Dielectric Loss in Vanadyl Pnictates

1990 ◽  
Vol 210 ◽  
Author(s):  
Joseph F. Lomax ◽  
John J. Fontanella ◽  
Mary C. Wintersgill ◽  
Anthony Kotarski
Keyword(s):  
Dielectric Loss ◽  
Complex Impedance ◽  
Audio Frequency ◽  
Vanadyl Phosphate ◽  
Nonstoichiometric Compound ◽  
Proton Movement ◽  
Related Compounds ◽  
Water Species ◽  
Acid Nature ◽  
Chemical Evidence

AbstractThe results of audio frequency complex impedance studies for vanadyl phosphate and its hydrates (VOPO4*nH2O;n=0,1,2) are reported. Measurements were made at seventeen frequencies between 10 and 105 Hz over the temperature range 5.5-380K. Two lowtemperature features were observed and are correlated with particular water species between the VOPO4 layers. In light of chemical evidence and compleximpedance measurements on related compounds, it is speculated that VOPCO4*nH2O (Pc = P, As) can be thought of as a mixed nonstoichiometric compound [VO(HPcO4)]x[VOPcO4O4]1-x*nH2O and the solid Brϕnsted acid nature of the compound is related to proton movement between layer pnictates and intralayer waters.

Intercalation of Ferrocene and Related Compounds into Interlayer Spaces of Vanadyl Phosphate

1990 ◽  
Vol 19 (5) ◽  
pp. 787-790 ◽  
Author(s):  
Gen-etsu Matsubayashi ◽  
Seiji Ohta
Keyword(s):  
Vanadyl Phosphate ◽  
Related Compounds

Non-Debye and CPA Behaviors of Ionic Materials

1997 ◽  
Vol 500 ◽  
Author(s):  
J. C Wang
Keyword(s):  
Dielectric Loss ◽  
Complex Impedance ◽  
Thermal Fluctuations ◽  
Wide Frequency Range ◽  
Loss Peak ◽  
Warburg Impedance ◽  
Interfacial Processes ◽  
Wide Range ◽  
Ionic Materials ◽  
Hopping Models

ABSTRACTNon-Debye and constant-phase-angle (CPA) behaviors associated with the bulk and interfacial processes involving ionic materials are discussed in terms of complex impedance, admittance, and dielectric spectra. The yielding of a CPA and/or a broad non-Debye dielectric loss peak in a spectrum from fractal, pore, and ion-hopping models are compared and reviewed. The observed wide frequency ranges of the CPA behavior suggest that the fractal and pore models, which require a wide range of special structures down to very fine scales, may not be realistic. The ion-hopping model treats the bulk and interfacial processes as a chemical reaction having a thermally-activated Arrhenius form. Because of thermal fluctuations, the activation energies for ion hopping (e.g., in a potential double-well) have a double-exponential distribution which yields a non-Debye dielectric loss peak and a CPA spectrum over a wide frequency range above the loss peak. The distribution also has a special temperature dependence which may explain the invariance of dielectric spectral shapes with temperature, an observation by Joscher. The construction of CPA elements (in a generalized Warburg impedance form) using three distinct types of resistor-capacitor networks are presented and used to aid the discussion.

Conductivity and dielectric analysis of nanocolloidal polypyrrole particles functionalized with higher weight percentage of poly(styrene sulfonate) using the dispersion polymerization method

2017 ◽  
Vol 37 (5) ◽  
pp. 481-492 ◽  
Author(s):  
S. Maruthamuthu ◽  
J. Chandrasekaran ◽  
D. Manoharan ◽  
R. Magesh
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Dispersion Polymerization ◽  
Complex Impedance ◽  
Weight Percentage ◽  
Morphological Variations ◽  
Styrene Sulfonate ◽  
Low Dielectric ◽  
Poly Styrene Sulfonate ◽  
Polymerization Method

Abstract Nanocolloidal polypyrrole/poly(styrene sulfonate) PPy:PSS composites were prepared by dispersion polymerization of pyrrole with 0.5 wt%, 1 wt%, 2.5 wt%, 5 wt%, 10 wt% and 15 wt% of PSS. Higher doping level of PPy was confirmed with increased S/N value of elemental analysis. Morphological variations of PPy composite matrix based on PSS were analyzed in which spherical shaped PPy particles of 20–40 nm were obtained for 1:1 wt% of PPy:PSS. Presence of higher concentration of PSS within the PPy matrix substantially improved its thermal stability. Dielectric properties were investigated using complex impedance analyzer as a function of frequency (50 Hz–5 MHz) and temperature between 30°C and 120°C. PPy, with improved dispersion, showed higher dielectric constant values up to 15 wt% of anionic polyelectrolyte PSS and the dielectric loss varied between 4.7 and 7.9 for different wt% of PSS. AC conductivity (σac) enhanced up to 1:1 wt% of PPy:PSS composite, which is found to be the optimum wt% in this study. DC conductivity was found to decrease after 1:1 wt% of PPy:PSS composite, which is due to excess oxidation, leading to reduced π conjugation of PPy chains. Higher dielectric constant values of composite, with relatively low dielectric loss values, indicate their potential usage in the electric and electronic industry.

scholarly journals Диэлектрическая спектроскопия пленок VO-=SUB=-2-=/SUB=-:Ge

2019 ◽  
Vol 45 (11) ◽  
pp. 44
Author(s):  
А.В. Ильинский ◽  
Р.А. Кастро ◽  
А.А. Кононов ◽  
М.Э. Пашкевич ◽  
И.О. Попова ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Dielectric Permittivity ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Complex Impedance ◽  
High Sensitivity ◽  
Circuit Diagram ◽  
Frequency Range ◽  
Cole Diagram ◽  
Additional Maximum

AbstractThe frequency dependencies of complex impedance $$\dot {Z}$$ , dielectric permittivity ε, and dielectric loss tangent tanδ of thin (1400 Å ) films V_1 –_ x Ge_ x O_2 (for x = 0 and 0.03) are studied in the frequency range of 10‒10^6 Hz at 300 K. It is found that, at x = 0, the frequency dependence of tanδ has a maximum at a frequency of 100 kHz, whereas at x = 0.03 an additional maximum in the region of 10 kHz is detected. Also, the Cole–Cole diagram of VO_2:Ge films acquires a feature in the form of an additional semicircle. Owing to the extremely high sensitivity of the dielectric spectroscopy method, the proposed equivalent circuit diagram of the sample allowed detecting the existence of two sets of VO_2 nanocrystallites in the V_0.97Ge_0.03O_2 film, including Ge-doped nanocrystallites and practically nondoped ones.

scholarly journals Flavonoid Glycosides and their p-Coumaroyl Esters from Campylospermum calanthum Leaves

2012 ◽  
Vol 67 (5-6) ◽  
pp. 233-243 ◽  
Author(s):  
Savio S. Elo Manga ◽  
Anastasie E. Tih ◽  
Bintou Abderamane ◽  
Raphael T. Ghogomu ◽  
Alain Blond ◽  
...  
Keyword(s):  
Spectral Data ◽  
Spectroscopic Analysis ◽  
Methanol Extract ◽  
2D Nmr ◽  
Flavonoid Glycosides ◽  
Flavonoid Aglycones ◽  
New Compounds ◽  
Related Compounds ◽  
Chemical Evidence

Six new compounds, comprising three flavonoid glycosides and their respective coumaroyl esters, have been isolated and characterized from the methanol extract of the leaves of Campylospermum calanthum, along with three known flavonoid aglycones, 7-O-methyl apigenin (1), 7-O-methyl luteolin (2), and 7-O-methyl quercetin (3). Their structures were elucidated based on chemical evidence as well as spectroscopic analysis including 1D and 2D NMR (1H-1H COSY, HSQC, HMBC, and NOESY) spectroscopy and by comparing their spectral data with those reported for related compounds

scholarly journals Synthesis and characterization of strontium-doped barium titanate thin film by dip and dry technique

2021 ◽  
pp. 2150002
Author(s):  
S. G. Chavan ◽  
A. N. Tarale ◽  
D. J. Salunkhe
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Dielectric Constant ◽  
Dielectric Loss ◽  
Complex Impedance ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Dip Coating ◽  
Morphological Properties ◽  
Constant Frequency

Thin films of polycrystalline (Ba[Formula: see text]Sr[Formula: see text]TiO3 ([Formula: see text] = 0.2 and 0.3) with Perovskite structure were prepared by a dip and dry technique on a platinum-coated silicon substrate. The good quality thin films with uniform microstructure and thickness were successfully produced by dip-coating techniques annealed at 730[Formula: see text]C for 1 h. The resulting thin film shows a well-developed dense polycrystalline structure with more uniform grain size distribution. The BST thin films were characterized for their structural, Raman spectroscopy, morphological properties, and complex impedance properties. The dielectric constant-frequency curve showed the good dielectric constant and loss dielectric loss with low-frequency dispersion. The BST 0.3 thin film reveals that the dielectric constant and dielectric loss at a frequency of 1 kHz were 578 and 0.02, respectively. The obtained results on dielectric properties can be analyzed in terms of the Maxwell–Wagner model.

The Dielectric Characteristics of Sr and Mg Doped CCTO Ceramics

2011 ◽  
Vol 687 ◽  
pp. 416-421 ◽  
Author(s):  
Qiu Xiang Liu ◽  
Xin Gui Tang ◽  
Yan Ping Jiang ◽  
F. L. Dong
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Solid Phase ◽  
Complex Impedance ◽  
Impedance Analysis ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Practical Applications ◽  
Complex Impedance Analysis ◽  
Mg Doped

Two kinds ceramics of pure CaCu3Ti4O12 (CCTO) and Sr/Mg doped (Ca0.25Cu0.75)0.5Sr0.5TiO3 + xMgO (x=0.01, 0.03, 0.05, 0.1, denoted as CCST-M-1, CCST-M-3, CCST-M-5, CCST-M-10, respectively) were prepared using the traditional solid phase reaction method. The dielectric properties were measured by HP 4194A Impedance/Gain-Phase Analyzer with the frequency range from 100 Hz to 1MHz. The temperature dependence of dielectric constant and loss tangent were measured for different frequencies. The variation relation of the critical temperature with the frequency was fitted theoretically which is in agreement with the Arrhenius law for pure CCTO. According to a variable power law to describe the paraelectric dielectric constant of ferroelectrics with diffuse phase transitions, the theoretical fitting was carried out for doped samples, and it was suggested that all doped samples exhibited the Debye-like relaxation. Among the doped and pure CCTO samples, CCST-M-1 was of the lowest dielectric loss at the whole measurement frequency, and whose I–V response curve was nonlinear suggesting a non-ohmic contact. The complex-impedance analysis results showed that the reduction in dielectric loss of CCST-M-1 sample can be attributed to the increase of grain boundary resistance. It is expect that these results are helpful to promote the CCTO-related materials to practical applications.

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