Correlation of Heating Rates, Crystal Structures, and Microwave Dielectric Properties of Li2ZnTi3O8 Ceramics

Abstract

The correlation of heating rates, crystal structures, and microwave dielectric properties of Li 2 ZnTi 3 O 8 ceramics was thoroughly investigated. Ionic polarizability, atomic packing fractions, bond strengths, and octahedral distortion of Li 2 ZnTi 3 O 8 ceramics were calculated on the basis of structure refinement data. The ''black core'' phenomenon resulting from reduction of Ti 4+ ions was observed for Li 2 ZnTi 3 O 8 ceramic sintered at 1°/min; reduction of Ti 4+ ions could be limited by heating more rapidly. For heating rates from 1 to 7°/min, the dielectric constants (e r ) of Li 2 ZnTi 3 O 8 ceramics were mainly determined by ionic polarizability. The temperature coefficient of the resonant frequency (s f ) of Li 2 ZnTi 3 O 8 ceramics was determined by bond strengths. Li 2 ZnTi 3 O 8 ceramic sintered at 1°/min had the lowest quality factor (Q 9 f); this was related to the high dielectric loss as a result of oxygen vacancies formed by reduction of Ti 4+ ions. Q 9 f values of Li 2 ZnTi 3 O 8 ceramics also decreased with increasing heating rate from 3 to 7°/min, owing to reduced packing fractions and average grain sizes. Li 2 ZnTi 3 O 8 ceramic sintered at 3°/min had the optimum microwave dielectric properties of e r = 26.6, Q 9 f = 83,563 GHz, and s f = À12.4 ppm/°C.

Improving the Electrochemical Performance of Li2ZnTi3O8 by Surface KCl Modification

“…The binding energy of surface elements acquired from XPS could provide further information for structural change (Figure 8). In the survey spectra (Figure 8a), the C 1s peak (284.78 eV) is used as a reference for identifying other elements, besides the Li 1s, O 1s, Zn 2p, and Ti 2p peaks presented in P-LZTO and LZTO/KCl, 33 Cl 2p peak also displays in LZTO/KCl. The signal of K 2p could hardly be distinguished in the survey spectrum due to the less amount of K on the surface of LZTO particle and the overlap of K 2p peak (292.93 eV) with C 1s peak (284.78 eV) resulted from the similar binding energies of them, but could be revealed by the core level spectrum of K 2p (Figure 8e).…”

In Situ Synthesis of Reduced Graphite Oxide-Li2ZnTi3O8 Composite as a High Rate Anode Material for Lithium-Ion Batteries

“…The enlarged (311) peak in Figure 1b reveals a slight shift to a lower angle in LZTO@RGO10 and LZTO@RGO25 owing to the creation of oxygen vacancies due to the incomplete crystallinity of LZTO in the presence of RGO. 40 This lattice property may be suitable for rapid transportation of Li + ions during the charge-discharge process. Due to the fact that LZTO@RGO composites have smaller crystalline size and larger lattice constants, we expect that Li + diffusion can be easier than that of the pristine LZTO anode.…”

The latest process and challenges of microwave dielectric ceramics based on pseudo phase diagrams

“…Except for the sintering temperature, the heating rates and substation will directly influence the grain size, densification, and properties. Lu et al [254] pointed out that the sintering rate increasing from 3 to 7 /min would deteriorate the quality f ℃ actor of Li 2 ZnTi 3 O 8 ceramics. If ball milling is applied for the raw materials at first for 4 h, then the sintering temperature of Li 2 ZnTi 3 O 8 ceramics could reduce from 1075 to 925 , and those ceramics were chemically ℃ compatible with Ag [255].…”