Kiracı, AliKiracı, Ali2020-01-312020-01-312019Kiraci, A., "A phenomenological study on ferroelectric pyridinium tetrafluoroborate (C5NH6) BF4", Thermochimica Acta, Vol. 680, (2019).0040-6031https://hdl.handle.net/20.500.12416/2398The temperature dependence of the specific heat C-V of (C5NH6)BF4 was analyzed according to a power law formula with a critical exponent alpha deduced from the compressible Ising model in the vicinity of the phase transition temperatures of T-C1 = 238 K and T-C2 = 204 K. The extracted values of the critical exponent alpha within the temperature intervals of vertical bar T - T-C1 vertical bar < 6 K and also T - T-C2 < 6 K were consistent with that predicted from the 3d-Ising model (alpha = 0.10) while obtained values of alpha within the temperature interval of T-C2 - T < 6 K were consistent with that predicted from 2-d potts model (alpha = 0.30). In addition, the thermodynamic quantities: the internal energy (U), the entropy (S) and the Helmholtz free energy (F) of this compound were calculated on the basis of the extracted values of the critical exponent a below and above the phase transition temperatures of T-C1 and T-C2.eninfo:eu-repo/semantics/closedAccessIsing ModelSpecific HeatFree EnergyCritical Exponent(C5NH6)BF4Article68010.1016/j.tca.2019.178371