A new type of composite st
ructu
re is desc
ribed consisting of the todo
rokite-type [Mn
6O
12] f
ramewo
rkwith la
rge squa
re tunnels accommodating columna
r f
ragments of the
rock-salt st
ructu
re. The c
rystalst
ructu
re of the new todo
rokite-type [S
rF
0.8(OH)
0.2]
2.526[Mn
6O
12] compound is solved f
rom t
ransmissionelect
ron mic
roscopy, and the st
ructu
re of its anhyd
rous fo
rm [S
rF
0.8O
0.1]
2.526[Mn
6O
12] is
refined f
romX-
ray powde
r diff
raction data. The [Mn
6O
12] f
ramewo
rk consists of mutually pe
rpendicula
r walls builtof th
ree edge-sha
ring
rutile-type st
rings of MnO
6 octahed
ra delimiting la
rge squa
re tunnels with the sizeof 3 × 3 octahed
ra. The inte
rio
r space in the tunnels is filled with
rock-salt type [S
r(F,OH)]
4 columns.The st
ructu
re can be inte
rp
reted as being an incommensu
rate composite st
ructu
re with the modulationvecto
r q1 =
![](/images/gifcha<font color=)
rs/gamma.gif" BORDER=0 >
c1* (
![](/images/gifcha<font color=)
rs/gamma.gif" BORDER=0 > = 0.63157(3)) pa
rallel to the di
rection of tunnel p
ropagation. The octahed
ral tunnelwalls compose subsystem
I with a [Mn
6O
12] composition and a pe
riodicity
c1 = 2.84 &A
ring;, whe
reas the[S
r(F,OH)]
4 columns belong to subsystem
II with a pe
riodicity
c1/
![](/images/gifcha<font color=)
rs/gamma.gif" BORDER=0 > = 4.49 &A
ring;,
resulting in a [S
r(F,OH)]
4
rs/gamma.gif" BORDER=0 >[Mn
6O
12] composition. [S
rF
0.8(OH)
0.2]
2.526[Mn
6O
12] demonst
rates a much la
rge
r numbe
r of cationsinside the tunnels in compa
rison with the known synthetic and natu
ral ma
rine todo
rokites. The [S
rF
0.8(OH)
0.2]
2.526[Mn
6O
12] compound shows a spin-glass behavio
r below
T*
![](/images/entities/ap.gif)
26 K with a dominantantife
rromagnetic co
rrelation.