Extender structure effect melting point

The surface of an ionic crystal is structurally different from that of the bulk solid. Weil 24> contends that the surface extends for ca. 10,000 atom layers this means that the surface of a crystal, as examined by attenuated reflection spectroscopy, should show signs of this difference. Cooney et al. 25> took this idea up, and used the p2-mode of N03 in LiN03 and NaN03 to detect this effect the surface depth found is far greater than that predicted theoretically, and is dependent upon temperature (up to the melting point). Molten nitrates are studied very much in order to determine what the nature of the liquid state is, e.g. Devlin, James and Freeh 26) and references therein, James and Leony 27>, and Brooker 2 . 

The determination of Cpa can be effected by extrapolating to room temperature the values measured beyond the melting point that of Cpc can be done on single crystals, on extended chains, or for polymers having simple molecular structure by extrapolating the values obtained on model molecules. For polyethylene, the following values were obtained ... 

---