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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>G.W. Morey</dc:contributor>
  <dc:contributor>C.C. Silber</dc:contributor>
  <dc:creator>J.J. Rowe</dc:creator>
  <dc:date>1967</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Melting and subsolidus relations in the system K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;were studied using heating-cooling curves, differential thermal analysis, optics, X-ray diffraction at room and high temperatures and by quenching techniques. Previous investigators were unable to study the binary MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;system and the adjacent area in the ternary system because of the decomposition of MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;and CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;at high temperatures. This problem was partly overcome by a novel sealed-tube quenching method, by hydrothermal synthesis, and by long-time heating in the solidus. As a result of this study, we found: (1) a new compound, CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;·3MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;(m.p. 1201°C) with a field extending into the ternary system; (2) a high temperature form of MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;with a sluggishly reversible inversion. An X-ray diffraction pattern for this polymorphic form is given; (3) the inversion of β-CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;(anhydrite) to α-CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;at 1195°C, in agreement with&amp;nbsp;&lt;/span&gt;&lt;span class="small-caps"&gt;grahmann&lt;/span&gt;&lt;span&gt;;&amp;nbsp;&lt;/span&gt;&lt;sup&gt;(1)&lt;/sup&gt;&lt;span&gt;&amp;nbsp;(4) the melting point of MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;is 1136°C and that of CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;is 1462°C (using sealed tube methods to prevent decomposition of the sulphates); (5) calcium langbeinite (K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;·2CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;) is the only compound in the K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;binary system. This resolved discrepancies in the results of previous investigators; (6) a continuous solid solution series between congruently melting K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SOP&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;·2MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;(langbeinite) and incongruently melting K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;·2CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;(calcium langbeinite); (7) the liquidus in the ternary system consists of primary phase fields of K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;, MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;, CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;, langbeinite-calcium langbeinite solid solution, and CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;·3MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;. The CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;field extends over a large portion of the system. Previously reported fields for the compounds (K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;·MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;·nCaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;), K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;·3CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;and K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;·CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;&amp;nbsp;were not found; (8) a minimum in the ternary system at: 740°C, 25% MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;, 6% CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;, 69% K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;; and ternary eutectics at 882°C, 49% MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;, 19% CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;, 32% K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;; and 880°, 67·5% MgSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;, 5% CaSO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;, 27·5% K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;SO&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt;.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1016/0022-1902(67)80075-7</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Elsevier</dc:publisher>
  <dc:title>The ternary system K2SO4 MgSO4 CaSO4</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>