Calculation of the order parameter and dielectric susceptibility under the electric field near the incommensurate phase in NaNO2 using Landau model

YURTSEVEN H. H., AKAY SEFER Ö.

Philosophical Magazine, cilt.105, sa.3, ss.208-227, 2025 (SCI-Expanded) identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 105 Sayı: 3
  • Basım Tarihi: 2025
  • Doi Numarası: 10.1080/14786435.2024.2412599
  • Dergi Adı: Philosophical Magazine
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Chemical Abstracts Core, Communication Abstracts, Compendex, INSPEC, Metadex, Civil Engineering Abstracts
  • Sayfa Sayıları: ss.208-227
  • Anahtar Kelimeler: dielectric susceptibility, incommensurate phase, Landau mean field model, NaNO2, Order parameter
  • Marmara Üniversitesi Adresli: Evet

Özet

Temperature dependences of the order parameters (P and Ψ) and inverse susceptibilities (χp−1 and χΨ-1) are calculated for the ferroelectric(FE)-incommensurate (INC)–paraelectric (PE) transitions in NaNO2 at zero (E = 0) and constant electric fields E by the Landau phenomenological model. For the calculation of the polarisation P and the order parameter Ψ, the phase line equations are fitted to the observed data (E = 0) from the literature. On this basis, E-T phase diagram including the ferroelectric, incommensurate and paraelectric phases is constructed using the observed (E-T) data for NaNO2 as reported in the literature. In the presence of the polarisation P (secondary order parameter), which has a biquadratic coupling with the Ψ (primary order parameter) in the incommensurate phase, the Landau model presented here describes the observed behaviour of the FE-INC and INC-PE transitions in NaNO2. Under constant electric fields, our predictions can be compared with the experiments. This method of calculation can be applied to some other crystals exhibiting the incommensurate phase between the FE and PE phases.