Dielectric characterization of coals

2003 ◽  
Vol 81 (3) ◽  
pp. 599-610 ◽  
Author(s):  
J M Forniés-Marquina ◽  
J C Martín ◽  
J P Martínez ◽  
J L Miranda ◽  
C Romero
Keyword(s):  
Room Temperature ◽  
Elemental Carbon ◽  
Time Domain Reflectometry ◽  
Electromagnetic Analysis ◽  
Characteristic Parameters ◽  
Static Permittivity ◽  
Dielectric Characterization ◽  
Coal Characterization ◽  
5 Ghz

Application of an electromagnetic analysis for coal characterization is attempted. By time domain reflectometry (TDR), dispersion spectra in the DC – 5 GHz range of a wide variety of coals are obtained for room temperature. Static permittivity and relaxation frequency of the different samples are compared with parameters obtained by chemical analysis. Comparison reveals the usefulness of the electromagnetic characterization for the establishment of coal rank, and shows how an analysis of the dielectric characteristic parameters can provide approximate ideas about moisture, elemental carbon, hydrogen, and sulphur contents. PACS Nos.: 39.30+w, 82.53Kp, 77.22Gm

scholarly journals Time domain reflectometry for dielectric characterization of olive mill wastewater contaminated soils

2020 ◽  
Vol 51 (4) ◽  
pp. 248-254
Author(s):  
Alessandro Comegna ◽  
Antonio Coppola ◽  
Giovanna Dragonetti
Keyword(s):  
Olive Oil ◽  
Time Domain ◽  
Contaminated Soils ◽  
Oil Industry ◽  
Time Domain Reflectometry ◽  
Olive Mill Wastewater ◽  
Management Problem ◽  
Dielectric Characterization ◽  
Olive Mill

Olive mill wastewater (OMW) is a compound originating from oil mills during oil extraction processes. In the Mediterranean area, more than 30 million m3 of OMW are produced each year, which represents 95-97% of the world production. Such volumes of untreated OMW are usually directly disposed of into drainage systems, water bodies (such as streams, lagoons and ponds) or are sprinkled on soils, causing potentially severe environmental problems to soils and groundwater. Consequently, there is a serious waste management problem related to the olive oil industry, because these practices no longer being acceptable. In the case of on-land OMW disposal, the characterization and the identification of this contaminant in soils is a fundamental task especially with a view to maintaining the integrity and quality of agroecosystems. In recent years, soils have been extensively studied to detect contaminants by using various geophysical methods. Among such techniques, time domain reflectometry (TDR) has shown, in different contexts, evident sensitivity and resolution capability for the characterization of contaminated soil sites. In order to further exploit the potential of the TDR technique, in this study we conducted a series of laboratory-controlled tests to explore how OMW influences the dielectric response of contaminated soils. This investigation led to the development of an empirical dielectric model to estimate the presence of OMW in variably saturated-contaminated soils with different textures and pedological features. In particular, the soils selected belong to two typical pedological units in southern Italy which account for approximately 90% of the Italian olive plantations and one of the highest concentrations of the olive oil industry in Italy. In these districts, as well as in other European and Mediterranean countries, there is the controversial habit to spread OMW on soils.

scholarly journals Dielectric characterization of the system Sr1-xGdxTi1-xCoxO3 (x = 0.10) using impedance spectroscopy

2010 ◽  
Vol 7 (2) ◽  
pp. 499-504
Author(s):  
H. S. Tewari ◽  
P. K. Sakharkar
Keyword(s):  
Dielectric Properties ◽  
Impedance Spectroscopy ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Solid State Reaction Method ◽  
Electrical Behavior ◽  
Cooling Rates ◽  
Impedance Analyzer ◽  
Dielectric Characterization

The structure of ceramic grain boundaries, boundary composition, the boundary charge and associated space charge controls the dielectric and electrical behavior of ceramics. Various methods were researched and applied to increase the dielectric constant by formation of insulating layers between semi-conducting grains. In this communication, we are reporting the effect of cooling rates from sintering temperature to room temperature on dielectric properties of the resulting ceramics in the system, Sr1-xGdxTi1-xCoxO3 with x = 0.10. All the samples in this system were prepared by conventional high temperature solid state reaction method. The samples were cooled at different cooling rates from sintering temperature to room temperature. The capacitance and dielectric loss were measured as a function of frequency and temperature using HP 4192A LF impedance analyzer. The samples cooled from different cooling rates from sintering temperature show interesting dielectric properties due to formation of insulating layers between grains. The impedance spectroscopy is used successfully in explaining the dielectric properties of these materials.

Dielectric behavior of a quaternary composite (RE, BT, MnO2, CaO) in the band (DC–2 GHz)

2018 ◽  
Vol 84 (1) ◽  
pp. 10201 ◽  
Author(s):  
Mounir Bouchaour ◽  
Juan Pablo Martínez Jiménez ◽  
Nacerdine Bouzit ◽  
Nacerdine Bourouba
Keyword(s):  
Atmospheric Pressure ◽  
Room Temperature ◽  
Volume Fraction ◽  
Low Frequency ◽  
Wide Band ◽  
Dielectric Behavior ◽  
Resin Matrix ◽  
Ternary Composite ◽  
Dielectric Characterization

The main objective of this paper is to study the dielectric behavior of a quaternary composite, made from a mixture of barium titanate (BT), manganese dioxide (MnO2) and calcium oxide (CaO) in the same epoxy resin matrix (RE) maintained at 70% by volume fraction, while those of the other constituents are variable and completing each other in a way to achieve the remaining proportion, i.e. 30%. Random mixtures are made at room temperature and under atmospheric pressure. A dielectric characterization of this mixture type was performed by time-domain spectroscopy (TDS) over a frequency wide band (DC–2 GHz). This has been carried out to illustrate the effect of two oxides (MnO2 and CaO) simultaneously at low frequency (500 MHz), in the presence of (BT), on the composite dielectric behavior. This has led consequently to make a comparison between the present acquired results and those of the ternary composite, where (MnO2) and (CaO) act separately. The results obtained so far in this study allowed us to check the validity of the modified Lichtenecker law (MLL)-based predictive model in the quaternary composite case. The interest of this study lies on applications of these materials in microelectronics circuits and absorber materials in telecommunication domain.

Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 880-881
Author(s):  
Bradley L. Thiel ◽  
Chan Han R. P. ◽  
Kurosky L. C. Hutter ◽  
I. A. Aksay ◽  
Mehmet Sarikaya
Keyword(s):  
Grain Boundary ◽  
Cuprous Oxide ◽  
Room Temperature ◽  
Boundary Phase ◽  
Spectroscopic Techniques ◽  
Transition Width ◽  
Practical Applications ◽  
Thin Foils ◽  
Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

Microwave dielectric characterization of bulk ferroelectrics

1998 ◽  
Vol 08 (PR9) ◽  
pp. Pr9-113-Pr9-116 ◽  
Author(s):  
C. M. Weil ◽  
R. G. Geyer ◽  
L. Sengupta
Keyword(s):  
Dielectric Characterization ◽  
Microwave Dielectric

scholarly journals Synthesis and characterization of a new ZIF-67@MgAl2O4 nanocomposite and its adsorption behaviour

RSC Advances ◽  
2021 ◽  
Vol 11 (22) ◽  
pp. 13245-13255
Author(s):  
Mehdi Davoodi ◽  
Fatemeh Davar ◽  
Mohammad R. Rezayat ◽  
Mohammad T. Jafari ◽  
Mehdi Bazarganipour ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnesium Aluminate ◽  
Synthesis And Characterization ◽  
Magnesium Aluminate Spinel ◽  
Adsorption Behaviour ◽  
Zeolitic Imidazolate Framework ◽  
Simple Method

New nanocomposite of zeolitic imidazolate framework-67@magnesium aluminate spinel (ZIF-67@MgAl2O4) has been fabricated by a simple method at room temperature with different weight ratios.

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