2000 Volume 95 Issue 7 Pages 182-192
Thermal structure deformation of ScAlO3 perovskite was studied by in situ X-ray single crystal structure analysis at high temperatures. As temperature increases, all structure parameters of the orthorhombic perovskite shift very slightly toward the ideal polyhedral symmetries. The cell volume shows a quadratic thermal expansion expressed by V(T)/V293=1+1.151×10−5T+9.218×10−9T2. The expansions of ScO8 and void space are significant for the cell volume expansion because they occupy large volume in the unit cell. The tilting and rotation of AlO6 octahedral linkage are a little changed by the anisotropic thermal motion of O1 and O2. Higher order anisotropic anharmonic thermal parameters of γpqr and δpqrs of O1 and O2 atoms are increased noticeably with temperature. Anharmonic motions of oxygen atoms, inducing the tilting and rotation of AlO6 octahedra mainly control the thermal changes of perovskite structure.