Structural and dielectric properties of Ba5LnSn3Nb7O30 (Ln=La, Nd) ceramics

Fang, Liang; Chen, L; Zhang, H; Diao, Chunli; Run-zhang, Yuan

doi:10.1016/j.matlet.2004.03.042

Cited by 35 publications

(9 citation statements)

References 14 publications

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“…Interest on tungsten bronze structured dielectric ceramics in polycrystalline or single crystal form has increased considerably because of their interesting properties for device applications [1][2][3][4][5][6] 30 , consisting complex array of distorted BO 6 octahedra sharing corners providing three different interstices (A 1 , A 2 , B 1 , B 2 and C) for cation substitution. Due to the complex structure, its physical properties can be tailored through suitable cation substitutions, but these physical properties are also dependent on the synthesis route, environment and time of formation.…”

Section: Introductionmentioning

confidence: 99%

Frequency dependent electrical properties of Na2Pb2R2W2Ti4Nb4O30 (R = Nd, Sm) ceramics

2014

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Abstract:In the present research work, frequency dependent electrical properties of tungsten bronze structured compounds Na 2 Pb 2 R 2 W 2 Ti 4 Nb 4 O 30 (R = Nd, Sm) are reported. X-ray diffraction (XRD) study of polycrystalline ceramic samples confirms the formation of compounds with orthorhombic structure. Analysis of frequency dependent electrical data in the framework of modulus and conductivity formalism suggests the presence of thermally activated relaxation process in the compounds, which show Arrhenius behavior. The magnitudes of activation energies give the nature of the relaxing species. The real and imaginary parts of complex modulus trace the depressed semicircle in complex plane, suggesting non-Debye type relaxation process in the materials. The power law behavior of admittance data is successfully modeled by introducing constant phase element (CPE) to the equivalent circuit. A large value of power law parameter (n) of CPE below ferroelectric transition temperature (T c ) is attributed to the cooperative response of the dipoles which is reduced above T c . This behavior is correlated with the frequency dependence of CPE, suggesting a physical meaning to it. The frequency dependent AC conductivity at different temperatures follows Jonscher's universal power law. Almond and West formalism is used to estimate the hopping rate, activation enthalpy and charge carrier concentration in the materials.

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Section: Introductionmentioning

confidence: 99%

Frequency dependent electrical properties of Na2Pb2R2W2Ti4Nb4O30 (R = Nd, Sm) ceramics

2014

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“…The first compounds of the TB-type tungsten bronze structure reported to be ferroelectric were lead metaniobate A 6 B 10 O 30 . There is still plenty of scope to develop many new materials by substituting a variety of cations at different interstitial sites (i.e., A 1 A 2 B 1 B 2 ), and that can tailor the physical properties significantly for applications because of their high dielectric constant and low loss tangent [10,11]. Detailed literature surveys performed by the authors show, that although a lot of work has been done on TB structured compounds [12][13][14][15][16], no reports on structural, dielectric, and impedance properties of KCa 2 Nb 5 O 15 were available.…”

Section: Introductionmentioning

confidence: 99%

Structural and electrical properties of KCa2Nb5O15 ceramics

Behera¹,

Nayak

Choudhary³

2008

Open Physics

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Abstract:A polycrystalline sample of KCa 2 Nb 5 O 15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature. A preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound shows a uniform grain distribution throughout the surface of the sample. Studies of temperature variation on dielectric response at various frequencies show that the compound has a transition temperature well above the room temperature (i.e., 105 0 C), which was confirmed by the polarization measurement. Electrical properties of the material have been studied using a complex impedance spectroscopy (CIS) technique in a wide temperature (31-500 0 C) and frequency (10 2 -10 6 Hz) range that showed only bulk contribution and non-Debye type relaxation processes in the material. The activation energy of the compound (calculated from both the loss and modulus spectrum) is same, and hence the relaxation process may be attributed to the same type of charge carriers. A possible 'hopping' mechanism for electrical transport processes in the system is evident from the modulus analysis. A plot of dc conductivity (bulk) with temperature variation demonstrates that the compound exhibits Arrhenius type of electrical conductivity.

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“…Recently, owing to the rapid progress in microwave telecommunications, satellite broadcasting, and other related technologies, a number of Ba based TB compounds with dielectric constant nearly 100 have attracted much attention because of their importance in the miniaturization of microelectronic devices [6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Structural, dielectric, electrical and piezoelectric properties of Ba4SrRTi3V7O30 (R=Sm, Dy) ceramics

Sahoo¹,

Panigrahi²,

Patri³

et al. 2008

Open Physics

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Abstract:Polycrystalline samples of Ba 4 SrRTi 3 V 7 O 30 (R=Sm and Dy), members of the tungsten-bronze family, were prepared using a high-temperature, solid-state reaction technique and studied their electrical properties (using complex impedance spectroscopy) in a wide range of temperature (31-500 • C) and frequency (1 kHz -1 MHz). Preliminary structural (XRD) analyses of these compounds show the formation of single-phase, orthorhombic structures at room temperature. The scanning electron micrographs (SEM) provided information on the quality of the samples and uniform distribution of grains over the entire surface of the samples. Detailed studies of the dielectric properties suggest that they have undergone ferroelectric-paraelectric phase transition well above the room temperatures (i.e., 432 and 355 • C for R= Sm and Dy, respectively, at frequency 100 kHz). Measurements of electrical conductivity (ac and dc) as a function of temperature suggest that the compounds have semiconducting properties much above the room temperature, with negative temperature coefficient of resistance (NTCR) behavior. The existence of ferroelectricity in these compounds was confirmed from a polarization study.

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Structural and dielectric properties of Ba5LnSn3Nb7O30 (Ln=La, Nd) ceramics

Cited by 35 publications

References 14 publications

Frequency dependent electrical properties of Na2Pb2R2W2Ti4Nb4O30 (R = Nd, Sm) ceramics

Frequency dependent electrical properties of Na2Pb2R2W2Ti4Nb4O30 (R = Nd, Sm) ceramics

Structural and electrical properties of KCa2Nb5O15 ceramics

Structural, dielectric, electrical and piezoelectric properties of Ba4SrRTi3V7O30 (R=Sm, Dy) ceramics

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