Polaron Tunneling Research Articles

Conductivity behavior and impedance studies in BaTiO3–CoFe2O4 magnetoelectric composites

Two phase magneto-dielectric composite of Barium titanate and Cobalt ferrite (BT-CFO) has been prepared via solid state reaction technique. The structure has been investigated by Raman spectroscopy and confirms the presence of composite phase. Electrical properties of BT-CFO composites were studied thoroughly in 100 Hz to 1 MHz frequency range and in 50 °C–450 °C temperature range. The dielectric measurements reveal Maxwell-Wagner polarization and thermal activated relaxation process arising from movement of defects and ions in BT and BT-CFO composites. Particularly BT-5CFO composite exhibited a surprising low dielectric loss ≈0.3 over the frequency range of 100 Hz-1MHz and promises industrial application. The thermal variation of Impedance parameters reveals the resistive nature of the composites and the presence of two thermally activated relaxation mechanism present in BT and BT-CFO composites. The modulus studies confirm the non-Debye type relaxation processes prevalent in BT-CFO composites. The electrical conduction mechanism occurs through over-lapping large polaron tunneling (OLPT) in BT and through non-overlapping small polaron tunneling (NSPT) at low temperatures to correlated barrier hopping (CBH) at high temperatures in BT-CFO composites. The addition of CFO in BT localizes the polarons and enhances the conductivity. The magneto-dielectric coupling effect (% MD) is found to have a maximum value of 1.2 in magnitude at 7 kOe for BT-5CFO composite and increases with the amount of CFO in BT-CFO composite. These results could be beneficial in enhancing the properties of BT-CFO based systems.

Synthesis, crystal structure, Hirshfeld surface analysis and dielectric properties of a new centrosymmetric hybrid compound (C4H12NO3)CdCl3·H2O

A new organic–inorganic hybrid centrosymmetric compound, (C4H12NO3)CdCl3·H2O, was synthesized by the slow evaporation method at room temperature and characterized by single X-ray diffraction (SCXRD). The results of the X-ray diffraction study demonstrated that this material crystallizes in the triclinic system with the space group P1¯ and the following unit cell parameters a = 6.822(6) Å, b = 8.96(2) Å, c = 10.034(3) Å, α = 72.901(3)°, β = 71.927(3)°, γ = 89.099(3)° and Z = 2. In the crystal structure, the atomic arrangement is described as an alternation of organic and inorganic layers along the a-axis. The anionic layers are formed by [CdCl5O]− octahedrons, while the cationic layers are made up of [C4H12NO3]+ cations. The crystal packing is governed by NH⋯Cl, NH⋯O, CH⋯Cl, OH⋯Cl and OH⋯O hydrogen bonds, forming a three dimensional supramolecular network. Hirshfeld surfaces and 2D fingerprint plots were determined for visualizing, exploring and quantifying the intermolecular interactions in the crystal lattice of the title compound. Infrared and Raman spectroscopy were reported at room temperature in the frequency domains 400–4000 cm−1 and 50–500 cm−1, respectively. Differential scanning calorimetry (DSC) revealed one exothermic peak located at around T1 = 368 K. Electrical and dielectric properties were investigated as a function of temperature (300–430 K) in the frequency range 40 Hz–110 MHz. The electrical and dielectric studies were performed by means of impedance spectroscopy and dielectric permittivity ε',ε''. Nyquist curves were well fitted to an equivalent circuit formed by parallel combination resistance and capacity fractal of the bulk. The frequency dependence of the alternative current (AC) conductivity was analyzed using the Jonscher law. Overlapping-large polaron tunneling (OLPT) and non-overlapping small polaron tunneling (NSPT) conduction mechanism models successfully explained the behavior of the exponent n.

Synthesis, structural characterization and electrical conduction mechanism of the new organic–inorganic complex: ([(C3H7)4N]FeCl4)

A new organic–inorganic hybrid material, tetrapropylammonium tetrachloferrate, has been synthesized and characterized by single-crystal X-ray diffraction, thermal analysis, vibrational and impedance spectroscopies. The single crystals were obtained by slow evaporation of an aqueous solution of the reactants at room temperature. The [(C3H7)4N]FeCl4 compound crystallizes in the orthorhombic system (Pbca space group). The structural analysis shows the presence of cavities arranged in the [100] direction. It is formed by six cations ([(C3H7)4N]+) which accommodate the anionic group ([FeCl4]−). The differential scanning calorimetry (DSC) indicates the presence of three phase transitions, located at T = 333, 368 and 398 K. Besides, the impedance spectra were explored with an equivalent circuit including a parallel combination of resistance and fractal capability. From Jonscher’s power law, the Correlation Barrier Hopping (CBH) and the Non-overlapping Small Polaron Tunneling (NSPT) model prevailed the conduction mechanism in the title compound. Furthermore, the electrical modulus analysis shows the non-Debye type conductivity relaxation.

Investigation on the optical, electrical, dielectric, and magnetic properties of (1−x)La0.7Ca0.3MnO3/xCoFe2O4 nanocomposites

(1−x)La0.7Ca0.3MnO3/xCoFe2O4 (x = 0, 0.1, 0.3) nanocomposites are fabricated by glycine-nitrate method. XRD patterns and FTIR spectra confirm the phase formation of the nanocomposite. FESEM images divulge a reduction in the average particle size with enhanced incorporation of CoFe2O4. The band gap increases moderately followed by a blue shift in UV–Vis absorption peaks. Frequency-dependent impedance and dielectric properties are investigated at and above the room temperature. The impedance of the system gets enhanced while the conductivity reduces accordingly. Nyquist plot of impedance displays the contribution of diverse nanostructures on the electrical property using R(QgRg)(QgbRgb) circuit. Two types of conduction mechanism are observed in the studied system. The conduction in the low frequency regime is associated with correlated barrier hopping type conduction mechanism and in the high frequency regime is associated with overlapped large polaron tunneling conduction mechanism. The dielectric constant and tangent loss both are reduced on the incorporation of CoFe2O4. Comparatively low tangent loss value for x = 0.3 reflects suitability in high-frequency device applications. The saturation magnetization Ms and squareness ratio S is also high for x = 0.3 that is valuable for possible use of the (1−x)La0.7Ca0.3MnO3/xCoFe2O4 nanocomposites in memory devices.

AC conductivity and mechanism of conduction study of Ba0.2Sr1.8FeMoO6 double perovskite using impedance spectroscopy

The barium-stronium double perovskite Ba0.2Sr1.8FeMoO6 compound have been synthesized by the sol - gel method and characterized by X-ray diffraction (XRD) technique. The title material crystallizes in the monoclinic system with P21/n space group. The dielectric properties, impedance characteristics, and modulus were studied over a range of frequency (200 Hz to 5 MHz) and temperature (318 K–373 K). The frequency and temperature dependence of dielectric permittivity, dielectric loss, and electric modulus is studied. The frequency analysis of modulus properties showed a distribution of relaxation times. Conductivity plots against frequency at a higher frequency suggested the response obeying the universal power law. The temperature behavior of the frequency exponents shows that the overlapping large polaron tunneling (OLPT) model is well adapted to this material. The activation energy associated with the impedance relaxation and the electric modulus spectra is close to the activation energy for dc conductivity indicating the similar nature of relaxation and conductivity.

Low temperature electrical impedance spectroscopy characterization of n type CuInSe2 semiconductor compound

In this report, the ternary chalcopyrite semiconductor n-CulnSe2 (n-CIS112) was studied using impedance spectroscopy (IS) over a wide range of temperatures [80 K, 300 K] and frequencies [20 Hz, 1 MHz]. The ingot was grown by vertical Bridgman technique. The experimental data are analyzed to estimate the activation and relaxation energies. The activation energies agree with those reported from Hall effect measurements. The predominance of both “bulk” and “grain-boundary” contributions to the electrical conduction is confirmed by using impedance and modulus formalism. AC electrical conductivity data σac(ω,T) for n-CulnSe2 are discussed using the theoretical Overlapping Large Polaron Tunneling process.

Small polaron hopping conduction in NiMnO3/NiMn2O4 nano-cotton and its emerging energy application with MWCNT

Self-assembled ilmenite/spinel NiMnO3/NiMn2O4 nano-cotton and it's MWCNT blended composites were synthesized via one-step sol-gel auto combustion and ultra-sonication techniques with a perspective to investigate its dielectric, conduction mechanism and enhanced electrochemical performance to explore its applications as supercapacitor materials and high-temperature energy storage devices. The as-prepared double phase oxides were characterized initially by X-ray diffractometry, FTIR and Raman techniques to ascertain its phase formation and structural information. The FESEM and TEM micrographs reveal the growth of nanoparticles homogeneously and cotton-like morphology over observed space. The EDS elemental analysis and mappings exposed the true stoichiometrical ratios of elemental particles Ni, Mn, O and C and their uniform distribution. The coercivity (264 Oe) and saturation magnetization (1.2 emu/gm.) of MWCNT blended NiMnO3/NiMn2O4 oxides curtailed significantly than NiMnO3/NiMn2O4 which recommends its approach towards the superparamagnetic region. The fitted Nyquist plot (Z'vs.Z'') distinguished the individual contribution of grain and grain boundary and activation energy for grain (0.87 eV) and grain boundary (1.2 eV) was estimated from liner plot of extracted data. The frequency dispersing conductivity spectra was fitted with a modified equation of Jonscher's Power Law proposed by us, σac(ω)=σ0(dc)+A(ω−b)n and temperature dependent frequency exponent (n) and Ln (A) suggests non-overlapping small polaron tunneling (NSPT) model for its conduction mechanism. Displacement of both Ni2+ and Ni3+ ions through the channel like cavities of ilmenite/spinel structure along a, b and c axis provides strong support of the NSPT model. The electrochemical supercapacitor properties of NiMnO3/NiMn2O4 and MWCNT blended NiMnO3/NiMn2O4 were examined in 2 M aqueous KOH solution and excellent capacitive properties were observed for both compounds. Higher capacitance value (1347 F-g−1) and energy density 140 W h kg−1 were obtained at a current density of 5 A g−1 for MWCNT blended NiMnO3/NiMn2O4 with compared to its parent counterparts.

Investigation of Ac conductivity mechanism and dielectric relaxation of semiconducting neodymium-vanadate nanocomposites: temperature and frequency dependency

A few binary nanocomposite systems of the overall composition formula xV2O5–(1-x) Nd2O3 for x = 0.2, 0.4, 0.6 and 0.8 has been synthesized via the rapid cooling process. The identification of crystal morphology, lattice fringes of the nanocrystallites, and the selected area electron diffraction patterns have been carried out using the transmission electron microscopy (TEM). TEM micrographs confirm the nanocrystallite development and amorphous character of the nanocomposites. The ac conductivity has been explored in the frequency window from 42 Hz to 5 MHz and in a wide temperature range. The dependency of ac conductivity spectra on frequency and temperature obey Almond-West formalism and Jonscher’s universal power-law. With an increment in temperature, ac conductivity increases, indicating semiconducting behavior. The power-law exponent (s) values are less than unity and increase in relation to the temperature, suggesting non-overlapping small polaron tunneling (NSPT) is the relevant ac conductivity mechanism. The reducing nature of the ac conductivity activation energy, the activation energy for polaron migration and tunneling distance are responsible for the rising of ac conductivity. The increment in the density of defect states within the mobility gap makes ac conductivity to rise as well. The scaled spectra of ac conductivity prove that conductivity relaxation process is temperature independent but composition dependent. In the electrical conduction process, only 66%–71% of the total charge carriers are involved. The values of dielectric constant (ε/) and dielectric loss (ε//) increase with temperature rise and drop with a rise in frequency. The coinciding scaled complex electric modulus spectra (M/ and M//) point out that the dynamical relaxation mechanism is a non-Debye type and is independent of temperature but depend on composition.

Ferroelectric properties and alternative current conduction mechanisms of lithium rubidium molybdate

The lithium rubidium molybdate compound LiRbMoO4 was prepared by the solid-state reaction method. XRD spectra revealed a single phase material with an orthorhombic structure. The internal Raman modes were observed at room temperature. The dielectric measurement exhibited three subsequent phase transitions: two structural transitions at the neighborhood of 397 K and 420 K followed by a ferro-paraelectric transition at 424 K. The Nyquist plot was proved to be a non-Debye relaxation mechanism. The combined spectroscopic plots of the imaginary part of electric impedance and modulus in the temperature range of 581–718 K at various frequencies confirmed the non-Debye behavior. The AC conductivity was found to follow the Jonscher’s universal dynamic law ωS, and the overlapping large polaron tunneling model (OLPT) was proposed to describe the conduction mechanism.

Non-overlapping small polaron tunneling conduction coupled dielectric relaxation in weak ferromagnetic NiAl2O4

The inverse spinel nickel aluminate micro-particles was successfully synthesized via solid-state synthesis techniques. The single phase cubic structure with space group Fd3m of the as-prepared sample was entrenched from Rietveld refinement of x-ray diffraction pattern. In addition, the photoluminescence (PL) and FTIR spectra were also performed to give strong evidence of its pure phase formation. The narrow hysteresis m–h loop and UV-DRS spectra at room temperature demonstrate its weak ferromagnetic and semiconducting nature with saturation magnetization 64.96 × 10−3 emu gm−1 and direct optical band gap 2.03 eV respectively. The high-resolution FESEM micrographs and EDS elemental analysis exhibit its grain growth in µm range (217 µm) and presence of elemental compound Ni, Al and O respectively. The electrical transport properties were accomplished by complex impedance spectroscopy as a function of frequency (100 Hz–1 MHz) with the evolution of high temperature (300 °C–500 °C). The Nyquist plots (Z″ versus Z′) were well fitted with an equivalent circuit model (QR) (QR) consisting of a series combination of intra and inter-granular contribution. Furthermore, the imaginary modulus spectra were also fitted with Kohlrausch–Williams–Watts (KWW) function, which represents two thermally activated peaks of grain and grain boundary effects. The low-frequency dispersive ac conductivity was elucidated using the following equation: . The increasing nature of temperature dependent frequency exponent (n) suggests the quantum mechanical tunneling: non-overlapping small polaron tunneling (NSPT) concept for conduction mechanism. In low-frequency region, the lattice and charge carrier polarization simultaneously contribute in dielectric permittivity.

Physical properties of the organic polymeric blend (PVA/PAM) modified with MgO nanofillers

Magnesium oxide/polyvinyl alcohol/polyacrylamide (MgO/PVA/PAM) nanocomposite films were prepared via a solution chemical method. The effect of PVA and MgO nanoparticles (NPs) loading on the physical properties of PAM is discussed. X-ray diffraction reveals that the average MgO crystallite size of the NPs is ∼25 nm, while adding PVA increases the crystallinity of PAM. FTIR spectra confirm the interaction between blend chains and MgO NPs. Differential scanning calorimetry thermograms illustrate the miscibility between the PVA and the PAM. The melting temperature, the glass transition, as well as the equilibrium swelling ratio, depend on the films' composition. PAM showed a transmittance of 87%, that increased to 90% after PVA addition, but decreased to 74% after MgO loading. Meaningful changes are observed in the extinction coefficient and indirect/direct band gap of PAM due to PVA blending and MgO addition. The influence of MgO NPs on the dielectric constant ( ɛ′) of the blend film is reported. The maximum value of AC conductivity of the blend is 4.77 × 10−3 Sm−1, which increased to 8.07 × 10−3 Sm−1 by increasing the MgO loading to 5.0 wt.%. The conduction mechanism changed from the correlated barrier hopping, in the blend, to the large Polaron tunneling with MgO loading. The observed improvements in optical properties and AC conductivity encourage the use of these nanocomposite films in the semiconductors industry.

Synthesis, Characterization and Electrical Admittance Study of LaCrO3 Perovskite Compound

We synthesized the ferroelectric perovskite oxide LaCrO3 (LCO) using solid-state reaction method. Scanning electron microscope (SEM), energy x-ray dispersive (EDX) and X-ray diffraction (XRD) have been employed to study structural and chemical analysis of synthesized powder, respectively. Electrical admittance properties of the perovskite oxide sample was performed in wide range frequency (1Hz10MHz) and temperature (-100 °C to +100 °C) using dielectric/impedance spectrometer. The results showed that the LCO has different activation energies and the calculated activation energies are of 0.175 eV and 0.220 eV from the Gdc vs. 1000/T and 0.152 eV and 0.197 eV from the f min vs. 1000/T plots, respectively. The temperature-dependent exponent s showed that the overlapping large polaron tunneling (OLPT), quantum mechanical tunneling (QMT) and the correlated barrier hopping (CBH) conduction mechanism models can be suggested for the LCO compound.

Conducting polymers X: Dielectric constant, conduction mechanism and correlation between theoretical parameters and electrical conductivity of poly (N,N′-bis-sulphinyl p-phenylenediamine-2,6-diaminipyridine) and poly (N,N′-bis-sulphinyl p-phenylenediamine-3,5-diamine-1,2,4-trizole)

Poly (N,N′-bis-sulphinyl p-phenylenediamine-2,6-diaminipyridine) (PBSPDP) and poly (N,N′-bis-sulphinyl p-phenylenediamine-3,5-diamine-1,2,4-trizole) (PBSPDT) were synthesized by Micheal addition polymerization method using thionyl chloride and characterized by the FTIR and 1H NMR techniques. The number average molecular weight (Ṁn) of BSPDP and BSPDT were calculated using 1H NMR data and are found to be ∼3984 and 2156 g/mole, respectively. DC and AC electrical conductivities were measured at different temperatures confirming the semiconductor behaviors due to the delocalization of electrons of N, S and O atoms. The dielectric constants of the two polymers were investigated and the σAC was found 5.8 × 10−5 Ω−1 m−1 for PBSPDP and 9.62 × 10−5 Ω−1 m−1 for PBSPDT at 90 °C and applied frequency about 3 MHz. A theoretical study was used to calculate LUMO and HOMO energies. The high negative charges in the nitrogen atoms as well as the low activation energies of PBSPDT than PBSPDP were attributed the increased values of electrical conductivities. The impedance analyses suggested that the equivalent circuit of the both PBSPDP and PBSPDT can be presented by parallel RC model. The conduction mechanism for the electrical conductivity of the prepared polymers was found to be overlapping large polaron tunneling (OLPT). These polymers may be promising for applications such as electrochemical sensors with attractive features such as ease of synthesis, high sensitivity and fast response time.

Strontium-substituted La0.75Ba0.25−xSrxFeO3 (x = 0.05, 0.10 and 0.15) perovskite: dielectric and electrical studies

La0.75Ba0.25−xSrxFeO3 perovskite compounds with different strontium concentrations were synthesized via the sol–gel method. X-ray diffraction (XRD) data indicated that all obtained samples crystallize in the orthorhombic structure with the Pnma space group. The dielectric properties of these samples, using complex impedance spectroscopy technique have been carried out as function of frequency and temperature as well. An adequate electrical equivalent circuit has been used to evaluate the grain and grain boundary contributions in complex impedance results. Furthermore, the AC conductivity spectra obey to Jonscher’s universal power law. The behavior of the exponent “S” suggests that the conduction mechanism follows the overlapping large polaron tunneling (OLPT) process for x = 0.05, while for both compounds x = 0.10 and x = 0.15 the non-overlapping small polaron tunneling (NSPT) is the applicable model. The behavior of e″ as a function of both frequency and temperature has been described by Giuntini model.

Effect of titanium doping on conductivity, density of states and conduction mechanism in ZnO thin film

High quality, ~ 120 nm thin ZnO and Ti-doped ZnO (TZO) films were deposited on silicon substrates using magnetron co-sputtering technique. Surface roughness of the films was ~ 2 nm. Ti incorporation effect on the structure, morphology, conductivity, density of states (DOS) and conduction mechanism was investigated in detail. Ti ions were incorporated in the interstitial sites of hexagonal ZnO lattice. Average crystallite size increased from ~ 16.63 to ~ 19.08 nm upon Ti doping in ZnO film. Conduction mechanism changed from overlapping large polaron tunneling (OLPT) for undoped ZnO film to corelated barrier hopping (CBH) for TZO film. The experimental data were fitted theoretically using OLPT and CBH models to calculate frequency and temperature-dependent DOS. An enhancement of ac conductivity and DOS was observed with the doping of Ti in ZnO thin film. Complex modulus study of TZO film revealed transition from long-range mobility to short-range mobility with increase in frequency.

Electric and magnetic transport analysis of Na0.5Bi0.5TiO3 nanoparticles for temperature and magnetoimpedance sensor applications

Abstract Polycrystalline nano grain size Na0.5Bi0.5TiO3 (NBT) system is synthesized by using modified sol–gel method. X-ray diffraction (XRD), Transmission electron microscopy (TEM) studies and Field emission scanning electron microscopy (FESEM) are employed for structural and morphological confirmation. Electrochemical transport properties of this nano system have been investigated systematically in the range of temperature (30 °C−450 °C) and frequency (100 Hz−1 MHz) with the help of complex impedance spectroscopic technique. From impedance and modulus results, two (one at low and another at high temperature regime) positive temperature coefficient of resistance (PTCR) to negative temperature coefficient of resistance (NTCR) transitions are observed which is useful for electrochemical temperature sensor application. From electric transport analysis it found that due to small polaron hopping of charge carriers at NBT-NBT interfaces system shown PTCR nature. However, the system has shown both −ve magnetoresistance [MR (%)] and magnetocapacitance [MC (%)] at RT due to overlapping of large polaron tunnelling (OLPT) at NBT-NBT interfaces (which is explored with the help of magnetic transport analysis).

Optical and AC conductivity studies on Li2-xRbx MoO4 (x = 0, 0.5, 1) compounds

In this work, we are interested in the new compounds Li1.5Rb0.5MoO4 preparation by the solid state method. Also, we present a comparative study with LiRbMoO4 and Li2MoO4. The X-ray powder diffraction indicates that these compounds crystallize at room temperature in the monoclinic, orthorhombic and trigonal systems with the P21, Pcab and R-3 space groups, respectively. The shapes of the grains for these ceramics were observed by means of scanning electron microscopy (SEM) images. The Tauc model was used to determine the optical gap energy (4, 4.3 and 3.9 ev) and the urbach energies (1.51, 0.35 and 1.14 ev) of our compounds. The electric and dielectric proprieties of Li1.5Rb0.5MoO4 have been studied. We carried out complex impedance spectroscopy in the frequency range 200 Hz-5 MHz at different temperatures (575–723 K). The complex impedance diagram showed a single semicircle, implying that the response originates corresponding to the grains. As a result, an electrical equivalent circuit has been proposed. The spectra follow the Arrhenius law with two energies of activation 1.58 eV for impedance measurements and 1.25 eV for that of modulus. The alternative current (AC) electrical conduction of the three compounds is governed by the overlapping large polaron tunneling (OLPT).

An investigation of S–Se–Te semiconducting glassy alloys: Structural characterization and electrical conductivity

A sequence of chalcogenide glassy alloys, xS-(1-x) (0.5Te-0.5Se) for x = 0.1, 0.14, 0.24 and 0.34 have been prepared using well-established melt quenching method. The XRD patterns reveal the existence of crystallinity, superimposing over the amorphous glassy matrix. The effects of increasing values of mean crystallite size and optical band gap energy with composition cause electrical conductivity to reduce. The DC conductivities of the present system have been explored using Mott and Greaves's variable range hopping model. The values of temperature dependent small polaron hopping distance (Rhop) and hopping energy (Whop) are in agreement with the nature of DC conductivity. The anomaly of the sample for x = 0.14 may arise due to the lesser number of localized or defect states within the mobility gap and higher values of small polaron hopping distance and average hopping energy. The well-known Meyer-Neldel rule, Jonscher's Universal power-law and Almond-West formalism have been employed to investigate the AC conductivity spectra. The reducing nature of power-law exponent (s) with increasing temperature of the samples for x = 0.1 and 0.14 indicates that correlated barrier hopping (CBH) model is the best model for AC conduction mechanism. On the other hand, non-overlapping small polaron tunneling (NSPT) process is the suitable AC conduction mechanism of the samples for x = 0.24 and 0.34 due to the increasing nature of s with temperature. The conductivity scaling signifies temperature independency and composition dependency of electrical relaxation process.

Study of electrical and dielectric properties of palladium-phthalocyanine (PdPc) in pellet form

A pressed pellet of palladium phthalocyanine (PdPc) was characterized by impedance spectroscopy. The dielectric properties were investigated in a wide frequency (102–108 Hz) and temperature (300–440 K) ranges. The values of activation energy, the relaxation time, and the critical frequency were closed to each other, indicating that the same type of charge carriers is responsible for electrical conduction and relaxation phenomenon in the samples. According to the values of the frequency exponent s and the conductivity, the conduction mechanism was determined for both the as prepared and annealed films. The AC conductance obeyed Jonscher’s universal power law, and the conduction mechanism was interpreted by the overlapping large polaron tunneling (OLPT) process. Thus, a significant correlation was established between the temperature and activation energy. A metal semiconductor transition of this material was observed at 440 K. The obtained results demonstrate the potential of this material for photovoltaic applications.

The dielectric and electrical properties of bismuth oxide nanoparticles within organic network: the effect of temperature and the role of polarons

In this communication, we report the dielectric property of organic molecule functionalized bismuth oxide nanoparticles under different temperature and frequency condition. A large value of dielectric constant and a non-Debye type of relaxation phenomena has been witnessed due to the polaron induced polarization of the system. The frequency dependent electrical modulus of the material is discussed in the light of localized and non-localized relaxation process of the polaron. The AC-conductivity behaviour is modeled based on two different mechanisms, (a) polaron tunneling (at lower frequency) and (b) polaron hopping (at higher frequency). The organic-inorganic hybrid system also exhibited a unipolar resistive switching performance with a stable ON/OFF current ratio (∼102) when used as an active material for a suitable device under a DC-bias.