THE PRECISION OF THERMAL-EXPANSION TENSORS OF TRICLINIC AND MONOCLINIC CRYSTALS

If thermal-expansion-tensor components alpha-ij are determined from temperature-induced changes in d values, most authors first calculate the unit-cell parameters at different temperatures. From these, the alpha-ij are computed. It is shown that this procedure involves a reduced precision if compared with the direct least-squares determination of alpha-ij from changes in the d values.