Structure and dynamics on superionic conducting phosphate glasses by neutron scattering

Abstract

Neutron diffraction and inelastic scattering experiments have been performed on superionic conducting phosphate glasses, AgI–AgPO₃ and its undoped glass AgPO₃. In general, the static, elastic and dynamic structure factors S(Q), S(Q, ω=0), S(Q, ω), respectively, exhibit a prepeak at very low Q∼0.7 Å⁻¹ related to the intermediate range order ∼10 Å, but not for the AgPO₃. The low-energy excitation, or Boson peak (BP), at around 2–3 meV appears in all undoped and doped glasses.The amplitude of the BP increases and the position shifts to lower energy with addition of AgI. The inelastic contribution can be expressed in terms of sound waves, ΔS(Q,ω) α Q² S(Q), which is consistent with an acoustic mode. The expansion of the phosphate network plays a dominant role on increasing the mobility of the Ag ions, the ionic conductivity, the prepeak and the BP intensities.