Investigating the broadband microwave absorption of nanodiamond impurities

Cuenca, Jerome A. ORCID: https://orcid.org/0000-0003-1370-1167, Thomas, Evan L. H., Mandal, Soumen ORCID: https://orcid.org/0000-0001-8912-1439, Williams, Oliver Anuerin ORCID: https://orcid.org/0000-0002-7210-3004 and Porch, Adrian ORCID: https://orcid.org/0000-0001-5293-8883 2015. Investigating the broadband microwave absorption of nanodiamond impurities. IEEE Transactions on Microwave Theory and Techniques 63 (12) , pp. 4110-4118. 10.1109/TMTT.2015.2495156

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Abstract

Broadband microwave complex permittivity measurements of nanodiamond powders are presented. Previous studies show that measurements of dielectric loss strongly correlate with the presence of nondiamond surface impurities. In this study, the frequency dependence of these losses is investigated using the microwave cavity perturbation (MCP) and broadband coaxial probe (BCP) methods. This allowed further understanding as to what mechanisms contribute to the microwave absorption (free electron conduction or dielectric loss from the disordered surfaces). A multimode MCP system is used which utilizes ${rm TM}_{0np}$ modes to provide partial spectral characterization. The MCP results revealed minimal frequency dependence, unlike any static conduction-related mechanism. The BCP measurements corroborate the MCP results with much higher spectral resolution, and further demonstrate that disorder related loss may dominate over free electron conduction from 1–10 GHz. From 0.1–1 GHz, free electron conduction has a greater influence with a characteristic $1/f$ dependence implying that conduction may dominate at lower frequencies. However, the BCP method, while repeatable, lacks in precision compared to the cavity method. Nonetheless, the major conclusion in this paper is that through simple microwave permittivity measurements, nondiamond carbon impurities in nanodiamond powders are measurable most likely because of disorder related losses as opposed to free electron conduction.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Engineering Physics and Astronomy
Publisher:	IEEE
ISSN:	0018-9480
Funders:	EPSRC
Date of First Compliant Deposit:	30 March 2016
Date of Acceptance:	17 November 2015
Last Modified:	06 Jan 2024 02:38
URI:	https://orca.cardiff.ac.uk/id/eprint/83771

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