Preparation and growth mechanism of different morphological TaC_x whiskers

Tantalum carbide (TaC_K) whiskers were successfully synthesized via different methods and different starting raw materials in the presence of Ni powder used for the catalysis of synthesis. In the Ta₂O₅-NaCl-C-Ni and Ta₂O₅- NaF-C-C₁₂H₂₂O₁₁ (sucrose) systems the whiskers grew via a vapor-liquid-solid (VLS) mechanism and exhibit a fairly straight fiber morphology. In the Ta₂O₅-KCl-C-Ni system, some whiskers grew via a VLS mechanism and others via a LS mechanism. Some whiskers grew with a zigzag shape tip and conical shaped morphology. All whiskers were grown under similar reaction conditions at temperatures which range from 1150°C to 1350°C in a nitrogen ambient atmosphere. The compositions, morphology, crystal structure and growth mechanism were investigated in detail.