Synthesis, crystal and electronic structures of La 3Cr 2N 6

Abstract

The rare earth–transition metal ternary nitride La 3Cr 2N 6 was synthesized from the elements and an excess of sodium and gallium at 900 ∘C in a sealed niobium tube. This compound crystallizes in the tetragonal space group I 4 / m m m (No. 139) with a = 3.8525 ( 5 ) Å and c = 20.508 ( 4 ) Å . It is isostructural with the recently discovered ternary nitrides R 3M 2N 6 (R=La, Ce or Pr; M=V, Nb or Ta) and with the high T c superconducting copper oxide La 2− x Sr x CaCu 2O 6. Band structure calculations using density functional theory show that La 3Cr 2N 6 contains CrN 2 conducting layers.