Pulsed Injection MOCVD of YSZ Thin Films onto Dense and Porous Substrates

Abstract

In this work, we describe the preparation of YSZ layers on dense and porous substrates using the pulsed injection metal±or-ganic (MO) CVD technique. In this technique, the vapor phase is obtained by injecting micro-droplets of a solution, consisting of the required amounts of Zr(tmhd) 4 and Y(tmhd) 3 precursors in monoglyme, into a heated evaporator. The droplet characteristics (volume, precursor concentration, and injection frequency) were studied in order to control the growth rate and the microstructure of the layers. The optimum deposition parameters needed to achieve dense film microstructure on dense substrates were determined. For these optimized experimental conditions, we evaluated the growth rate of the layers as a function of temperature. The activation energy in the kinetically limited regime was found to be 96 kJ mol ±1 . The structure of the layers was analyzed as a function of the film composition. A concentration of 11 mol-% of yttria fully stabilizes the cubic phase. This process has been applied to the preparation of dense YSZ membranes on porous substrates in order to use the YSZ layer as a solid electrolyte (SE) in electrochemical devices such as solid oxide fuel cells (SOFC), oxygen sensors, and generators. Dense YSZ layers were obtained on samples of porous alumina, and on YSZ-Ni cermets. Characterization by scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed no cracks or voids along the grain boundaries, nor secondary phases due to chemical interaction with the substrate.

Synthesis and characterization of Sm(DPM)3 used as precursor for MOCVD

“…The relative area ratio of the three peaks is close to the ratio of protons quantities in the three groups correspondingly, which is R 1 =ðR 2 þ R 3 Þ ¼ 18: The results concluded from 1 H-NMR spectrum confirm that the freshly prepared Sm(DPM) 3 complex is of high purity and without crystallization of water molecules, in agreement with elemental analyses. However, there were not any evident changes in the 1 H-NMR spectrum of aged Sm(DPM) 3 , indicating that the complex is relatively stable compared with Ce(DPM) 4 , Gd(DPM) 3 and Y(DPM) 3 [16]. Fig.…”

“…In previous papers [16] Ce(DPM) 4 , Gd(DPM) 3 and Y(DPM) 3 have been researched. This paper described the volatility, stability and thermal decomposition of Sm(DPM) 3 by elemental analyses, nuclear magnetic resonance ( 1 H-NMR) spectroscopy, thermogravimetry-differential thermal (TG-DTA) analysis, Fourier transform infrared (FTIR) spectroscopy and mass spectroscopy (MS).…”

“…Several techniques have been employed to prepare the metal-oxide thin films such as vapor-processing methods [4][5][6][7][8], and conventional ceramic processing methods [9][10][11][12][13]. However, metal-organic chemical vapor deposition (MOCVD) method has still drawn much attention because it offers thin dense film, good step coverage, and uniform film composition over a large-size wafer [14,15].…”

Deposition of yttria-stabilized zirconia thin films by high power impulse magnetron sputtering and pulsed magnetron sputtering

“…However, these methods are not suitable for producing dense and thin (a few µm in thickness) YSZ electrolytes. The latter can be achieved by synthesizing YSZ thin films employing a variety of chemical and physical methods [6] such as pulsed laser ablation (PLD) [7,8] chemical vapor deposition (CVD) [9], atomic layer deposition (ALD) [10], spin coating [11] and magnetron sputtering [12,13,14,15,16,17]. An issue often encountered when depositing YSZ thin films by physical vapor deposition techniques (PVD) (e.g., magnetron sputtering) at relatively low synthesis temperatures is the formation of underdense and columnar microstructures.…”

MOCVD of YSZ coatings using β-diketonate precursors

“…: +1 865 574 6852; fax: +1 865 574 4913. alternative to EB-PVD and APS, with the added potential for better overall coverage as well as the ability to produce thick (>250 m), strain-tolerant, columnar coatings. Y(tmhd) 3 and Zr(tmhd) 4 (tmhd, 2,2,6,6-tetramethyl-3,5-heptanedianato, CH 3 -C(CH 3 ) 2 -C(=O)-CH 2 -C(=O)-C(CH 3 ) 2 -CH 3 ) precursors were chosen as source reagents because of their high solubility in most industrial solvents [11,12], and because of reported relatively high growth efficiencies (up to 35%) and moderate to high growth rates (10-50 m h −1 ) [7,8,[13][14][15][16][17][18]. The tmhd precursors can be used with an aerosol-assisted liquid delivery (AALD) method, which allow for continuous precursor introduction and effective evaporation.…”