The Structural Anomaly of Zinc: Evolution of Lattice Constants and Parameters of Thermal Motion in the Temperature Range of 40 to 500 K

作者：Nuss Juergen; Wedig Ulrich; Kirfel Armin; Jansen Martin^*

来源：Zeitschrift fur Anorganische und Allgemeine Chemie, 2010, 636(2): 309-313.

DOI：10.1002/zaac.200900460

• Element structures
• Crystal growth
• Metal-metal interactions
• X-ray diffraction

The crystal structure of elemental zinc deviates from the ideal hexagonal close packing by a significantly increased c/a ratio. We determined the evolution of the lattice constants and thermal displacement parameters in the temperature range of 40 to 500 K by accurate single-crystal X-ray diffraction. The c axis varies linearly within the whole temperature range, whereas the a lattice constant stays constant below approximate to 160 K, which indicates that at lower temperatures the Zn-Zn distances are no longer thermally contractible in the ab plane. As a further significant observation, the thermal expansion coefficient along the c direction exceeds the one in a direction by a factor of similar to 10. and consequently the c/a ratio slightly reduces. bill stays unusually high (c/a = 1.826, extrapolated for T = 0 K). The thermal motion of zinc shows a striking anisotropy as expressed by a ratio U-33/U-11 of approximate to 2.6 at 500 K. This ratio decreases significantly towards lower temperatures and reaches almost 1.6 at 40 K. The thermal behavior as observed is thus reflecting the structural and bonding anisotropy of zinc at ambient conditions, but thermal motion turns isotropic at cooling, in contrast to the atomic equilibrium structure.

• 出版日期2010