Response surface method optimization for the formation of yitrium iron garnet and its kinetic studies for dielectric resonator antenna application made by solid state sintering
| dc.contributor.author | Wan Fahmi Faiz Wan Ali | |
| dc.date.accessioned | 2021-03-23T08:37:58Z | |
| dc.date.available | 2021-03-23T08:37:58Z | |
| dc.date.issued | 2014-12-01 | |
| dc.description.abstract | Single phase dielectric materials are desirable for dielectric resonator antenna (DRA) applications to avoid any surface reflection which will deteriorate the DRA performance due to the presence of unwanted phase cause the electromagnetic wave be reflected from it. However, to synthesize a single phase material such as yttrium iron garnet (YIG) is challenging. The presence of the secondary phase such as YFeO3 (YIP) in YIG negatively influences its DRA performance. In this investigation, the percentage of YIG formation was optimized via conventional solid state reaction (CSSR). Three factors that involved for this investigation are (i) effect of formation temperature, (ii) Fe2O3 particle size and, (iii) excess Fe2O3 have been investigated This can be achieved through the design of experiment (DOE) via the response surface method (RSM) approach. Based on DOE analysis, it was found that at 1240 oC of the formation temperature with 5 μm of Fe2O3 particle size and 8 wt.% of excess Fe2O3 in the standard YIG stoichiometry able to obtain YIG purity up to 99.2 %. Meanwhile, the kinetic and phase transformation mechanism studies indicated the formation of single phase YIG is in accordance the Ginstling-Brounshtein-Habert (GBH) model. The model described that two reacted layer formed throughout the YIG formation; first layer is the formation of YIP phase and further reaction between Fe2O3 with YIP will form a second layer (YIG). Later, the optimized factors for YIG formation (OPYIG) from DOE was sintered at 1420 oC for 6 hours in order to form a high density final product (firing optimization). The average grain size of the sintered OPYIG is 5.98 μm, the density measured via Archimedes principle is 5.023 g/cm3 and 0.2 % porosity. The measured dielectric properties (dielectric constant, εr = 15.72 and tangent loss, tan δ = 0.0069) show that OPYIG is a suitable material for DRA applications. For the best DRA performance, the OPYIG position has to be in 36 mm distance from the microstrip port. At this position, the DRA measurement of OPYIG shows very strong HEM11 excitation mode and resonated at 12.501 GHz. The observed radiation pattern shows OPYIG has exhibited a stable and bi-directional pattern indicated that the signal could be received by two preferred directions. Therefore, high purity YIG is successfully synthesized via CSSR route and suitable for DRA applications that covers the Ku-band (12 GHz to 18 GHz) frequency range. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/12504 | |
| dc.language.iso | en | en_US |
| dc.title | Response surface method optimization for the formation of yitrium iron garnet and its kinetic studies for dielectric resonator antenna application made by solid state sintering | en_US |
| dc.type | Thesis | en_US |
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