Entropy-Assisted, Long-Period Stacking of Honeycomb Layers in an AlB2‑Type Silicide

Configurational entropy can impact crystallization processes, tipping the scales between structures of nearly equal internal energy. Using alloyed single crystals of Gd2PdSi3 in the AlB2-type structure, we explore the formation of complex layer sequences made from alternating, two-dimensional triangular and honeycomb slabs. A four-period and an eight-period stacking sequence are found to be very close in internal energy, the latter being favored by entropy associated with covering the full configuration space of interlayer bonds. Possible consequences of polytype formation on magnetism in Gd2PdSi3 are discussed.

组态熵（configurational entropy）可对结晶过程产生影响，在内能近乎相等的结构之间决定其形成倾向。我们采用具有AlB₂型结构的Gd₂PdSi₃合金单晶，探究由交替排布的二维三角与蜂窝状薄片构成的复杂层序的形成机制。研究发现，四周期与八周期堆垛序列的内能极为接近，其中八周期堆垛因与覆盖层间键全组态空间相关的熵而更具优势。本文还讨论了Gd₂PdSi₃中多型体形成对其磁性可能产生的影响。