Heat Capacity and Thermal Expansion of NH_3CH_2COOH・H_2PO_3(Condensed Matter : Structure, Mechanical and Thermal Properties)

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Heat capacity of glycinium phosphite was measured by adiabatic calorimetry in a temperature range from 90 K to 300 K. A λ-type anomaly characteristic of the second order phase transition was observed at 224.3 K (T_C). The jump of the heat capacity at T_C is estimated as Δc = 7.1 ± 0.2JK^<-1> mol^<-1>. The transition enthalpy and transition entropy were estimated as ΔH = 82.20 ± 0.07 J mol^<-1> and ΔS = 0.40 ± 0.01 JK^<-1> mol^<-1> respectively. Thermal expansions of the crystal were also measured along the crystallographic a, b and c axes using the strain gages. The volume thermal expansion shows clear anomaly at T_C. The jump of thermal expansion coefficient at T_C is estimated as Δα_v = -2.7 ± 0.3 × 10^<-5>K^<-1>.
社団法人日本物理学会の論文
2004-07-15