Vapour pressure and standard enthalpy of sublimation of alkali-metal fluoroborates

log(p/Pa) [NaBF4,orthorhombic]=7.06(±0.03)−3734(±360) (K)/Tlog(p/Pa) [NaBF4,monoclinic]=6.03(±0.04)−3192(±80) (K)/TThe enthalpy pertaining to the transition from the orthorhombic to the monoclinic phase at 527 K, was found to be 10.4 kJ mol−1.log(p/Pa) [RbBF4]=6.21(±0.04)−4020(±87) (K)/Tlog(p/Pa)[CsBF4]=7.77(±0.04)−5209(±108) (K)/T By using the third law analyses of the data, image of MBF4 (M = Na, Rb or Cs) at 298 K were determined to be 89.4 ± 1.5, 123.4 ± 1.9 and 135.7 ± 0.8 kJ mol−1, respectively.