Howard T. Evans Jr.
1979
<p><span>The thermal expansion of anhydrite, CaSO</span><span>4</span><span>, has been measured from 22° to 1,000° C by X-ray diffraction, using the Guinier-Lenné heating powder camera. The heating patterns were calibrated with Guinier-Hägg patterns at 25° C, using quartz as internal standard. Heating experiments were run on natural anhydrite (Bancroft, Ontario), which at room temperature has lattice constants in close agreement with those of synthetic material. The orthorhombic unit cell at 22° C (space group</span><i class="EmphasisTypeItalic">Amma</i><span>) has </span><i class="EmphasisTypeItalic">a</i><span>=7.003 (1) Å, </span><i class="EmphasisTypeItalic">b</i><span>=6.996 (2) Å and </span><i class="EmphasisTypeItalic">c</i><span>=6.242 (1) Å, </span><i class="EmphasisTypeItalic">V</i><span>=305.9 (2) Å</span><span>3</span><span>. At room temperature, the thermal expansion coefficients α and β (α in °C</span><span>−1</span><span>×10</span><span>4</span><span>, β in °C</span><span>−2</span><span>×10</span><span>8</span><span>) are for </span><i class="EmphasisTypeItalic">a</i><span>, 0.10, −0.69; for</span><i class="EmphasisTypeItalic">b</i><span>, 0.08, 0.19; for </span><i class="EmphasisTypeItalic">c</i><span>, 0.18, 1.60; for </span><i class="EmphasisTypeItalic">V</i><span>, 0.37, 1.14. Second-order coefficients provide an excellent fit over the whole range to 1,000° C.</span></p>
application/pdf
10.1007/BF00308361
en
Springer
The thermal expansion of anhydrite to 1000° C
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