Wet Chemical Route Research Articles

Comparative Antimicrobial Activity of Silver Nanoparticles Obtained by Wet Chemical Reduction and Solvothermal Methods.

The synthesis of nanoparticles from noble metals has received high attention from researchers due to their unique properties and their wide range of applications. Silver nanoparticles (AgNPs), in particular, show a remarkable inhibitory effect against microorganisms and viruses. Various methods have been developed to obtain AgNPs, however the stability of such nanostructures over time is still challenging. Researchers attempt to obtain particular shapes and sizes in order to tailor AgNPs properties for specific areas, such as biochemistry, biology, agriculture, electronics, medicine, and industry. The aim of this study was to design AgNPs with improved antimicrobial characteristics and stability. Two different wet chemical routes were considered: synthesis being performed (i) reduction method at room temperatures and (ii) solvothermal method at high temperature. Here, we show that the antimicrobial properties of the obtained AgNPs, are influenced by their synthesis route, which impact on the size and shape of the structures. This work analyses and compares the antimicrobial properties of the obtained AgNPs, based on their structure, sizes and morphologies which are influenced, in turn, not only by the type or quantities of precursors used but also by the temperature of the reaction. Generally, AgNPs obtained by solvothermal, at raised temperature, registered better antimicrobial activity as compared to NPs obtained by reduction method at room temperature.

AlPO 4 film with rose surface structure: One‐step coating process, superhydrophilic and rapid super‐spreading

The construction of superhydrophilic surface structure usually requires auxiliary means with the aid of equipment or templates, and so on, which leads to the disadvantages of complicated production processes and high production costs. Here, we report a simple and rapid sol-gel process to prepare large-area, rose-like AlPO4 arrays through precise control of the low-temperature self-assembly process. The innovative application of AlPO4 array membrane to the superhydrophilic field, achieves a contact angle of less than 5° with 4 μL of water in 10 ms. The prepared AlPO4 superhydrophilic coated glass has good visible light transmittance, good wear resistance and durability. In addition, the morphology and size of AlPO4 array depend on the low temperature process and the composition of the sol, which can be adjusted by controlling the process. The study of this wet chemical route will provide useful information for the design and preparation of biomimetic micro-nano structures.

Recent advances in the tuning of the organic framework materials – The selections of ligands, reaction conditions, and post-synthesis approaches

Organic framework materials, particularly metal-organic frameworks (MOFs), graphene-organic frameworks (GOFs), and covalent organic frameworks (COFs), have led to the revolution across fields including catalysts, sensors, gas capture, and biology mainly owing to their ultra-high surface area-to-volume ratio, on-demand tunable crystal structures, and unique surface properties. While the wet chemistry routes have been the predominant synthesis approach, the crystal phase, morphological parameters, and physicochemical properties of organic framework materials are largely affected by various synthesis parameters and precursors. In this work, we specifically review the influences of synthesis parameters towards crystal structures and chemical compositions of organic framework materials, including selected ligand types and lengths, reaction temperature/solvent/reactant compositions, as well as post-synthesis modification approaches. More importantly, the subsequent impacts on the general electronic, mechanical, surface chemical, and thermal properties as well as the consequent variation in performances towards catalytic, desalination, gas sensing, and gas storage applications are critically discussed. Finally, the current challenges and prospects of organic framework materials are provided.

A novel method for the formation of bioceramic nano-calcium hydroxyapatite coatings using sol-gel and dissolution-precipitation processing

The wet chemistry route has been developed to prepare calcium hydroxyapatite (Ca10(PO4)6(OH)2, (HA)) thin films on a silicon substrate using the novel low-temperature sol-gel and dissolution-precipitation approach. The calcium carbonate thin films on the silicon substrate were obtained by spin-coating technique when substrates were repeatedly coated with 10, 20 and 30 layers of sol-gel solution. The composites formed of crystalline and amorphous CaCO3 were obtained by calcination of the coatings for different time at 600°C. A dissolution-precipitation procedure was used for the preparation of calcium hydroxyapatite thin films on silicon substrate at 80°C. The obtained synthesis products were characterised by X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM) and Raman spectroscopy.

Impact of ruthenium metallic particles on the dissolution of UO2 in nitric acid

UO2 pellets incorporating 3 mol.% of Ru was prepared by using a wet chemistry route and then characterised. The speciation, morphology, as well as spatial distribution of Ru in the sintered samples, were determined. The synthesised samples were submitted to dissolution tests in 0.1 M nitric acid at 60 °C and the dissolution of pure UO2 pellets was also studied with and without the presence of Ru metallic particles in the solution. The evolution of the U, Ru, and nitrous acid concentrations in solution was measured and the residues of dissolution were further characterised. The obtained results unambiguously demonstrated the catalytic activity of Ru-metal particles during UO2 dissolution in nitric acid provided that a solid/solid interface existed between UO2 and Ru-metal particles. This positive impact on the dissolution kinetics of UO2 was supported by redox reactions taking place at both nitric acid solution/Ru-metal particles and at Ru-metal particles/UO2 interfaces.

Hollow CoNiS polyhedrons/MnCoNi layered double hydroxide nanorod arrays on nickel foam as integral electrodes for improved oxygen evolution reaction in alkaline media

AbstractThe oxygen evolution reaction (OER) with sluggish kinetics in electron transportation has been the key process to develop water splitting technology for the hydrogen production. Here, we successfully prepared hollow CoNiS polyhedrons/MnCoNi layered double hydroxide (MCN LDH) nanorod arrays on Ni foam (labeled as CNS/MCN LDH/NF) through a two‐step wet chemical route, employing NF‐supported MCN LDH nanoneedle arrays as the substrate. ZIF‐67 polyhedrons first loaded on MCN LDH to form ZIF‐67/MCN LDH/NF, and then ZIF‐67/MCN LDH/NF was sulfurized to obtain the final product. The investigations revealed that MCN LDH could not be sulfurized under the current sulfurization conditions and simultaneously nickel element entered the sulfurized product to form hollow CoNiS polyhedrons. Electrochemical tests showed that the as‐obtained CNS/MCN LDH/NF electrode merely required 259 mV of overpotential in 1.0 M KOH solution to deliver the current density of 50 mA cm−2, which was lower than 372 mV of the hollow Co9S8polyhedrons/NF electrode. Furthermore, the as‐constructed CNS/MCN LDH/NF electrode could continuously and stably work at the current density of 100 mA cm−2for 110 h, indicating its superb long‐term stability.

Impact of Nd3+ and Ni2+ dopants on the structural, electrical and dielectric behaviour of PbZrO3 nanocrystalline material

Pb1−4.75x Nd0.5x Ni4x ZrO3 (where x = 0.00, 0.01, 0.02, 0.03, 0.04 and 0.05) nanocrystals were synthesized through the micro-emulsion, a wet chemical route. The prepared samples were annealed at 700°C for 3 h. Nanocrystalline samples were characterized by various techniques like XRD (X-rays diffraction), FTIR (Fourier transform infrared spectroscopy), SEM (Scanning electron microscopy), dielectric properties, and dc-electrical resistivity. XRD analysis of synthesized nanocrystals confirmed the phase development of orthorhombic perovskite structure. The average measured size of nanocrystals was about 21 nm. Some other parameters like densities (bulk and X-rays) and porosity of the nanomaterials were also calculated from obtained XRD data. The obtained results showed the effect of dopant materials (Nd3+ and Ni2+ metal ions) incorporation. The FTIR spectra elucidated the intrinsic cations vibrations in the characteristic perovskite orthorhombic structure. The SEM results revealed that nano-grains were synthesized successfully and their average observed size was 60 nm. It was observed that with the addition of dopant material, the dielectric parameters like dielectric constant, loss factor, and conductivity were showed an overall decreasing trend. The average calculated value of the ac conductivity at the frequency of 3 GHz was observed as 1.45 × 10−2 (Ω-cm)−1. By using the current–voltage (I–V) characteristics, the dc-electrical resistivity was calculated in the range between 2.68 × 1010 and 4.82 × 1010 Ω-cm. The dc-electrical resistivity was increased with the increase of doping contents.

Cuprous Oxide Nanoparticles: Synthesis, Characterization, and Their Application for Enhancing the Humidity-Sensing Properties of Poly(dioctylfluorene).

In this paper, we report on the synthesis—via the wet chemical precipitation route method—and thin film characteristics of inorganic semiconductor, cuprous oxide (Cu2O) nanoparticles, for their potential application in enhancing the humidity-sensing properties of semiconducting polymer poly(9,9-dioctylfluorene) (F8). For morphological analysis of the synthesized Cu2O nanoparticles, transmission electron microscope (TEM) and scanning electron microscope (SEM) micrographs are studied to investigate the texture, distribution, shape, and sizes of Cu2O crystallites. The TEM image of the Cu2O nanoparticles exhibits somewhat non-uniform distribution with almost uniform shape and size having an average particle size of ≈24 ± 2 nm. Fourier transformed infrared (FTIR) and X-ray diffraction (XRD) spectra are studied to validate the formation of Cu2O nanoparticles. Additionally, atomic force microscopy (AFM) is performed to analyze the surface morphology of polymer-inorganic (F8-Cu2O) nanocomposites thin film to see the grain sizes, mosaics, and average surface roughness. In order to study the enhancement in sensing properties of F8, a hybrid organic–inorganic (F8-Cu2O) surface-type humidity sensor Ag/F8-Cu2O/Ag is fabricated by employing F8 polymer as an active matrix layer and Cu2O nanoparticles as a dopant. The Ag/F8-Cu2O/Ag device is prepared by spin coating a 10:1 wt% solution of F8-Cu2O nanocomposite on pre-patterned silver (Ag) electrodes on glass. The inter-electrode gap (≈5 μm) between Ag is developed by photolithography. To study humidity sensing, the Ag/F8-Cu2O/Ag device is characterized by measuring its capacitance (C) as a function of relative humidity (%RH) at two different frequencies (120 Hz and 1 kHz). The device exhibits a broad humidity sensing range (27–86%RH) with shorter response time and recovery time, i.e., 9 s and 8 s, respectively. The present results show significant enhancement in the humidity-sensing properties as compared to our previously reported results of Ag/F8/Ag sensor wherein the humidity sensing range was 45–78%RH with 15 s and 7 s response and recovery times, respectively. The improvement in the humidity-sensing properties is attributed to the potential use of Cu2O nanoparticles, which change the hydrophobicity, surface to volume ratio of Cu2O nanoparticles, as well as modification in electron polarizability and polarity of the F8 matrix layer.

Electroanalytical investigation of quantum-dot based deposition of metal chalcogenides on g-C3N4 for improved photochemical performance

ZnS passivation layer is deemed as a superior passivation layer; however, compositing it with another metal chalcogenide material may assists to control the innate high charge recombination in graphitic carbon nitride (g-C3N4) 2D material. In this work, we deposited ZnS and In2S3 quantum dots (QDs) on g-C3N4 separately and together in mutable way, so that the detrimental charge carrier is reduced and the optimal combination of g-C3N4 (ZnS/In2S3 or In2S3/ZnS) is realized via simplistic wet-chemical route. Among all the prepared samples, g-C3N4/ZnS/In2S3 (Eg = 2.67 eV) showed superior photocatalytic performance by degrading 93.98% RhB dye, indicating better control on charge carrier recombination in g-C3N4 as revealed by spectroscopic techniques utilizing photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). Whereas, pristine g-C3N4 degraded the dye by 38.97% and the degradation percentage got increased a little bit by deposition of g-C3N4/ZnS and g-C3N4/In2S3 single passivation layers (SPLs) i.e., 47.06% and 64%, respectively. However in g-C3N4/In2S3/ZnS, double passivation layer DPL degraded 70.72% of the dye.

Upgraded charge transport in g-C3N4 nanosheets by boron doping and their heterojunction with 3D CdIn2S4 for efficient photodegradation of azo dye

The facilitation of charge transport toward the targeted chemical reaction is a challenging task for two-dimensional (2D) nanomaterials. We demonstrate the effectiveness of two different strategies, non-metal doping and heterojunction formation, to adjust the electronic and molecular structures of g-C3N4 nanosheets (CN), which could widen the visible-light response and improve the photo-induced electron–hole separation. The g-C3N4 nanosheets containing impurity levels (boron doping (BCN)) were prepared by a high-temperature solid-state reaction. Additionally, by anchoring the 3D dichalcogenide structures (CdIn2S4) elicited by a wet chemical route, hybrid BCN/CdIn2S4 nanostructures were obtained. The resulting BCN/CdIn2S4 (BCN–CIS3) nanostructures exhibited an excellent degradation efficiency (95%) for methyl orange (MO) compared to pristine g-C3N4 nanosheets (CN) (28%) and boron-doped g-C3N4 (BCN) (35%). All the optimized photocatalysts were thoroughly characterized using various techniques and investigated for comparative structural, optical, morphological, and catalytic properties. Our results reveal that introducing boron atoms into the lattice of g-C3N4 nanosheets leads to reduction in the band-gap energy and rapid electron transfer. The formation of heterojunctions with the 3D CdIn2S4 further assists in improving the degradation efficiency by minimizing the undesired electron–hole recombination, as confirmed by time-resolved photoluminescence (TRPL) analysis. This work proposes feasible strategies and their synergy to develop innovative materials for sustainable energy conversion and environmental remediation applications.

N-Methyl-2-pyrrolidone as a Reaction Medium for Gold(III)-Ion Reduction and Star-like Gold Nanostructure Formation.

The efficiency of a wet chemical route to synthesize gold nanostructures with tunable size and shape significantly depends on the applied solvent and the interaction of solvent molecules with other species such as gold ions. The ability of the organic solvent N-methyl-2-pyrrolidone (NMP) as a suitable medium for application in star-like gold nanostructure (AuNS) synthesis with a tunable morphology at ambient conditions has been investigated. The time-dependent analysis of the UV–vis absorption spectra of AuIIICl4– in a pure NMP solution illustrates the role of NMP as simultaneous complexing and reducing agents. Kinetic studies indicate that AuIIICl4– in NMP solution is reduced to AuICl2–, with no need to use another reducing agent, any external energy sources, or solvent pretreatment. This is because AuI species stay stable in this solution unless poly(vinylpyrrolidone) (PVP) catalyzes their disproportionation. Morphological studies by transmission electron microscopy (TEM) specify the high-yield synthesis of AuNS with monocrystalline spikes in a concentrated NMP solution by PVP. This study illustrates that the presence of seeds, as another agent to catalyze the disproportionation of AuI species, makes it possible to synthesize AuNS in varying concentrations of PVP in this medium. The role of PVP concentration and the presence of seeds in the formation kinetics, morphology, and optical properties is systematically discussed. The results achieved through this study develop a straightforward and safe procedure for AuNS synthesis in high yield in a water-miscible organic polar solvent with tunable morphology and optical properties. Considering the high capability of NMP to dissolve various types of polymers and hydrophobic ligands, synthesizing AuNS in this solvent opens a window to a practical and easy way to fabricate gold-based nanomaterials with fascinating optical properties.

Design of Experiment: A Rational and Still Unexplored Approach to Inorganic Materials’ Synthesis

This review was devoted to outlining the use and potential increasing application of the Design of Experiment (DoE) approach to the rational and planned synthesis of inorganic nanomaterials, with a particular focus on polycrystalline nanostructures (metal and alloys, oxides, chalcogenides, halogenides, etc.) produced by sustainable wet chemistry routes based on a multi-parameter experimental landscape. After having contextualised the stringent need for a rational approach to inorganic materials’ synthesis, a concise theoretical background on DoE is provided, focusing on its statistical basis, shortly describing the different sub-methodologies, and outlining the pros and cons of each. In the second part of the review, a wider section is dedicated to the application of DoE to the rational synthesis of different kinds of chemical systems, with a specific focus on inorganic materials.

Phase transformation, morphology, DC electrical resistivity and dielectric properties investigations of properties of manganese doped barium titanate nanoparticles

In this work, manganese (Mn) doped barium titanate BaTi1-xMnxO3 nanoparticles with varying composition of Mn (x = 0.0, 0.10 and 0.20) were prepared by using sol–gel self-ignition wet chemical route. The influence of Mn doping on crystal structure, infra-red, morphology, DC electrical resistivity and frequency dependent dielectric studies was systematically investigated. To know the crystalline nature and purity of the prepared samples, a non-destructive X-ray diffraction (XRD) tool was used. The analysis of XRD results revealed that pure BaTiO3 and BaTi1-xMnxO3 with x = 0.1, samples show tetragonal structure and for higher Mn content (x = 0.20) shows the hexagonal structure. The values of interplanar spacing, Miller indices, etc. were used to determine the unit cell parameters, X-ray density and unit cell volume. The highest intensity peak (110) observed in XRD pattern was considered to determine the crystalline size and which is found to be in the range of 3 to 8 nm. Scanning electron microscopy (SEM) technique was employed to study the surface morphology. SEM analysis confirm the dense nature of the grains with hexagonal shape for x = 0.2. EDX results confirm the presence of Ba, Ti, Mn and O elements as per the stoichiometric proportion. The functional groups and chemical bonds of Mn doped BaTiO3 were obtained by Fourier transform infrared spectroscopy (FTIR). The temperature dependant DC electrical resistivity studies were performed by standard two probe technique. The conductivity plot exhibits negative temperature coefficient (NTC). The activation energy and resistivity both decreased with Mn doping. The dielectric properties such as dielectric constant (ε′), dielectric loss (ε″) and dielectric loss tangent (tan δ) were studied by means of LCR-Q meter. The variation of these parameters as a function of frequency shows the exponential decrease. The dielectric constant and dielectric loss reduces, whereas dielectric loss tangent increase on Mn doping. The ac conductivity increases with frequency.

Effects of growth time on the material properties of CdTe/CdSe core/shell nanoparticles prepared by a facile wet chemical route

This study presents a facile synthetic approach used to prepare CdTe/CdSe core/shell nanoparticles (NPs). The effects of reaction time on the material properties of the CdTe/CdSe NPs are reported. It was realized that the reaction time has significant impact on the CdSe shell growth on the CdTe core. Various techniques were used to characterize the as-prepared CdTe/CdSe NPs. The x-ray diffraction (XRD) was used to study the crystal structure and the possible growth of the CdSe shell on the CdTe core. The results obtained indicated the formation of zinc blende crystal structure which was transformed from a polycrystalline to single crystalline structure. The XRD pattern displayed features that are intermediate between the CdTe and CdSe, a sign of shell formation and not two separate compounds formed. This was also supported by high resolution transmission electron microscope images obtained. The crystallite sizes estimated using Scherrer formula were all less than 3 nm showing that the NPs are in quantum confinement regime. Scanning electron microscope was used to determine the surface topography while the energy x-ray dispersive spectrometer displayed the elemental composition of the as-prepared NPs. SEM and HRTEM images showed uniformly distributed spherical NPs with some agglomerations observed at longer duration of synthesis. The optical properties (photoluminescence (PL) and absorbance) investigated at different reaction times (20, 40, 60 and 80 min) presented novel features which show the formation of a thin CdSe shell on the CdTe core NPs. The PL emission wavelength was dramatically red shifted upon the growth of the CdSe shell on the CdTe core (from 541–615 nm). Other unique features of the as-grown CdTe/CdSe NPs are discussed in detail. The obtained results displayed good material properties of the CdTe/CdSe NPs suitable for use in biomaging applications.

Electroreforming of Glucose/Xylose Mixtures On PdAu Based Nanocatalysts

AbstractThe electroreforming of glucose/xylose mixtures has been evaluated at Pd1‐xAux/C anodes in 0.10 mol L−1 NaOH electrolyte. The catalysts synthesized by a wet chemistry route are comprehensively characterized by physicochemical and electrochemical techniques. From linear scan voltammetry and in situ Fourier transform infrared spectroscopy measurements, it was shown that the Pd0.3Au0.7/C material led to the best electrocatalytic behavior towards the electrooxidation of glucose/xylose mixtures in terms of activity (higher current densities at lower potentials) and selectivity (lower dissociative adsorption). Six‐hour chronoamperometry measurements were performed at 293 K in a 25 cm2 electrolysis cell at +0.4 V and +0.6 V and the reaction products were analyzed by high performance liquid chromatography. The main products were gluconate and xylonate, but the contributions of xylose to all formed products was always lower in percentages than the initial xylose ratios in solutions, showing that glucose was more electro‐reactive than xylose at Pd0.3Au0.7 surface.

Silk fibroin induced homeotropic alignment of perovskite crystals toward high efficiency and stability

The photoactive lead halide perovskites with a highly crystalline structure and low trap state density were regarded as the prerequisites for achieving high photovoltaic performance. The perovskite thin films were typically synthesized by simple wet chemistry routes, where the fluctuations in the fabrication readily generate lattice defects and induce stacking faults during the crystal growth. The growth of highly crystalline and low-defect perovskite usually needs complicated synthetical manipulation and well-designed additive engineering. Here in this work, we reported a naturally available protein, silk fibroin (SF), whereby the highly ordered β-sheets component can adequately interact with perovskite intermediates and work as the crystal growth template and trap passivation agent, which induced facile self-assembly of the perovskite crystals with homeotropic alignment structure and low defect concentrations. As a result, the SF incorporated perovskite layer exhibited a much-improved conversion efficiency with charge carrier mobility 1000 times higher than that of pristine film, as well as showed robust stability under various harsh conditions.

Understanding Alkali Contamination in Colloidal Nanomaterials to Unlock Grain Boundary Impurity Engineering.

Metal nanogels combine a large surface area, a high structural stability, and a high catalytic activity toward a variety of chemical reactions. Their performance is underpinned by the atomic-level distribution of their constituents, yet analyzing their subnanoscale structure and composition to guide property optimization remains extremely challenging. Here, we synthesized Pd nanogels using a conventional wet chemistry route, and a near-atomic-scale analysis reveals that impurities from the reactants (Na and K) are integrated into the grain boundaries of the poly crystalline gel, typically loci of high catalytic activity. We demonstrate that the level of impurities is controlled by the reaction condition. Based on ab initio calculations, we provide a detailed mechanism to explain how surface-bound impurities become trapped at grain boundaries that form as the particles coalesce during synthesis, possibly facilitating their decohesion. If controlled, impurity integration into grain boundaries may offer opportunities for designing new nanogels.

Structural and photoluminescence studies of Gd2O3 doped with Ln3+ (Ln = Eu/Tb) and sensitised with Li+/Bi3+

A facile direct precipitation method was used for the synthesis of Gd2O3 based luminescence nanoparticles. Eu3+ and Tb3+ doped nanoparticles co-doped with Li+/Bi3+ were prepared by wet chemical route at a relatively low temperature of 120 °C followed by annealing at 500 and 900 °C for 2 h. A series of red and green colour emitting phosphors have been developed. The syntrhesised nanoparticles are studied using various characterisation techniques like X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM) and Photoluminescence (PL) spectroscopy. These characterisation provides the insight of structural and optical properties of the material. Both Eu3+ and Tb3+ doped samples exhibit strong emission on UV light excitation. The role of sensitisers like Li+/Bi3+ are studied in detail. The synthesized nanoparticles Gd2O3:Ln3+ (Ln = Eu/Tb) and Gd2O3:Ln3+ co-doped with Li+/Bi3+ nanoparticles can be used in many fluorescent materials, luminescence, and electroluminescent devices.

Exsolution in La and Ni co-doped strontium titanate: a suitable anode for running SOFCs on ammonia as alternative fuel

Ammonia exhibits interesting features as fuel to feed Solid Oxide Fuel Cell. Herein, Ni and La co-doped strontium titanate was synthetized using wet chemistry route. Ni nanoparticles emerged via exsolution in reducing environment to decorate the surface. X-Ray Diffraction measurements exhibits perovskite structure was also preserved after the exsolution, as expected. H2 – Temperature Programmed Reduction highlights the great resistance of titanates in anode operation condition. Ammonia conversion in nitrogen and hydrogen were investigated by catalytic tests. It begins to decompose at 560°C and the full yield was achieved at 720°C. Electrochemical measurements were recorded at 800°C using 10% of ammonia in Ar. They were analysed though the model of equivalent circuit and two processes were attributed. Results certify Ni exsolution strongly enhances the hydrogen oxidation and the total polarisation resistance in ammonia approaches to the one in hydrogen.

The electrical behaviour of ultrafine bismuth phosphate particles under a range of temperature and frequency conditions.

Organic-molecule-stabilized ultrafine bismuth phosphate was synthesized by applying a wet chemical complexation-mediated route. Structural analysis confirmed the formation of monoclinic-phase nanoparticles made up of four-coordinated PO4 tetrahedral and eight-coordinated BiO8 polyhedral units. The dielectric, electrical conductivity, and impedance behaviour of the synthesized material was investigated under a wide range of frequency and temperature conditions. An alternating current conductivity study confirmed that the conduction process was followed by small and large polaron tunnelling mechanisms. An electric field-induced polarization study showed the formation of a hysteresis loop, generated as a result of the strong dipolar interactions through the Biδ+-Oδ--type covalent bonds.