Slope Of Ln Research Articles

Transport and Kinetic Property of the Butyric Acid in Water: A Simulation Study

Microbiota is defined as a class of all microorganisms which includes fungi, protozoa, bacteria and viruses. About 90 % of all microbiota in our body are found in our gut that regulates host immunity. The gut-brain axis is a bidirectional communication system that allows gut microbiota to communicate with the brain and vice versa. Studies suggest that the gut dysbiosis may enhance neurotoxic substances such as short-chain fatty-acids (SCFAs which are acetate, propionate, and butyrate) to the blood circulation and even to the brain through damaged blood brain barrier (BBB) and may cause protein aggregation which are implicated in the pathogenesis of several neurodegenerative diseases like Alzheimer’s disease (AD), Parkinson’s disease (PD), prion disease, motor neuron disease, Huntington’s disease (HD), Amyotrophic lateral sclerosis (ALS). Specifically, butyric acid are the main SCFA product that may impact on gut health. Therefore, this article aims to investigate the transport and kinetic properties such as diffusion coefficient, activation energy and radial distribution function of butyric acid in water at different temperatures through molecular dynamics simulations. The self and binary diffusion coefficient of butyric acid in water obtained from our MD simulation are found to be 0.8699×10−9m2s−1 and 0.8714×10−9m2s−1, respectively at 300 K and the activation energy for self-diffusion coefficient of water estimated from the slope of ln(D) versus 1/T is equal to 16.07 kJ/mol. Our results are in accordance with those obtained from the experimental values. This study offers an alternate approach to researching the diffusion of butyric acid in living organisms. This knowledge contributes to advancements in various fields, including nutrition, gastroenterology, microbiology, and pharmacology.

Structural and Electrical Studies of Polycrystalline Pr𝑥Y1−𝑥FeO3 Materials Prepared Through Sol-Gel Route

Objectives: Investigations on structural, morphological and electrical studies of Pr substituted YFeO3 samples synthesized through sol-gel route are presented in this paper. Methods: PrxY1-xFeO3 (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) samples are synthesized by sol-gel auto combustion method. Structural characterization of the samples is done by using X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM) and Energy dispersive X-ray (EDX) techniques. Electrical properties are studied by J-E and Ln J-Ln E measurements. Findings: Rietveld refined XRD structural analysis shows sharp intense peaks indicating the crystalline nature of the samples and all the samples possess distorted orthorhombic structure with space group Pbnm. FESEM analysis shows non-uniform nature of grain size with increasing porosity. EDX data confirms elemental composition, weight and atomic percentage of the prepared samples which further confirms their purity. The leakage current density increases with increase in Pr doping. The slopes of Ln J-Ln E graphs of all the samples are in the range of 1.11 to 1.51 confirming that Ohmic conduction is predominant conduction mechanism. Novelty: Investigations on the effect of Pr substitution on electrical properties of single phase YFeO3­ samples reveal that the substitution of Pr in YFeO3 decreases the ferroelectric nature of the samples. Keywords: Sol-gel method, XRD, FESEM, EDX, Electrical Properties

Determination of Activation Energy for Static Recrystallization in Al-Mg-Si Alloys with Different Zr Contents

In this study, activation energies required for the static recrystallization behavior during the annealing process after cold deformation of Al-Mg-Si alloy to which zirconium was added in various proportions were investigated. Depending on the zirconium content, the activation energies of the alloys were found and compared both experimentally and by calculation. For this purpose, alloys containing 0.1, 0.2 and 0.3 wt-% Zr were cold rolled after taking into solution and quenching. And then, the alloys were annealed at 375 °C and 500 °C for different annealing times. After the alloys were prepared metallographically, their grain structures were examined microscopically. Depending on the temperature, recrystallization-% was found by image analysis and experimental recrystallization-% curves were drawn. The time taken for recrystallization-50% to experimentally find the activation energy required for recrystallization to occur was found from the curves. These values were replaced in the relevant formulations and the required activation energy was experimentally found from the slope of the Arrhenius equation and the ln t50% and 1/T graph. In order to find the recrystallization-% by calculation, the nucleation rate and growth rate of the new recrystallized grains were found by image analysis. By substituting these values in Johnson-Mehl-Avrami equation, the calculated recrystallization-% curves of the alloys were found. From here, using the relevant equations, Arrhenius equation was passed and the activation energy was calculated from the slope of ln k and 1/T graph. The results showed that the activation energy increased with the increase of the zirconium ratio, and even the most effective zirconium ratio was between 0.1-0.2% by weight in increasing the activation energy. Therefore, this ratio should be considered in processes where recrystallization, which also affects other properties of the alloy, is not desired.

Geotechnical and thermal analysis and complex impedance spectroscopy characterization of pure Moroccan bentonite material for civil engineering applications

Combined modulus and impedance spectra are employed in the present work to explore electrical inhomogeneity and carriers’ behaviors in a pure bentonite Moroccan clay based on equivalent circuit. It has been clearly observed that the electrical properties change due to the increase of temperature from 300 °C to 700 °C. The frequency-dependent imaginary modulus M" and imaginary impedance Z" curves has only one peak at each temperature indicating the predominance of the contribution of grains to the total electrical conduction in bentonite. The positions of these peaks move to higher frequencies when the temperature increases in relation with the distribution of relaxation time. Moreover, the activation energy for the conduction process in bentonite is determined from the slope of ln(ρdc) versus of 1/T in the order of 700 meV in good agreement with that obtained from the proposed equivalent circuit. On the other hand, let’s present a geotechnical study that show that our material is a swelling clay, very plastic and could be used as a binder. The external stress dependence of the bulk density, Young’s module and maximum stress are analysed. The thermal conductivity determined following the device of Lee's disks where two copper disks of thickness of 15 mm and diameter of 30 mm were used

Effects of hydrogen implantation on the magnetocaloric properties of amorphous FeZr films

We report on the effects of H-implantation on the magnetic and magnetocaloric properties of amorphous FeZr films. Arrott plots reveal a second order ferromagnetic to paramagnetic phase transition for the as-grown and H-implanted films, with an increase in TC from 160 to 200 K upon implantation. The maximum change in magnetic entropy (-ΔSM) increases from 0.66 to 0.77J/kgK for a field change μ0ΔH = 1.5T, as well as the relative cooling power (RCP) values were improved from 84.5 to 108.6J/kg. This improvement was attributed to the increase in magnetization and chemical inhomogeneity induced by the implantation process. The increase in the chemical inhomogeneity was supported by the determination of the local exponent n extracted from the slope of Ln(−ΔSM) as a function of Ln(μ0H), which is line with the simulated depth profile of hydrogen atoms through the FeZr film.

Transport Properties of CaSi<sub>2</sub> and Ca<sub>2</sub>Si Thin Films

Resistivity, r (T), and Hall coefficient in weak (B < 1 T) magnetic fields, R (T), are investigated in Ca2Si and CaSi2 films at temperatures T between ~ 20 - 300 K. In CaSi2, r (T) is typical of metals increasing with T within the whole temperature range. On the other hand, the resistivity of Ca2Si is pertinent of semiconductors. Namely, it is activated below T ~ 200 K, exhibiting different slopes of ln r vs. T -1 plots at lower and higher T, and a weak increase between T ~ 200 - 300 K. Both materials demonstrate a complex dependence of R (T), including a change of the sign. Transport properties above have been analyzed assuming two groups of charge carriers, electrons and holes, contributing them.

Rapid Laser Reactive Sintering Synthesis of Colossal Dielectric CCTO Ceramics

Calcium copper titanate (CCTO) ceramics were successfully synthesized using a rapid laser reactive sintering method without conventional long heat treatment times. The microstructure, dielectric properties, and impedance spectroscopy results for CCTO sintered at laser power rates of 25–85 W were investigated in detail. The X-ray diffractometry results showed that prepared CCTO is polycrystalline in a cubic structure with high purity. Scanning electron microscopy showed that CCTO sintered at 85 W has a dense microstructure with an average grain size of 30 nm. The dielectric permittivity of CCTO ceramics increased with increasing laser power over the entire frequency range and achieved a value of almost 105 in the low-frequency region. The dielectric permittivity maintained almost constant values from 102 Hz to 107 Hz, with lower dielectric loss (~0.1) from 103 Hz to 106 Hz, demonstrating good frequency stability. The impedance spectroscopy study showed that grain and grain boundary resistance decreased with rising laser power based on two parallel Resistor-Capacitance (RC) equivalent circuits in series. The activation energies for the grain boundaries were calculated from the impedance using the slope of ln σ versus 1/T and were found to be in the range of 0.53–0.63 eV. CCTO synthesized by rapid laser reactive sintering is competitive for practical applications.

A detailed comparative study on electrical and photovoltaic characteristics of Al/p-Si photodiodes with coumarin-doped PVA interfacial layer: the effect of doping concentration

In this study, three different poly(vinyl alcohol) (PVA) films doped with weight percentages of 0.05, 0.10 and 0.20 coumarin were coated on p-Si wafer via spin-coating method for the purpose of investigating the interaction of coumarin dopant with polymer host at molecular level. Therefore, metal–polymer–semiconductor (MPS) structures were formed and their current–voltage (I–V) and admittance measurements were taken to compare the main electrical parameters of the MPS structures with different film thicknesses. The values of ideality factor (n), barrier height (Φb), rectification ratio (RR = IF/IR), series resistance (Rs) and energy-dependent profiles of surface states (Nss) were calculated using the forward bias I–V data. There exists increasing trend for Nss values from mid-gap energy of Si toward the bottom of conductance band. The highest values of RR and photosensitivity (Iphoto/Idark) were found as 4.62 × 104 at ± 4 V for the MPS structure with 0.10 wt% coumarin doping level, respectively. The photoresponse of the structures was also analyzed using $$I_{\text{ph}} = AP^{m}$$ relation, and the value of m was obtained from the slope of ln(Iph)–Ln(P) plot for each diode as 1.48, 1.27 and 1.57, respectively. Experimental results suggest that 0.10% coumarin-doped PVA caused MPS structure to reveal better performance considering higher RR and lowest Nss, and so it can be considered as an alternative interfacial layer material for replacing traditional insulators.

Orbital Control of Long-Range Transport in Conjugated and Metal-Centered Molecular Electronic Junctions

Large area molecular junctions consisting of covalently bonded molecular layers between conducting carbon electrodes were compared for Co and Ru complexes as well as nitroazobenzene and anthraquinone to investigate the effect of molecular structures and orbital energies on electronic behavior. A wide range of molecular layer thickness (d) from 1.5–28 nm was examined and three distinct transport regimes in attenuation plots of current density (J) vs thickness were revealed. For d 12 nm, transport depends on the electric field rather than bias, with the slope of ln J vs d near-zero when plotted at a constant electric field. At low temperature (T < 150 K), transport is nearly activationless and likely occurs by sequential tunneling and/or field-induced i...

Identified Of Indicator And Material For Product Shelf Life Recorder Smart Label

Shelf life is an important factor in determining the quality and safety of food for consumption. Refrigerator becomes an alternative in extending product shelf life. Shelf life is difficult to be identified if the product stored for too long. Smart label of Time Temperature Indicators (TTI) can record the product shelf life based on its storage time. In this research, identification of indicator and material for smart label development based on liquid diffusion in material was conducted. This study used several types of materials (Buffalo paper, HVS 80 gr, photo paper, concord, drawing paper and cardboard duplex), low viscosity indicators (board-marker ink, stamp, tubs, permanent tattoo and non-permanent tattoos) and high viscosity indicators (cooking oil, lubricant A and lubricant B). The initial phase was characterizations such as grammage, density, mass density and viscosity test aimed to determine the properties of indicators and materials. Identification was implemented by measuring the diffusion length of indicator in the material at 24, 48, 72 and 96 h in temperature of 30.15°C and 50°C for cooking oil, while 30.15°C and 5°C for oil A and B. The slope of diffusion length versus time is called by rate constant (k), where as the slope of ln k versus 1/T is called by activation energy (Ea). Best indicator and the material were selected based on their high value of Ea. Result showed that the ink was not be absorbed during storage due to its high volatility and low viscosity, while cooking oil, lubricant A and lubricant B have specific diffusion length during storage. These indicators and mediums were able to detect up to 4 days of shelf life during storage. Based on activation energy, the most suitable indicator for smart label was lubricant A. The best materials for this label development sequentially from low-to-high activation energy were Buffalo paper, duplex cartons, drawing paper, concord, HVS 80 g and photo paper

Homoleptic Trivalent Tris(alkyl) Rare Earth Compounds.

Homoleptic tris(alkyl) rare earth complexes Ln{C(SiHMe2)3}3 (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnI3THFn and 3 equiv of KC(SiHMe2)3. X-ray diffraction studies reveal 1a-d are isostructural, pseudo-C3-symmetric molecules that contain two secondary Ln↼HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with Ln{C(SiDMe2)3}3 and DFT calculations. The Ln↼HSi and terminal SiH exchange rapidly on the NMR time scale at room temperature, but the two motifs are resolved at low temperature. Variable-temperature NMR studies provide activation parameters for the exchange process in 1a (ΔH⧧ = 8.2(4) kcal·mol-1; ΔS⧧ = -1(2) cal·mol-1K-1) and 1a-d9 (ΔH⧧ = 7.7(3) kcal·mol-1; ΔS⧧ = -4(2) cal·mol-1K-1). Comparisons of lineshapes, rate constants (kH/kD), and slopes of ln(k/T) vs 1/T plots for 1a and 1a-d9 reveal that an inverse isotope effect dominates at low temperature. DFT calculations identify four low-energy intermediates containing five β-Si-H⇀Ln and one γ-C-H⇀Ln. The calculations also suggest the pathway for Ln↼HSi/SiH exchange involves rotation of a single C(SiHMe2)3 ligand that is coordinated to the Ln center through the Ln-C bond and one secondary interaction. These robust organometallic compounds persist in solution and in the solid state up to 80 °C, providing potential for their use in a range of synthetic applications. For example, reactions of Ln{C(SiHMe2)3}3 and ancillary proligands, such as bis-1,1-(4,4-dimethyl-2-oxazolinyl)ethane (HMeC(OxMe2)2) give {MeC(OxMe2)2}Ln{C(SiHMe2)3}2, and reactions with disilazanes provide solvent-free lanthanoid tris(disilazides).

Design and Development of an Embedded System for the Measurement of Boltzmann’s Constant

Objectives: In this paper we present the design and development of an embedded system for the measurement of Boltzmann’s constant using Texas Instruments’ microcontroller: MSP430G2553. Methods/ Statistical Analysis: A transistor connected in common-base configuration with collector and base maintained at the same voltage (known as diode connected transistor or Transdiode) is used as the Device Under Test (DUT). The base-emitter voltage (VBE) is varied by a stepper motorized potentiometer whose rotation is controlled by microcontroller. The collector current (IC) is measured by converting it into voltage (V) by I-to-V converter using operational amplifier. The temperature of the bath where DUT is placed is measured using LM35 temperature sensor. The base-emitter voltage VBE, collector current IC and temperature in Kelvin T are measured using MSP430G2553 microcontroller. The data is captured using terminal software PuTTY. These files are imported to the scientific graph plotting software Origin. The graphs are drawn between natural log values of IC versus VBE at ambient temperature. To perform the measurement at different temperatures a heater system with constant current source is designed and constructed in the laboratory. Findings: From the slope of ln(IC) versus VBE graph Boltzmann’s constant is calculated. The values of Boltzmann’s constant at different temperatures are averaged and compared with standard CODATA (2014) value and percentage of error is determined. Application/Improvement: Microcontroller based embedded system for the measurement of Boltzmann’s constant is rarely seen in literature. In the present work, a fully automatic electronic circuit for the estimation of Boltzmann’s constant is designed and developed. The system is built around Texas Instruments’ MSP430G2553 microcontroller and cost-effective, off-the-shelf components are used in the circuit construction.

Abnormal Temperature Dependence of Mobility in a Disordered System With Traps: Experiment and Theory

Mobility μ is essential in electronic and optoelectronic devices. Abnormal temperature T dependence of the carrier mobility μ of poly [2-methoxy-5-2-ethyl-hexyloxy]-p-phenylenevinylene (MEH-PPV)/InP nanocrystal composites was observed using the time-of-flight technique. The slope of ln(μ) as a function of 1/T <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> dramatically changed before and after the critical temperature T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> of 283 K. Using the variable range hopping theoretical mode, a new trap-filling factor (FF) was proposed as a key parameter to illustrate the effect of the trap on the mobility. According to FF, there are three regions. When FF ≫ 1 and FF≪1, the carrier behavior follows the Fermi and Boltzmann distributions, respectively. When FF~1, the derived transition temperature of 282.4 K represents a transition point from Fermi to Boltzmann distribution, which is consistent with T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> in the experiment. Finally, a universal dependence of ln(μ) on T was concluded based on FF in a disordered system with traps.

Erratum to: Anisotropic Diffusion Behavior of Al in Mg: Diffusion Couple Study Using Mg Single Crystal

IN the calculation of the interdiffusion coefficients of two intermediate phases and the impurity diffusion coefficients ofAl in hcpMg, a small numerical errorwas found. The error does not change the main conclusions of the work but can lead to small errors in the diffusion calculations. The following is a revision of the interdiffusion coefficients and impurity diffusion coefficient. The numbering of figures, tables and references used in this erratum are the same as the original paper for convenience. Interdiffusion coefficients for two intermediate phases (Mg17Al12 and Mg2Al3) were calculated using the Heuman-Matano method by identifying the Matano plane from Al concentration profile throughout the whole diffusion zone quantified by Electron Probe Micro Analyzer (EPMA). For example, the position of the Matano plane for the sample annealed after 72 hours at 693 K (420 C) is marked in Figure 1. The revised interdiffusion coefficients for the Mg17Al12 and Mg2Al3 intermediate phases are presented in Table III and in Figure 4 with comparison to previous studies. Our results are in good agreement with Brennan et al. The revised values for the Al impurity diffusion coefficient in hcp Mg from the multiphase diffusion calculation used in the original paper are plotted in Figure 7(a). In order to confirm the impurity diffusion, a Gaussian solution of Fick’s second law is also applied to analytically calculate impurity diffusion coefficient in this erratum. In the analytical method, the impurity diffusion coefficient for each sample was calculated from the slope of ln (Al concentration) vs square of penetration distance in dilute Al concentration region of hcp Mg solid solution. As can be seen in Figure 7(a), the analytical results are in good agreement with the results obtained from multiphase diffusion simulation. The revised Al impurity diffusion coefficients, depending on the orientation of hcp Mg, were plotted in Figure 7(b) and compared with previous studies. The revised optimized mobilities of Al in hcp Mg along the aand c-axis of Mg crystal are

A facile synthesis of silver nanoparticle with SERS and antimicrobial activity using Bacillus subtilis exopolysaccharides

In this study, we report a facile synthesis of silver nanoparticle having SERS and antimicrobial activity using bacterial exopolysaccharide (EPS). Bacillus subtilis (MTCC 2422) was grown in nutrient broth and the extracellular EPS secreted by the organism was extracted and purified. The purified EPS was used for the synthesis of silver nanoparticles. The kinetics of silver nanoparticle synthesis was deduced by varying the exposure time and the concentration of EPS. The rate constant (k) for the synthesis of silver nanoparticle was calculated from the slope of ln(A∞ − At) versus time plot. The k value was found to be 3.49 × 10−3, 5.81 × 10−3 and 5.03 × 10−3 per min for particle synthesis using 2, 5 and 10 mg/mL EPS, respectively. The nanoparticles synthesised had an average particle size of 5.18 ± 1.49 nm, 1.96 ± 0.77 nm and 2.08 ± 0.88 nm for 2, 5 and 10 mg/mL EPS, respectively. The synthesised particles were characterised using UV-Vis absorbance spectroscopy, high-resolution transmission electron microscopy (HRTEM) attached to EDS (energy dispersive spectroscopy), Fourier transform infrared spectroscopy (FTIR), surface enhanced Raman spectroscopy (SERS) and zeta potential analyser. To our knowledge, this is the first study to report SERS activity of microbial Bacillus subtilis EPS-based synthesis of silver nanoparticle. HRTEM images showed silver nanoparticle entrapped in polysaccharide nanocages. Silver nanoparticle showed higher adherence towards the bacterial surface, with good bactericidal activity against Pseudomonas aeroginosa and Staphylococcus aureus.

Electrical Behaviors of LEDs Prepared by Wide-Band GaN Material

Electrical behaviors of light-emitting diodes (LEDs) prepared by wide-band GaN material were measured accurately using alternating-current (AC) small-signal together with an I-V plot. An abnormal negative capacitance (NC) was observed in all measurend LEDs, and at the same voltage the lower the frequency is, the more obvious NC is. Form the slopes of ln(I)-V plot and the relation between NC and voltage the ideality factor was approximately obtained.

Electrical and optical properties of a-Se xTe 100– x thin films

The dc electrical conductivity of as deposited thin films of a-Se x Te 100− x ( x=3, 6, 9 and 12) is measured as a function of temperature range from 298 to 383 K. It is observed that the dc conductivity increases exponentially with the increase in temperature in this glassy system. The value of activation energy calculated from the slope of ln σ dc vs. 1000/ T plot, is found to decrease on incorporation of dopant (Se) content in the Te system. On the basis of pre-exponetial factor ( σ 0), it is suggested that the conduction is due to thermally assisted tunneling of the carriers in the localized states near the band edges. The optical absorption measurements show an indirect optical band gap in this system and it decreases on increasing Se concentration. The optical constants (extinction coefficient ( k) and refractive index ( n)) do change significantly with the photon energy and also with the dopant Se concentration. The decrease in optical band gap may be due to the decrease in activation energy in the present system. It is also found that the real and imaginary parts of dielectric constants show a significant change with the photon energy as well as with the dopant concentration. With large absorption coefficients and compositional dependence of optical band gap and optical constants ( n and k), these materials may be suitable for optical disk applications.

Electrical properties of thin films of a-Ga x Te100− x composed of nanoparticles

Thin films of Ga x Te100− x (x = 3, 6, 9 and 12) have been synthesized by thermal evaporation. From SEM images, it is observed that all the films contain nanoparticles of sizes varying from 100 to 200 nm. The dc electrical conductivity of the as-deposited films of Ga x Te100−x nanoparticles is measured as a function of temperature range from 298 to 383 K, and increases exponentially with temperature. The value of the activation energy, calculated from the slope of ln σ dc versus 1000/T plots, is found to decrease with increase in the Ga content. On the basis of the value of the pre-exponential factor σ o, it is suggested that the conduction is due to thermally assisted tunneling of carriers in localized states near the band edges. The optical measurements suggest an indirect optical band gap in this system. The value of the optical band gap decreases on increasing the Ga concentration.

On the mechanism of current-transport in Cu/CdS/SnO 2/In–Ga structures

The structural and optical properties of CdS films deposited by evaporation were investigated. X-ray diffraction study showed that CdS films were polycrystalline in nature with zinc-blende structure and a strong (1 1 1) texture. The study has been made on the behavior of Cu/n-CdS thin film junction on SnO 2 coated glass substrate grown using thermal evaporation method. The forward bias current–voltage ( I– V) characteristics of Cu/CdS/SnO 2/In–Ga structures have been investigated in the temperature range of 130–325 K. The semi-logarithmic ln I– V characteristics based on the Thermionic emission (TE) mechanism showed a decrease in the ideality factor ( n) and an increase in the zero-bias barrier height ( Φ Bo) with the increasing temperature. The values of n and Φ Bo change from 8.98 and 0.29 eV (at 130 K) to 3.42 and 0.72 eV (at 325 K), respectively. The conventional Richardson plot of the ln( I o/ T 2) vs q/ kT shows nonlinear behavior. The forward bias current I is found to be proportional to I o( T)exp( AV), where A is the slope of ln( I)– V plot and almost independent of the applied bias voltage and temperature, and I o( T) is relatively a weak function of temperature. These results indicate that the mechanism of charge transport in the SnO 2/CdS/Cu structure in the whole temperature range is performed by tunneling among interface states/traps or dislocations intersecting the space-charge region. In addition, voltage dependent values of resistance ( R i ) were obtained from forward and reverse bias I– V characteristics by using Ohm's law for each temperature level.

Structural, optical and transport properties of Al 3+ doped BiFeO 3 nanopowder synthesized by solution combustion method

Aluminum doped Bismuth ferrite (BFO) nanopowders (grain size 13–20 nm) having composition Bi 1− x Al 2 x Fe 1− x O 3 ( x = 0.00, 0.025, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) were successfully synthesized by solution combustion method using citric acid as fuel at a temperature as low as 200 °C. As-prepared samples were examined by powder XRD for phase identification and crystallite size determination. The d.c. resistivity as a function of temperature was measured by standard two probe setup which exhibits clear metal to insulator transition for all samples. FTIR analysis was carried out to identify the chemical bonds present in the system. The optical band gap was calculated from the UV–vis absorbance spectra using classical Tauc relation which was found to vary from 2.78 eV to 2.93 eV for different Al 3+ concentrations. The activation energies calculated from the slopes of ln( ρ) versus 10 3/ T plots are in the range 0.54–0.73 eV.