Electron Paramagnetic Resonance Studies of Ferroelectric Fe 3+ ‐Doped Tris‐Sarcosine Calcium Chloride Monocrystals

Ferroelectric tris‐sarcosine calcium chloride (TSCC) single crystals are investigated using the EPR method in X‐ and Q‐band in a temperature range from 3.7 to 300 K. The spectra of the Fe 3+ ions substituted for Ca 2+ ions are well described by a spin Hamiltonian of orthorhombic symmetry with the following parameters at room temperature: g = 2.005 ± 0.002, D = ( −1250 ± 10) × 10 −4 cm −1 , E = (−70 ± 5) × 10 −4 cm −1 , F = (30 ± 6) × 10 −4 cm −1 , a = (81 ± 7) × x 10 −4 cm −1 . The structural ferroelectric phase transition is evidenced in a splitting of the EPR lines, which is proportional to the spontaneous polarization of the crystal. This proportionality allows to determine the coefficients A, B , and C of the Landau expansion of the free energy G . The results are compared with dielectric measurements and EPR measurements of TSCC:Mn 2+ .