ALBERT

Description: 〈p〉Publication date: March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Acta Materialia, Volume 166〈/p〉 〈p〉Author(s): Sinan S. Faouri, Ali Mostaed, Julian S. Dean, Dawei Wang, Derek C. Sinclair, Shiyu Zhang, William G. Whittow, Yiannis Vardaxoglou, Ian M. Reaney〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ceramics-ceramic composites in series (1-〈em〉x〈/em〉)Li〈sub〉2〈/sub〉MoO〈sub〉4〈/sub〉-〈em〉x〈/em〉BaFe〈sub〉12〈/sub〉O〈sub〉19〈/sub〉 (LMO-BF12, 0.00 ≤ 〈em〉x〈/em〉 ≤ 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 〈em〉x〈/em〉BF12-(1-〈em〉x〈/em〉)LMO (0.0 ≤ 〈em〉x〈/em〉 ≤ 0.15) series resonated at MW frequencies (∼6 GHz) with 5.6≤〈em〉ε〈/em〉〈sub〉〈em〉r〈/em〉〈/sub〉 ≤ 5.8 and 〈em〉Qf〈/em〉 = 16,000–22,000 GHz, despite the black colour of compositions with 〈em〉x〈/em〉 〉 0. The permeability of the composites was measured in the X band (∼8 GHz) and showed an increase from 0.94 (〈em〉x〈/em〉 = 0.05) to 1.02 (〈em〉x〈/em〉 = 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 〈em〉ε〈/em〉〈sub〉〈em〉r〈/em〉〈/sub〉 as a function of 〈em〉x〈/em〉 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.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S1359645418310085-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉