35Cl nuclear quadrupole resonance (NQR) study of ion mobility in (ND4)2PtCl4

35Cl nuclear quadrupole resonance was applied to study molecular dynamics in (ND4)2PtCl4. The spin-lattice relaxation time T1Q, the quadrupole resonance frequency νQ, the line width δν and the integrated intensity T∫F(ν) dν of the resonance line F(ν) multiplied by the temperature T to compensate for the Curie law effect were measured in a wide temperature range 12.4 K<T<425 K. Effects due to cation and anion mobility were clearly seen and their contributions are disentangled. Domain structure and diverse mobility of ammonium ions in the ordered phase are the basic assumptions underlying the fitting of the experimental data. An order-disorder phase transition takes place at 148 K and appears visible in all measured quantities. Unrestricted mobility of ammonium ions dominates above the phase transition. At higher temperatures, mobility of the planar PtCl42- ions, first torsional oscillations and then reorientational jumps, becomes detectable