###### Abstract  
The sintering behavior, microstructure analysis, crystallization, and microwave performance of (Mg\({}_{0.6}\)Zn\({}_{0.4}\))\({}_{1-y}\)Ni\({}_{y}\)TiO\({}_{3}\) (\(y=0.01\)-\(0.2\)) ceramics, processed with raw powders of MgO, NiO, ZnO, and TiO\({}_{2}\) via the conventional solid-state method, are investigated. The main phases of (Mg\({}_{0.6}\)Zn\({}_{0.4}\))\({}_{1-y}\)Ni\({}_{y}\)TiO\({}_{3}\) ceramics were obtained. With partial replacement by Ni\({}^{2+}\), the (Mg\({}_{0.6}\)Zn\({}_{0.4}\))\({}_{0.95}\)Ni\({}_{0.05}\)TiO\({}_{3}\) could be well sintered at 1200 \({}^{\circ}\)C, and the microwave performance was shown to be positively correlated with sintering temperature. The permittivity (\(\epsilon_{r}\)) saturated at 18.7-19.3, and the quality factor (Q/) values approached 72,000-165,000 (GHz) as the sintering temperatures increase from 1125 to 1250 \({}^{\circ}\)C. The temperature coefficient of resonance frequency (\(\tau_{f}\)) falls in a stable range of \(-62.9\) to \(-66\) ppm/\({}^{\circ}\)C as sintering temperature rising. A permittivity (\(\epsilon_{r}\)) of 19.3, a maximum Q/ value of 165,000 (GHz), and a temperature coefficient (\(\tau_{f}\)) of \(-65.4\) ppm/\({}^{\circ}\)C were measured for the samples at 1200 \({}^{\circ}\)C/4 h. (Mg\({}_{0.6}\)Zn\({}_{0.4}\))\({}_{0.95}\)Ni\({}_{0.05}\)TiO\({}_{3}\) material system shows high potential for applications of high frequency-selection components in satellite communication and 5G wireless telecommunication systems.  
dielectric materials; microwave properties; microstructure; low loss +
Footnote †: journal: Applied Sciences  
**Citation:** [PERSON]; [PERSON]; [PERSON]; [PERSON] Microwave Performance, Microstructure, and Crystallization of (Mg\({}_{0.6}\)Zn\({}_{0.4}\))\({}_{1-y}\)Ni\({}_{y}\)TiO\({}_{3}\) Ilmenite Ceramics. _Appl. Sci._**2021**, _11_, 2952.  
[[https://doi.org/10.3309/app11072962](https://doi.org/10.3309/app11072962)]([https://doi.org/10.3309/app11072962](https://doi.org/10.3309/app11072962))  
Academic Editor: [PERSON]  
Received: 20 February 2021  
Accepted: 22 March 2021  
Published: 25 March 2021  
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**Construction:** (2021) 11, 2952. [[https://doi.org/10.3390/app11072952](https://doi.org/10.3390/app11072952)]([https://doi.org/10.3390/app11072952](https://doi.org/10.3390/app11072952))  
**Abstract:** The sintering behavior, microstructure analysis, crystallization, and microwave performance of (Mg\({}_{0.6}\)Zn\({}_{0.4}\))\({}_{1-y}\)Ni\({}_{y}\)TiO\({}_{3}\) (\(y=0.01\)-\(0.2\)) ceramics, processed with raw powders of MgO, NiO, ZnO, and TiO\({}_{2}\) via the conventional solid-state method, are investigated. The main phases of (Mg\({}_{0.6}\)Zn\({}_{0.4}\))\({}_{1-y}\)Ni\({}_{y}\)TiO\({}_{3}\) ceramics were obtained. With partial replacement by Ni\({}^{2+}\), the (Mg\({}_{0.6}\)Zn\({}_{0.4}\))\({}_{0.95}\)Ni\({}_{0.05}\)TiO\({}_{3}\) could be well sintered at 1200 \({}^{\circ}\)C, and the microwave performance was shown to be positively correlated with sintering temperature. The permittivity (\(\epsilon_{r}\)) saturated at 18.7-19.3, and the quality factor (Q/) values approached 72,000-165,000 (GHz) as the sintering temperatures increase from 1125 to 1250 \({}^{\circ}\)C. The temperature coefficient of resonance frequency (\(\tau_{f}\)) falls in a stable range of \(-62.9\) to \(-66\) ppm/\({}^{\circ}\)C as sintering temperature rising. A permittivity (\(\epsilon_{r}\)) of 19.3, a maximum Q/ value of 165,000 (GHz), and a temperature coefficient (\(\tau_{f}\)) of \(-65.4\) ppm/\({}^{\circ}\)C were measured for the samples at 1200 \({}^{\circ}\)C/4 h. (Mg\({}_{0.6}\)Zn\({}_{0.4}\))\({}_{0.95}\)Ni\({}_{0.05}\)TiO\({}_{3}\) material system shows high potential for applications of high frequency-selection components in satellite communication and 5G wireless telecommunication systems.