EFFECT OF DOPANTS ON CeO_2 BASED SOLID STATE ELECTROLYTES FOR INTERMEDIATE TEMPERATURE ELECTROCHEMICAL DEVICES

摘要

The present work aims at the investigation of the influence of different dopants' ionic radii and their concentration on both the lattice parameters and the density of Ce_(1-x)Ln_xO_(2-δ) (x = 0-0.20; Ln = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb) solid solutions, multi-component Ce_(1-x)Ln_(x/2)Ln_(x/2)O_(2-δ) (x = 0-0.20; Ln = Sm, La, Gd and Ln' = Dy, Nd, Y), Ce_(0.8)(Sm_(1-x)M_x)_(0.2)O_(2-δ)Aw, (M= Ca, Sr; x=0.0-1.0) and Ce_(0.8)(Sm_(1-x-y)Ba_yM_x)_(0.2)O_(2-δ) (M=Ca, Sr; x=0, 0.15, 0.20; y=0.05, 0.1) systems. The electrical conductivity measurements of the samples were carried out by using the four-point dc technique in different atmospheres. Temperature and oxygen partial pressure were varied automatically by means of microprocessor system ZIRKONIA-318 in the range of 623 - 1173 K and 0.1-10~(23) atm, respectively. To describe the electrolytic properties of solid electrolytes the notation of the EDB (electorytic domain boundary) - the critical oxygen partial pressure (P_(O_2)~*) at which the values of the electronic and ionic components of conductivity are equal- is often used. The values of the critical partial pressure of oxygen for different compositions at 1023 K were calculated from dependences of total conductivity vs. oxygen partial pressure in proposal that ionic conductivity depends on dopand's concentration, but isn't influenced by P_(O_2) .