Xuefeng Shen,Qian Zhang,Tianxiang Ning,Jianlei Liu,Taoyong Liu,Zhiwei Luo,Yao He,Chunchun Qin,Anxian Lu
Garnet solid electrolyte is the most promising candidate among inorganic solid electrolytes due to its wide potential window, good compatibility and high safety. In this work, a dual doping strategy is offered for the development of garnet-type electrolytes with high ionic conductivity . Te 6+ is introduced into the Zr sites to stabilize the high-ionic conductivity cubic phase. Simultaneously, Sr 2+ enter the La sites to achieve a fine-tuning of the Li + concentration by charge compensation, acting as a sintering agent of Te 6+ /Sr 2+ doped electrolytes. The structure, chemical composition and ionic conductivity of Li 7 − 2 y + x La 3 − x Sr x Zr 2 − y Te y O 12 ( x = 0–0.25, and y = 0.35) electrolytes are systematically investigated by X-ray diffraction, Raman spectroscopy , scanning electron microscope , Energy Dispersive X-ray Spectroscopy, Inductively Coupled Plasma-Optical Emission Spectrometry and Alternating Current impedance. The results show that the optimal amount of Sr 2+ substitution helps to reduce the total resistance by promoting the growth of grains and ceramic densification . Among the investigated compositions, the composition with Li 6.425 La 2.875 Sr 0.125 Zr 1.65 Te 0.35 O 12 exhibits excellent performance with relative density of 97.95%, conductivity of 4.27 × 10 −4 S cm −1 at 25 °C and activation energy of 0.30 eV. The assembled Li/Li 6.425 La 2.875 Sr 0.125 Zr 1.65 Te 0.35 O 12 /Li symmetrical batteries are cycled galvanostatically under different current densities. The results show that the symmetrical battery can achieve good cyclic stability, good Li + stripping and plating process and low overpotential.
With the robust advancement of fifth-generation (5G) wireless communication and the steady progression of sixth-generation (6G) wireless communication toward practical implementation, the communication sector has imposed unprecedented requirements on microwave dielectric ceramics, particularly concerning their crucial performance parameters, including a suitable dielectric constant, ultra-low dielectric loss, and a near-zero temperature coefficient of resonant frequency. CoMo 1- x Te x O 4 ( x = 0.01, 0.03, 0.05, 0.07) ceramics were successfully synthesized via the conventional solid-state reaction method. The mixed powders underwent pre-calcination at 500 °C, and the samples were subsequently sintered for 4 h within the temperature range of 550 °C to 650 °C. The results of X-ray diffraction (XRD) analysis and Rietveld refinement reveal that when x ≤ 0.03, the obtained samples are monoclinic ceramic crystals belonging to the C 2/ m space group. When the Te 6+ content x ≥ 0.05, a monoclinic crystal structure with the P 2/ c space group emerges. Moreover, at x = 0.07, the quality factor of the sintered ceramic samples reaches its maximum value at 600 °C. According to scanning electron microscopy (SEM) analysis, the relative density has a significant impact on the dielectric constant and quality factor of the ceramics. Raman spectroscopy was utilized to probe the internal lattice vibration modes. The results demonstrate that the dielectric constant ( εᵣ ) of the ceramics exhibits a close correlation with the Raman spectral shifts, while the quality factor ( Q × f ) is strongly associated with the full—width at half-maximum (FWHM) of the Raman peaks. At 600 °C, the CoMo 1- x Te x O 4 ceramics exhibit excellent dielectric properties: a dielectric constant ε r = 9.13 (± 0.06), a quality factor Q × f = 84,224 (± 2301) GHz, and a temperature coefficient of resonant frequency τ f = -72.8 (± 1.3) ppm/°C. The ionic polarizability and relative density are the primary determinants of ε r . The Q × f is influenced by the packing density and relative density. Based on the P–V–L theory, the Mo–O bonds make a significant contribution to the quality factor ( Q × f ) and the temperature coefficient of resonant frequency ( τ f ). Notably, at 600 °C, the ceramics still maintain an appropriate dielectric constant ( ε r ) and high-performance Q × f values. This research holds an indispensable role in the development of ultra-low temperature co—fired ceramics (ULTCC).
危险品化学品经营许可证（带存储）