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A microcontact impedance study on NASICON-type Li1+xAlxTi2−x(PO4)3 (0 ≤ x ≤ 0.5) single crystals
We successfully demonstrated the applicability of microcontact impedance spectroscopy (MC IS) on Li + conducting solid electrolytes and measured the Li + bulk conductivity ( σ b ) of LiTi 2 (PO 4 ) 3 (LTP) and Li 1+ x Al x Ti 2− x (PO 4 ) 3 (LATP) single crystals independent of microstructural effec...
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| Main Authors: | , , , , , , |
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| Format: | Article |
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| Summary: | We successfully demonstrated the applicability of microcontact impedance spectroscopy (MC IS) on Li
+
conducting solid electrolytes and measured the Li
+
bulk conductivity (
σ
b
) of LiTi
2
(PO
4
)
3
(LTP) and Li
1+
x
Al
x
Ti
2−
x
(PO
4
)
3
(LATP) single crystals independent of microstructural effects (
e.g.
, grain boundaries, pores, and density). The crystals had a size of about 100 μm in each direction and crystallized with NASICON-type structure (
R
3&cmb.macr;
c
). Finite element calculations were performed to validate the impedance data analysis. A strong increase in
σ
b
in the order of three magnitudes (3.16 × 10
−6
to 1.73 × 10
−3
S cm
−1
) was found after incorporating 0.1 mol Al
3+
per formula unit into LTP. Moreover, since the crystal structural changes are almost linear in the LATP system up to
x
= 0.5, the increase of
σ
b
is most probably related to additional Li
+
sites at the M
3
(36
f
) position. The additional Li
+
leads to a displacement of Li
+
occupying the M
1
(6
b
) sites towards the nearest-neighboring M
3
position, and therefore opens the fast-conducting pathway within the NASICON structure. A significant change in
σ
b
was also observed as the Al
3+
content further increased (
x
= 0.1 to 0.5). The highest
σ
b
value of 5.63 × 10
−3
S cm
−1
was obtained for samples with
x
= 0.4.
We successfully demonstrated the applicability of microcontact impedance spectroscopy (MC IS) on Li
+
conducting solid electrolytes and measured the Li
+
bulk conductivity (
σ
b
) of LiTi
2
(PO
4
)
3
(LTP) and Li
1+
x
Al
x
Ti
2−
x
(PO
4
)
3
(LATP) single crystals independent of microstructural effects (
e.g.
, grain boundaries, pores, and density). |
|---|---|
| ISSN: | 2050-7488 2050-7496 |
| DOI: | 10.1039/c5ta08545d |