Formation of Met-Cars and Face-Centered Cubic Structures: Thermodynamically or Kinetically Controlled?

摘要: On the basis of a series experimental studies from our laboratory, it is well established that metallocarbohedrenes, or Met-Cars for short, are stable class cluster materials. To account their exceptional stability, we initially proposed pentagonal dodecahedron structure. This cage-like structure consistent with all findings. In general, there two possible structures can be developed in these metal-carbon systems, i.e., and cubes. Since only one structural pattern generally observed particular system, has been suggested thermodynamical stabilities might responsible selective formation specific structures, e.g., fcc structures. Herein, present new results on system Nb[sub m]C[sub n] under various conditions. It shown conditions extremely critical either cubic as predicted by Reddy Khanma. Moreover, data show do not develop top Met-Cars, but rather, they grow independently. The experiments were performed using both time-of-flight quadrupole mass spectrometer techniques coupled laser vaporization source. 23 refs., 1 fig.