Ferroelectricity in (CH_3NHCH_2COOH)_3・CaCl_2

概要

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Tris-sarcosine calcium chloride, (CH_3NHCH_2COOH)_3CaCl_2, is ferroelectric below the Curie Point, 127°K, where the dielectric constant, ε_b, at low frequencies shows a sharp peak. The dielectric constants ε_a and ε_c. do not show any noticeable anomaly at the Curie point. The dielectric measurement at a microwave frequency of 9.4 Gc/s indicates that there is a marked dielectric dispersion in the Curie temperature region. The spontaneous polarization is 0.27 μCoul/cm^2 at 78°K. The high-temperature phase is orthorhombic with space group P_<nma> and a=9.153 Å, b=17.48 Å, c=10.28 Å at room temperature. The low-temperature phase may possibly be orthorhombic with point group C_<2v>. The measurement of specific heat as a function of temperature yields δS=(0.38±0.04) cal/mole・degree. The results are discussed in comparison with those of some ferroelectrics such as (glycine)_3・H_2SO_4.
社団法人日本物理学会の論文
1965-11-05