Zeolites with large
cavities that are accessible via wide pore
windows are desirable but very rare. They have been dominantly used
as catalysts in industry. Here we report a novel porous germanosilicate
SCM-25, the zeolite structure containing ordered meso-cavities (29.9
× 7.6 × 6.0 Å
3
) interconnected by 10- and
12-ring channels. SCM-25 was synthesized as nanosized crystals by
using a simple organic structure-directing agent (OSDA). Three-dimensional
(3D) electron diffraction shows that SCM-25 crystallizes in the orthorhombic
space group
Cmmm
with
a
= 14.62
Å,
b
= 51.82 Å,
c
= 13.11
Å, which is one of the zeolites with the largest unit cell dimensions.
We demonstrate that 3D electron diffraction is a powerful technique
for determining the complex structure of SCM-25, including the disorders
and distributions of framework atoms silicon and germanium. SCM-25
has a high surface area (510 m
2
/g) and high thermal stability
(700 °C). Furthermore, we propose a potential postsynthetic strategy
for the preparation of zeolites with ordered meso-cavities by applying
the ADOR (assembly–disassembly–organization–reassembly)
approach.