Study on the stress generation during gel/ceramic thin film conversion

1采用溶胶-凝胶法，以醇盐溶胶为涂布液，在硅片上制备了SiO_2和TiO_2凝胶薄膜。在红外加热炉中以恒定速率加热凝胶膜至800℃，并使用光学显微镜进行原位观察。研究发现，裂纹发生在升温阶段，且裂纹起始温度低于结晶起始温度。发现裂纹起始温度随初始膜厚的增加和升温速率的降低而降低。2以聚乙烯吡咯烷酮（PVP）为涂层溶液，采用溶胶-凝胶法在石英玻璃和MgO单晶衬底上制备了BaTiO_3薄膜。扫描电镜观察表明，沉积在石英玻璃衬底上的薄膜具有沿沿着扩展的微裂纹。而在MgO单晶衬底上沉积的薄膜上没有发现微裂纹， ...更多信息 所提供的被认为是由膜中的张应力形成的，这被认为是由于膜和衬底之间的热膨胀系数不匹配而产生的。3使用含有二乙醇胺、乙酰丙酮或乙酸作为螯合剂的醇盐溶液，通过溶胶-凝胶法在二氧化硅玻璃衬底上沉积二氧化钛薄膜。通过测量衬底弯曲来测量烧制膜中的应力，以及螯合剂对应力的影响。应力为拉伸应力，其大小顺序为乙酸<乙酰丙酮<二乙醇胺。螯合剂对应力的影响被解释在膜的致密程度的差异。4 BaTiO_3，Fe_2O_3和PZT薄膜沉积在石英玻璃基板上使用醇盐或金属盐溶液含有PVP作为涂层解决方案。在BaTiO_3、Fe_2O_3和PZT薄膜中，PVP/Ti（OC_3H_7^i）_4 = 0.5、PVP/Fe（NO_3）_3 = O和PVP/（Ti（OC_3H_7^i）_4 + Zr（OC_3H_7^n）_4）的摩尔比分别达到最大值。少

1 Silica and titania gel films were deposited on silicon wafers by sol-gel method using alkoxide-derived sols as the coating solutions. The gel films were heated at constant rates in an infrared furnace up to 800℃, and in situ observation was made using an optical microscope. The cracking was found to occur during the heating-up stage, and the cracking onset temperature was lower than that of crystallization. The cracking onset temperatures were found to decrease with increasing initial film thickness and with decreasing heating rate.2 BaTiO_3 thin films were deposited on silica glass and MgO single crystal substrates by sol-gel dip-coating using an alkoxide solutions containing polyvinylpyrrolidone (PVP) as the coating solution. SEM observation revealed that the fihns deposited on the silica glass substrates have microcracks propagating along grain boundaries. On the other hand, no microcracks were found on the films deposited on the MgO single crystal substrates, The microcracks obse … More ived are supposed to be formed by tensile stress in films, which is thought to be generated as a result of the thermal expansion coefficient mismatch between the film and the substrates.3 Titania thin fihns were deposited on silica glass substrates by sol-gel method using alkoxide solutions containing diethanolamine, acetylacetone or acetic acid as the chelating agents. The stress in the fired films were measured by measuring the substrate bending, and the effect of the chelating agent on the stress. The stress was tensile, increasing in the order of acetic acid < acetylacetone < diethanolarnine. The effect of the chelating agent on the stress was interpreted in terms of the difference in the degree of film densification.4 BaTiO_3, Fe_2O_3 and PZT thin films were deposited on silica glass substrates using alkoxide or metal salt solutions containing PVP as the coating solutions. The critical thickness, the maximum thickness achievable without cracking via single-step deposition was found to increase by incorporating PVP in solutions, showing maximum around mole ratios of PVP/Ti(OC_3H_7^i)_4 = 0.5, PVP/Fe(N0_3)_3 = O and PVP/ (Ti(OC_3H_7^i)_4 + Zr(OC_3H_7^n)_4) for BaTiO_3, Fe_2O_3 and PZT films, respectively. Less