Thermal expansion of tourmaline single crystals from 80 to 300 K

Abstract

The thermal expansion and coefficient of linear thermal expansion of elbaite, schorl, and uvite specimens in the a and c directions have been determined from 80 K to room temperature with use of the standard strain-gauge technique. At room temperature it was found that for elbaite, ${\ensuremath{\alpha}}_{a}$=3.86\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$ ${\mathrm{K}}^{\mathrm{\ensuremath{-}}1}$ and ${\ensuremath{\alpha}}_{c}$=9.11\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$ ${\mathrm{K}}^{\mathrm{\ensuremath{-}}1}$; for schorl, ${\ensuremath{\alpha}}_{a}$=3.48\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$ ${\mathrm{K}}^{\mathrm{\ensuremath{-}}1}$ and ${\ensuremath{\alpha}}_{c}$=8.54\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$ ${\mathrm{K}}^{\mathrm{\ensuremath{-}}1}$; and for uvite, ${\ensuremath{\alpha}}_{a}$=3.17\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$ ${\mathrm{K}}^{\mathrm{\ensuremath{-}}1}$ and ${\ensuremath{\alpha}}_{c}$=8.32\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$ ${\mathrm{K}}^{\mathrm{\ensuremath{-}}1}$. It was observed that the anisotropy in thermal expansion along the a and c directions of tourmalines is directly related to the anisotropy in the corresponding adiabatic elastic constants.