Thermodynamic properties of ammonium haloplatinates: II. Heat capacity and thermodynamic functions of deuterated ammonium hexachloroplatinate (ND4)2PtCl6 at temperatures from 5 K to 350 K

The heat capacity of deuterated ammonium hexachloroplatinate (ND4)2PtCl6 was measured at temperatures from 5 K to 350 K by adiabatic calorimetry. One λ-shaped anomaly, absent in the undeuterated salt, was found in the curve for heat capacity against temperature. This λ-shaped transition reaches its maximum Cp,m [approximate] 59.3·R at (27.2±0.05) K with ΔtrsSom = (1.216±0.004)·R, characteristic of an order-disorder transition. Smoothed values of the standard thermodynamic quantities for pure (ND4)2PtCl6 are tabulated at temperatures up to 350 K.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29263/1/0000321.pd