Preparation of LiZn _(0.9)PO _4:Mn _(0.1)·H _2O via a simple and novel method and its non-isothermal kinetics using iso-conversional calculation procedure

摘要

The LiZn _(0.9)PO _4:Mn _(0.1)·H _2O was synthesized via solid-state reaction at room temperature using LiH _2PO _4·H _2O, ZnSO _4· 7H _2O, MnSO _4·H _2O and Na _2CO _3 as raw materials. The experimental results show that the synthesized product is orthorhombic LiZn _(0.9)PO _4: Mn _(0.1)·H _2O, monoclinic LiZn _(0.9)PO _4:Mn _(0.1) is a green-yellow emitting phosphor which can be obtained after calcining LiZn _(0.9)PO _4:Mn _(0.1)·H _2O at 600°C in air. Based on the iterative iso-conversional procedure, the average values of the activation energies associated with the thermal dehydration of LiZn _(0.9)PO _4:Mn _(0.1)·H _2O, was determined to be 90.28 kJ mol ~(-1). Dehydration of the crystal water molecule of LiZn _(0.9)PO _4:Mn _(0.1)·H _2O is single-step reaction mechanism. A method of multiple rate iso-temperature was used to determine the most probable mechanism g(α) of the dehydration step. It is Mample single model (g(α) = -ln(1 - α)) and is controlled by random nucleation and subsequent growth mechanism. The pre-exponential factor A was obtained on the basis of E _a and g(α). Besides, the thermodynamic parameters (ΔS ~≠, ΔH ~≠, and ΔG ~≠)) of the dehydration reaction of LiZn _(0.9)PO _4:Mn _(0.1)·H _2O were determined.