High quality factor cold sintered Li2MoO4BaFe12O19 composites for microwave applications
journal contributionposted on 07.02.2019, 10:23 by Sinan S. Faouri, Ali Mostaed, Julian S. Dean, Dawei Wang, Derek C. Sinclair, Shiyu Zhang, William WhittowWilliam Whittow, J. C. Vardaxoglou, Ian M. Reaney
Ceramics-ceramic composites in series (1-x)Li2MoO4-xBaFe12O19 (LMO-BF12, 0.00 ≤ x ≤ 0.15) have been cold sintered at 120 °C and their structure and properties characterized. X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that compositions were dual phase and had a dense microstructure. Composites in the xBF12-(1-x)LMO (0.0 ≤ x ≤ 0.15) series resonated at MW frequencies (∼6 GHz) with 5.6≤εr ≤ 5.8 and Qf = 16,000–22,000 GHz, despite the black colour of compositions with x > 0. The permeability of the composites was measured in the X band (∼8 GHz) and showed an increase from 0.94 (x = 0.05) to 1.02 (x = 0.15). Finite element modelling revealed that the volume fraction of BF12 dictates the conductivity of the material, with a percolation threshold at 10 vol% BF12 but changes in εr as a function of x were readily explained using a series mixing model. In summary, these composites are considered suitable for the fabrication of dual mode or enhanced bandwidth microstrip patch antennas.
Ian M. Reaney and Julian S. Dean would like to acknowledge the Engineering and Physical Sciences Research Council (EPSRC) grants, EP/L017563/1 and EP/N010493/1.
- Mechanical, Electrical and Manufacturing Engineering