Potts tricritical points

Figure 51. Experimental phase diagram of CO physisorbed on graphite with the phases fluid (F), commensurate (CD) and incommensurate (ID) orientationaliy disordered solids, reentrant fluid (RF), second-layer fluid (2F), vapor (2V), liquid (2L), and orientationaliy disordered solid (2SD) phases. Filled circles and triangles represent phase boundary locations from heat capacity and vapor pressure measurements, respectively. Solid and dashed lines indieate phase boundaries believed to be associated with first-order and continuous transitions, respectively dash-dotted lines correspond to speculated boundaries. The large filled triangle and the large filled circle mark the two-dimensional Potts tricritical and critical points, respectively the tricritical point marked with an open triangle is tentative. Lines I-VII with arrows are experimental paths of the heat capacity scans shown in Fig. 52. Coverage unity corresponds to a coverage of CO forming a complete (Vs x VS) monolayer. (Adapted from Fig. 1 of Ref. 112.)...

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