The vapor pressure of249Bk metal has been measured over the range 1100ndash;1500 K, using combined target and mass spectrometric Knudsen effusion techniques. Vapor pressure data are combined with an appropriate estimate for the solid heat capacity and the estimated crystal entropy Sdeg;298, to produce enthalpy, entropy, and free energy functions from 298 to 2000 K. The vapor pressures are described by the equations: Log10P(atm) = minus;(15thinsp;718 plusmn;253)/T+578plusmn;0.21 lsqb;solid, 1107ndash;1319 Krsqb;, Log10P(atm) = minus;(14thinsp;902 plusmn;244)/T+5.14plusmn;0.17 lsqb;liquid, 1345ndash;1528 Krsqb; from which we calculate Dgr;Hdeg;298(2nd law) = 73thinsp;960plusmn;1150 cal/mol lsqb;solidrsqb;, Dgr;Hdeg;298(2nd law) = 73thinsp;980plusmn;1120 cal/mol lsqb;liquidrsqb;, and Dgr;Hdeg;298(3rd law) = 74thinsp;220plusmn;180 cal/mol lsqb;solid and liquidrsqb;.
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