University of Oulu

Petra S Pálvölgyi et al 2020 Nanotechnology 31 435203

Ultra-low permittivity porous silica-cellulose nanocomposite substrates for 6G telecommunication

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Author: Pálvölgyi, Petra S.1; Nelo, Mikko1; Pitkänen, Olli1;
Organizations: 1Microelectronics research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, P.O. Box 4500, FI-90014, Finland
2Fibre and Particle Engineering Research Unit, Faculty of Technology, University of Oulu, P.O. Box 4300, FI-90014, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
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Language: English
Published: IOP Publishing, 2020
Publish Date: 2020-09-22


The continuously increasing demand for faster data traffic of our telecommunication devices requires new and better materials and devices that operate at higher frequencies than today. In this work, a porous composite of silica nanoshells and cellulose nanofibers is demonstrated as a suitable candidate of dielectric substrates to be used in future 6G frequency bands. The hollow nanospheres of amorphous SiO2 with outstanding electromagnetic properties were obtained by a template-assisted Stöber process, in which a thin shell of silica is grown on polystyrene nanospheres first, and then the polymer core is burned off in a subsequent step. To be able to produce substrates with sufficient mechanical integrity, the nanoshells of SiO2 were reinforced with cellulose nanofibers resulting in a porous composite of very low mass density (0.19 ± 0.02 g cm−3), which is easy to press and mold to form films or slabs. The low relative dielectric permittivity (εr = 1.19 ± 0.01 at 300 GHz and εr = 1.17 ± 0.01 at 2.0 THz) and corresponding loss tangent (tan δ= 0.011 ± 0.001 at 300 GHz and tan δ = 0.011 ± 0.001 at 2.0 THz) of the composite films are exploited in substrates for radio frequency filter structures designed for 300 GHz operation.

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Series: Nanotechnology
ISSN: 0957-4484
ISSN-E: 1361-6528
ISSN-L: 0957-4484
Volume: 31
Issue: 43
Article number: 435203
DOI: 10.1088/1361-6528/aba4cc
Type of Publication: A1 Journal article – refereed
Field of Science: 221 Nanotechnology
Funding: The authors thank the technical assistance of Kai Metsäkoivu and Sami Saukko (Center of Microscopy and Nanotechnology, Univ. Oulu), Mika Huuhtanen (Environmental and Chemical Enineering, Univ. Oulu), and Yang Bai (Microelectronics Research Unit, Univ. Oulu), and the financial support received from EU Interreg Nord—Lapin liitto, University of Oulu (project Entity, and PoC Grant No. 24303414116) and EU BBI-JU (project NewPack, Grant No. 792261).
EU Grant Number: (792261) NEWPACK - Development of new Competitive and Sustainable Bio-Based Plastics
Copyright information: © The Authors 2020. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.