Preparation of Li 3N single crystal by floating zone technique

Abstract

Single crystals of the superionic conductor, Li 3N, have been prepared by a floating zone technique in an infrared imaging furnace. The following peculiar shape transformation of the single crystal is observed: The cross-section of the single crystal at the solid-liquid interface is round. However, it is square at a position about 20 mm below the molten zone. As a result, a single crystal in the shape of a square prism and with dimensions of 9 × 9 × 60 mm 3 was obtained. Impurity oxygen as well as hydrogen was detected in the crystal, which could possibly enhance the ionic conductivity. The crystals shows thehighest ionic conductivity ( σ ⊥ c) = 2.0 S m −1 at 300 K) and the smallest activation energy for Li + ion transport ( E a = 0.15 eV) ever known on this material.