ABSTRACT

The MAB phases are a family of layered ternary transition metal borides, with atomically laminated crystal structures comprised of transition metal boride (M-B) layers interleaved by single, or double, Al (A) layers. Herein, density functional theory is implemented to evaluate the thermodynamic stability of disordered (Mn_1-xCr_x)₂AlB₂, and disordered and ordered (Mn_1-xCr_x)₃AlB₄ quaternaries. The (Mn_1-xCr_x)₂AlB₂ solid solutions were synthesized over the entire range of substitution. A (Mn_1-xCr_x)₃AlB₄ solid solution was produced, on the base of Cr₃AlB₄, to form (Mn_0.33Cr_0.66)₃AlB₄. Powder X-ray diffraction shows lattice parameter shifts and unit cell expansions indicative of successful solid solution formations.

摘要

MAB相是层状三元过渡金属硼化物的族，原子层叠的晶体结构由单层或双层Al（A）层交错而成的过渡金属硼化物（MB）层组成。在本文中，采用密度泛函理论来评估无序（Mn _1-x Cr _x）₂ AlB ₂和无序有序（Mn _1-x Cr _x）₃ AlB ₄四元系的热力学稳定性。在整个取代范围内合成了（Mn _1-x Cr _x）₂ AlB ₂固溶体。A（锰_1-x铬_x）₃ AlB ₄固溶体在Cr ₃ AlB ₄的基础上生成，形成（Mn _0.33 Cr _0.66）₃ AlB ₄。粉末X射线衍射显示晶格参数移动和晶胞膨胀，表明成功形成固溶体。