Spectroscopic, dielectric properties and phase transition of Bis (diethylammonium) hexachlorido stannate(IV)

The [C₄H₁₀NH₂]₂SnCl₆ compound is characterized by using the X-ray powder analysis, thermogravimetric analysis, differential scanning calorimetry analysis, ¹³C and ¹¹⁹Sn (CP/MAS NMR) analysis, vibrational spectroscopy and complex impedance spectroscopic data. The results show that this compound exhibits a phase transition at 326 K which was characterized by differential scanning calorimetry (DSC), X-rays powder diffraction, Raman spectroscopy and dielectric measurements. The most important changes are observed for four lines at 3207 cm⁻¹, 3056 cm⁻¹, 3000 cm⁻¹ and 1538 cm⁻¹ (at room temperature) issued from asymmetric and symmetric stretching vibrations of ν_s(NH₂), ν_s(NH₂), ν_as(NH₂) and ν_δ(NH₂) band, respectively. The assignment of the observed IR and Raman lines was performed by comparison with the homologous compounds. Dielectric data were analyzed using complex permittivity ε* and complex electrical modulus M* for the sample at various temperatures. The Z′ and Z" versus frequency plots are well fitted to an equivalent circuit model. The analysis of Nyquist plots are well fitted to an equivalent circuit consisting of series of combination of grains and grain boundary elements. The AC conductivity was studied using the following equation: ${\sigma }_{AC}\left(\omega \right)=\frac{{\sigma }_s}{1+{\tau }^2{\omega }^2}+\frac{{\sigma }_{\infty }{\tau }^2{\omega }^2}{1+{\tau }^2{\omega }^2}+A{\omega }^s$. The conductivity follows the Arrhenius relation. Hopping frequency was determined and activation energy of hopping is almost equal to the activation energy of conduction. The temperature dependence of the power law exponent s and a.c conductivity σ_ac is reasonably interpreted by the quantum mechanical tunneling (QMT) and the barrier hopping (CBH) model. The modulus plot can be characterized by full width at half height or in terms of a non-experiential decay function ϕ(t) = exp(−t/τ)β.