| Effect of dissolution on dielectric properties of Y‑α/β SiAlON fabricated by SPS |
| R. Noori1,2, Parvin Alizadeh1, S. S. S. Afghahi2 |
1Tarbiat Modares University Faculty of Engineering, Tehran, Iran
2Department of Engineering, Imam Hossein University, Tehran, Iran |
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Received: June 4, 2021; Revised: August 10, 2021 Accepted: September 11, 2021. Published online: November 30, 2021. |
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| ABSTRACT |
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In this study, different initial compositions of Y-Si-Al-O-N system were selected in such a way that the sintered phase structures to be obtained as α-SiAlON, β-SiAlON and α/β SiAlON with various amounts of dissolution in each of these phases. Sintering parameters for all samples were the same and applied by SPS technique. Densification and phase transformation progress at lower temperature and shorter period resulting in a fine-grained structure because of high heating rate along with inducing the pulsed current. Dielectric properties of samples were investigated within the considered 8.2–12.4 GHz frequency range. In the case that the additives were not participated as solutes in the structure of Si3N4 and aggregated in the amorphous form at grain boundaries, dielectric constant was decreased; otherwise, when they were dissolved in the structure, it led to enhancement of bond length in Si3N4 and change of its covalent feature into ionic feature associated with increase of dielectric constant. Examination of dielectric loss peak revealed that by increase of amount of dissolution, the resonance peak shifts to lower frequencies indicating the longer natural period of corresponding dipoles which may be caused by increase of bond length and decrease of its strength. |
| Key words:
α/β SiAlON · Dielectric properties · SPS · Resonance peak · Dissolution · Si3N4 |
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