Effect of quenching rate on the structure, ion transport, and crystallization kinetics in lithium-rich phosphate glass

Abstract

The report investigates the effect of quenching rate on the structure, lithium ion dynamics, and crystallization kinetics of mol% 60Li2O–40P2O5 glass. Quenching rate of the order of 105 K s−1 has been achieved using a twin-roller rapid quenching setup. Raman and FT-IR studies reveal that the rapidly quenched glass is more disordered with a reduced amount of pyrophosphate structural units (P2O7 4−) in the glass matrix as compared with the conventionally quenched glass. Non-isothermal differential scanning calorimetry brings out that the rapidly quenched glass undergoes three-phase crystallization while the conventionally quenched glass depicted predominantly single-phase crystallization. The phases are identified as lithium metaphosphate (LiPO3), pyrophosphate (Li4P2O7), and orthophosphate (Li3PO4). The activation energy for crystallization for the major phase Li4P2O7 calculated using thermoanalytical methods turns out to be 287 kJ mol−1. The above structural differences between the rapidly and conventionally quenched glasses result in superior conduction characteristics for the rapidly quenched glass depicting ionic conductivity of 1.0 × 10−6 S cm−1 at 343 K with an activation energy of 0.63 eV for lithium ion motion. Microstructural studies on the glass ceramics divulge surface, 2D, and 3D crystal growth mechanism for lithium meta-, pyro-, and ortho-phosphate phases, respectively.