Microwave absorption of magnesium/hydrogen-treated titanium dioxide nanoparticles

Green, Michael; Tran, Anh Thi Van; Smedley, Russell; Roach, Adam; Murowchick, James B.; Chen, Xiaobo

doi:10.1016/j.nanoms.2019.02.001

Cited by 66 publications

(42 citation statements)

References 47 publications

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“…This procession of increasing activity appears to be quasi‐exponential across the various loadings with respect to the lossy portion, which is likely due to the Kramers–Kronig relations of causality compounding in the lossy portion, as though the lossless portion of permittivity increases increasingly as a function of wt%, it does so at a less pronounced rate. [ 15,46,47 ] This understanding is also represented in the dielectric loss ratio, which is the ratio of the lossy portion of permittivity with respect to the lossless, represented as tgδ ε in Figure 2C. This ratio generally increases as a function of wt%, suggesting that the response as a causal relationship is indeed compounding as the wt% is increased.…”

Section: Figurementioning

confidence: 88%

“…From the experimentally determined dielectric and magnetic responses, the reflection loss can be derived from Equations () and (), [ 46,47 ] were the reflection loss as RL of a single plane‐wave absorber is the function of the input impedance Z in . [ 52–54 ] Z in is in turn a function of frequency and thickness, and furthermore the permittivity and permeability parameters ε′, ε″, μ′, and μ″, which are all in turn a function of frequency.…”

Section: Figurementioning

confidence: 99%

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Obtaining Strong, Broadband Microwave Absorption of Polyaniline Through Data‐Driven Materials Discovery

Green

Tran

Chen

2020

Adv Materials Inter

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materials development methods do not guarantee results. Yet, the continued development of microwave absorbing materials is imperative. These materials are highly utilized in the defense [16-22] and telecommunications industries, [18,23-27] as means for reducing radar cross sections for stealth technology, [28,29] and providing electromagnetic interference shielding for the information processing and transport capabilities in electronic devices. The progression of research and development in the field of MAMs continues to accelerate, and researchers are in need of new methods for materials development and analysis. One of the most common components integrated into materials systems for microwave absorption is polyaniline. [30-36] This polymer, particularly the protonated Emeraldine Salt variation due to its high conductivity, is a popular material for MAM research and development due the strong dielectric response it demonstrates when irradiated with GHz-range electromagnetic energy. [15] For example, Liu et al. embedded a graphene-polyaniline matrix with nickel ferrite in an attempt to synergistically couple the magnetic properties of the ferrite with the dielectric nature of the matrix. This coupling resulted in a strong microwave interaction and reflection loss of −50.5 dB at 12.5 GHz, with an effective bandwidth of 5.3 GHz. [30] Wang et al. took a similar approach, imbedding a nickel-zinc ferrite into a polyaniline matrix, with a similar goal of coupling the strong dielectric action of the polyaniline material with a magnetic material. The maximal reflection loss realized by these efforts was −41 dB at 12.8 GHz and a 5 GHz effective bandwidth with a material thickness of 2.6 mm. [31] In this study, we demonstrate for the first time a data-driven process for optimizing the microwave absorbing properties of polyaniline. The final reflection loss is maximally reported as −88.54 dB with (f, d) coordinates of (7.0 GHz, 3.8 mm) 5.5 GHz with a 2.1 mm thickness. These results are record-setting for polyaniline-based materials, and the methods used to achieve these experimentally-validated results are thought to be scalable and applicable to the type of research methodologies prevalent in MAM development. As such, this type of data-driven optimization has the potential to revolutionize materials R&D for microwave absorption. The polyaniline materials were synthesized according to standard literature procedures [37] and characterized via X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and Microwave absorbing materials (MAMs) are highly utilized in the defense and telecommunications industries, as means for reducing radar cross sections for stealth technology, and providing electromagnetic interference shielding for the information processing and transport capabilities in electronic devices. Polyaniline materials have attracted enormous attention in the field of MAM development due to their strong dielectric properties. In this manuscript, the strong dielectric action of polyaniline is utilized to demonstrate...

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Section: Figurementioning

confidence: 88%

Section: Figurementioning

confidence: 99%

Obtaining Strong, Broadband Microwave Absorption of Polyaniline Through Data‐Driven Materials Discovery

Green

Tran

Chen

2020

Adv Materials Inter

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“…Additionally, hydrogenation of TiO 2 nanocrystals can also result in visible-light-responsible materials (Chen et al., 2011). The latest studies show that these low-energy absorption materials arouse utilities in visible light water splitting and microwave and terahertz absorption (Green et al., 2018a, Green et al., 2018b, Green et al., 2019a, Green et al., 2019b, Guan and Chen, 2018, Tian et al., 2017). Unfortunately, harsh reaction conditions and long-time treatment have limited the practicality of these methods, especially in the context of on-site fabrication and reprocessing of light harvesting devices.…”

Section: Introductionmentioning

confidence: 99%

Modification of TiO2 Nanoparticles with Organodiboron Molecules Inducing Stable Surface Ti3+ Complex

Cao

Zhou

et al. 2019

iScience

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SummaryAs one of the most promising semiconductor oxide materials, titanium dioxide (TiO2) absorbs UV light but not visible light. To address this limitation, the introduction of Ti3+ defects represents a common strategy to render TiO2 visible-light responsive. Unfortunately, current hurdles in Ti3+ generation technologies impeded the widespread application of Ti3+ modified materials. Herein, we demonstrate a simple and mechanistically distinct approach to generating abundant surface-Ti3+ sites without leaving behind oxygen vacancy and sacrificing one-off electron donors. In particular, upon adsorption of organodiboron reagents onto TiO2 nanoparticles, spontaneous electron injection from the diboron-bound O2− site to adjacent Ti4+ site leads to an extremely stable blue surface Ti3+‒O−· complex. Notably, this defect generation protocol is also applicable to other semiconductor oxides including ZnO, SnO2, Nb2O5, and In2O3. Furthermore, the as-prepared photoelectronic device using this strategy affords 103-fold higher visible light response and the fabricated perovskite solar cell shows an enhanced performance.

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“…Ever since the revelation that reflection loss as a parameter of interest was shown to not be the defining characteristic of radar-absorbing materials (RAM) Green, Liu, et al, 2019;Green, Tran, et al, 2019), the RAM development community has been bereft of the tools necessary to determine the parameters desired by the new RAM performance hierarchy. Elucidating the new parameters of interest, such as the effective bandwidth, requires non-trivial derivations and calculations that many labs in the RAM community are simply not prepared to handle, at least not at the scale necessary for thorough characterization.…”

Section: Discussionmentioning

confidence: 99%

libRL: A Python library for the characterization of microwave absorption

Green¹,

Chen²

2019

JOSS

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Microwave absorption of magnesium/hydrogen-treated titanium dioxide nanoparticles

Cited by 66 publications

References 47 publications

Obtaining Strong, Broadband Microwave Absorption of Polyaniline Through Data‐Driven Materials Discovery

Obtaining Strong, Broadband Microwave Absorption of Polyaniline Through Data‐Driven Materials Discovery

Modification of TiO2 Nanoparticles with Organodiboron Molecules Inducing Stable Surface Ti3+ Complex

libRL: A Python library for the characterization of microwave absorption

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