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Temperature characterization of dielectric permittivity and ac conductivity of nano copper oxide-doped polyaniline composite

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Journal of Advanced Dielectrics 2016年第3期6卷 27-33页

作者： L.N.Shubha P.Madhusudana Rao Department of Electronics St.Francis College for Women BegumpetHyderabad 500011TelanganaIndia Department of Physics Jawaharlal Nehru Technological University Hyderabad KukatpallyHyderabad 500085TelanganaIndia

The polyaniline/copper oxide(PANI/CuO)nanocomposite was prepared by mixing solutions of polyaniline and copper oxide nanoparticles in dimethyl sulfoxide(DMSO).The synthesized polymer nanocomposites were characterized by X-ray powder diffraction(XRD),scanning electron microscope(SEM)and UV-visible *** characteristic peaks in XRD and UV-visible spectra confirmed the presence of CuO in the polymer *** images indicated morphological changes in the composite matrix as compared to the pristine *** DC conductivity measurements were performed using two-probe method for various *** conductivity and dielectric response of the composites were investigated in the frequency range of 10^(2)-10^(6)Hz using LCR *** permittivityε′(w)and dielectric loss factorε″(w)were *** was observed thatε′(w)andε″(w)decrease with increase in frequency at all *** a particular frequency it is observed that bothε′(w)andε″(w)increase with increase in *** was also observed that ac conductivity increased with increase in frequency and temperature.

关键词： ac conductivity dielectric permittivity dielectric loss factor polyaniline composite

Master curve generation and modeling of ac conductivity for Mn_(0.7+x)Zn_(0.3)Si_(x)Fe_(2-2x)O_(4) spinel ferrite system

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Journal of Advanced Dielectrics 2017年第3期7卷 54-63页

作者： N.H.Vasoya Prafulla K.Jha K.G.Saija J.A.Bhalodia K.B.Modi Department of Physics Faculty of ScienceM.S.University of Baroda Vadodara 390002India Smt.R.P.Bhalodia Mahila College Upleta 360490India Department of Physics Saurashtra UniversityRajkot 360005India

The compositional dependence of ac conductivity(δac),real(δ′)and imaginary(δ′′)parts of complex electric conductivity(δ*)was investigated as a function of temperature(T)and frequency(f) for Mn_(0.7+x)Zn_(0.3)Si_(x)Fe_(2-2x)O_(4),x=0.0,0.1,0.2 and 0.3 spinel ferrite *** compositional dependence of lattice constant values suggested that the most of the substituted Si4+-ions reside at grain boundaries and only a few Si-ions are inside *** variation ofδ_(ac)(x,f,T)is explained on the basis of segregation and diffusion of Si4+ions at grain boundaries and grains,respectively,and the electrode *** variation of ac conductivity at fixed frequency suggested two different mechanisms which could be responsible for conduction in the *** is found that δ*is not the preferred presentation for dielectric data and the scaling process of real part of conductivity by normalized frequency and the scaled frequency were found *** fitting results of ac conductivity data with path percolation approximation were found suitable in low-frequency regime while in high-frequency regime,effective medium approximation(EMA)was found successful.

关键词： Ferrites ac conductivity scaling modeling.

IMPEDANCE SPECTROSCOPY AND ac conductivity STUDIES OF FERROELECTRIC(K_(0.5)Na_(0.5))NbO_(3)CERAMICS

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Journal of Advanced Dielectrics 2011年第3期1卷 351-356页

作者： P.PALEI P.KUMAR National Institute of Technology Rourkela 769008 India

Lead free(K_(0.5)Na_(0.5))NbO_(3)(KNN)ceramics were prepared by conventional solid state reaction *** single perovskite phase formation,calcination temperature was optimized at 850℃for 6h,whereas for dense morphology the sintering of the ceramic was carried out at 1120℃for 4h.X-ray diffraction XRD analysis confirmed the formation of single phase with orthorhombic structure at room *** analysis and ac conductivity studies of the KNN sample was carried out in the temperature range of 703-773 *** study showed the increase in conducting behavior at higher *** temperature dependence of ac conductivity indicated that the conduction process is due to doubly ionized oxygen vacancies in the higher temperature region.

关键词： Perovskite sintering ac conductivity impedance oxygen vacancies

Dielectric relaxation and scaling of ac conductivity observed in mixed valence perovskite Eu_(2)CoMnO_(6)

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Journal of Advanced Dielectrics 2021年第6期11卷 52-58页

作者： Md.G.Masud B.K.Chaudhuri Department of Physics Basanti Devi College147B Rash Behari AvenueKolkata 700029India Center for Rural and Cryogenic Technologies Jadavpur UniversityKolkata 700032India Formerly at Solid State Physics Department Indian Association for the Cultivation of Science Kolkata 700032India

Monophasic and polycrystalline double perovskite Eu_(2)CoMnO_(6)has been synthesized,and its structural characterization,fre-quency and temperature-dependent dielectric relaxation have been *** thermally activated dielectric relaxation was explained using the empirical Havriliak-Negami(HN)dielectric relaxation function with an estimated activation energy E~0.22 eV and attempt frequency f0~2.46×10^(9)*** frequency-dependent ac conductivity data,over a wide range of tempera-ture(100-325 K),followed the empirical universal power law behavior(~f n,n is the constant exponent)showing two different frequency exponents,respectively,in the high-and low-temperature *** high-temperature(>275 K)conductivity data followed the continuous time random walk(CTRW)approximation model proposed by ***,this model failed to repro-duce the observed conductivity spectra in the low-temperature side(conductivity data can be scaled to the master curve with suitably chosen scaling parameters.

关键词： Dielectric relaxation ac conductivity scaling perovskite

Effect of Li^(+)ion mobility on the grain boundary conductivity of Li_(2)TiO_(3) nanoceramics

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Journal of Advanced Ceramics 2014年第2期3卷 98-108页

作者： Umasankar DASH Subhanarayan SAHOO S.K.S.PARASHAR Paritosh CHAUDHURI School of Applied Sciences KIIT University Bhubaneswar-751024India Department of Electrical and Electronics Engineering Trident Academy of TechnologyBhubaneswar-751024India Institute for Plasma Research BhatGandhinagarGujurat-382428India

Lithium titanate(Li_(2)TiO_(3))is one of the most promising candidates among the tritium breeding materials because of its good tritium release *** concentration has much significance on the diffusivity of tritium in the *** nanocrystalline single-phase Li_(2)TiO_(3) with monoclinic structure has been prepared by high energy ball milling followed by calcination at 700℃for 2 *** field emission scanning electron microscopy(FESEM)studies confirmed uniform distribution of nanocrystalline phase with particle size below 100 *** study of the Li^(+)ion diffusion on the sintered sample was investigated by means of electrical conductivity *** properties of the samples were studied in wide temperature(50-500℃)and frequency(100 Hz-1 MHz)*** complex impedance spectroscopy(CIS)studies showed the presence of both bulk and grain boundary effects in nanocrystalline Li_(2)TiO_(3).The bulk resistance of the samples has been observed to decrease with rise in temperature showing a typical negative temperature coefficient of resistance(NTCR)*** low activation energies of the samples suggested the presence of singly ionized oxygen vacancies in the conduction *** hopping frequency shifted toward higher frequency with increase in *** energy of 0.86 eV was calculated from ac conductivity.

关键词： high energy ball milling ac conductivity impedance spectroscopy nanocrystalline

Enhanced electrical conductivity in Zr-Doped(La_(0.7)Ba_(0.3))(Mn_(0.5)Fe_(0.5))O_(3)solid solutions

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Journal of Advanced Dielectrics 2020年第6期10卷 61-68页

作者： Yogesh Kumar Jaswinder Pal Parambir Singh Malhi Rakesh Kumar CT University Sidhwan Khurd LudhianaPunjab 142024India Department of Physics Baba Farid College(Affiliated to Punjabi UniversityPatiala)BathindaPunjab 151001India Department of Chemistry Guru Nanak Dev University AmritsarPunjab 143005India Ludhiana Group of Colleges Chokimann LudhianaPunjab 142001India

The perovskite(La_(0.7)Ba_(0.3))(Mn_(0.5)Fe_(0.5))_(1−x)Zr_(x)O_(3),where x=0.1,0.2 and 0.3,ceramics were synthesized by solid-state reaction *** introductory structural studies were followed through by X-ray diffraction technique and the results have disclosed that all the samples were crystallized into an isolated *** Zr substitution in the resulting solid solutions increases the electrical conductivity and the maximum value of ac conductivity has been found to be~118.8 ***^(−1)for x=0.3 at 200°C(at 1 MHz).The frequency dependence of ac conductivity data follows Jonscher’s power *** variation of the exponent n versus temperature follows the nonoverlapping small polaron tunneling(NSPT)*** dielectric relaxation has been observed to be of non-Debye nature for all measuring temperatures(50-200°C).The impedance spectroscopy reveals that all the samples exhibit negative temperature coefficient of resistance(NTCR)*** prepared samples(for x>1)are supposed to be suitable for cathode materials in SOFCs.

关键词： SOFC perovskite X-Ray Diffraction(XRD) ac conductivity dielectric

Temperature-dependent dielectric properties of Au/Si_3N_4/n-Si (metal insulator semiconductor) structures

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Chinese Physics B 2013年第11期22卷 541-546页

作者： T.Ataseven A.Tataroglu Physics Department Faculty of Sciences Gazi University Teknikokullar

The dielectric properties of Au/Si3N4/n-Si （MIS） structures are studied using the admittance measurements （C–V and G/ω–V） each as a function of temperature in a range from 80 K to 400 K for two frequencies （100 kHz and 1 MHz）. Experimental results show that both the dielectric constant （ε’） and the dielectric loss （ε＂） increase with temperature increasing and decrease with frequency increasing. The measurements also show that the ac conductivity （σac） increases with temperature and frequency increasing. The lnσac versus 1000/T plot shows two linear regions with different slopes which correspond to low （120 K–240 K） and high （280 K–400 K） temperature ranges for the two frequencies. It is found that activation energy increases with frequency and temperature increasing.

关键词： Au/Si3N4/n-Si (metal-insulator-semiconductor) structure admittance measurements dielectricproperties ac conductivity

Grain boundary effect on structural, optical, and electrical properties of sol-gel synthesized Fe-doped SnO_(2) nanoparticles

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Chinese Physics B 2021年第4期30卷 555-564页

作者： Archana V Lakshmi Mohan Kathirvel P Saravanakumar S Department of Sciences Amrita School of EngineeringCoimbatoreAmrita Vishwa VidyapeethamIndia Research and Development Center Bharathiar UniversityCoimbatore-641046TamilnaduIndia GRD Center for Materials Research Department of PhysicsP S G College of TechnologyCoimbatore-641004TamilnaduIndia Department of Physics N S S CollegePandalam-689501KeralaIndia

Tin oxide(SnO_(2)) and iron-doped tin oxide(Sn_(1-x)Fe_(x)O_(2),x=0.05 wt%,0.10 wt%) nanoparticles are synthesized by the simple sol-gel *** structural characterization using x-ray diffraction(XRD) confirms tetragonal rutile phases of the *** variations in lattice parameters and relative intensity with Fe-doping concentration validate the incorporation of iron into the *** compressive strain present in the lattice estimated by using peak profile analysis through using Williamson-Hall plot also exhibits the influence of grain boundary formation in the *** radiative recombination and quenching observed in optical characterization by using photoluminescence spectrum(PL) and the shift in the band gap estimated from UV-visible diffused reflectance spectrum corroborate the grain boundary *** spectrum and the morphological analysis by using a field emission scanning electron microscope(FESEM) also indicate the formation of grain *** compositional analysis by using energy dispersive x-ray spectrum(EDAX) confirms Fe in the SnO_(2) *** conductivity studies exhibit that the impendence increases with doping concentration increasing and the loss factor decreases at high frequencies with doping concentration increasing,which makes the Sn_(1-x)Fe_(x)O_(2) a potential candidate for device applications.

关键词： sol-gel compressive strain grain boundary ac conductivity

Microwave-assisted synthesis of Mg:PbI2 nanostructures and their structural,morphological,optical,dielectric and electrical properties for optoelectronic technology

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Chinese Physics B 2020年第11期29卷 420-426页

作者： Mohd.Shkir Ziaul Raza Khan T Alshahrani Kamlesh VChandekar M Aslam Manthrammel Ashwani Kumar S AlFaify Advanced Functional Materials and Optoelectronics Laboratory(AFMOL) Department of PhysicsCollege of ScienceKing Khalid UniversityAbha 61413P.O.Box 9004Saudi Arabia Department of Physics College of ScienceUniversity of HailP.O.Box 2440HailSaudi Arabia Department of Physics College of SciencePrincess Nourah Bint Abdulrahman UniversityRiyadh 11671Saudi Arabia Department of Physics Rayat Shikshan Sanstha’sKarmaveer Bhaurao Patil CollegeVashiNavi Mumbai 400703India Department of Physics IK Gujral Punjab Technical UniversityJalandhar 144603India

This work reports the cost-effective growth of Mg:PbI2 nanostructures with 0,1,2.5 and 5.0 wt.%Mg doping ***,vibrational,morphological properties are analyzed using x-ray diffraction(XRD),Raman spectroscopy and scanning electron microscopy(SEM).XRD and Raman studies confirm the monophasic hexagonal system of Mg:PbI2,and no additional impurity peaks are *** Scherrer formula is used to determine sizes of crystallites to be in the range of 47-52 ***/SEM e-mapping analyses confirm the incorporation of Mg in PbI2 matrix and its uniform distribution throughout the *** hexagonal nanosheet-and nanoplate-like morphologies are detected in SEM images for pure and Mg-doped *** optical band gap of nanostructures is obtained from Tauc’s relation to be in the range 3.0-3.25 *** and electrical properties are found in significant enhancement as Mg doping in PbI2 matrix,also the conduction mechanism is discussed.

关键词： Mg:PbI2 nanostructures structural properties optical band gap dielectric constant ac conductivity