Tangdong Feng,Yiwen Hu,Xue Chang,Wanxia Huang,Daoyuan Wang,Hongfu Zhu,Tianyu An,Wenping Li,Kun Meng,Xueguang Lu,Basanta Roul,Sujit Das,Hua Deng,Kirill I. Zaytsev,Li-Guo Zhu,Qiwu Shi
The dynamic control of terahertz (THz) wave transmission on flexible functional materials is a fundamental building block for wearable electronics and sensors in the THz range. However, achieving high-efficiency THz modulation and low insertion loss is a great challenge while maintaining the excellent flexibility and stretchability of the materials. Herein, we report a Ti3C2Tx MXene/waterborne polyurethane (WPU) membrane prepared by a vacuum-assisted filtration method, which exhibits excellent THz modulation properties across stretching. The hydrophilic Ti3C2Tx MXene and WPU enable the uniform 3D distribution of Ti3C2Tx MXene in the WPU matrix. Particularly, the stretchability with the maximum strain of the membranes can reach 200%, accompanied by dynamic tuning of THz transmittance for more than 90% and an insertion loss as low as −4.87 dB. The giant THz modulation continuously decreases with MXene content per unit area, accompanied by a lower density of the MXene interface and diminished THz absorption during stretching. Such a design opens a pathway for achieving flexible THz modulators with a high modulation depth and low insertion loss, which would be used for THz flexible and wearable devices.
Yanpu Chen,Jiaxin Zhao,Yuanjie Yang,Shengran Lin,Peng Wang,Liren Lou,Wei Zhu,Guanzhong Wang
A new method to prepare AlScN/diamond structure was proposed to fabricate high frequency surface acoustic wave (SAW) resonators . The AlScN/diamond structure was prepared by growing a diamond layer on the AlScN surface and removing the Si substrate . Highly c-axis oriented AlScN thin films with 2.37° full width at half maximum (FWHM) on the X-Ray rocking curve of the (002) peak were deposited by reactive ion assisted sputtering. This method solved the problem of high roughness synthetic diamond worsening sputtered AlScN quality without using polishing. A high electromechanical coupling coefficient (K eff 2 ), 4.31 %, was obtained from the 2.77 GHz SAW devices of AlScN/diamond structure, and its insertion loss is 15.46 dB. The AlScN/diamond SAW devices exhibit lower insertion loss and higher K eff 2 in comparison to AlScN/Si devices. The proposed AlScN/diamond structure fabrication process showed a feasibility of mass production of high frequency SAW resonators with excellent performance.
Lijin Cheng,Pengxiang Hao,Fei Liu,Yan Li,Yujie Zhao,Shaojun Liu
The (1-x)Mg 2 TiO 4 -xCa 0.8 Sr 0.2 TiO 3 (MT-CST) ceramic filters with intricate structures, low insertion loss and near-zero resonant frequency temperature coefficient were successfully fabricated by heated-assisted digital light processing (DLP). The excellent dielectric properties of DLP-printed ceramic filters could be attributed to the utilization of ceramic slurries with high solid loading, the improvement of forming accuracy and the control of CST content. The increasing of curing temperature could facilitate the mobility of the molecular segments and increase the activation energy of the free radicals, consequently leading to the reduction in viscosity and the improvement in curing properties of the MT-CST ceramic slurries with 57.5 vol% solid loading. The forming accuracy was regulated by fine-tuning the exposure energy densities. The excess curing width of precision model increased from 25 to 35 μm when the exposure energy densities increased from 7 to 11 mJ/cm 2 . The 0.91MT-0.09CST ceramics sintered at 1450 ℃ for 4 h exhibited excellent dielectric properties: ε γ = 17.5; Q × f = 46,800 GHz; τ f = -3.21 ppm/℃. The DLP-printed 0.91MT-0.09CST ceramic filters showed an excellent insertion loss of −1.3 dB.
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