List of Abbreviations (In Order of Appearance)
YSZ	yttria-stabilized zirconia
CGO10	Ce0.9Gd0.1O2−δ
CGO20	Ce0.8Gd0.2O2−δ
GDC	Ce0.8Gd0.2O1.9
ScCeSZ	Sc0.1Ce0.01Zr0.89O1.91
ScYbSZ	Sc0.09Yb0.01Zr0.9O1.95
XRD	X-ray diffraction spectroscopy
EDS	energy-dispersive X-ray spectroscopy
EIS	electrochemical impedance spectroscopy
SOFC	solid oxide fuel cell
List of Symbols (In Order of Appearance)
Zr4+	zirconium cation
MeO	metal in the second oxidation state oxide
${\mathit{Me}}_{\mathit{Zr}}^{″}$	zirconia in the fourth oxidation state ion sitting on metal in the second oxidation state lattice site with double positive charge
$V_0^{••}$	double positively charged oxygen vacancy
$O_0^x$	an oxygen ion sitting on lattice site with neutral charge
${\mathit{Me}}_2{O}_3$	metal in the third oxidation state oxide
${\mathit{Re}}_2{O}_3$	a rare earth oxide
Ce4+	ceria cation in the fourth oxidation state
Ce3+	ceria cation in the third oxidation state
δ	oxygen deficiency in metal-doped oxide ceramic
X	Vegard’s Slope
ri	difference between the ionic radii of the dopant metal and Ce4+ for the coordination number equal to 8
zi	charge difference between the introduced ion and Ce4+ ions
σ	specific conductivity
2Θ	angle between incident beam and the crystallographic reflection plane in XRD
A	lattice constant
R1, R2, R3	resistor elements
CPE1, CPE2, CPE3	constant phase elements
L1	inductance element
R1, R2, R3	resistance parameters of resistors
CPE1-T, CPE2-T, CPE3-T	time parameter in constant phase elements
CPE1-P, CPE2-T, CPE3-T	phase parameter in constant phase element
L	inductance element parameter
Z′	real impedance component
Z″	imaginary impedance component
Y′	real admittance component
Y″	imaginary admittance component
T	absolute temperature
t	temperature in degrees Celsius
q	valency of mobile ions
c	relative concentration of mobile ions to the number of possible positions in the lattice
μ	mobility of the ions
$e^{-}$	electron
$V_0^{n-}$	n-time negatively charged oxygen vacancy
O2−	oxygen anion
A	a constant in Arrhenius law
EA	the activation energy for conduction
k	Boltzman’s constant
$P_O$	oxygen partial pressure
m	a parameter determined by both the type of the carrier (n or p) and the defects (e.g., oxygen vacancy) in the semiconductor
${\left(\mathit{OH}\right)}^{-}$	hydroxide ion
n	numbers of electrons
$H_i^{•}$	proton in interstitial site
${\left(\mathit{OH}\right)}_O^{•}$	hydroxide ion sitting on oxygen lattice site with positive charge
List of Chemical Formulas (In Order of Appearance)
Ce0.8Gd0.2O1.9	assumed composition of commercial material (specimen GDC)
Sc0.1Ce0.01Zr0.89O1.95	assumed composition of commercial material (specimen ScCeSZ)
Sc0.09Yb0.01Zr0.9O1.95	assumed composition of commercial material (specimen ScYbSZ)
Ce(Re)O2−δ	rare earth doped ceria
NH3	gaseous ammonia
H2	gaseous hydrogen
ZrO2	zirconia
CO	carbon monoxide
SiO2	silica
MnO2	manganese oxide
Al2O3	aluminum oxide
CaO	calcium oxide
MgO	magnesium oxide
Y2O3	ytrria
Sc2O3	scandia
Yb2O3	ytterbium oxide
Si3N4	a silicon nitride
AlN	aluminum nitride
CuO	copper (II) oxide
c-ZrO2	cubic zirconia
N2O	nitrous oxide
H2O	water