The information of Ammonium hexafluorophosphate

Ammonium hexafluorophosphate is a frequently accessible anatomy of the hexafluorophosphate anion.NH4PF6 undergoes two transitions at ambient burden on cooling: Fm over barm-C2 / c and an isosymmetric C2/c-C2/c transition. Isosymmetric transitions accept to be discontinuous. However, while this alteration displays a abeyant heat, there is little assurance of a aperture in neutron crumb diffraction or nuclear alluring resonance, constant with getting abutting to a Landau analytical point. The applied implications of hardly alternate isosymmetric transitions are discussed.The three phases of solid ammonium hexafluorophosphate (NH4PF6) accept been advised by cw and pulsed NMR methods amid 298 ° and 77 ° K. The proton and fluorine added moments of 1.8 and 1.9 G2, respectively, at 298 ° K are constant with rapid, randomized reorientations of NH4 + and PF6-ions, while the beyond ethics at 77 ° K crave that there be little or no motional absorption by reorientations of the PF6-ions even admitting the absorption by NH4 + reorientations is still present. For both nuclear breed the spin-lattice alleviation time ( T1) studies of the two low-temperature phases acknowledge three autransitions action in NH4PF6 amid 300 ° and 473 ° K.dible regions: Amid 109 ° and 110 ° K their alleviation is exponential with time. Amid 105 ° and 87 ° K the alleviation is nonexponential, but may be bidding as the sum of two exponential terms. At anniversary temperature the aforementioned brace of time constants applies to both nuclear species. At 77 ° K the alleviation is afresh exponential, with altered T1's for protons and fluorine. The nonexponential behavior in arena is attributed to circuit barter amid protons and fluorine nuclei. It after-effects from accentuation of the H ☒ F dipole-dipole interactions by about apathetic reorientations of the PF6-ions. This estimation was accepted by a abstraction of the fluorine T1 of ND4PF6, for which alone exponential decays were observed. Activation ambit for the PF6-reorientation were bent from the fluorine T1 in ND4PF6. The ambit depend somewhat aloft temperature, getting 4.1 ± 0.2 kcal / mole and (3.7 ± 0.5) × 10-16 sec aloft 130 ° K and 4.4 ± 0.3 and ( 5.2 ± 1.5) × 10-17 below. A aperture occurs in the T1's at the 192 ° K appearance transition, and in the top temperature NaCl appearance the T1's are about absolute of temperature and apparently are absolute by spin-rotation interactions. DTA abstracts announce that no added appearance 
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