Morphology and Structure of Ceramic Thin Films Deposited by Spray Pyrolysis

Abstract

The method of Spray Pyrolysis (SP) was applied to prepare thin films of ceramic or ceramic-metal (cermets) composites based on Cu starting from aqueous solutions of soluble metal salts. Specifically, air pressurized spray pyrolysis was used in order to prepare thin film cermets of Cu-CeO2, Cu-La0.75Sr0.25Cr0.5Mn0.5O3-δ (Cu-LSCM) and the perovskite La0.75Sr0.25MnO3 (LSM) onto dense and porous YSZ substrates. These films have the potential for application in ceramic fuel cells, ceramic membranes, batteries, catalysis and oxygen sensors. Emphasis was given on tuning process parameters such as substrate temperature, solution concentration, nozzle to substrate distance, solution flowrate and deposition time to obtain films with the desired morphology, thickness and crystal structure. Film microstructure was analyzed by scanning electron microscopy (SEM) and it was found that thin defect-free films with excellent adhesion to the substrate could be produced on dense and porous ceramic substrates. X-ray diffraction (XRD) analysis showed that the films were crystalline with only the desired functional phases at relatively low (i.e. 700°C) post-deposition sintering temperatures. It was found that for a given established set of other operational parameters, substrate deposition temperature in conjunction with precursor solution concentration constitute the most significant factors that affect film morphology, adhesion and thickness.

Fabrication of Fluorite and Perovskite Functional Films by Solution Spray Pyrolysis

“…LSM and CGO). Dense YSZ substrates were either fabricated or obtained from NEYCO (France) [4]. LSF70 pellets were synthesized from the corresponding powders (prepared also from the respective metal nitrates by a co-precipitation method) and sintered at 1250°C in air for 6h to a final density of 92% of the theoretical.…”

“…In the solution spray pyrolysis (SSP) technique [4], molecular precursors of the desired film are sprayed via a solution onto the substrate held at certain temperature. In principle, salt precipitation, decomposition and subsequent sintering of the formed oxides are combined into one process.…”

Fabrication of Thin Functional Films by Solution Aerosol Thermolysis (SAT)

“…The experimental apparatus used for the spray pyrolysis deposition experiments has been described in detail in previous communications 12,13 and is shown in Figure 1. The system basically consists of a syringe pump which controls the solution flow rate during spraying and an air compressor (vol.50L) with manometer and flow controller which controls the air flow rate.…”

“…In a recent publication, 12 we have used the technique of SAT for fabricating films of cermets of the type Cu-CeO 2 , Cu-La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-δ (Cu-LSCM) and the single phase perovskite La 0.75 Sr 0.25 MnO 3 (LSM) onto dense and porous YSZ substrates, identifying the substrate deposition temperature and precursor solution concentration as being the most significant factors that affect film morphology, adhesion and thickness. Moreover, Krestou et al 13 identified an effect of the type of precursor salt in addition to the above parameters.…”

“…14,15 Moreover, under reducing conditions, it presents an interesting combination of an electronic and ionic conductor suitable in sensors and ceramic electrochemical devices. 12 On the other hand, LSM is a p-type electrically conducting perovskite that renders it suitable for many environmental and energetic catalytic applications, ceramic electrochemical cells and sensors. 16,17 It also exhibits interesting magnetic properties that can be tailored via the synthesis process.…”