Crossover from overlap large polaron to small polaron tunneling: A study of conduction mechanisms and phase transitions in a new long chain organic inorganic hybrid

• Published in: The Journal of physics and chemistry of solids 2021-02, Vol.149, p.109787, Article 109787
• Main Authors: Tammam, A.K., Gawad, D., Mostafa, M.F.
• Format: Article
• Language: English
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2020.109787

AC-conductivity study of the new long chain hybrid [NH3 (CH2)8 NH3]Cl2 in the temperature range 210 K–420 K showed the following consecutive phase transitions: (PhaseVIII)T7=232.5K(PhaseVII)T6=253K(PhaseVI)T5=287.9K(PhaseV)T4=316.5K(PhaseIV)T3=330.7K(PhaseIII) T2=378.8 K(PhaseII)T1=399 K(PhaseI). Transitions are confirmed by differential scanning calorimetry (DSC). Room temperature X-ray powder diffraction indicated a monoclinic P21/c with crystallographic parameters a = 18.179 Å, b = 15.380 Å, c = 4.881 Å and β = 109.54(0), V = 1286 (Å)3, Z = 4. Frequency dependent ac-conductivity at different temperatures is interpreted in terms of the jump relaxation model and is fitted to super-linear power law σtot = σdc + A1ωs1+ A2ωs2. The fit parameters lnA1/s1 and lnA2/s2 are sensitive to the type of conduction mechanism. Temperature and frequency dependence of ac-conductivity indicated that in the low (T