Manfred Burianek, Thomas F. Krenzel, Martin Schmittner, Jürgen Schreuer, Reinhard X. Fischer, Manfred Mühlberg, Gwilherm Nénert, Hartmut Schneider, Thorsten M. Gesing
June 11, 2013
A part of the pseudo-binary join Bi 2 O 3 –Bi 2 Mn 4 O 10 of the ternary system Bi 2 O 3 –MnO–MnO 2 was examined using thermo-analytical methods. Because Bi 2 Mn 4 O 10 melts incongruently single crystals of up to 20mm in diameter were grown by the top seeded solution growth method in the temperature range from about 1223K to 1173K. Single crystal neutron diffraction confirmed the principles of the crystal structure of Bi 2 Mn 4 O 10 but revealed much smaller distortions of the cation coordination polyhedra. In contrast to the anisotropy observed in other mullite-type Bi containing compounds, the linear thermal expansion of Bi 2 Mn 4 O 10 , as studied by means of dilatometry and X-ray powder diffraction techniques, is characterized by α 11 > α 33 > α 22 at room temperature. The relatively large expansion along the a -axis can be attributed to the two oxygen atoms bridging two corner shared MnO 5 tetrahedral pyramids which alternate with the structural void between two adjacent Bi 3 + cations.