I.J. Induja, M.T. Sebastian, Microwave dielectric properties of mineral sillimanite obtained by conventional and cold sintering process, Journal of the European Ceramic Society, Volume 37, Issue 5, 2017, Pages 2143-2147, ISSN 0955-2219, https://doi.org/10.1016/j.jeurceramsoc.2017.01.007
Microwave dielectric properties of mineral sillimanite obtained by conventional and cold sintering process
|Author:||Induja, I.J.1; Sebastian, M.T.2|
1Materials Science & Technology Division, National Institute for Interdisciplinary Science Technology, Thiruvananthapuram, 695019, India
2Microelectronics Research Unit Faculty of Information Technology & Electrical Engineering, University of Oulu, Oulu, P.O. Box 4500, FI90014, Finland
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe2019052016173
|Publish Date:|| 2019-05-31
The sillimanite (Al₂SiO₅) mineral has been sintered by conventional ceramic route and by cold sintering methods. The mineral has very poor sinterability and transformed to mullite on sintering above 1525 °C. The dielectric properties of sillimanite mineral (Al₂SiO₅) are investigated at radio and microwave frequency ranges. The mineral sintered at 1525 °C has low εᵣ of 4.71 and tanδ of 0.002 at 1 MHz and at microwave frequency εᵣ = 4.43, Qᵤ × f = 41,800 GHz with τf = −17 ppm/°C. The sintering aid used for cold sintering Al₂SiO₅ is sodium chloride (NaCl). The Al₂SiO₅—NaCl composite was cold sintered at 120 °C. XRD analysis of the composite revealed that there is no additional phase apart from Al₂SiO₅ and NaCl. The densification of the Al₂SiO₅—NaCl composite was confirmed by using microstructure analysis. The Al₂SiO₅—NaCl composite has εᵣ of 5.37 and tanδ of 0.005 at 1 MHz whereas at microwave frequency it has εᵣ = 4.52, Qu × f = 22,350 GHz with τf = −24 ppm/°C. The cold sintered NaCl has εᵣ = 5.2, Qu × f = 12,000 GHz with τf = −36 ppm/°C.
Journal of the European Ceramic Society
|Pages:||2143 - 2147|
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
216 Materials engineering
© 2017 Elsevier Ltd. All rights reserved. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/.