Effect of annealing temperature on magnetic phase transition in Fe3O4 nanoparticles

Carbon materials have aroused extensive interests for their remarkable electrical properties as electromagnetic wave (EMW) absorption. However, the synthesis of the wide-band electromagnetic wave absorbent is an insuperable challenge for attaining effective refection loss and electromagnetic matching. Herein, a facile method for large-scale synthesis of monodispersed Fe/Fe 3 O 4 /C composite microspheres is proposed. The carbon microspheres (1-2 μm in diameter) imbedded with nanosized Fe/Fe 3 O 4 2 particles (10-20 nm) are uniformly produced by polymerization and carbothermic reduction processes. The products exhibit the minimum refection loss-45.5 dB at 9.4 GHz and a broad bandwidth of 4.1 GHz below-10 dB from 7.8 GHz to 11.9 GHz with a thickness of 3.0 mm. The absorption mechanism indicates a unique deviated Debye dipolar relaxation effect in the absorbing bandwidth.

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“…88-0866 ) [38]. The crystallite size of the as-prepared Fe 3 O 4 was calculated by the Debye-Scherrer equation [15,39]:…”

Section: Resultsmentioning

confidence: 99%

In-situ growth of Fe/Fe3O4/C hierarchical architectures with wide-band electromagnetic wave absorption

Meng

Zhang

et al. 2018

Ceramics International

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“…Here, the crystalline size L (diffraction angle at 2q ¼ 4.5 ~4 .6 ) of P3OT in the P3OT/PCBM/sorbitol derivative blend is calculated by using the Scherrer equation [43]:…”

Section: Resultsmentioning

confidence: 99%

Structure difference of sorbitol derivatives influences the crystallization and performance of P3OT/PCBM organic photovoltaic solar cells

Wang

Zhang

Liu

et al. 2017

Organic Electronics

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“…1a, some changes in the magnetite phase occurred, maghemite (a = 8.379 Å), iron (a = 2.868 Å) and traces of hematite (proto) being identified in the diffraction pattern of Fe 3 O 4 /MGNC, in addition to magnetite (a = 8.343 Å) and graphite. Since magnetite nanoparticles are very sensitive to oxidation in the presence of oxygen, these phase modifications can be ascribed to the progressive oxidation of Fe 2+ ions in the inverse spinel structure of magnetite to Fe 3+ -most likely during the Fe 3 O 4 /MGNC synthesis step performed in liquid phase (i.e., in oxidative media), resulting in its partial oxidation to maghemite and hematite [33,34].…”

Section: Materials Characterizationmentioning

confidence: 99%

Hybrid magnetic graphitic nanocomposites towards catalytic wet peroxide oxidation of the liquid effluent from a mechanical biological treatment plant for municipal solid waste

Ribeiro

Rodrigues

Silva

et al. 2017

Applied Catalysis B: Environmental

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a b s t r a c tMagnetite, nickel and cobalt ferrites were prepared and encapsulated within graphitic shells, resulting in three hybrid magnetic graphitic nanocomposites. Screening experiments with a 4-nitrophenol aqueous model system (5 g L −1 ) allowed to select the best performing catalyst, which was object of additional studies with the liquid effluent resulting from a mechanical biological treatment plant for municipal solid waste. Due to its high content in bicarbonates (14350 mg L −1 ) and chlorides (2833 mg L −1 ), controlling the initial pH was a crucial step to maximize the performance of the catalytic wet peroxide oxidation (CWPO) treatment. The catalyst load was 0.5 g L −1 , a very low dosage when compared to the high chemical oxygen demand (COD) of the effluent − 9206 mg L −1 . At the optimum operating pH (i.e., pH = 6), ca. 95% of the aromaticity was converted and ca. 55% of COD and total organic carbon (TOC) of the liquid effluent was removed. The biodegradability of the liquid effluent was enhanced during the treatment by CWPO, as reflected by the 2-fold increase of the five-day biochemical oxygen demand (BOD 5 ) to COD ratio (BOD 5 /COD), namely from 0.21 (indicating non-biodegradability) to 0.42 (suggesting biodegradability of the treated wastewater). In addition, the treated water revealed no toxicity against selected bacteria.Lastly, a magnetic separation system was designed for in-situ catalyst recovery after the CWPO reaction stage. The high catalyst stability was demonstrated through five reaction/separation sequential experiments in the same vessel with consecutive catalyst reuse.

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Effect of annealing temperature on magnetic phase transition in Fe3O4 nanoparticles

Cited by 120 publications

References 41 publications

In-situ growth of Fe/Fe3O4/C hierarchical architectures with wide-band electromagnetic wave absorption

In-situ growth of Fe/Fe3O4/C hierarchical architectures with wide-band electromagnetic wave absorption

Structure difference of sorbitol derivatives influences the crystallization and performance of P3OT/PCBM organic photovoltaic solar cells

Hybrid magnetic graphitic nanocomposites towards catalytic wet peroxide oxidation of the liquid effluent from a mechanical biological treatment plant for municipal solid waste

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