Fabrication of porous thick films using room‐temperature aerosol deposition

Abstract

A novel technique for the rapid room‐temperature deposition of porous ceramic, glass, or metal thick films using the aerosol deposition (AD) method is presented. The process is based on the co‐deposition of the desired film material and a second water‐soluble constituent, resulting in a ceramic‐ceramic composite. Following the subsequent removal of water‐soluble end member, a network of pores is retained. To demonstrate the process, porous BaTiO3 thick films were fabricated through co‐deposition with NaCl. Microstructural images show the clear development of a porous structure, which was found to enhance the dielectric properties over dense thick films, possibly related to the lower extent of internal residual stress. This simple but highly effective porous structure fabrication can be applied to any film and substrate material stable in water and is promising for the application of AD‐processed films in gas sensors, solid oxide fuel cells, and humidity sensors.

Temperature‐induced changes of the electrical and mechanical properties of aerosol‐deposited BaTiO3 thick films for energy storage applications

“…The expected appearance of a crystallographic phase transition in BT from tetragonal to cubic structure at 120°C is only found during heating of the as‐processed film (Figure 2A); it is not observed during any subsequent heating or cooling cycle. The origin of such anomaly during the first heating cycle may be related to the atmospheric moisture content 44 . The absence of a distinct phase transition is possibly due to the existence of nanograins in the range of 30–50 nm 42,45–47 .…”

“…43 Nevertheless, comparing the as-processed (Figure 2A) and thermally treated (Figure 2B) states, annealing of AD thick films significantly increases the observed roomtemperature permittivity by 100%, a feature that is also observed in porous structures using the identical coatingsubstrate combination. 44 The expected appearance of a crystallographic phase transition in BT from tetragonal to cubic structure at 120 • C is only found during heating of the as-processed film (Figure 2A); it is not observed during any subsequent heating or cooling cycle. The origin of such anomaly during the first heating cycle may be related to the atmospheric moisture content.…”

“…The origin of such anomaly during the first heating cycle may be related to the atmospheric moisture content. 44 The absence of a distinct phase transition is possibly due to the existence of nanograins in the range of 30-50 nm. 42,[45][46][47] A striking feature of annealed AD-BT films is the reduction in frequency dispersion, indicated by a nearly constant permittivity below 100 • C (Figure 2B).…”

Multifunctional energy storage and piezoelectric properties of 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 thick films on stainless-steel substrates

“…However, little research has been done on the integration of ferroelectric ceramics on SS. Currently, there are few reports on the deposition of Pb(Zr,Ti)O 3 -based [14,[17][18][19][20][21], BaTiO 3 -based [22][23][24] and (K,Na)NbO 3 -based [25] thick films on SS. In our previous work, energy storage-efficient PMN-10PT thick films were integrated on SS substrates [26], while this study focuses on a ferroelectric PMN-35PT with a composition close to the morphotropic phase boundary responsible for high piezoelectric response in bulk ceramics [3][4][5].…”