant over the frequency range 50 Hz to 300 K Hz and afterwards it increases exponentially. Further, PMMA with Fe2O3+ Al2O3 have been characterized using X-Ray diffractometer for the crystallinity. The morphological studies have been made using the FESEM.

scholarly journals Dielectric properties of zinc sulfide concentrate during the roasting at microwave frequencies

2017 ◽  
Author(s):  
Guangjun He ◽  
Shiwei Li ◽  
Kun Yang ◽  
Jian Liu ◽  
Peng Liu ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Zinc Sulfide ◽  
Apparent Density ◽  
Loss Tangent ◽  
Loss Factor ◽  
Microwave Energy ◽  
Dielectric Loss Factor ◽  
Sulfide Concentrate

Microwave technology has a potential application in the extraction of zinc from sulphide ores, knowledge of the dielectric properties of these ores plays a major role in the microwave design and simulation for any process. The dielectric properties of zinc sulfide concentrate for two different apparent densities—1.54 and 1.63 g/cm3—have been measured by using the resonance cavity perturbation technique at 915 and 2450 MHz during the roasting process for the temperature ranging from room temperature to 850 °C. The variations of dielectric constant, the dielectric loss factor, the dielectric loss tangent and the penetration depth with the temperature, frequency and apparent density have been investigated numerically. The results indicate that the dielectric constant increases as the temperature increases and temperature has a pivotal effect on the dielectric constant, while the dielectric loss factor has a complicated change and all of the temperature, frequency and apparent density have a significant impact to dielectric loss factor. Zinc sulfide concentrate is high loss material from 450 to 800 °C on the basis of theoretical analyses of dielectric loss tangent and penetration depth, its ability of absorbing microwave energy would be enhanced by increasing the apparent density as well. The experimental results also have proved that zinc sulfide concentrate is easy to be heated by microwave energy from 450 to 800 °C. In addition, the experimental date of dielectric constant and loss factor can be fitted perfectly by Boltzmann model and Gauss model, respectively.

Dielectric properties of normal, reduced, and specially reduced rutile (TiO2) single crystals at room temperature

1969 ◽  
Vol 47 (1) ◽  
pp. 3-6 ◽  
Author(s):  
H. B. Lal ◽  
K. G. Srivastava
Keyword(s):  
Dielectric Constant ◽  
Relaxation Time ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Oxygen Vacancy ◽  
Single Crystals ◽  
Room Temperature ◽  
Interfacial Polarization ◽  
Absorption Peak ◽  
Single Relaxation Time

The variation of the dielectric constant (ε′) and the dielectric loss (ε″) have been studied as a function of frequency (102 to 1010 c.p.s.) for normal (as grown), reduced (heated in vacuum), and specially reduced (heated in vacuum in presence of an asymmetric d.c. field) rutile single crystals parallel to c-axis at room temperature. Dispersions in ε′ have been observed in the frequency ranges 102 to 103 and 107 to 109 c.p.s. for all the samples with absorption peaks in ε″ at 2 × 102 and 6 × 107 c.p.s. Also an extra absorption peak in ε″ has been found at 2 × 104 c.p.s. for the specially reduced sample. The absorption peak at 2 × 102 c.p.s. has been observed by many workers and is typical for interfacial polarization. The peak at 6 × 107 c.p.s. appears to be due to a dipole rotation process with a single relaxation time and is identified as due to relaxation of dipoles formed between Ti3+ and a neighboring oxygen vacancy. The possible mechanism of relaxation for the 2 × 104 c.p.s. absorption peak is also discussed.

MEASUREMENT OF THE DIELECTRIC PROPERTIES OF LOW LOSS MATERIALS AT MILLIMETER WAVELENGTHS

1958 ◽  
Vol 36 (12) ◽  
pp. 1672-1677
Author(s):  
A. G. Mungall
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Brewster Angle ◽  
Angle Of Incidence ◽  
Low Loss ◽  
Millimeter Wavelengths ◽  
Space Technique

Measurement at millimeter wavelengths of the dielectric properties of low loss materials by a free space technique is described. The dielectric constant is determined from the Brewster angle, and the dielectric loss tangent from the attenuation coefficient measured at the Brewster angle of incidence. Results are given for bakelite at wavelengths between 5 and 10 mm. Details of the instrument, which was specifically designed for these measurements, are also given.

Characterization and dielectric properties of sodium fluoride doped talc

Clay Minerals ◽  
2014 ◽  
Vol 49 (4) ◽  
pp. 551-558
Author(s):  
S. Gümüştas ◽  
K. Köseoğlu ◽  
E. E. Yalçinkaya ◽  
M. Balcan
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Firing Temperature ◽  
Room Temperature ◽  
Dielectric Measurements ◽  
Frequency Range ◽  
Detailed Characterization ◽  
Circuit Element

AbstractThe purpose of this paper is to determine the effect of NaF and firing temperature on the dielectric properties (dielectric constant and dielectric loss) of talc, which is used in the electrical and electronic industries as a circuit element. A detailed characterization of the samples was made by XRD, FTIR, SEM and TG-DTG methods. Dielectric measurements were performed in the frequency range from 1 MHz to 80 MHz at room temperature. The dielectric constant value increased with an increase in firing temperature due to the removal of polarizable compounds from the talc structure. The higher dielectric constant values were obtained by addition of NaF. The dielectric loss of NaF doped talc decreased with the increase of firing temperature and increased with the increase of the amount of NaF.

Surface Morphology and Dielectric Properties of KNN/PI Films

2014 ◽  
Vol 1015 ◽  
pp. 240-243
Author(s):  
Jia Qi Lin ◽  
Hui Lin ◽  
Ying Liu
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Surface Morphology ◽  
Loss Tangent ◽  
Mass Fraction ◽  
Dispersion Polymerization ◽  
Polymerization Process ◽  
Insulating Properties

Polyimide (PI) films filled with K0.5Na0.5NbO3 particles at different weight 0wt%,5wt%,10wt%,15wt% and 20wt% had been prepared by in-situ dispersion polymerization process in this article. then we measured morphology and dielectric properties. when the mass fraction of KNN reach 20%, its dielectric constant achieve 4.9(100Hz) with the dielectric loss tangent value is less than 0.025 (100 Hz).it Shows the good insulating properties.

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