Nearly-zero thermal expansion along the layer-stacking axis of ZnSe-based inorganic-organic hybrid semiconductor materials

Zero thermal expansion (ZTE) is a desired but rare material property. Herein we report a unique family of inorganic-organic hybrid semiconductors with general formula [ZnSe(L)_0.5] (L = organic diamine) that exhibit nearly-zero thermal expansion along the layer-stacking axis in the temperature range of 5-300 K. The unit cell parameters and crystal structures of [ZnSe(en)_0.5], [ZnSe(pda)_0.5], [ZnSe(bda)_0.5], and [ZnSe(ptda)_0.5] (en = ethylenediamine, pda = propanediamine, bda = butanediamine, and ptda = pentanediamine) have been refined by the Rietveld method by using powder samples, and their thermal expansion properties have been analyzed and rationalized on the basis of their crystal structures and symmetry. [ZnSe(ptda)_0.5] features a very small negative linear thermal expansion coefficient (-7.8 × 10^-7 K^-1) that approaches the smallest values reported to date. A new family of inorganic-organic hybrid semiconductors α-[ZnSe(L)_0.5] (L = ethylenediamine, propanediamine, butanediamine, and pentanediamine) exhibit unique nearly-zero thermal expansion along the layer-stacking axis.