THE HIGH-TEMPERATURE PREPARATION AND PROPERTY MEASUREMENTS OF CATAN2 - A TERNARY SUPERCONDUCTING NITRIDE

Highly crystalline CaTaN2 was prepared by the reaction of Ca(NH2)(2) a nd Ta3N5 in a specially designed reaction vessel at high temperatures (> 1300 degrees C). Even when reaction conditions varied considerably, the samples were always contaminated by small amounts of Ca2TaN3, TaN , or TaN0.1. SQUID measurements obtained on a sample contaminated by C a2TaN3 and a sample contaminated by TaN and TaN0.1 showed superconduct ing transitions at 9.6 K and 9.1 K, respectively. Resistivity measurem ents carried out on a sintered pellet of CaTaN2 contaminated by TaN0.1 showed a rho(300 K) = 0.0147 omega cm and weakly rising resistivity w ith lower temperatures, likely due to the random alignment of the poly crystalline grains.