More Like this

1. Magnetic Sensing Potential of Fe 3 O 4 Nanocubes Exceeds That of Fe 3 O 4 Nanospheres

   https://doi.org/10.1021/acsomega.7b01312  

   Kolhatkar, Arati G. ; Chen, Yi-Ting ; Chinwangso, Pawilai ; Nekrashevich, Ivan ; Dannangoda, Gamage C. ; Singh, Ankit ; Jamison, Andrew C. ; Zenasni, Oussama ; Rusakova, Irene A. ; Martirosyan, Karen S. ; et al ( November 2017 , ACS Omega)
2. Lattice Expansion in Metal Oxide Nanoparticles: MgO, Co 3 O 4 , & Fe 3 O 4

   https://doi.org/10.1111/jace.14478  

   Rodenbough, Philip P. ; Zheng, Chengjunyi ; Liu, Yuxuan ; Hui, Chenyuan ; Xia, Yuxuan ; Ran, Ziying ; Hu, Yanjun ; Chan, Siu-Wai ; Wong-Ng, ed., W. ( January 2017 , Journal of the American Ceramic Society)
3. Oxygen Reduction Electrocatalysis with Epitaxially Grown Spinel MnFe 2 O 4 and Fe 3 O 4

   https://doi.org/10.1021/acscatal.1c05172  

   Bredar, Alexandria R. ; Blanchet, Miles D. ; Burton, Andricus R. ; Matthews, Bethany E. ; Spurgeon, Steven R. ; Comes, Ryan B. ; Farnum, Byron H. ( March 2022 , ACS Catalysis)

   Nanocrystalline MnFe2O4 has shown promise as a catalyst for the oxygen reduction reaction (ORR) in alkaline solutions, but the material has been sparingly studied as highly ordered thin-film catalysts. To examine the role of surface termination and Mn and Fe site occupancy, epitaxial MnFe2O4 and Fe3O4 spinel oxide films were grown on (001)- and (111)-oriented Nb:SrTiO3 perovskite substrates using molecular beam epitaxy and studied as electrocatalysts for the oxygen reduction reaction (ORR). High-resolution X-ray diffraction (HRXRD) and X-ray photoelectron spectroscopy (XPS) show the synthesis of pure phase materials, while scanning transmission electron microscopy (STEM) and reflection high-energy electron diffraction (RHEED) analysis demonstrate island-like growth of (111) surface-terminated pyramids on both (001)- and (111)-oriented substrates, consistent with the literature and attributed to the lattice mismatch between the spinel films and the perovskite substrate. Cyclic voltammograms under a N2 atmosphere revealed distinct redox features for Mn and Fe surface termination based on comparison of MnFe2O4 and Fe3O4. Under an O2 atmosphere, electrocatalytic reduction of oxygen was observed at both Mn and Fe redox features; however, a diffusion-limited current was only achieved at potentials consistent with Fe reduction. This result contrasts with that of nanocrystalline MnFe2O4 reported in the literature where the diffusion-limited current is achieved with Mn-based catalysis. This difference is attributed to a low density of Mn surface termination, as determined by the integration of current from CVs collected under N2, in addition to low conductivity through the MnFe2O4 film due to the degree of inversion. Such low densities are attributed to the synthetic method and island-like growth pattern and highlight challenges in studying ORR catalysis with single-crystal spinel materials. 

   more » « less
4. Optical thermal insulation via the photothermal effects of Fe 3 O 4 and Fe 3 O 4 @Cu 2−x S thin films for energy-efficient single-pane windows

   https://doi.org/10.1557/mrc.2020.4  

   Lin, Jou ; Zhao, Yuan ; Shi, Donglu ( March 2020 , MRS Communications)

   To address critical energy issues in civic structures, we have developed a novel concept of optical thermal insulation (OTI) without relying on a conventional thermal intervention medium, such as air or argon, as often used in conventional window systems. We have synthesized the photothermal (PT) materials, such as the Fe 3 O 4 and Fe 3 O 4 @Cu 2− x S nanoparticles, that exhibit strong UV and near-infrared (NIR) absorptions but with good visible transparency. Upon coating the inner surface of the window glass with a PT film, under solar irradiation, the inner surface temperature rises due to the PT effect. Subsequently, the temperature difference, Δ T , is reduced between the single pane and room interior. This leads to lower the thermal loss through a window, reflected by the U -factor, resulting in considerable energy saving without double- or triple-glazing. Comparing with the Fe 3 O 4 coatings, Fe 3 O 4 @Cu 2− x S is spectrally characterized with a much stronger NIR absorbance, contributing to an increased PT efficiency under simulated solar irradiation (0.1 W/cm 2 ). PT experiments are carried out via both white light and monochromic NIR irradiations (785 nm). The parameters associated with the thermal performance of the PT films are calculated, including PT conversion efficiency, specific absorption rate (SAR), and U -factor. Based on the concept of OTI, we have reached an optimum U -factor of 1.46 W/m 2 K for a single pane, which is satisfactory to the DOE requirement (<1.7 W/m 2 K). 

   more » « less
5. Effect of interface on epitaxy and magnetism in h-RFeO 3 /Fe 3 O 4 /Al 2 O 3 films (R  =  Lu, Yb)

   https://doi.org/10.1088/1361-648X/aa5fec  

   Zhang, Xiaozhe ; Yin, Yuewei ; Yang, Sen ; Yang, Zhimao ; Xu, Xiaoshan ( April 2017 , Journal of Physics: Condensed Matter)