Table 1 Calculated and experimental 95Mo NMR parameters of Ba7Nb4MoO20, showing the peak assignment to the M2 site

From: Hidden chemical order in disordered Ba7Nb4MoO20 revealed by resonant X-ray diffraction and solid-state NMR

   

DFT-calculated

DFT-calculated

Experimental

Experimental

Models a

Site

Polyhedron b

peak position (ppm)c

|CQ | (MHz)d

peak position (ppm)

|CQ | (MHz)d

(4), (5)

M1

(Mo1)O6

+269 ~ +270

1.47, 2.00

not observed

 

(1)–(3), (5)

M2

(Mo2)O4

–29.1 ~ –36.8

0.36 ~ 0.90

–47

≤ 2

(7)–(10)

M2

(Mo2)O5

–57 ~ +80

5.1 ~ 10.7

not observed

 

(6)

M3

(Mo3)O6

+145

2.87

not observed

 

(7), (8)

M4

(Mo4)O6

+47, +49

5.17, 5.23

not observed

 
  1. aEach model is shown in Supplementary Figs. 6, 7.
  2. bMoi denotes the Mo atom at the Mi site.
  3. cDFT-calculated peak position under 18.79 T was obtained using the correlation in Supplementary Fig. 5a, including the second-order quadrupolar shift.
  4. dQuadrupolar coupling constant |CQ|. Experimental |CQ| was estimated from the NMR spectrum (Fig. 3b) with DMFIT69.
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