Calcium germanate can be formed by firing the
oxides together at about 750–800°C:
CaO + GeO2?CaGeO3
A single-crystal X-ray study indicates that the perovskite
form of CaGeO3 is orthorhombic (Pbnm) and isotypic
with GdFeO3. The cell dimensions are:
a = 5.2608 ? , b = 6.2688 ? , c = 7.4452 ? , V = 366.43?3,
Z = 4, dcalc = 5.17 g/cc. The crystal structure is close to
that of SmAlO3. Although the unit cell of CaGeO3 is
pseudocubic, the structure itself is very distorted
through the tilting and distortion of polyhedra. The
oxygen polyhedra are less tilted and less distorted
than those of other GdFeO3-type perovskites.
Ca2GeO4 has been tested as a host for lasers, using
Nd3+
as the activator. Large crystals of highly doped
Ca2GeO4:Cr4+
were grown by a top-seeded meltsolution
growth method. Absorption and emission
measurements for various crystal orientations have
been performed.
