Phase Evolution, Microstructure, and Microwave Dielectric Properties of Reaction-Sintered Li2ZnTi3O8 Ceramic Obtained Using Nanosized TiO2 Reagent

Abstract

Dielectric ceramics in the Li 2 ZnTi 3 O 8 system were synthesized using TiO 2 nanoparticle reagent by the reaction-sintering process. The special effects of the TiO 2 nanoparticle reagent on the densification, phase distribution, microstructure, and dielectric properties were characterized using powder x-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). A single phase of Li 2 ZnTi 3 O 8 ceramic was confirmed by the XRD pattern at all temperatures except 1075°C. The reaction between the starting materials was accelerated using TiO 2 nanoparticles, with pure Li 2 ZnTi 3 O 8 phase being created even at low sintering temperature of 900°C, along with increasing green specimen density at the compaction stage. The presence of TiO 2 phase in the Li 2 ZnTi 3 O 8 ceramic improved the s f value and shifted it to near zero at 1075°C, and the ceramic exhibited excellent microwave dielectric properties of e r = 23.5, Q Â f = 71,000 GHz, and s f = À3.5 ppm/°C.

Phase evolution and microwave dielectric properties of BaTi4O9ceramics prepared by reaction sintering method

“…The reaction sintering process is a simple and effective process in preparing functional ceramics due to withdrawing calcination and reducing grinding, compared with the conventional solid‐state method. To date, many electric‐functional ceramics were prepared by this method successfully, such as Pb(Mg 1/3 Nb 2/3 )O 3 , ZnNb 2 O 6 , BaTi 9 O 20 , and Li 2 ZnTi 3 O 8 . Liou et al used reaction sintering method to prepare BaTi 4 O 9 ceramic with high sintered density (98.2%‐99.5% of theoretical value) for pellets sintered at 1200‐1280°C for 2‐6 hours in 2005 .…”

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

“…Phase evolution of (1-x)Li 2 ZnTi 3 O 8 -xTiO 2 system indicated that pure Li 2 ZnTi 3 O 8 with cubic structure was observed when x ≤ 0.2 (the lattice parameter is similar to MgFe 2 O 4 with space group of Fm3 ¯m ( 227)), solid solution was exited in the range of 0.2 ≤ x ≤ 0.4 with cubic structure (the lattice parameters is similar to Zn 2 Ti 3 O 8 with space group of P4332 (212)), and rutile TiO 2 phase appeared when x ≥ 0.6 [263]. The τ f value moves from -15 to 102.4 in (1-x)Li 2 ZnTi 3 O 8 -xTiO 2 (0 ≤ x ≤ 0.4) [264]; meanwhile, near zero τ f value was also achieved by Bari et al [265] in this system. 4 wt% TiO 2 was added into Li 2 ZnTi 3 O 8 with different particle sizes, where the nanoparticles and micron particles all generated a more uniform microstructure and relative density reached to 98.5% [266].…”

Comparison of different methods for Li2MTi3O8 (M – Co, Cu, Zn) synthesis

“…In order to obtain Li titanates, a high‐temperature solid‐state synthesis method is used that provides the formation of dense ceramics by sintering a stoichiometric mixture of powders of titanium dioxide (TiO 2 ), lithium carbonate (Li 2 CO 3 ) and zinc oxide (ZnO) or acetate (synthesis of Li 2 ZnTi 3 O 8 9‐12 ), or with cobalt oxide (CoO) or acetate (synthesis of Li 2 CoTi 3 ), 13,14 or with Cu and Zn oxides (synthesis of Li 2 Cu x Zn 1‐x Ti 3 O 8 ) 15 . Along with the ceramic method, the sol–gel method was used to obtain Li titanates with a developed specific surface area (SSA) and increased electrochemical activity for using Li‐ion current sources as the anode material 16‐19 .…”