Table 2. Bulk Na-Ion Conductivities (σ_bulk) and Activation Energies (E_a) of Na₃Sc₂(PO₄)₃ Single Crystals Compared to Literature Values for Polycrystalline Samples^a.

	Ea [eV]
phase	α	β	γ	σbulk @49 °C [S cm–1]
this study	0.39	0.39	1.70 × 10–3
Boehm5	0.56	0.45	0.15	1.25 × 10–3
Delmas20		1.10	0.42
Winand22	0.49	0.34
Sorokin23		0.55	0.42

^aSince no σ_bulk values are reported in literature, we used the only available Nyquist plot of ref (5) to extract σ_bulk, lit. = 1.25 × 10^–3 S cm^–1 at 49 °C (see Table 2).