本論文使用混合氧化物法製造SrMg2AlxFe16-xO27(x=0.0、0.2、0.4、0.6、0.8、1.0) 鋁摻雜的W型鐵氧體陶瓷樣品，其燒結溫度為1200°C至1400°C，用以研究鋁摻雜後的結構、微結構和介電特性變化。由X射線繞射結果發現，摻Al樣品的鍶鎂鐵氧化物的主要相是W型六方鐵氧體(h-鐵氧體)。還可以觀察到，隨著燒結溫度的升高，Al摻雜樣品的結構逐漸從M型六方鐵氧體轉變為W型六方鐵氧體，並且六方鐵氧體結構的a軸和c軸長度隨著燒結溫度的升高而縮小。OM圖像顯示晶粒尺寸隨著燒結溫度的增加而增大，但發現1300℃燒結樣品的晶粒尺寸大於其他燒結溫度的樣品。“Topas 軟體”分析結果表示，在 1300°C 燒結樣品中觀察到混合相樣品中W型鐵氧體有最大佔相比，由於Al離子半徑較小，W型六方鐵氧體相的a軸和c軸長度隨著Al摻雜量的增加而減小。磁性能測量數據表明，樣品的交流磁導率隨著燒結溫度的升高而增加，1300℃燒結溫度下樣品的交流磁導率會隨著非磁性Al摻雜比例的增加而緩慢降低。在摻雜配比x低於0.8時，發現在1300℃燒結樣品的介電常數可以通過增加Al摻雜濃度來提高，但在微波頻率下差異逐漸收斂，但介電損耗(tan δ)也會隨著Al摻雜濃度的增加而增加。
In this thesis, we use the mixed-oxide method to synthesis the Al-doped W-type hexagonal ferrite (h-ferrite) ceramic and the sintering temperature of SrMg2AlxFe16-xO27 (X=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) sample are varied from 1200oC to 1400oC in order to study the structure, microstructure and dielectric properties with aluminum-doped. The majority phase of strontium magnesium iron oxide with Al-doped samples is W-type hexagonal ferrite (h-ferrite), which was checked by X-ray diffraction results. It also can be observed that the structure of Al-doped samples gradually changes from M-type h-ferrite to W-type h-ferrite with sintering temperature increasing, and the a-axis and c-axis lengths of h-ferrite phases are decreasing with sintering temperature increasing. The OM images report that the grain size was growth with Al-doped amounts increasing, and those also shows that the grain size of 1300°C sintering sample is larger than it of the others sintering temperature’s samples. The “Topas software” analysis results report that the maximum W-type ferrite phase percentage of the mix-phase samples are observed of the 1300°C sintering samples, which a-axis and c-axis lengths of h-ferrite phases are decreasing with Al-doped amount increasing due to Al-ion’s smaller radii. The magnetic property measurement data shows that AC permeability of samples are increasing with the sintering temperature increasing and it of the 1300°C sintering temperature of samples are slowly decreasing with non-magnetic Al-doping ratio increasing, but the divergences will be gradually convergence at microwave frequency. The dielectric constant of 1300°C sintering samples can enhance by increasing Al-doped concentrations before the doped level X is lower than 0.8, but the dielectric loss (tan δ) is also increasing with Al-doped concentrations increasing.
