From binary to ternary and back to binary: Transition of electromagnetic wave shielding to absorption among MAB phase Ni <sub>3</sub>ZnB <sub>2</sub> and corresponding binary borides Ni <sub> <i>n</i>+1 </sub>B <sub> <i>n</i> </sub> ( <i>n</i> = 1, 3)
Cheng‐Wen Wu, Fan Zhang, Qin Zhi, Bo Song, Yongqiang Chen, Hailong Wang, Rui Zhang, Hongxia Li, Bingbing Fan
Abstract
Due to the chemical inertness of nickel and boron, the preparation of nickel borides and corresponding layered ternary transition metal borides Ni<sub>3</sub>ZnB<sub>2</sub> (MAB phase) has always required high-temperature and/or high-pressure conditions. Yet, an innovative and efficient approach to prepare Ni<sub>3</sub>ZnB<sub>2</sub> at only 600 °C and without applied pressure is presented in this study. It is discovered that by simply adjusting the temperature, a phase transition from Ni<sub>3</sub>ZnB<sub>2</sub> to Ni<sub>4</sub>B<sub>3</sub> with a layered structure could be induced. This transition between binary-component and ternary-component brings about significant variation of electromagnetic wave (EMW) shielding/absorption performance of prepared borides. For instance, Ni<sub>2</sub>B is of good EMW shielding performance (42.54 dB in X band) and Ni<sub>3</sub>ZnB<sub>2</sub> is of weak EMW shielding (13.43 dB in X band); Ni<sub>3</sub>ZnB<sub>2</sub> has poor EMW absorption performance (-5 dB) while Ni<sub>4</sub>B<sub>3</sub> has excellent EMW absorption performance (-45.19 dB) at a thickness of 2.7 mm with effective absorption bandwidth (10.4 GHz).