scholarly journals Morphological aspects of Bismuth ferrite powders prepared by microwave-assisted hydrothermal method

2019 ◽  
Vol 1 (1) ◽  
pp. 52-53
Keyword(s):  
Reaction Mechanism ◽  
Hydrothermal Method ◽  
Bismuth Ferrite ◽  
Magnetic Behavior ◽  
Secondary Phase ◽  
Secondary Phases ◽  
Hydrothermal Conditions ◽  
Microwave Assisted ◽  
Microwave Hydrothermal ◽  
Morphological Aspects

BiFeO3 particles were synthetized by a fast, reproducible and environmental friendly microwave-assisted hydrothermal method. The aim of the study was the investigation of increased pressure and mineralizer concentration on the reaction mechanism, morphology of particles and aggregates as well as magnetic behavior. Powders were studied when using KOH mineralizer concentration from 4 to 12 M at room temperature and under microwave-hydrothermal conditions at 40 bar and 150 or 200°C. The reaction mechanism depends on the temperature of the microwave-hydrothermal treatment and the concentration of KOH mineralizer. The precursor powder obtained after coprecipitation step consists of Bi2O3, Fe2O3 and Bi25FeO40 in different ratios. After the treatment at 40 bar and 150°C for 1h the reaction between precursors is not complete, therefore resulting secondary phases of Bi25FeO40 and Fe2O3. BiFeO3 particles were successfully synthesized at 40 bar under microwave-hydrothermal conditions at a temperature of 200°C and a concentration of KOH of at least 8M. At 6M, the composition consisted of 98.5% BiFeO3 and 1.5% Bi2O3 as evidenced by Rietveld refinement. The competition between dissolution and precipitation of Bi3+ and Fe3+ in KOH solutions of different concentrations was investigated by Raman spectroscopy and EDS analysis. Thus, at 200°C there was evidenced a Bi2O3 secondary phase for 6 M KOH concentration and poor control of Bi/Fe ratio in BiFeO3 at KOH concentrations of 10 and 12 M. Particle and aggregates morphology depicted by FE-SEM investigations showed a tendency to form irregular shaped particles at KOH concentration of 6 M, for which the reaction is not complete. When increasing the concentration, BiFeO3 particles exhibit regular shapes from cubic at 8 M to cvasi-spherical at 14 M. M-H curves characteristics illustrate that Bi/Fe ratio and preferential orientation of crystal growth influence the magnetic behavior of BiFeO3 crystalline powders.

Rapid synthesis of single-phase bismuth ferrite by microwave-assisted hydrothermal method

2016 ◽  
Vol 175 ◽  
pp. 1-5 ◽  
Author(s):  
Wenqian Cao ◽  
Zhi Chen ◽  
Tong Gao ◽  
Dantong Zhou ◽  
Xiaonan Leng ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Single Phase ◽  
Bismuth Ferrite ◽  
Rapid Synthesis ◽  
Microwave Assisted

COMPARATIVE STUDY OF MAGNETIC BEHAVIOR OF RuSr2RE1.5Ce0.5Cu2O10-δ WHERE RE = Eu AND Sm

2009 ◽  
Vol 23 (17) ◽  
pp. 3486-3491
Author(s):  
R. NIGAM ◽  
A. V. PAN ◽  
S. X. DOU
Keyword(s):  
Magnetic Behavior ◽  
Secondary Phase ◽  
Systematic Investigation ◽  
Zero Field ◽  
Secondary Phases ◽  
Preparation Conditions ◽  
Small Peak ◽  
Treatment Conditions ◽  
Similar Preparation ◽  
Superposition Effect

Systematic investigation of structural, magnetic and transport properties of RuSr 2 RE 2-x Ce x Cu 2 O 10 with RE being Sm and Eu has been performed. We present the experimental evidence that the synthesis of RuSr 2 Eu 1.5 Ce 0.5 Cu 2 O 10 under non-optimised heat treatment conditions may results in the formation of secondary RuSr 2 EuCu 2 O 8 phase. In contrast, similar preparation conditions for RuSr 2 Sm 1.5 Ce 0.5 Cu 2 O 10 samples lead to the pure phase. Consequently, RuSr 2 Eu 1.5 Ce 0.5 Cu 2 O 10 samples exhibit a small peak around 125 K in the temperature dependence of dc magnetization, pronounced irreversibility between zero-field cooled and field cooled curves at temperatures higher than the peak temperature, and the bell shaped behavior of the coercive field as the function of temperature above Curie's temperature. These anomalous features, which may arise due to the superposition effect of the main and secondary phases, which are both magnetic, are completely absent for RuSr 2 Sm 1.5 Ce 0.5 Cu 2 O 10 sample, which does not consist of the secondary phase.

Ultra Fast Hematite Preparation using a Microwave-Assisted Hydrothermal Method

2013 ◽  
Vol 3 (4) ◽  
pp. 477-484
Author(s):  
Arnayra Silva ◽  
Jefferson Andrade ◽  
Graziela Casali ◽  
Severino Lima ◽  
Elson Longo ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Microwave Assisted

Luminescent properties of Y(OH)3: Tb nanopowders synthesized by microwave-assisted hydrothermal method

2019 ◽  
Vol 21 (5) ◽  
Author(s):  
I. A. Garduño-Wilches ◽  
G. Alarcón-Flores ◽  
S. Carmona-Téllez ◽  
J. Guzmán ◽  
M. Aguilar-Frutis
Keyword(s):  
Hydrothermal Method ◽  
Luminescent Properties ◽  
Microwave Assisted

An Orthorhombic Modification of KCoPO4 Stabilized under Hydrothermal Conditions: Crystal Chemistry and Magnetic Behavior

2021 ◽  
Author(s):  
Olga V. Yakubovich ◽  
Larisa V. Shvanskaya ◽  
Nadezhda B. Bolotina ◽  
Anna G. Ivanova ◽  
Galina V. Kiriukhina ◽  
...  
Keyword(s):  
Crystal Chemistry ◽  
Magnetic Behavior ◽  
Hydrothermal Conditions ◽  
Orthorhombic Modification

scholarly journals Microwave-Assisted vs. Conventional Hydrothermal Synthesis of MoS2 Nanosheets: Application towards Hydrogen Evolution Reaction

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1040 ◽  
Author(s):  
Getachew Solomon ◽  
Raffaello Mazzaro ◽  
Vittorio Morandi ◽  
Isabella Concina ◽  
Alberto Vomiero
Keyword(s):  
Hydrothermal Synthesis ◽  
Hydrothermal Method ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
Crystal Morphology ◽  
Synthesis Method ◽  
Synthesis Methods ◽  
Mos2 Nanosheets ◽  
Microwave Assisted

Molybdenum sulfide (MoS2) has emerged as a promising catalyst for hydrogen evolution applications. The synthesis method mainly employed is a conventional hydrothermal method. This method requires a longer time compared to other methods such as microwave synthesis methods. There is a lack of comparison of the two synthesis methods in terms of crystal morphology and its electrochemical activities. In this work, MoS2 nanosheets are synthesized using both hydrothermal (HT-MoS2) and advanced microwave methods (MW-MoS2), their crystal morphology, and catalytical efficiency towards hydrogen evolution reaction (HER) were compared. MoS2 nanosheet is obtained using microwave-assisted synthesis in a very short time (30 min) compared to the 24 h hydrothermal synthesis method. Both methods produce thin and aggregated nanosheets. However, the nanosheets synthesized by the microwave method have a less crumpled structure and smoother edges compared to the hydrothermal method. The as-prepared nanosheets are tested and used as a catalyst for hydrogen evolution results in nearly similar electrocatalytic performance. Experimental results showed that: HT-MoS2 displays a current density of 10 mA/cm2 at overpotential (−280 mV) compared to MW-MoS2 which requires −320 mV to produce a similar current density, suggesting that the HT-MoS2 more active towards hydrogen evolutions reaction.

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