本研究之目的在於探討以固態燒結法製備Ba5Nb4O15微波介電材料品質因子的不穩定性，Ba5Nb4O15材料系統由於具有高品質因子(Q)，高介電常數(K)，和趨於零的共振頻率溫度係數(τf)，而被廣泛應用於微波介電材料的研究上，但是大多數的研究都是在探討外在因素對電性的影響，很少有文章在探討燒結溫度對成分內在結構因素與電性方面的相互關係。
為了製備具有高品質因子的Ba5Nb4O15微波介電材料，本研究主要針對3 個地方做變數，影響品質因子的最大原因為材料的緻密性，一般陶瓷材料的緻密性會因為燒結溫度的提升而增加，所以第一個參數為溫度，燒結溫度分別為1190oC、1259oC、1345oC、1520oC，接著考慮到之後商業化的大量製作，所以在配比方面可能會有些許的誤差，而為了瞭解比例的偏差是否對材料的電性產生影響，所以第二個參數為Ba/Nb的莫爾比，分別為4.95:4、5:4、5.05:4，再來因為每一家粉末提供廠商來自於不同的礦產，所以造成粉末的些許不一樣，所以第三個參數為三家廠商所提供的m相Nb2O5、o相Nb2O5、m+o相Nb2O5。
本研究主要分為三部分，第一部分首先將試片以同比例做分組，之後對各個不同比例、不同相以及在不同溫層燒結溫度的燒結行為與電性做探討，由實驗發現材料燒結過程中會產生晶粒異常成長，導致緻密性變差使得品質因子降低，所以得出在1259oC燒結不產生晶粒異常成長時有較佳電性，第二部分以針對同比例不同相Nb2O5在1259oC燒結做探討，發現以o相Nb2O5為原始粉末之試片具有較佳品質因子，因為o相Nb2O5所具有的F含量較多，且因為F有助於燒結所以燒結出來的晶粒成長較良好，第三部分針對不同比例同相Nb2O5在1259oC燒結做探討，發現比例4.95燒結出來的電性較佳，綜合以上三部分得知o相Nb2O5是影響品質因子最主要原因，當以o相Nb2O5且在比例為4.95(Nb rich)時可得到一組較佳之微波介電特性，品質因子(Qf): 22370、介電常數(K) : 36.3

The purpose of this study is to investigate the instability in the solid state sintering process of Ba5Nb4O15 microwave dielectric material quality factor. Ba5Nb4O15 material systems has a high quality factor (Q), high dielectric constant (K), and low temperature coefficient at resonant frequency(τf), which is widely used in research on microwave dielectric materials. However, most papers focus on the relationships between micro-wave properties and extrinsic parameters, few published papers investigates the phe-nomena between sintering temperature and dielectric properties.
To prepare Ba5Nb4O15 microwave dielectric material with high quality factor , the study focused on three variants that influenced the quality factor.For most of the ce-ramic material system the sample gets densified with increase in sintering temperature. So, we took temperature as the first variant with temperature values 1190 oC, 1259 oC, 1345 oC, and 1520 oC. There may be a little error in aspect ratio while taking into ac-count for the commercial mass- production, so in order to realize whether the propor-tion of deviation affects the electrical properties, the second variant is the Ba/Nb molar ratio and values are 4.95: 4,5: 4,5.05: 4, The Nb2O5 powder provided by the vendor were of different phase, so the sample prepared from these powder will have different properties. Therefore, third variants is to use different phase of Nb2O5 viz. m-phase Nb2O5, o-phase Nb2O5 and (m + o) phase Nb2O5.
This study is divided into three parts, the first part is to study the relation between the sintering temperature and electrical properties of the samples group together by keeping the same molar ratio and varying the phase of the Nb2O5 starting powder. Ab-normal grain growth was observed above 1345 oC temperature, resulting into low den-sified sample and in turn reduced quality factor. Sample sintered at 1259 oC showed better electrical properties.The second part is to investigate using different phase Nb2O5 keeping the molar ratio constant and sintering at 1259 oC. Ba5Nb4O15 samples with m-phase Nb2O5 showed better electrical properties. This can be attributed to the similarity in the structure of Nb2O5 and Ba5Nb4O15 which will ease the atomic diffu-sion and form a complete crystal. The third part is to investigate the prepared samples sintered at 1259 oC using the same m-Nb2O5 powder and varying the molar ratio. Molar ratio with 4.95 showed better electrical properties. So we can know from above three parts that m-phase Nb2O5 is the main reason affecting the quality factor, when we pre-pare using m-phase Nb2O5 at molar ratio 4.95 (Nb rich), we can get better microwave dielectric properties , quality factor (Qf ): 22370, dielectric constant (K): 36.3

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