Heat capacity of deuterated ammonium tetrafluoroborate ND 4BF 4 from 7 K to 348 K

Abstract

The heat capacity of deuterated ammonium tetrafluoroborate ND 4BF 4 was measured from 7 K to 348 K by adiabatic calorimetry. The curve for heat capacity against temperature is smooth with a broad maximum between 120 K and 165 K, and the peak value in C p, m ≈ 14.9· R occurs between 145 K to 155 K. The shape of the broad maximum is similar to that found in other anisotropic salts and is believed to be a result of contributions both from the rotation of the ND 4 + ion and from a larger than usual dilation of the unit cell. Values of the standard thermodynamic quantities are tabulated up to 350 K.