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Synthesis of α-Fe2O3 nanoparticles and analyzing the effect of annealing temperature on its properties

Thimmiah Bhargavi Ram, Nallathambi Gobi

Materials Science Poland

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2020

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Vol. 38, No. 1

116--121

EN

α-Fe2O3 nanoparticles were synthesized via co-precipitation technique using ferric and ferrous salts and potassium hydroxide as precipitation agents. The samples were calcined at 350 °C, 550 °C and 750 °C for 3 hours. The obtained iron oxide was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and dynamic light scattering (DLS). Crystallinity of the sample was studied by X-ray diffraction. SEM micrographs showed nonuniform size distribution of the particles forming agglomerates. TGA analysis revealed trace amount of weight loss and material stability for the samples calcined at temperatures above 500 °C. DLS results indicated that increasing of annealing temperature resulted in reduction of the particle size and more uniform size distribution. At the maximum annealing temperature of 750 °C, the mean diameter of the particles of 100 nm was observed.

2

Dielectric properties of Bi-substituted LDHs synthesized by co-precipitation and sol-gel methods

Sokol Denis, Ivanov Maksim, Salak Andrei N., Grigalaitis Robertas, Banys Juras, Kareiva Aivaras

Materials Science Poland

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2019

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Vol. 37, No. 2

190--195

EN

Magnesium-aluminum-bismuth layered double hydroxides (Mg3Al1-xBix; LDHs) were prepared using both coprecipitation and sol-gel methods. For the preparation of Mg/Al/Bi LDH by the co-precipitation method, the appropriate amounts of dissolved starting materials (Al(NO3)3·9H2O, Mg(NO3)2·6H2O and Bi(NO3)3·5H2O) were mixed with a solution of NaHCO3:NaOH. In the sol-gel processing, the precursor Mg–Al–Bi–O gels were synthesized using the same starting materials and ethylene glycol as complexing agent. The mixed-metal oxides obtained by subsequent heating of Mg–Al–Bi–O gels at 650 °C were reconstructed to Mg3Al1-xBix LDHs in water at 80 °C. All the synthesized products were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and dielectric measurements.

3

Synthesis and characterization of Ag-chalcogenide nanoparticles for possible applications in photovoltaics

Chand S., Sharma P.

Materials Science Poland

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2018

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Vol. 36, No. 3

375--380

EN

Bottom-up technique has been used to synthesize Ag-chalcogenide nanoparticles. This work reports on the synthesis of Ag2Se by varying the molar ratio of capping agent and pH of the solution. The synthesized nanoparticles have been characterized in terms of structural parameters using X-ray diffraction. By this technique, various parameters such as crystallite size, dislocation density and strain of the nanoparticles were calculated. The crystallite size decreased with the increase in pH of the solution. The optical characterization was carried out by UV-Vis-NIR spectrophotometer. With the decrease in the crystallite size, a blue shift in the absorption peak of the nanoparticles was observed. These properties are suitable for energy harvesting with the help of photovoltaics.

4

Antibacterial activity of iron oxide nanoparticles synthesized by co-precipitation technology against Bacillus cereus and Klebsiella pneumoniae

Ansari S. A., Oves M., Satar R., Khan A., Ahmad S. I., Jafri M. A., Zaidi S. K., Algahtani M. H.

Polish Journal of Chemical Technology

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2017

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Vol. 19, nr 4

110--115

EN

The present study investigates the synthesis and characterization of iron oxide nanoparticles (Fe3 O4 -NPs) for their antibacterial potential against Bacillus cereus and Klebsiella pneumonia by modified disc diffusion and broth agar dilution methods. DLS and XRD results revealed the average size of synthesized Fe3 O4 -NPs as 24 nm while XPS measurement exhibited the spin-orbit peak of Fe 2p3/2 binding energy at 511 eV. Fe3 O4 -NPs inhibited the growth of K. pneumoniae and B. cereus in both liquid and soild agar media, and displayed 26 mm and 22 mm zone of inhibitions, respectively. MIC of Fe3 O4 -NPs was found to be 5 μg/mL against these strains. However, MBC for these strains was observed at 40 μg/mL concentration of Fe3 O4 -NPs for exhibiting 40–50% loss in viable bacterial cells and 80 μg/mL concentration of Fe3 O4 -NPs acted as bactericidal for causing 90–99% loss in viability. Hence, these nanoparticles can be explored for their additional antimicrobial and biomedical applications.

5

Synthesis and characterization of AgFeO2 delafossite with non-stoichiometric silver concentration

Siedliska K., Pikula T., Chocyk D., Jartych E.

Nukleonika

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2017

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Vol. 62, No. 2

165--170

EN

The simple co-precipitation method was used to prepare AgxFeO2 delafossite with non-stoichiometric silver concentration in the range of x = 0.05–1. The obtained material was investigated using X-ray powder diffraction and 57Fe Mössbauer spectroscopy at room temperature. The structural and hyperfine interaction parameters were recognized in relation with decreasing silver concentration. The study revealed that the delafossite structure of AgxFeO2 was maintained up to x = 0.9; as the range of silver concentration was decreased to 0.05 ≤ x ≤ 0.8, a mixture of AgFeO2, Fe2O3 or/and FeOOH was formed.

6

Structural and morphological analysis of barium cerate electrolyte for SOFC application

Kumar A. S., Balaji R., Puviarasu P., Jayakumar S.

Materials Science Poland

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2017

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Vol. 35, No. 1

120--125

EN

Gadolinium doped barium cerate (BCG) electrolytes Ce0.8Gd0.2 O1.9 + xBaO (x = 0.1 and 0.4) were prepared by wet chemical method for the use in solid oxide fuel cells operating at intermediate temperatures (600 °C to 800 °C). The as-prepared powder sample was calcined at 900 °C. The calcination temperature was identified using differential scanning calorimetry (DSC) analysis. The orthorhombic perovskite phase formation was confirmed by XRD analysis. From TEM results, the particle size was found to be about 32 nm which is in a good agreement with XRD results. BCG nanoparticles were formed at lower sintering temperature due to using microwave furnace. By reducing the sintering temperature of solid electrolyte through microwave technique, the percentage of barium loss was successfully reduced and the prepared electrolyte can be a good choice for solid oxide fuel cells operating at intermediate temperatures.

7

Structural and luminescent properties of Fe3+ doped PVA capped CdTe nanoparticles

Ravindranadh K., Rao M. C.

Materials Science Poland

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2017

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Vol. 35, No. 2

390--397

EN

During recent decades, magnetic and semiconductor nanoparticles have attracted significant attention of scientists in various fields of engineering, physics, chemistry, biology and medicine. Fe3+ doped PVA capped CdTe nanoparticles were prepared by co-precipitation method and characterized by powder X-ray diffraction, SEM, TEM, FT-IR, optical, EPR and PL techniques to collect the information about the crystal structure, coordination/local site symmetry of doped Fe3+ ions in the host lattice and the luminescent properties of prepared sample. Powder XRD data revealed that the crystal structure belongs to a cubic system and its lattice cell parameters were evaluated. The average crystallite size was estimated to be 8 nm. The morphology of prepared samples was analyzed by using SEM and TEM investigations. Functional groups of the prepared sample were observed in FT-IR spectra. Optical absorption and EPR studies have shown that on doping, Fe3+ ions enter the host lattice in octahedral site symmetry. PL studies of Fe3+ doped PVA capped CdTe nanoparticles revealed UV and blue emission bands. CIE chromaticity coordinates were also calculated from the emission spectrum of Fe3+ doped PVA capped CdTe nanoparticles.

8

The effect of magnetite nanoparticles synthesis conditions on their ability to separate heavy metal ions

Bobik M., Korus I., Dudek L.

Archives of Environmental Protection

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2017

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Vol. 43, no. 2

3--9

EN

Magnetite nanoparticles have become a promising material for scientific research. Among numerous technologies of their synthesis, co-precipitation seems to be the most convenient, less time-consuming and cheap method which produces fine and pure iron oxide particles applicable to environmental issues. The aim of the work was to investigate how the co-precipitation synthesis parameters, such as temperature and base volume, influence the magnetite nanoparticles ability to separate heavy metal ions. The synthesis were conducted at nine combinations of different ammonia volumes - 8 cm3, 10 cm3, 15 cm3 and temperatures - 30°C, 60°C, 90°C for each ammonia volume. Iron oxides synthesized at each combination were examined as an adsorbent of seven heavy metals: Cr(VI), Pb(II), Cr(III), Cu(II), Zn(II), Ni(II) and Cd(II). The representative sample of magnetite was characterized using XRD, SEM and BET methods. It was observed that more effective sorbent for majority of ions was produced at 30°C using 10 cm3 of ammonia. The characterization of the sample produced at these reaction conditions indicate that pure magnetite with an average crystallite size of 23.2 nm was obtained (XRD), the nanosized crystallites in the sample were agglomerated (SEM) and the specific surface area of the aggregates was estimated to be 55.64 m2·g-1 (BET). The general conclusion of the work is the evidence that magnetite nanoparticles have the ability to adsorb heavy metal ions from the aqueous solutions. The effectiveness of the process depends on many factors such as kind of heavy metal ion or the synthesis parameters of the sorbent.

PL

Nanocząstki magnetytu stanowią obiecujący materiał badań ze względu na możliwość ich praktycznego zastosowania w różnorodnych dziedzinach. Wśród wielu metod ich syntezy, jako jedną z najwygodniejszych, najmniej pracochłonnych oraz ekonomicznych, wyróżnić można chemiczne współstrącanie. Efektem metody chemicznego współstrącania są drobne nanocząstki tlenku żelaza o dużej czystości, odpowiednie do zastosowań w zagadnieniach środowiskowych. Celem pracy było badanie w jaki sposób warunki syntezy chemicznego współstrącania, takie jak temperatura reakcji czy też ilość użytej zasady wpływają na zdolności separacyjne nanocząstek magnetytu względem jonów kilku metali ciężkich. Syntezy prowadzone były w dziewięciu kombinacjach przy różnej objętości dodawanego amoniaku – 8 cm3, 10 cm3, 15 cm3 oraz temperaturze – 30°C, 60°C, 90°C. Powstałe podczas każdej z syntez tlenki żelaza były badane jako adsorbenty jonów siedmiu metali ciężkich: Cr(VI), Pb(II), Cr(III), Cu(II), Zn(II), Ni(II) and Cd(II). Ponadto próbka magnetytu zsyntezowanego w wybranych warunkach była badana przy użyciu metod XRD, SEM oraz BET. Analizując wyniki procesu sorpcji stwierdzono, iż najbardziej efektywny materiał, dla większości metali ciężkich, powstał w temperaturze 30°C przy użyciu 10 cm3 amoniaku. Dodatkowa charakterystyka powstałego w tych warunkach sorbentu wykazała, iż stanowił on czysty magnetyt o średniej wielkości ziarna 23,2 nm (XRD). Ponadto wykazano, iż pojedyncze ziarna w badanej próbce są zaglomerowane (SEM) a powierzchnia właściwa agregatów wynosi 55,64 m2/g (BET). Ogólnym wnioskiem z pracy jest dowód, iż warunki syntezy badanego adsorbentu mają wpływ na jego zdolność separacyjne względem niektórych jonów metali ciężkich.

9

Effect of calcination temperature on the structural, optical and magnetic properties of pure and Fe-doped ZnO nanoparticles

Singh R. P. P., Hudiara I. S., Rana S. B.

Materials Science Poland

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2016

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Vol. 34, No. 2

451--459

EN

In the present study, pure ZnO and Fe-doped ZnO (Zn0.97Fe0.03O) nanoparticles were synthesized by simple coprecipitation method with zinc acetate, ferric nitrate and sodium hydroxide precursors. Pure ZnO and Fe-doped ZnO were further calcined at 450 ºC, 600 ºC and 750 ºC for 2 h. The structural, morphological and optical properties of the samples were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and UV-Vis absorption spectroscopy. The X-ray diffraction studies revealed that the as-synthesized pure and doped ZnO nanoparticles have hexagonal wurtzite structure. The average crystallite size was calculated using Debye-Scherrer’s formula. The particle size was found to be in nano range and increased with an increase in calcination temperature. SEM micrographs confirmed the formation of spherical nanoparticles. Elemental compositions of various elements in pure and doped ZnO nanoparticles were determined by EDX spectroscopy. UV-Vis absorption spectra showed red shift (decrease in band gap) with increasing calcination temperature. Effect of calcination on the magnetic properties of Fe-doped ZnO sample was also studied using vibrating sample magnetometer (VSM). M-H curves at room temperature revealed that coercivity and remanent polarization increase with an increase in calcination temperature from 450 ºC to 750 ºC, whereas reverse effect was observed for magnetization saturation.