In both Solid Oxide Fuel Cells (SOFC) and Solid Oxide Electrolysis Cells (SOEC), GDC (Gadolinium-Doped Ceria)—also known as CGO—is the primary alternative to the traditional YSZ electrolyte. It is the material of choice for Intermediate Temperature (IT) operation, as it solves the conductivity bottleneck that occurs when YSZ is used below 750 °C.

GDC is favored for its superior oxygen ion (O^{2-}) conductivity at reduced temperatures. At 600 °C, GDC has an ionic conductivity comparable to YSZ at 800 °C (~0.01 S/cm to 0.1 S/cm). (1) Intermediate Temperature (500°C–700°C): Lowering the temperature allows for the use of cheaper stainless steel interconnects and reduces the rate of material degradation and thermal stress. (2) Mechanism: Doping Ceria (CeO2) with Gadolinium (Gd^{3+}) creates oxygen vacancies in the fluorite lattice. Because Gd^{3+} has a very similar ionic radius to Ce^{4+}, it minimizes lattice strain, leading to a high mobility of oxygen ions.

Part Number	CITSOFECOCEGDC (C-ITSOFEC-OCE-GDC)
Purity	≥99.5%
Chemical Formula	(1) GDC10: (Gd0.10Ce0.90)O1.95 (2) GDC20: (Gd0.20Ce0.80)O1.95
PSD (D50)	0.5-3.0 um
Surface Area	5-9 m2/g
XRD
Ion Conductivity
Package Grade	100 or 500 g/bottle (other grades, such as 1000 g or larger can be supplied upon request)

References:

1. S. J. Kim, et al.,Effect of Ce0.43Zr0.43Gd0.1Y0.04O2−δ contact layer on stability of interface between GDC interlayer and YSZ electrolyte in solid oxide electrolysis cell, J. Power Source, 2015, 284, 617-622.
2. H. Fan, et al., Electrochemical performance and stability of lanthanum strontium cobalt ferrite oxygen electrode with gadolinia doped ceria barrier layer for reversible solid oxide fuel cell, J. Power Sources, 2014, 268, 634-639.