Sol-gel thin films are formed by gravitational or centrifugal draining accompanied by vigorous drying. Drying largely establishes the shape of the fluid profile, the timescale of the deposition process, and the magnitude of the forces exerted on the solid phase. The combination of coating theory and experiment should define coating protocols to tailor the deposition process to specific applications.

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Review of sol-gel thin film formation

Epitaxial thin films of inorganic single crystals can be grown on single-crystal substrates with a variety of different solution chemistries. This review emphasizes chemical solution deposition, in which a solution is used to deposit a layer of precursor molecules that decompose to low-density, polycrystalline films during heating. Ways to control film cracking during deposition and heat treatment and why many precursors synthesize metastable crystalline structures are discussed, and the different mechanisms that convert the polycrystalline film into a single crystal are reviewed. Hydrothermal epitaxy, in which single crystal thin films are directly synthesized on templating substrates in an aqueous solution at temperatures <150°C, is also discussed.

https://science.sciencemag.org/content/sci/273/5277/903.full.pdf

Chemical Solution Routes to Single-Crystal Thin Films

Four topics in the field of electronic ceramics are reviewed: multilayer ceramic capacitors, piezoelectric ceramics, electrooptic ceramics, and ferroelectric thin films. They all are related to ferroelectric ceramic materials. The scope of this review is limited to oxide compounds, because oxide ferroelectrics, for the most part, exhibit the most useful properties and have found the most applications. The underlying physical concepts, ceramic and/or thin-film fabrication, structure/property relationships, specific applications, and future prospects in each of the four electronic ceramic application areas are discussed. >

Topics in electronic ceramics

Sol-gel processing of electrical and magnetic ceramics

This paper reports on crack-free Pb(Zr,Ti)O[sub 3] (PZT) thin films with preferred orientation that were prepared successfully on MgO (100), SrTiO[sub 3] (100), and Pt/Ti/SiO[sub 2]/Si substrates from metal alkoxide solutions Calcination of precursor films in a H[sub 2]O[minus] O[sub 2] gas mixture was found to be effective not only for low-temperature crystallization of perovskite PZT, but also for obtaining the preferred orientation of PZT films Single-phase PZT films with high preferred orientation were synthesized on MgO (100) and Pt/Ti/SiO[sub 2]/Si substrates at 550[degrees] and 600[degrees] C for 2 h, respectively The PZT film on the Pt/Ti/Si-O[sub 2]/Si substrate showed a permittivity of 520, tan [delta] of 003, a remanent polarization of 24 [mu]C/cm[sup 2], and a coercive field of 54 kV/cm

Synthesis of Highly Oriented Lead Zirconate–Lead Titanate Film Using Metallo‐organics

Homogeneous and stoichiometric LiNbO{sub 3} films were prepared on substrates from double alkoxide solutions by a dip-coating method. Structural control of the double alkoxide solution is critical in synthesizing crystalline stoichiometric LiNbO{sub 3} films. The coordination states of alkoxides in solution were monitored by Ir and NMR spectroscopy. A viscosity of the double alkoxide solution was adjusted to a value of 6 {times} 10{sup {minus}3} to 7 {times} 10{sup {minus}3} N{center dot}s/m{sup 2} (6 to 7 cP) by partial hydrolysis and the concentration of the solution. Amorphous LiNbO{sub 3} films prepared on Si- or sapphire-single-crystal substrates from controlled alkoxide solutions began to crystallize at temperatures as low as 250{degree}C. Films on sapphire substrates crystallized with the preferred orientation along each orientation, such as (001), (110), and (012) but not on Si(100) and Si(111) substrates. The crystallinity of the initial thin-film coating of LiNbO{sub 3} significantly influenced the crystallization of films deposited subsequently.

Shinichi Hirano

Papers

Preparation of crystalline LiNbO sub 3 films with preferred orientation by hydrolysis of metal alkoxides