Atta Ullah,Hanxing Liu,Hua Hao,Javed Iqbal,Zhonghua Yao,Minghe Cao
(1- x )Mg 0.90 Ni 0.1 SiO 3 - x TiO 2 ( x = 0, 0.01, 0.03, 0.05) ceramics were successfully formed by the conventional solid-state methods and characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS), and their microstructure and microwave dielectric properties systematically investigated. It was observed that when TiO 2 content increased from 0 to 5 wt%, the Q u f o of the sample decreased from 118,702 GHz to 101,307 GHz and increases the τ f value from −10 ppm/°C to +3.14 ppm/°C accompanied by a notable lowering in the sintering temperature (125 °C). A good combination of microwave dielectric properties (ε r ∼ 8.29, Q u f o ∼ 101,307 GHz and τ f ∼ −2.98 ppm/°C) were achieved for Mg 0.90 Ni 0.1 SiO 3 containing 3 wt% of TiO 2 sintered at 1300 °C for 9 h which make this material of possible interest for millimeter wave applications.
Solid-state sodium–metal batteries will not achieve reasonable power density without electrolytes that solve the dendrite (filamentation) problem. Metal-filament formation during plating at ceramic/metal interfaces can cause electrical failure by internal short-circuit or mechanical failure by electrolyte fracture. Herein, an Na 3 Zr 2 Si 2 PO 12 (NZSP) sodium-ion-conducting NASICON electrolyte in which TiO 2 is incorporated as an additive is presented, leading to a two-phase composite NZSP(TiO 2 ) with improved density, Young's modulus, hardness, grain structure, and bulk permittivity. These features of NZSP(TiO 2 ) suppress dendrite growth along grain boundaries, microcracks, and micropores. As well as demonstrating ultralow ceramic/Na kinetic resistance with electrochemical measurements, X-ray photoelectron spectroscopy is performed to probe interfacial reaction mechanisms. The TiO 2 phase forms within grain boundaries and along NZSP surfaces. This modifies the two-phase material's microstructure and improves its electrochemical performance, while also increasing the critical current density for dendrite formation. Design guidelines are discussed to mitigate microscopic defects and dendrites in two-phase ceramic electrolytes.
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