Synthesis, Crystal Structure Refinement, and Electrical Conductivity of Pb_(8−x)Na₂Sm_x(VO₄)₆O_(x/2)

Table 5

Activation energy (eV) for the samples Pb_(8−𝑥)Na₂Sm_𝑥(VO₄)₆O_(𝑥/2).

𝑥=0	𝑥=0.05	𝑥=0.1	𝑥=0.15	𝑥=0.2
0.49 (300–440°C)*	0.52	0.61	0.69	0.79
1.61 (440–480°C)*	0.98	1.10	1.32	1.49
4.84 (480–530°C)*	3.18	2.62	2.44	2.49
1.41 (530–600°C)*	2.89	2.20	1.55	1.06

∗Temperature ranges are given for Pb₈Na₂(VO₄)₆ (𝑥=0); they are approximately the same for other compositions.