Defect Properties and Lithium Incorporation in Li2ZrO3

Lithium zirconate is a candidate material in the design of electrochemical devices and tritium breeding blankets. Here we employ an atomistic simulation based on the classical pair-wise potentials to examine the defect energetics, diffusion of Li-ions, and solution of dopants. The Li-Frenkel is the lowest defect energy process. The Li-Zr anti-site defect cluster energy is slightly higher than the Li-Frenkel. The Li-ion diffuses along the c axis with an activation energy of 0.55 eV agreeing with experimental values. The most favorable isovalent dopants on the Li and Zr sites were Na and Ti respectively. The formation of additional Li in this material can be processed by doping of Ga on the Zr site. Incorporation of Li was studied using density functional theory simulation. Li incorporation is exoergic with respect to isolated gas phase Li. Furthermore, the semiconducting nature of LZO turns metallic upon Li incorporation.

Non-isothermal reaction mechanism and kinetic analysis for the synthesis of monoclinic lithium zirconate (m-Li2ZrO3) during solid-state reaction

Non-isothermal reaction mechanism and kinetic analysis for the synthesis of monoclinic lithium zirconate (m-Li2ZrO3) were investigated by processing of TG-DTA, along with XRD, DLS, and HRTEM. For this purpose, the solid-state reaction of Li2CO3 with ZrO2 was carried out by TG-DTA at different heating rates (10, 20, and 30 °C/min) from room temperature to 1100 °C. The thermal data was used to calculate the kinetic parameters by two types of isoconversional methods: Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS). The reaction mechanism was determined by the model-fitting method, applying the Coats-Redfern (CR) approximation to the different solid-state reaction models. The results confirmed the formation of pure m-Li2ZrO3, consists of semispherical particles of about 490 nm, using a very short reaction time. The average activation energy obtained by FWO and KAS methods were 274.73 and 272.50 kJ/mol, respectively. It was found that the formation of m-Li2ZrO3 from Li2CO3 with ZrO2 is governed by the three-dimensional diffusion mechanism. Based on these results, a microscopic reaction model of the formation of m-Li2ZrO3 was proposed.

Influence of Texture Evolution on Mechanical and Damping Properties of SiC/Li2ZrO3/Al Composite Through Friction Stir Processing

In this study, parent aluminum (Al), silicon carbide (SiC) reinforced Al, zirconia (ZrO2) coated SiC reinforced Al, and lithium zirconate spinel (Li2ZrO3, LZO) encapsulated SiC incorporated Al metal matrix composites were processed via friction stir processing (FSP) technique to observe the influence of grain refinement on mechanical and damping properties. Electron backscattered diffraction (EBSD) analysis were conducted for detailed and deep understanding of possible mechanism and microstructure at longitudinal cross sections of the samples. Further, the room temperature mechanical properties and thermal cyclic (−100 to 400 °C) damping performance of the friction stir processed composites were studied. The results obtained in this investigation show that storage modulus of pristine Al, SiC reinforced Al, ZrO2 coated SiC reinforced Al, and LZO coated SiC reinforced Al were improved by a factor of 1.09, 1.17, 1.09, and 1.38, respectively, after FSP. Additionally, the ultimate tensile strength (UTS) and hardness of the friction stir processed SiC/Li2ZrO3/Al composite were improved by a factor of 1.08 and 1.11, respectively, after FSP was compared with an unprocessed composite.