Field Emission Scanning Electron Micrographs Research Articles

Investigation of the structure and magnetic properties of Sn substituted Li-Zn ferrites fabricated by sol–gel process

A series of Sn doped Li-Zn ferrite powders with composition of Li(0.2+0.5x)Zn0.6SnxFe(2.2−1.5x)O4 (x = 0.00, 0.02, 0.04, 0.06, and 0.08) are synthesized by sol–gel process. The ring-shaped bulk samples of all compositions are obtained by sintering at 950 °C for 3 h, and all the structural and magnetic measurements were carried out on the sintered bulk samples. X-ray diffraction (XRD) patterns confirmed the formation of single-phase spinel structure when x ≤ 0.06 and the second phase of SnO2 at x = 0.08. Field emission scanning electron micrograph (FE-SEM) is used to observe the surface morphology of the bulk samples and particle sizes (DSEM). Micrograph of the sample for x = 0.08 shows many small particles appearing on the surface of the aggregation bulk samples. Vibrating sample magnetometer (VSM) is employed to study the saturation magnetization (Ms) and coercivity (Hc). The Ms displays a downtrend with the increasing of doping concentration and all samples have a lower coercivity of less than 30 Oe. Initial permeability (μi) and Curie temperature (Tc) are measured in a furnace using HP4294A impedance analyzer. The μi increases with the Sn4+ concentration until x = 0.06 and the Tc decreases with the Sn4+ concentration. The cation distribution estimated from XRD pattern and magnetic properties analyses suggest that Li+ ions appear in the tetrahedral sites with increasing of Sn4+ and Li+ contents.

Effect of Sol-Gel Synthesized BiFeO<sub>3</sub> Nanoparticle Addition in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7–δ</sub> (Y123) Superconductor Synthesized by Standard Solid State Reaction Method

The effects of the multiforric BiFO3 nanoparticles addition on the structure and superconducting properties of YBa2Cu3O7–δ (Y123) with different concentrations were systematically investigated using X-ray diffraction (XRD), field emission scanning electron micrograph (FESEM), EDX and four point probe measurement. It was found that the added samples were predominant by Y-123 phase beside small amount of Y-211 and unreacted BiFeO3 secondary phases. Samples with less (wt.%) BFO added YBCO precursor powder preserved the orthorhombic structure similar to the pure YBCO, while samples with higher wt% addition show orthorhombic-to-tetragonal transition tendency. The samples became more porous and their grain size slightly decreased with addition of BiFeO3. The addition of nanoBiFeO3 disturbed the grain growth of Y123, thus resulting in the degradation of superconducting properties of the samples. The superconducting transition temperature (Tc onset) of samples decreased from 92 K for x=0.0 to 44 K for x=10.0 wt. %, which could be attributable to oxygen vacancy disorder.

Study of structural and magnetic properties and heat induction of gadolinium-substituted manganese zinc ferrite nanoparticles for in vitro magnetic fluid hyperthermia

This article outlines the synthesis of gadolinium (Gd)-doped manganese zinc ferrite magnetic nanoparticles (MNPs) as potential magnetic carriers for magnetic fluid hyperthermia (MFH). MNPs with high specific loss power (SLP; 146 W/g) have been developed and used for an in vitro hyperthermia study. The treatment of MFH is fruitful if there is an adequate number of MNPs in tumor cells with the highest SLP to rapidly generate heat while minimizing thermal injury to surrounding healthy tissue. X-ray diffraction patterns of the studied particles confirm the formation of a cubic spinel structure. Field emission scanning electron micrographs showed homogeneous distributions of particles with some agglomerates with a granular appearance. Transmission electron microscopy analysis showed the presence of agglomerated spherical particles at the surface. The substitution of Gd resulted in superparamagnetism at room temperature as confirmed by vibrating sample magnetometer analysis. The estimated saturation magnetization reduced from 48.6 to 28.2 emu/g with an increase in Gd concentration. However, the coercivity increased from 1093 Oe to 1597 Oe. Field cooled and zero field cooled measurements showed Curie temperatures from 315 to 326 K, as required for MFH applications. Cell viability measurements indicated that the MNPs are nontoxic to A549 cells for the studied concentrations of particle fraction and a contact time of up to 24 h. The interaction of the MNPs with A549 cells was highlighted from an image captured by an inverted microscope. In order to treat cancer in vivo, an in vitro hyperthermia study has initially been carried out with A549 cells.

Enhanced adsorption of nitrate from water by modified wheat straw: equilibrium, kinetic and thermodynamic studies.

This study represents the first attempt to chemically modify wheat straw (WS) using 3-chloropropyltrimethoxysilane (CPTMS) and (1,4-diazabicyclo[2.2.2]octane) (DABCO). Field emission scanning electron micrographs (FESEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectra confirmed the successful morphological and structural modification of WS and the thermal stability of the modified WS (MWS). The MWS was used to remove nitrate from water. The optimum conditions of nitrate adsorption onto MWS were examined by conducting batch experiments. The results indicated that 85% of nitrate was removed under the conditions of initial nitrate concentration = 20 mg L-1, initial solution pH = 7, contact time = 10 min, MWS dosage = 2 g L-1 and temperature ≈ 25 °C. The kinetic adsorption data were best fitted to the general order model and the adsorption process occurred in three distinct stages. The equilibrium adsorption data were well described by the Langmuir isotherm. Additionally, separation factor values were smaller than 1, implying that the adsorption process was favorable. The presence of competing anions impeded the nitrate adsorption in the order of sulfate > chloride > bicarbonate> phosphate. Thermodynamic parameters suggested that the adsorption process was exothermic, feasible and spontaneous in nature. Overall, the MWS could achieve efficient removal of nitrate under the simplest operating conditions.

Electrochemical behavior of composite electrode based on sulphonated polymeric surfactant (SPEEK/PSS) incorporated polypyrrole for supercapacitor

Sulfonated polymeric surfactants integrated polypyrrole composites have been prepared and exploited as electrode material for supercapacitor application where sulfonated poly (ether ether ketone) SPEEK and poly (styrene sulfonate) PSS have been used as surfactant as well as dopant in polypyrrole (PPy). These composites are conveniently prepared via in-situ chemical oxidation polymerization of pyrrole using FeCl3 as oxidant at varying weight ratio of SPEEK/PSS and investigated through Fourier transforms infrared spectroscopy, Thermal gravimetric analysis/Derivative thermal gravimetric, Field emission scanning electron microscopy, and electrochemical performance. Field emission scanning electron micrographs divulge granular morphology of composite with spongy and baggy structure. Electrochemical performance of all the composites has been investigated through cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements. Results reveal that electrochemical properties of composites significantly depend upon different feeding ratio of SPEEK or PSS due to the availability of sulfonating groups. After comparative study, high specific capacitance 330F/g of SP4 (PPy:SPEEK (w/w) 60:40) at scan rate of 2mV/s, that also correlates well with the GCD findings. High energy density obtained as 23.8Wh/kg of SP4 composite at power density of 1000W/kg demonstrates as new promising electrode material for supercapacitors.

Preparation of carrageenan-based functional nanocomposite films incorporated with melanin nanoparticles.

Melanin nanoparticles (MNP) were isolated from sepia ink, spherical and range in size from 40 to 160 nm. Carrageenan-based nanocomposite films with different concentration of MNP (0, 0.25, 0.5, 1.0, and 2.0 wt%) were prepared and their physical, thermal and UV-barrier properties were evaluated. Field emission scanning electron (FE-SEM) micrographs showed well-dispersed MNPs in the carrageenan matrix. The addition of MNP completely shielded the UV light and also affected the apparent color and transparency of the nanocomposite film. The addition of up to 1.0% by weight of MNP significantly increased the mechanical strength of the carrageenan film. The heat resistance of the carrageenan film also increased by mixing with MNP. Incorporation of MNP also reduce the water barrier property and increase the hydrophobicity of the carrageenan film. Also, the MNP-incorporated carrageenan nanocomposite films showed strong antioxidant activity with some antimicrobial activity against foodborne pathogenic bacteria, L. monocytogenes and E. coli.

A green, porous and eco-friendly magnetic geopolymer adsorbent for heavy metals removal from aqueous solutions

Geopolymers are a class of synthesized amorphous aluminosilicate materials that can be used as an adsorbent for the removal of heavy metals. In this paper, the bentonite clay was employed to synthesize geopolymer that can remove heavy metals such as Cu(II), Pb(II), Ni(II), Cd(II), and Hg(II) from industrial wastewaters. The Fe3O4 nanoparticles were applied to modify the geopolymer and the use of a geopolymer/Fe3O4 nanocomposite as an efficient and magnetic adsorbent for heavy metals removal from aqueous solution was investigated in this work, for the first time. The influence of different contact time and initial concentrations of metal ions on sorption was examined and the best result was achieved in 2 min contact time in the presence of 0.05 g nanocomposite. The prepared geopolymer and nanocomposite samples were characterized by Fourier transform infrared spectroscopy spectra, field-emission scanning electron micrograph images, thermogravimetric analysis, energy dispersive X-ray analysis, X-ray diffraction pattern and Brunauer-Emmett-Teller analysis. The prepared magnetic geopolymer base on bentonite clay showed 99%, 99%, 92%, 96% and 92% removal efficiency for the sorption of copper, lead, nickel, cadmium, and mercury ions from industrial wastewaters. The present work includes diverse advantageous such as environmentally-friendly protocol, magnetic separation, inexpensive raw materials, easy and simple conditions and high yields as same as short adsorption times.

Design and Development of Bismuth Ferrite Based Environmental Friendly Multiferroic for Devices

Abstract Recently, researches are mainly focussed on the development of eco-friendly materials for multifunctional devices. In the present communication, synthesis and detailed characterization of Bi(Ni0.30Ti0.30Fe0.40)O3 multiferroic material has been reported. This compound has been synthesized via a cost-effective (solid-state reaction or mixed oxide) technique in air atmosphere. Based on the analysis of X-ray diffraction data (collected on powder sample) crystal system, unit cell dimension and crystallite (particle) size of material were determined. The calculated particle size of the material is in the range of 28 to 52 nm. Analysis of the field emission scanning electron micrograph (FE-SEM) depicts uniform distribution of grains of varying dimension. Furthermore, the correlation between dielectric and impedance parameters is established using experimental data collected by a phase sensitive multimeter at various temperature and frequency. The impedance spectroscopic studies are performed in a broad range of temperature (300–780 K) and ac field frequencies (103 –106 Hz). As a result, the addition of Ni (nickel) and Ti (titanium) at the Fe (iron) site of BiFeO3 enhances electrical as well as multiferroic properties of the material.

Thermal Properties of Acylated Low Molecular Weight Chitosans

Acylated low molecular weight chitosans (LChA) were prepared from nucleophilic acylation of chitosan using acid anhydrides of short and medium chain length (4 - 10) to study the response of applied heat as a function of acyl chain length. Thermogravimetric analysis (TGA) revealed the decomposition of LChA consisted of glucosamine and acyl-glucosamine units around 141 - 151and#176;C to 400 - 410and#176;C. Both TGA and differential scanning calorimetry (DSC) analyses indicated that the introduction of acyl groups disrupted the hydrogen bonding of chitosan, the effect was more prominent as the degree of substitution and chain length of LChA increased. Grafting of acyl chains lowered the kinematic viscosity of LChA as the disruption of hydrogen bonding led to decreased hydrodynamic volume. Field emission scanning electron micrographs showed that LChA with longer chains having larger particle size due to bigger occupancy volume of acyl chains during spray drying.

Study on the effect of Zn2+ doping on optical and electrical properties of CuO nanoparticles

The present work outlines the synthesis of CuO and Zn-CuO nanoparticles via microwave combustion method using urea as a fuel. The structural, optical and electrical properties of the CuO and Zn-CuO nanoparticles were systematically characterized through UV–Visible spectroscopy (UV–Vis), Field-emission scanning electron microscopy (FE-SEM), Photoconductivity technique (I-V study), X-ray diffraction studies (XRD), Transmission electron microscopy (TEM) and Energy dispersive analysis X-rays spectrometer (EDAX). The average crystalline size and micro-strain of pure CuO and Zn-CuO nanoparticles were calculated using Debye-Scherrer and William-Hall (W-H) plot methods. The crystalline size was found to be decreased with increase in the concentration of Zn2+ up to 6 mol% and a further increase in the Zn2+ concentration resulted in the formation impurity phase. Field emission scanning electron micrographs show the monoclinic rod-like structure of CuO and Zn-CuO nanoparticles. Energy dispersive X-ray spectra display the existence of Zn2+ in Zn-CuO nanoparticles. The optical band gap values of CuO and Zn-CuO nanoparticles were determined by optical absorption method and the results show a slight decrease in the optical band gap with Zn2+ doping. Electrical properties of CuO and Zn-CuO films were performed using I-V characterization studies and the results shown that the enhancement of photocurrent is more in UV-light as compared to dark.

Fluoro-functionalized graphene oxide/polyaniline composite electrode material for supercapacitors

A novel high-performance electrode material based on fluoro-functionalized graphene oxide (GOF)/polyaniline (PANI) composites was synthesized via in situ polymerization of monomer in the presence of GOF. The composite was characterized by Fourier transform infrared spectrometry, X-ray diffraction (XRD), and the field emission scanning electron micrographs. The electrochemical properties of the composites were measured based on cyclic voltammetry, galvanostatic charge/discharge, and AC impedance spectroscopy. When the obtained composites with a mass ratio is 3% GOF/PANI, the results showed that GOF as a support material provides additional electron transfer paths, as well as active sites, for the electrochemical redox reaction of PANI, which helps to increase its pseudocapacitance. A specific capacitance of 502 F·g−1 was obtained at a current density of 1.0 A·g−1 in 1 mol·L−1 H2SO4, as well as excellent cycling stability with 95% of its initial capacitance after 600 cycles. These encouraging results illustrate the exciting potential for high-performance, electrical energy storage devices based on this new class of carbon material.

Electrodeposition of nano crystalline cobalt oxide on porous copper electrode for supercapacitor

The cobalt oxide thin films were prepared by electrodeposition methods on to porous copper substrate. As-deposited films were obtained as Co3O4 films with the help of heat treatment at 300 °C for 2 h. Their structural and surface morphological properties were investigated by using X-ray diffraction, Fourier transformation analysis and field emission scanning electron micrograph (FESEM), atomic force microscope, energy dispersive X-ray analysis techniques (EDAX). The X-ray diffractogram reveals the formation of cobalt hydroxide CoOOH with orthorhombic crystal structure and cobalt oxide Co3O4 with cubic crystal structure. The FESEM micrographs confirms the morphology of prepared films, also EDAX spectra confirms the presence of Co and O elements of the solid films. The electrochemical performance of the films was studied in aqueous 1 M KOH electrolyte using cyclic voltammetry. The cyclic voltammograms exhibits symmetric nature and increase in capacitance with respect to the film thickness. The maximum specific capacitance of cobalt hydroxide CoOOH is 602 F g−1 and cobalt oxide Co3O4 is found to be as 630 F g−1. The above investigation shows that low-cost cobalt oxide electrode can be a potential application in supercapacitor.

Synergistic improvement of epoxy composites with multi-walled carbon nanotubes and hyperbranched polymers

This paper presented the preparation of composites that consist of multi-walled carbon nanotubes (MWCNTs), hyperbranched polymers (HBPs), epoxy resins (EP) and curing agent. The influences of HBPs and MWCNTs content on the curing process of epoxy systems and mechanical performances of MWCNTs/HBPs/EP composites were discussed. Results from differential scanning calorimeter (DSC), tensile, impact and toughness tests are provided. The tensile and impact fracture surface were observed by field-emission scanning electron microscopy. The addition of HBPs resulted in accelerating the curing process of epoxy systems. MWCNTs/HBPs/EP composites were capable of increasing tensile strength by up to 38%, giving a tensile modulus of 25%, impact strength of 68%, fracture toughness of 66%, and a glass transition temperature (Tg) of 46% in comparison with unmodified epoxy thermosets. Field emission-scanning electron micrographs showed that these increases were associated with a synergistic effect of plastic deformation mechanism and crack pinning mechanism, which were induced by the present of HBPs and MWCNTs, respectively.

Enhanced dielectric and optical properties of nanoscale barium hexaferrites for optoelectronics and high frequency application

M-type barium hexaferrites with chemical composition Ba1–xDyxFe12–yCryO19 (x = 0.0,0.1,0.2, and y = 0.0,0.4,0.5) were synthesized via sol–gel auto-combustion method. The samples were pre-sintered at 400 °C for 3 h and sintered at 950 °C for 5 h. The changes in the structural, dielectric, and optical properties were studied after the substitution of Dy3+ and Cr3+ ions. X-ray diffraction (XRD) analysis confirms the formation of single phase hexaferrites with the absence of secondary phase. FTIR analysis gives an idea of the formation of hexaferrites with the appearance of two peaks at 438 cm–1 and 589 cm–1. The field emission scanning electron micrographs (FESEM) show a combination of crystallites with large shapes close to hexagonal platelet-like shape and others with rice or rod-like shapes, whereas EDX and elemental analysis confirm the stoichiometry of prepared samples. The calculated band gap from UV-vis NIR spectroscopy spectra was found to decreases with increase in Dy3+–Cr3+ substitution. The dielectric properties were explained on the basis of Maxwell–Wagner model. Enhancement of dielectric constant at higher frequencies was observed in all the samples. Low dielectric loss is also observed in all the samples and Cole–Cole plot shows that grain boundary resistance (Rgb) contribute most to the dielectric properties. The prepared samples exhibit properties that could be useful for optoelectronics and high frequency application.

Plasmon-induced photocatalytic degradation of methylene blue dye using biosynthesized silver nanoparticles as photocatalyst

ABSTRACTBio-fabrication of silver nanoparticles, using stem extracts of Nepeta leucophylla and their photocatalytic degradation activity, has been undertaken. The synthesized silver nanoparticles are characterized using ultraviolet-visible spectroscopy, Fourier transformed infrared spectroscopy, X-ray diffractometry, Transmission Electron Microscopy, Field Emission Scanning Electron Microscopy, Energy-dispersive X-ray spectroscopy and thermal gravimetric and differential scanning calorimetry analysis. The Surface Plasmon Resonance band detected at 430 nm in the ultraviolet-visible spectrum confirms the formation of silver nanoparticles in the aqueous solution. Transmission Electron and Field Emission Scanning Electron micrographs reveal that the synthesized silver nanoparticles are spherical with an average size in the range of 15–25 nm. But, the X-ray diffraction confirms the face-centred cubic structure of silver nanoparticles with an average crystal size of the nanoparticles is about 10 nm. Furthermore, the infrared spectrogram confirms that the stem extract of Nepeta leucophylla contains phenol which causes reduction of silver salt to silver nanoparticles and protein might act as an overlaying agent which prevents the agglomeration of these nanoparticles. Moreover, the photocatalytic degradation of methylene blue dye, by using biosynthesized silver nanoparticles of optimized dose (1.8 ml) for 180 min in the presence and absence of light are 82.8% and 61.25%, respectively, specifies that the resultant photocatalyst is proved to have good photocatalytic activity for the degradation of methylene blue dye from the liquid phase.

Bio-inspired self-healing cementitious mortar using Bacillus subtilis immobilized on nano-/micro-additives

Bio-inspired self-healing strategies are much innovative and potentially viable for the production of healable cement mortar matrix. The present research explores the feasibility of gram-positive “Bacillus subtilis” microorganisms in the effective healing of nano-/micro-scale-induced structural and non-structural cracks. The main concern related to the survival of such microorganisms in cementitious environment has been successfully addressed by devising proficient immobilization scheme coherently. The investigated immobilizing media includes iron oxide nano-sized particles, micro-sized limestone particles, and milli-sized siliceous sand. The effect of induced B. subtilis microorganisms immobilized on nano-micro-additives was analyzed by the quantification of average compressive resistance of specimens (ASTM C109) and healing evaluation. The healing process was mechanically gauged by compressive strength regain of pre-cracked specimens after the healing period of 28 days. The pre-cracking load was affixed at 80% of ultimate compressive stress “[Formula: see text]” while the age of pre-cracking was kept variable as 3, 7, 14, and 28 days to precisely correlate healing effectiveness as the function of cracking period. The healing mechanism was further explored by examining the healed micro-crack using field emission scanning electron micrographs, energy dispersive x-ray spectrographs, and thermogravimetry. The results revealed that B. subtilis microorganisms contribute extremely well in the improvement of compressive strength and efficient healing process of pre-cracked cement mortar formulations. The iron oxide nano-sized particles were found to be the most effective immobilizer for preserving B. subtilis microbes till the generation of cracks followed by siliceous sand and limestone particles. The micro-graphical and chemical investigations endorsed the mechanical measurements by evidencing calcite precipitation in the induced nano-/micro-cracks as a result of microbial activity.

PROCESSING, DIELECTRIC, IMPEDANCE SPECTROSCOPY OF ELECTRONIC MATERIAL: (Pb0.92Ga0.08)(Zr0.48Ti0.52)0.98O3

Purpose of Study: The present work shows studies of some physical properties of a gallium (Ga) modified lead zirconate titanate (PbZrTi)O3 with molar ratio Zr/Ti::48/52 (i.e., near morphotropic phase boundary (MPB)) having (Pb0.92Ga0.08)(Zr0.48Ti0.52)0.98O3 (PGaZT-8) as a chemical composition.
 Methodology: The material was fabricated employing high-temperature mixed oxide route.
 Main Finding: X-ray diffraction spectra suggest a distorted perovskite structure having two phases (tetragonal and monoclinic phases) with the substitution of small amount (2 and 4 wt %) of Ga in Pb(ZrTi)O3 (PZT). However, with higher concentration of Ga (6 and 8 wt %) in PZT, the multiphase perovskite structure is converted into an orthorhombic system with few impurity phase of Ti3O5. Analysis of field emission scanning electron micrograph (FESEM) of 8 wt% Ga modified PZT (PGaZT-8) shows the uniform distribution but different dimension and shape of grains depicting high-density ceramic sample. In the dielectric studies no dielectric anomaly exists in the experimental temperature range (25-500oC) in PGaZT-8, which determines the substitution of 8 wt% Ga in PZT (in MPB region) is found responsible for the suppression or shift (towards higher temperature) of known ferroelectric phase transition of PZT. There is an enhancement of permittivity, loss factor and conductivity as Pb site of PZT is doped with Ga.
 Applications of study: This study is useful for the determination of the characteristics of the prepared material as a base for device fabrication.
 Novelty of the Study: It is a systematic study of correlation of structural properties with the physical properties. It helps to understand the relaxation and conduction mechanism of PGaZT-8 using impedance and modulus spectroscopy.

Poly(ethylene imine)-modified magnetic halloysite nanotubes: A novel, efficient and recyclable catalyst for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives

In this study, a green magnetic nanocatalyst based on natural clay was fabricated. Magnetic nanoparticles were loaded on halloysite nanotubes (HNTs) and poly(ethylene imine) (PEI) was covalently grafted onto the surface of HNTs. The morphology and chemistry of the Fe3O4@HNTs-PEI nanocomposite was fully characterized by Fourier transform infrared (FT-IR) spectroscopy spectra, field-emission scanning electron micrograph (FE-SEM) images, thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) pattern and vibrating sample magnetometer (VSM) curve analyses. These characteristics confirmed the successful synthesis of the nanocomposite. The catalytic performance of Fe3O4@HNTs-PEI was utilized for the synthesis of pyranopyrazole derivatives. This heterogeneous catalyst exhibited high efficiency in green media under mild reaction conditions at room temperature and can be easily recovered from the reaction mixture by using an external magnet and reused for at least eight times without any significant decrease in catalytic activity.

Graphene-Oxide Coated Ag-Island-Based Inline LSPR Fiber Sensor

Graphene Oxide (GO) coated silver (Ag) island system based on localized surface plasmon resonance (LSPR) phenomenon have been developed using optical fiber as a sensing probe. The Ag-island is used to excite LSPR field which is responsible for the analyte sensing through a shift in resonance wavelength. The deposition of Ag-islands is confirmed from UV-VIS spectra and Field Emission Scanning Electron Micro-graph (FESEM). The usage of GO helps to protect Ag-island from oxidation along with opening a new window for bio-sensing due to its structural compatibility with the bio-sensing system. We have experientially observed that the GO as a dielectric overlayer on Ag-island shows a refractive index sensitivity of 2217.04 nm/RIU with a resolution of $4.05 \times 10^{-4}$ RIU.

Effects of Gd and Cr co-doping on multiferroic properties of Bi0.9Gd0.1Fe(1-x)CrxO3 (x = 0−0.08)

Gd and Cr co-doped Bi0.9Gd0.1Fe(1 − x)CrxO3 (x = 0 − 0.08) nanoparticles were synthesized via sol-gel method. Precursor salts of bismuth, iron, gadolinium and chromium were used as starting raw materials. Obtained nanoparticles were annealed at various temperatures between 400 − 700 °C. Optimal properties were found to display at 600 °C. X-ray diffraction (XRD) patterns revealed that the partial substitution of Bi3+ by Gd ions and Fe3+ by Cr ions in BiFeO3 (BFO) resulted in evolution of phase transition from rhombohedral to orthorhombic structure. The average crystallite size was found to vary from 16 to 68 nm depending on doping level. The field emission scanning electron micrographs demonstrated a distinct morphology of spherical and nano-sized particles. Ferroelectric measurements showed a substantial improvement in polarization in doped BFO under an applied field of ± 30 kV/cm. Magnetic properties measured at room temperature showed enhanced ferromagnetic characteristics with increasing doping level of Cr up to 6 % (at.) compared to that of un-doped BFO. An asymmetric shift both in the field and magnetization axes of M-H loops was also observed.