Structure, thermoelectric and electrical properties of bismuth-manganese oxide prepared by mechanochemical method (original) (raw)
Related papers
Journal of Nanoparticle Research
We have studied the formation of BiMnO3 (BMO) nanocrystalline perovskite powder produced by high-energy milling of the constituent oxides. The crystal structure and the amount of crystalline and amorphous phases in the powder as a function of the milling time were determined with XRPD using Rietveld refinement. BMO perovskite formed directly from highly activated nano-sized constituent oxides after 240 min of milling and subsequently grew during prolonged milling. The morphology, structure, and chemical composition of the powder were investigated by SEM and TEM. A clear ferromagnetic transition was observed at T C ~66 K for a sample milled for 240 min and increased with milling time. The magnetic hysteresis behavior is similar to that of a soft ferromagnet. The magnetic properties of the obtained BMO powders were found to change as a function of milling time in a manner consistent with variations in the nanocomposite microstructure.
Journal of Materials Science: Materials in Electronics
Bismuth and manganese oxides were mixed as source-materials using the mechanochemical technique followed by heat treatment to prepare the phase Bi2Mn4O10. The X-Ray Diffraction (XRD) analysis was carried out to obtain the formed phases during the mechanochemical process. Bismuth manganese oxide phase with the chemical formula Bi2Mn4O10 was formed at heat treatment 1073 K and was partially decomposed to γ-Bi12.8O19.2 and α-Mn2O3 after 5 h of milling time. The variation of the crystallite size is obtained at different milling time (1 h, 5 h, 10 h, 15 h, 30 h and 50 h). The temperature dependency of the DC electrical conductivity was observed at different milling times in the temperature range 300–425 K for the samples milled at 5 h, 10 h, 30 h and 50 h. The temperature dependency (300–4 80 K) of the thermoelectric power/Seebeck coefficient (S) and its modulus variation with milling time were observed; the modulus varied in the range (45 µV/K-277 µV/K). The concentration of manganese i...
Multiferroic bismuth manganite prepared by mechanochemical synthesis
Journal of the European Ceramic Society, 2010
Multiferroic bismuth manganite (BiMnO 3) is known as a material that exhibits both ferromagnetic and ferroelectric properties making it interesting for various technological applications. Unfortunately, preparation of BiMnO 3 is not possible by a conventional solid-state reaction and it can form only from mixture of oxides at high pressures (>40 kbar). In this work single-phased BiMnO 3 was prepared for the first time by mechanochemical synthesis in a planetary ball mill. A mixture of Bi 2 O 3 and Mn 2 O 3 was intensively milled in air atmosphere, using stainless steel vials and balls. According to analysis of XPRD results BiMnO 3 obtained after milling for 240 min has a tetragonal structure with lattice parameters a = 3.9230 Å, c = 3.920 Å and a crystallite size of 16.8 nm. The cumulative energy introduced into the system during milling for 240 min was 401 kJ/g. It was found that the obtained powders were agglomerated. Corresponding agglomeration factors were calculated from the results of BET and particle size distribution analysis.
Study of ferromagnetic and ferroelectric properties of nanocrystalline Bi2Mn4O10
Applied Physics A
Nano-crystalline bismuth manganese oxide Bi2Mn4O10 was prepared from Bi2O3 and MnO2 by mechanochemical technique at different milling times followed by heat treatment at 1073 K. The crystal structural were obtained using X-ray diffraction (XRD) and TEM. We obtained the variation of the crystallite size and micro-strain with milling time. The magnetic parameters include the saturation magnetization, coercivity and squareness ratio were obtained by vibrating sample magnetometer (VSM). Each of the coercive field, Squareness ratio and saturation magnetization increased with increasing the milling time. The electrical conduction of the prepared samples was evaluated by AC conductivity measurements at different temperature, the dielectric parameters were plotted against temperature at different frequencies. The conduction mechanism is described by the correlated barrier hopping model (CBH). The recoverable energy density and loss energy was obtained to calculate the storage energy efficie...
ACS Omega
An organic−inorganic complexation method was applied for the synthesis of bismuth−manganese bimetallic oxide (BMO) nanoparticles where highly dispersed oxide particles were stabilized in an organic matrix (hexamethylenediamine). The as-synthesized hybrid material was subjected to microscopic, optical, and structural studies to gain comprehensive insights into the system. In the X-ray diffraction pattern, the majority of the diffracted peaks are matched to the orthorhombic phase of the Bi 3 Mn 2 O 7 structure. To extract the electrochemical property, the hybrid system was applied as an anode material and investigated for supercapacitive performance under alkaline conditions. The specific capacitance obtained was 612 F•g −1 at the current density of 1 A•g −1 , and under the same current density, the energy density and power density achieved were 137.78 W•h•kg −1 and 0.90 kW•kg −1 , respectively.
Microstructural properties of lead free BiMnO3 ceramic prepared by mechanochemical synthesis
IOP Conference Series: Materials Science and Engineering, 2019
The present paper reports the synthesis of BiMnO3 (BMO) using Bi2O3 and Mn2O3 as initial powder mixture through mechanochemical synthesis route by a planetary ball milling. The powder mixture was intensively milled in atmospheric temperature to achieve crystalline powder of BiMnO3 (BMO). For structural analysis of the sample the X-ray diffraction (XRD) and Scanning electron microscopy (SEM) investigation was carried. The XRD analysis clearly shows the single phase perovskite structure having monoclinic symmetry with lattice parameter a=5.883Å, c=7.525Å and space group P121/C1. SEM images confirm the achievement of polycrystalline morphology of BMO ceramic with visible grain boundary. It is also found that the presence of agglomerated structure was reduced as the milling time increases. The particle size of starting BMO was somewhat proportional to the grain size. The enhancement in the values of relative density from 90% to 97% of the resulting ceramics was recorded when the sample ...
Enhanced Magnetic Squareness in Manganese-Bismuth Mechanical Alloys Incorporating Magnesium Oxide
Materials Science, 2019
Manganese-bismuth (MnBi) mechanical alloys have been under development for novel permanent magnets without rareearth elements. The ball-milling of bismuth (III) oxide and manganese powders in this work leads to soft magnetic MnBi alloys with rod-like MnO impurity and highly unbalanced compositions. Interestingly, the introduction of magnesium (Mg) as reducing element during the milling gives rise to unique magnetic properties. The obtained MnBi alloys incorporating plate-like MgO has an enhanced magnetic squareness but minimal coercive field. The magnetic squareness remains high after the heat treatment and washing. The washing in ammonia also brings about a balanced composition between Mn and Bi.
Phase investigations of manganese-bismuth alloyed in a microwave furnace
Journal of Central South University, 2020
Implementation of manganese-bismuth (MnBi) alloys as high-performance permanent magnets is a challenge for physicists and engineers because the ferromagnetic low-temperature phase (LTP) is not exclusively obtained. In this work, melting powered by four commercial magnetrons of 2000-2500 W in a microwave furnace is demonstrated as a new route to alloy MnBi. Under an argon atmosphere, microwave heating transferred to pieces of broken Bi ingots and Mn flakes for 2 h gave rise to products of inhomogeneous composition and morphology. Scanning electron micrographs were classified into three regions according to morphology and elemental composition. Cubic-like clusters characterized as Mn precipitated over light solidified Bi-rich regions, and the MnBi phase was formed in homogeneous regions with a balanced composition between Mn and Bi. A ferromagnetic hysteresis loop was obtained in the ground powder with a coercivity of 40 kA/m. Subsequent annealing at 553 K under a pressure of 414 kPa for 12 h enhanced the MnBi phase with extended regions of balanced composition. It follows that the coercivity was increased to 60 kA/m. However, remanent magnetization was slightly reduced. This MnBi alloyed by microwave radiation can be further used in rare-earth-free magnets.
Structural mechanical properties of Sr doped Bismuth manganites
Bismuth strontium manganites Bi 1 -x Sr x MnO 3 (0.20 ≤ x ≤ 0.50) belonging to the orthorhombic structural family were prepared in furnace using a solid state reaction technique. Thick films of Bi (1 -x) Sr x MnO 3 were prepared by simple screen printing route. X ray diffraction data suggest that the synthesized materials have an orthorhombic structure. For synthesized materials, texture coefficient (TC), dislocation density (ρ D ), density of crystallites per unit area (ψ), and mechanical properties are reported along with the influence of x on the structure and mechanical properties of BiMnO 3 thick films.
Synthesis of Nanostructured Bismuth Ferrite by Mechano-Thermal Route
Advanced Materials Research, 2014
In this study, multiferroic BiFeO 3 (BFO) powders were synthesized via mechanical activation of Bi 2 O 3 and Fe 2 O 3 with the molar ratio of 1:1, using a planetary high energy ball mill and subsequent heat treatment. All samples were milled for 20 h and heat treated at various temperatures. XRD, FESEM, LPSA, and VSM techniques were used to evaluate the powder particle characteristics. FESEM images of 20 h milled sample indicated plate-like particles with a mean thickness of 45 nm and its LPSA results showed the mean agglomerate size of about 2.0 µm. XRD results of calcined samples showed that the BFO phase began to form at 650 °C and fully formed at 750 °C. In comparison to the conventionally processed samples, BFO phase formation temperature decreases by ∼100 °C in the samples produced by mechanical activation assisted process. VSM measurements of the sample heat treated at 750 °C revealed a saturation magnetization (M s ) of 0.054 emu/g and coercivity (H c ) of 412 Oe.