Synthesis of new lead‐containing MAX phases of Zr <sub>3</sub> PbC <sub>2</sub> and Hf <sub>3</sub> PbC <sub>2</sub>
Qiqiang Zhang, Bo Wen, Jia Luo, Yanchun Zhou, Xingyuan San, Yiwang Bao, Longsheng Chu, Qingguo Feng, Salvatore Grasso, Chunfeng Hu
Abstract
Abstract In this work, two new 312 MAX phases of Zr 3 PbC 2 and Hf 3 PbC 2 were successfully synthesized by spark plasma sintering. It is the first discovery of lead‐containing 312 MAX phases, which together with M 2 PbC (M = Ti, Zr, Hf) form the lead‐containing MAX phase family. Considering the extremely low electrical conductivity of Hf 2 PbC, these two new compounds are of great research value. Based on the Rietveld refinement results, their lattice parameters and atomic positions were well determined, as a = 3.3771(5) Å, c = 20.0070(9) Å for Zr 3 PbC 2 and a = 3.3357(1) Å, c = 19.7659(8) Å for Hf 3 PbC 2 , where M atoms are located at (0, 0, 0) and (1/3, 2/3, 0.1258(6)[Zr]; 0.1255(2)[Hf]), Pb atoms are located at (0, 0, 1/4), and C atoms are located at (1/3, 2/3, 0.0663(2)[Zr]; 0.0641(3)[Hf]), respectively. Additionally, the typical laminar microstructure of Zr 3 PbC 2 and Hf 3 PbC 2 grains was observed.