摘要
钛酸镁(MgTiO3)和钛酸锌(ZnTiO3)都是非常重要的微波陶瓷材料。MgTiO3因为具有很高的品质因数(Q值)、较低的介电损耗和适中的介电常数倍受关注。同时ZnTiO3在微波频段内具有较低的介电损耗,而且烧结温度较低,可以用作制备银、铜电极共烧中温低介电损耗微波材料,但是烧结温度高会分解。目前,大多数研究都集中在提高MgTiO3和ZnTiO3陶瓷粉体的纯度和降低其烧结温度。
为了进一步提高MgTiO3粉体的纯度和降低其烧结温度,对MgTiO3晶体的相演化过程的研究是非常有意义的。本文采用热重、X射线衍射、傅立叶红外变换和透射电镜等测试手段,通过硬脂酸凝胶法研究了MgTiO3纳米颗粒的相演化过程。在硬脂酸凝胶制备过程中,硬脂酸和硬脂酸镁和钛酸丁酯结合形成了镁钛氧网络聚合物结构,同时还有正丁醇的产生;在硬脂酸凝胶煅烧过程中存在着一系列的氧化和燃烧过程,同时有明显的热量放出;在450℃的时候出现了一个亚稳中间相Mg2Ti04,在550℃的时候消失,同时MgTiO3相产生。
MgTiO3和ZnTiO3薄膜作为特殊形态的材料,已经广泛渗透到当前科技的各个领域,并且在微电子集成元器件方面有很大的应用潜力。因此,MgTiO3和ZnTiO3的制备受到广泛的关注。本文主要探讨通过溶胶凝胶法制备MgTiO3和ZnTiO3薄膜。
实验以硝酸镁、硝酸锌、钛酸丁酯、醋酸、乙醇、乙二醇甲醚和聚乙烯吡咯烷酮(PVP)为原料,先制备出稳定溶胶然后在基体(硅片)上涂膜并经退火处理。实验中考察了不同因素对溶胶凝胶过程和薄膜形成过程的影响,在适宜的条件下制备出了均匀无裂纹的薄膜。分别利用X射线衍射分析(XRD)、热重分析(TGA-DTA)、傅立叶变换红外光谱分析(FT-IR)和原子力显微镜(AFM)等测试手段对实验样品进行了表征。实验结果表明,通过溶胶-凝胶法成功制备了表面均匀平整的MgTiO3和ZnTiO3薄膜。
Magnesium titanate (MgTiO3) and zinc titanate (ZnTiO3) are two important microwave ceramic materials. Much attention has been focused on the synthesis of MgTiO3 because of its high Q values, low dielectric loss and dielectric constant. Meanwhile, ZnTiO3 can be mixed with Ag, Cu, etc. to prepare electrodes because of its relatively low sintering temperatures and dielectric loss. However, ZnTiO3 is easily decomposed at high temperature. Up to now, most of the studies mainly focus on improving the purity and reducing sintering temperature of MgTiO3 and ZnTiO3 ceramic powder.
To improve the purity and reduce the sintering temperature of MgTiO3, investigating the phase evolution of MgTiO3 nanoparticles is very meaningful. In this work, stearic acid gel method is employed to study the phase evolution of MgTiO3 nanoparticles by Thermal gravimetric analysis, X-ray diffraction, Fourier transform infrared and Transmission electron microscopy. During the preparation of stearic acid gel, stearic acid and magnesium stearate combining with butyl titanate formed magnesium-titanium oxide network polymer, meanwhile n-butanol is generated; In the calcined process of stearic acid gel, a series of oxidation and combustion reactions occur, meanwhile apparent heat is given off; A metastable intermediate phase Mg2TiO4 is generated at 450℃and nearly disappeared at 550℃. Simultaneously, the phase of MgTiO3 appears.
MgTiO3 and ZnTiO3 thin films, being special morphology materials, have been used in many scientific fields and have the potential to be integrated directly into microelectronic devices. Therefore, much attention has been focused on the synthesis of MgTiO3 and ZnTiO3. The present work is made to investigate to prepare MgTiO3 and ZnTiO3 thin film.
In this work, using magnesium nitrate, zinc nitrate, butyl titanate, acetic acid, ethanol, 2-methoxyethanol and polyvinylpyrrolidone (PVP) as the starting materials, stable sol was firstly prepared, then coated on substrates (silicon), and finally annealed. In the experiments, some influence factors on the sol-gel and the thin film crystallization were investigated. The optimal conditions were chosen to synthesize uniform thin film without cracks. The obtained samples were characterized by TGA-DTA, XRD, FT-IR and AFM, respectively. The results indicate that uniform MgTiO3 and ZnTiO3 thin films can be successfully synthesized by sol-gel method.
引文
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