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Dielectric,ferroelectrics properties and impedance spectroscopy analysis of the[(Na_(0.535)K_(0.480))_(0.966)Li_(0.058)](Nb_(0.90)Ta_(0.10))O_(3)-based lead-free ceramics

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Journal of Advanced Dielectrics 2015年第1期5卷 50-56页

作者： M.Saidi A.Chaouchi S.D'Astorg M.Rguiti C.Courtois Laboratoire de Chimie Appliquée et Génie Chimique de l'UniversitéMouloud Mammeri de Tizi-Ouzou Algérie Laboratoire des Matériau Céramiques et Procédés Associés—Universitéde Valenciennes et du Hainaut-Cambrésis Boulevard Charles de Gaull 59600 MaubeugeFrance University of Lille Nord de France F-59000 Lille France

Polycrystalline of[(Na_(0.535)K_(0.480))_(0.966)Li_(0.058)](Nb_(0.90)Ta_(0.10))O_(3)samples were prepared using the high-temperature solid-state reaction technique.X-ray diffraction(XRD)analysis indicates the formation of a single-phase with orthorhombic *** impedance plots were used as tool to analyze the electrical behavior of the sample as a function of frequency at different *** ac impedance studies revealed the presence of grain effect,from 425℃*** impedance analysis indicated non-Debye type dielectric *** Nyquist plot showed the negative temperature coefficient of resistance(NTCR)characteristic of *** ac conductivity results were used to correlate with the barrier hopping(CBH)model to evaluate the binding energy(W_(m)),the minimum hopping distance(R_(min)),the density of states at Fermi level(N(E_(f))),and the activation energy of the compound.

关键词： Lead-free piezo-ceramics dielectric properties ac impedance spectroscopy dielectric relaxation conductivity

ac impedance Studies of SnO_2:Sc_2O_3 Based CO Sensor

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稀有金属材料与工程 2006年第A3期35卷 203-205页

作者： Gang Xu Shengming Xu Lili Wei Fang Wu Songzhe Chen Linyan Li Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China State Key Laboratory of Chemo/Biosensing and Chemometrics Hunan Univ Changsha 410082 China

Nanocrystalline SnO2:Sc2O3 was synthesized by a two-step hydrothermal process in the presence of urea. The transient response of the SnO2:Sc2O3 gas sensor to 200 mu g/g similar to 1000 gg/g CO was studied by ac impedance spectroscopy. Complex impedance measurement was carried out from 0.5 to 10(7) Hz, and the data were fitted with an equivalent circuit of two parallel circuits of a resistance and a constant phase element (CPE) in series. The sensitivity of the as-sintered samples demonstrated well linear relationship with the CO concentration. The doping of Sc2O3 could improve the CO sensitivity significantly, and the nanocrystalline SnO2:Sc2O3 at the composition of 8 similar to 10 mol% Sc2O3 promises good candidate materials in gas sensors.

关键词： ac impedance spectroscopy SnO2 Sc2O3 CO gas sensor

Dielectric relaxation and modulus spectroscopy analysis of(Na_(0.47)K_(0.47)Li_(0.06))NbO_(3) ceramics

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Journal of Advanced Dielectrics 2017年第3期7卷 37-47页

作者： Md Kashif Shamim Seema Sharma Sangeeta Sinha Eqra Nasreen Materials Research Laboratory Department of Physics A.N.College Patna 800013India Department of Environmental Science A.N.College Patna 800013India

We have investigated the structure,dielectric and electrical properties of lead-free polycrystalline (Na_(0.47)K_(0.47)Li_(0.06))NbO_(3) ceramics as a function of temperature and frequency in order to understand the intrinsic contribution of grain/bulk and grain boundary effects toward the dielectric response as well as the electrical conduction mechanism in the samples fabricated by microwave sintering method.X-ray diffraction analysis exhibits perovskite structure with orthorhombic symmetry,which is well supported by the Raman spectroscopic analysis.A minor secondary impurity phase of tungsten bronze structure was observed for samples sintered at 1050℃,which gets weaker for samples sintered at 1150℃.Dielectric permittivity was enhanced by 50%,although there was a reduction in the dielectric loss by about 50%at Curie temperature(450℃)for samples sintered at 1150℃.Complex impedance spectroscopic analysis indicated non-Debye-type dielectric relaxation present in the samples,and this phenomenon followed thermally activated process related to hopping *** plot showed the negative temperature coefficient of resistance,characteristic of the samples.

关键词： Lead-free piezo-ceramics dielectric properties ac impedance spectroscopy dielectric relaxation negative temperature coefficient of resistance(NTCR).

ac impedance Studies of SnO2:Sc2O3 Based CO Sensor

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稀有金属材料与工程 2006年第S3期 203-205页

作者： Gang Xu~1 Shengming Xu~(1,2) Lili Wei~1 Fang Wu~1 Songzhe Chen~1 Linyan Li~1 (1.Institute of Nuclear and New Energy Technology,Tsinghua University,Beijing 100084,China) (2.State Key Laboratory of Chemo/Biosensing and Chemometrics,Hunan Univ,Changsha 410082,China)

Nanocrystalline SnO2:Sc-2O3was synthesized by a two-step hydrothermal process in the presence of *** transient response of the SnO2:Sc2O3gas sensor to 200μg/g～100Oμg/g CO was studied by ac impedance spectroscopy. Complex impedance measurement was carried out from 0.5 to 10～7 Hz,and the data were fitted with an equivalent circuit of two parallel circuits of a resistance and a constant phase element （CPE） in *** sensitivity of the as-sintered samples demonstrated well linear relationship with the CO *** doping of Sc2O3could improve the CO sensitivity significantly,and the nanocrystalline SnO2:Sc2O3at the composition of 8～10 mol% Sc2O3promises good candidate materials in gas sensors.

关键词： ac impedance spectroscopy SnO2 Sc2O3 CO gas sensor

Electrical conductivity of MO(MO=FeO,NiO)-containing CaO-MgO-SiO_2-Al_2O_3 slag with low basicity

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Transactions of Nonferrous Metals Society of China 2011年第7期21卷 1648-1654页

作者：孙长余郭兴敏北京科技大学冶金与生态工程学院北京100083

As a fundamental study on recovery of valuable metals from nonferrous metallurgical slags,electrical conductivity values of MO（MO=FeO,NiO）-containing CaO-MgO-SiO2-Al2O3 slag with a low basicity were measured at different temperatures using ac impedance *** result shows that the electrical conductivity increased from 1.4 S/m to 14.4 S/m with the increase of the temperature from 1 573 to 1 773 K and the content of MO which is less than 12% under the constant mass ratio of （CaO＋MgO） to （SiO2＋Al2O3） of ***,the increase magnitude of the electrical conductivity was also promoted with the increase of the content of *** electrical conductivity of FeO-containing slags was close to that of NiO-containing slags when the content was less than 8%;however,it was obviously larger than that of NiO-containing slags when the content was 12%.The activation energy of the electrical conductivity decreased with the increase of MO content.

关键词： FeO NiO molten slag electrical conductivity ac impedance spectroscopy

impedance Spectroscopic Study on Room Temperature Ionic Liquid-Water Mixtures

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Journal of Chemistry and Chemical Engineering 2012年第4期6卷 383-390页

作者： Hiroshi Abe Masami Aono Yukihiro Yoshimura Department of Materials Science and Engineering National Defense Academy 1-10-20 Hashirimizu Kanagawa 239-8686 Japan Department of Applied Chemistry National Defense Academy 1-10-20 Hashirimizu Kanagawa 239-8686 Japan

ac impedance spectroscopy in pure room temperature ionic liquids （RTILs） and RTIL-water mixture was measured at the temperature of range from 30 ℃ down to -30 ℃. The cations of RTILs are N,N-diethyl-N-methyl-N-（2-methoxyethyl） ammonium （[DEME]）, 1-ethyl-3-methylimidazolium （[C2mim]） and l-butyl-3-methylimidazolium （[Camim]）, the anions are tetrafluoroborate （[BF4]） and bis（trifluoromethanesulfonyl）imide （[TFSI]）. In all pure RTILs, there are two kinds of local minima in real part of the ac impedance Zreal. By adding water to [DEME][BF4] （0 mol% 〈 x 〈 94 mol%） at room temperature, the local minimum value at higher frequency decreased remarkably at the fixed frequency with increasing water concentration. Above 94 mol% H20, a quite different profile of the ac impedance spectroscopy was obtained. In addition to Zreal. temperature dependence of an imaginary part of the impedance Zimag had an isosbestic point below 94 mol%. The isosbestic point disappeared above 94 mol%. The isosbestic point in Zing reveals an interaction between [DEME][BFa] and H2O.

关键词： Room temperature ionic liquids ac impedance spectroscopy aliphatic quaternary ammonium salt isosbestic point inimaginary part double local minima in real part.