Comparative study of physico-chemical properties of tetraalkylammonium perchlorates and composites on their basis

The effect of the cation in pure salts (n-CyH2y+1)(4)ClO4 (y = 3, 4) and in composites based on them with highly dispersed nanodiamonds (specific surface area 300 +/- 20 m(2)/g) has been studied using X-ray diffraction analysis (including high-temperature X-ray diffraction analysis), differential scanning calorimetry and impedance spectroscopy. Pure salts undergo 2 (n-C3H7)(4)ClO4 at 173 degrees C and 178 degrees C) or 1 (n-C4H9)(4)ClO4 at 60 degrees C) solid-solid phase transitions. Both salts undergo polymorphic transformations to a disordered weakly conducting cubic phase with the space group P (4) over bar 3n. The addition of nanodiamonds leads to a significant decrease in the enthalpies of phase transformations and intensities of reflections, which is associated with the formation of amorphous phases with a thickness of about 2 nm. The introduction of nanodiamonds leads to a significant increase in conductivity compared to the original compounds. The maximum conductivity values were achieved for the compositions 0.02(n-C3H7)(4)NClO4-0.98C(ND) (4.9 x 10(-4) S/cm at 165 degrees C) and 0.015(n-C4H9)(4)NClO4-0.985C(ND) (7.1 x 10(-4) S/cm at 165 degrees C), which is associated with the formation of a highly conductive amorphous phase, whose conductivity is 3-4 orders of magnitude higher than that of the original salts.