SOFC electrolyte conductivity: YSZ vs ScSZ
Seven reported conductivity figures for 8YSZ, 11ScSZ and 10Sc1CeSZ, each plotted with the temperature, atmosphere and densification route it was measured under. The ranges are drawn as ranges and the study in which 8YSZ out-performed the scandia-stabilised grade is kept in, because one line per material would be the wrong answer to this question.
Reported conductivity against measurement temperature
Four discrete measurement temperatures, drawn from several studies. Nothing is connected, fitted or averaged: each mark is one reported figure or one reported range, at the conditions its source states. Point at a mark, or move to it with the keyboard, to read its full conditions.
- 8YSZ
- 11ScSZ / 10Sc1CeSZ
- Reported range — both ends are reported values
- Non-conventional densification (spark-plasma sintered)
- *
- In one study 10Sc1CeSZ measured 0.019–0.046 S/cm at 600 °C while 8YSZ measured 0.059 S/cm in the same work — so 8YSZ came in above the whole scandia range, and the scandia result varied by more than a factor of two with the starting powder. A material’s intrinsic advantage can be erased entirely by processing, which is why this figure stays on the chart instead of being averaged away.
- SPS
- The 0.134 S/cm figure at 800 °C was reached by spark-plasma sintering. It is drawn as a hollow marker and kept out of the conventionally sintered range beside it, because a non-conventional densification route is not a like-for-like comparison with a conventionally sintered pellet.
There is no crossover temperature on this chart, by design. No line joins the marks and the temperature axis is not continuous, so there is no crossing point to read off. Our comparison is explicit that no single crossover temperature exists and that any figure quoted without the electrolyte thickness and the cell architecture is misleading. Use the ASR calculation below instead.
The spread is processing, not chemistry. Reported 8YSZ conductivity at 800 °C spans roughly 0.02 to 0.134 S/cm, and almost all of that spread is densification, grain size and grain-boundary chemistry rather than composition. A figure from one paper against a figure from another tells you very little; only paired measurements on comparably processed samples do.
The plotted data
The same seven figures as a table, so every value and every condition is readable without pointing at anything and without JavaScript.
| Material | Reported conductivity | Temperature | Atmosphere or basis | Densification | What qualifies the figure |
|---|---|---|---|---|---|
| 8YSZ | ~0.1 S/cm | 1000 °C | Air | Densification route not stated | The source quotes this figure as approximate. |
| 8YSZ | 78 mS/cm = 0.078 S/cm | 850 °C | Air | Densification route not stated | Measured against the other material in the same study. |
| 11ScSZ | 108 mS/cm = 0.108 S/cm | 850 °C | Air | Densification route not stated | Measured against the other material in the same study. |
| 8YSZ | ~0.02–0.045 S/cm | 800 °C | Air | Conventionally sintered | Reported as a range; the spread reflects processing, not chemistry. The source quotes this figure as approximate. |
| 8YSZ | 0.134 S/cm | 800 °C | Air | Spark-plasma sintered | Outlier by non-conventional densification — not comparable with the conventionally sintered figures, and not folded into their range. |
| 10Sc1CeSZ | 0.019–0.046 S/cm | 600 °C | Total conductivity | Densification route not stated | Measured against the other material in the same study. Varied by more than a factor of two with the starting powder. |
| 8YSZ | 0.059 S/cm | 600 °C | Total conductivity | Densification route not stated | Counterexample: here 8YSZ measured above the scandia-stabilised grade. Measured against the other material in the same study. |
Every figure is transcribed from the comparison table in our YSZ versus ScSZ guide, which cites the underlying literature. Two rows were reported in millisiemens per centimetre and are shown in both units; nothing else has been converted, rounded or combined.
What conductivity your thickness demands
Ohmic loss through the electrolyte is set by its area-specific resistance, and ASR = L/σ ties thickness and conductivity together. A commonly cited electrolyte target is 0.15 Ω·cm². Enter the thickness your cell architecture forces and read off the conductivity you then have to measure at your operating temperature.
Anode-supported cells run roughly 5–15 µm, and 3 µm has been demonstrated by magnetron sputtering. Electrolyte-supported layers run from about 75 µm to several hundred, with 200–350 µm a common band.
0.15 Ω·cm² is the commonly cited electrolyte target. Change it if your loss budget is written differently.
Thicknesses from the guide
- Conductivity required at the operating temperature
- ≥ 0.100 S/cm
From ASR = L/σ, for 150 µm inside a budget of 0.15 Ω·cm². It is a requirement on a measurement rather than on a material: the same composition lands on both sides of it depending on how it was made.
How the reported figures stand against it
Each reported figure, and the thickness it would support inside your budget. A range that straddles the requirement is marked as partly meeting it, because that is what the data says.
8YSZ ~0.1 S/cm — Meets the requirement
1000 °C · Air · Densification route not stated · supports 150 µm at this budget
The source quotes this figure as approximate.
8YSZ 0.078 S/cm — Below the requirement
850 °C · Air · Densification route not stated · supports 117 µm at this budget
Measured against the other material in the same study.
11ScSZ 0.108 S/cm — Meets the requirement
850 °C · Air · Densification route not stated · supports 162 µm at this budget
Measured against the other material in the same study.
8YSZ ~0.02–0.045 S/cm — Below the requirement
800 °C · Air · Conventionally sintered · supports 30–68 µm at this budget
Reported as a range; the spread reflects processing, not chemistry. The source quotes this figure as approximate.
8YSZ 0.134 S/cm — Meets the requirement
800 °C · Air · Spark-plasma sintered · supports 201 µm at this budget
Outlier by non-conventional densification — not comparable with the conventionally sintered figures, and not folded into their range.
10Sc1CeSZ 0.019–0.046 S/cm — Below the requirement
600 °C · Total conductivity · Densification route not stated · supports 28–69 µm at this budget
Measured against the other material in the same study. Varied by more than a factor of two with the starting powder.
8YSZ 0.059 S/cm — Below the requirement
600 °C · Total conductivity · Densification route not stated · supports 88 µm at this budget
Counterexample: here 8YSZ measured above the scandia-stabilised grade. Measured against the other material in the same study.
The line for your specification
Written as a measurement to be made rather than a material to be bought. Paste it into a qualification plan or an RFQ.
Electrolyte ASR budget 0.15 Ω·cm² at 150 µm → required ionic conductivity ≥ 0.100 S/cm (ASR = L/σ). To be verified at the operating temperature on identically processed pellets of each candidate powder, not from literature values.Do not carry these numbers into a design calculation. Every figure here is somebody else’s pellet. Measure conductivity on your own samples, at your operating temperature, in the relevant atmosphere, on identically processed samples of every candidate powder — and re-measure after ageing, because 8YSZ conductivity has been reported to fall by roughly 40% after 1,000 hours of annealing at 1000 °C.
Plain ScSZ has a transition inside the intermediate-temperature window. Scandia-stabilised zirconia undergoes a cubic-to-rhombohedral (β-phase) transition at around 650 °C that reduces conductivity — precisely where you would adopt ScSZ to gain it. Suppressing that transition is why co-doped grades such as 10Sc1CeSZ exist, so a figure measured on plain ScSZ near 650 °C does not transfer to a co-doped grade, or the other way round.