The space-group symmetries of a negative thermal expansion material Al 2(WO4)3 that undergoes a structural phase transformation at Tc = -22 °C have been investigated using convergent-beam electron diffraction. It has been confirmed that the space group of the room-temperature phase of Al2(WO4)3, which shows slightly negative thermal expansion, is orthorhombic Pbcn (No. 60). The space group of the low-temperature phase of Al2(WO 4)3, which shows positive thermal expansion, has been determined to be monoclinic P1121 /n (No. 14) with the lattice of am = ao -bo, bm = 2bo, and cm = co.
ASJC Scopus subject areas
- Physics and Astronomy(all)