Oxygen Permeability of Stabilized Zirconia Solid Electrolytes

Abstract

The oxygen permeability of solid electrolytes 85.0 mole per cent (m/o) ZrO~ -]-15.0 m/o CaO (I), 90.0 m/o ZrO2 -p 10.0 m/o Y208 (II), 89.0 m/o ZrO2 -t-8.0 m/o Y203 -}-3.0 m/o A120,~ (II1), 90.0 m/o ZrO2 + 10.0 m/o Sc203 (IV) is investigated at temperature range 900~176and partial pressures of oxygen 0.01-1.0 arm. The oxygen permeability in this range of oxygen pressures is proportional to Po21/4. It is shown that the diffusion coefficient of oxygen does not depend on its pressure in a gas atmosphere. Transport numbers of electron boles, which were found to be in limits 1.7 . 10 -a + 5 9 10 -5, were determined from the experimental data. The parameter p i/4 (H e = Ho~-) is also calculated.The oxygen permeability of solid electrolytes with zirconia base, play a big role in the functioning of certain electrochemical devices. However, there are only few investigations on this subject (1-4), and permeability of yttria-and scandia-stabilized zirconia is still not investigated.We investigated the permeability to oxygen of several solid electrolytes: 85.0 mole per cent (m/o) ZrO2 + 15.0 m/o CaO(I), 90.0 m/o ZrO2 -}-10.0 m/o Y208 (II), 89.0 m/o ZrO2 -t-8.0 m/o Y203 -t-3.0 m/o A1203 (III), and 90.0 m/o ZrO2 -I-10.0 m/o Sc203 (IV).The measurements were made by using a cell schematically shown in Fig. 1. We use the principle that the rate J of penetration of gas through a plate diaphragm of area S cm 2 is connected directly with a rate of pressure rise (2P/t) in a calibrated volume (5). The expression which shows this principle isWhere ~, V, p, R, and T are molecular weight, volume, and density of gas at the standard conditions, universal gas constant, and working temperature in ~ respectively. The permeability constant (~l) is given byRTSpAPo21/4 t sec 9 atm 1/4where I is the thickness of diaphragm and -~Po2 is the difference of oxygen pressures on the opposite sides of the diaphragm. The specimens were of oxide solid electrolyte tubes closed at one end. They were placed in an electric resistance furnace in which temperature was precisely controlled and was constant (with accuracy _ 2 ~ along the working length. The tubes were prepared by common technology (a shlicker method). They were 200 mm long, with 9.6 mm outside diameter and about 8.0 mm inside diameter. Porosity was about 5%. Water

Oxygen permeation through thin mixed‐conducting solid oxide membranes

“…Indeed for the thick oxide films the experimental results are consistent with the theoretical prediction (Alcock and Chan, 1972;Palguev et al, 1972;Fouletier et al, 1976;Dou et al, 1985;Park and Blumenthal, 1989;Bouwmeester et al, 1992). It is obvious, however, that the surface charge transfer reactions can be very important when the oxygen transport resistance in the bulk oxide becomes very small as a result of the increase in ionic and electronic conductivities or the decrease in film thickness.…”

“…In Figure 1 an oxide membrane is schematically divided into the bulk oxide and the adjacent interfaces, emphasizing both solid state diffusion and surface electrochemical reactions in the mass transport of the oxygen species. Among the limited experimental studies on oxygen permeation through fast ionic conductors, almost all studies focused on the oxygen permeation through relatively thick (> 500 pm) stabilized zirconia films which are essentially ionic conductors (Alcock and Chan, 1972;Palguev et al, 1972;Fouletier et al, 1976;Dou et al, 1985;Park and Blumenthal, 1989;Bouwmeester et al, 1992). In these studies, most researchers considered only the oxygen transport through the bulk oxide.…”

A Kinetic Study of the Electrochemical Vapor Deposition of Solid Oxide Electrolyte Films on Porous Substrates

“…[2], [4], [8], and [9]), it is found that the film growth rate is determined by the substrate pore structure (r, L), the diffusivity of oxygen source reactant in the substrate pore (Dw or Do), electrochemical transport properties (%o and a,~ charge-transfer reaction rate constants (a2 and ~4), and experimental conditions (controllable parameters Pw, Pc(w), and T). In principle, all these parameters except Pc(m) are known or available from experiments [e.g., oxygen permeation through YSZ pellets (14)(15)(16)(17)]. The oxygen partial pressure in the metal chloride vapor, Pc(m), is the value equilibrated with the metal oxides and chlorides in the chloride chamber.…”

“…[14] gives the following H(t) relation, for the case when P~w) and Po(~ are very low so that the first term in Eq. [14b] is neglected [16] which is the same as the model equation developed by Carolan and Michaels [6]. In this situation, H(t) is parabolic.…”

Fast Diffusion of Iron in Single Crystal Rutile and Iron Doped Rutile

“…Region of usual diffusion coefficient in oxides Ag(Agl) [3] Li ll [2] 0.5 Figure 1 O(CSZ) [7] ""~ ______ Na(~-AI203) […”