Non-adiabatic small polaron hopping conduction in sodium borate tungstate glasses

Alshahrani, Abdullah; Al‐Hajry, A.; El‐Desoky, M. M.

doi:10.1002/pssa.200306689

Cited by 63 publications

(31 citation statements)

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“…This figure illustrates a linear temperature dependence of the dc conductivity at high temperatures [454 K, whereas in the low temperature region below 454 K a non-linear dependence of dc conductivity was observed. This behavior is in agreement with that reported for different borate glasses [25,26], and is attributed to the change of conduction model from small polaron hopping (SPH) model at high temperature to Greaves variable range hopping (VRH) at low temperature [27]. At low temperatures, where the polaron binding energy is small and the static disorder energy of the system plays the dominant role in the conduction mechanism, Mott [27] has proposed that polarons may hop preferentially beyond nearest neighbors.…”

Section: Conductivitysupporting

confidence: 75%

Structure and electrical conductivity relaxation studies of Nb2O5-doped B2O3–Bi2O3–LiF glasses

Shaaban

2012

J Mater Sci

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Glasses with composition (70 -x) B 2 O 3 Á15Bi 2 O 3 Á15LiFÁxNb 2 O 5 with x = 0-1.0 mol% were prepared by conventional glass-melting technique. The molar volume V m values decrease and the glass transition temperatures T g increase with increase of Nb 2 O 5 content up to 0.2 mol%, which indicates that Nb 5? ions act as a glass former. Beyond 0.2 mol% Nb 2 O 5 the V m increases and the T g decreases, which suggests that Nb 5? ions act as a glass modifier. The FTIR spectra suggest that Nb 5? ions are incorporated into the glass network as NbO 6 octahedra, substituting BO 4 groups. The temperature dependence of the dc conductivity follows the Greaves variable range hopping model below 454 K, and follows the small polaron hopping model at temperatures [454 K. r dc , r ac conductivity and dielectric constant (e) decrease and activation energy for dc conduction DE dc which increases with increasing Nb 2 O 5 content up to 0.2 mol%, whereas r dc , r ac and (e) increase and DE dc decreases with increasing Nb 2 O 5 content beyond 0.2 mol%. The impedance spectroscopy shows a single semicircle or arcs which indicate only the ionic conduction mechanism. The electric modulus formalism indicates that the conductivity relaxation is occurring at different frequencies exhibit temperatureindependent dynamical process. The (FWHM) of the normalized modulus increases with increase in Nb 2 O 5 content suggesting that the distribution of relaxation times is associated with the charge carriers Li ? or F -ions in the glass network.

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Section: Conductivitysupporting

confidence: 75%

Structure and electrical conductivity relaxation studies of Nb2O5-doped B2O3–Bi2O3–LiF glasses

Shaaban

2012

J Mater Sci

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“…A strong electron-phonon interaction is considered to be responsible for the formation of small polarons [11] and the polaron hopping conduction model has been used to illustrate the semiconducting behavior. The semiconducting properties of transition metal oxide (TMO) arise from the presence of different valence states of transition metal ions [12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Transport properties of Ba-doped BiFeO3 multiferroic nanoparticles

El‐Desoky

Mostafa

Ayoub

et al. 2015

J Mater Sci: Mater Electron

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Multiferroic nanoparticles of Bi 1-x Ba x FeO 3 (BiBaFeO 3 ); (x = 0.10, 0.15, 0.20 and 0.25 mol%) samples were prepared using conventional solid-state method. The nanostructural and transport properties of the prepared samples were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and electrical conductivity. XRD patterns show the formation of BiBaFeO 3 with single-phase rhombohedral-hexagonal structure. The particles sizes were found to be in the range 20-33 nm. SEM micrograph revealed the nanostructure consisting of small, randomly oriented and non-uniform grains. Dc conductivity shows that all samples are semiconductor and the maximum was found at x = 0.15 mol%. This increase of the conductivity can be attributed to the decrease in grain boundary scattering due to the reduction in crystallite size. The calculated activation energy for the multiferroic nanoparticles was found to be 0.413-0.929 eV. The conduction was confirmed to obey non-adiabatic small polaron hopping (SPH). The electron-phonon interaction coefficient (c p ) was calculated and found to be in the range of (12.79-27.21). The hopping carrier mobility varied from 1.85 9 10 -7 cm 2 V -1 s -1 to 8.01 9 10 -13 cm 2 V -1 s -1 at 418 K. The conductivity was primarily determined by hopping carrier mobility.

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“…Sodium tungsten borate glasses containing up 37 mol% WO 3 showed an increase in density, refractive index, thermal expansion coefficient, and electrical conductivity [15]. Several studies have been carried out on the spectroscopic, thermal, density and structure properties of high WO 3 containing borate glasses [12,19,20] yet few studies have been carried out on the dc electrical conductivity [21]. The dielectric and optical properties of Zn-borate glasses containing 0.2-2.5 mol% WO 3 have been studied [6].…”

Section: Introductionmentioning

confidence: 99%

Dielectric, electrical and spectroscopic properties of barium borates of low WO3 content

Morsi

Abdelghany

Morsi

2015

J Mater Sci: Mater Electron

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Infrared and optical absorption UV-Vis measurements, electrical and dielectric properties were carried out for glasses with the composition (mol%) 60B 2 O 3 Á 40BaO containing 0.0, 3, 5 and 9 g WO 3 /100 g glass. Infrared absorption spectra of all glasses indicate the presence of both triangular BO 3 units and tetrahedral BO 4 units, and the latter is overlapped with stretching vibrations of WO 4 and WO 6 units. UV-Vis measurements reveal strong charge transfer cutoff and no absorption bands were recorded in the visible region. Upon increasing WO 3 content in the studied glasses the optical band gap (E opt ) and the electrical conductivity values increase whereas activation energy values decrease. The increase in the electrical conduction was attributed to the hopping mechanism between the two sites of tungsten (W 5? , W 6? ). In the low frequency region below 1 kHz the dielectric constant measured at 200 Hz and room temperature was increased from 27 to 177 on increasing WO 3 content from 0.0 to 9.0 g WO 3 per 100 g glass, respectively. At 300°C the dielectric constant reached a value of 435 for sample containing 9.0 g WO 3 per 100 g glass. The present results may make it as a promising candidate for energy storage in electronic applications.

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Non-adiabatic small polaron hopping conduction in sodium borate tungstate glasses

Cited by 63 publications

References 1 publication

Structure and electrical conductivity relaxation studies of Nb2O5-doped B2O3–Bi2O3–LiF glasses

Structure and electrical conductivity relaxation studies of Nb2O5-doped B2O3–Bi2O3–LiF glasses

Transport properties of Ba-doped BiFeO3 multiferroic nanoparticles

Dielectric, electrical and spectroscopic properties of barium borates of low WO3 content

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