Single-crystal growth of the ternary BaFe$_2$As$_2$ phase using the vertical Bridgman technique

TL;DR

This study investigates the solidification behavior of BaFe$_2$As$_2$ in the Ba-Fe-As system and successfully grows large single crystals using the vertical Bridgman technique, confirming their high quality through diffraction methods.

Contribution

It provides the first detailed analysis of the primary solidification field of BaFe$_2$As$_2$ and demonstrates a method to grow large, high-quality single crystals.

Findings

BaFe$_2$As$_2$ melts congruently.

Large single crystals (10x4x2 mm$^3$) were grown.

Crystals confirmed by X-ray Laue and neutron diffraction.

Abstract

Ternary Ba-Fe-As system has been studied to determine a primary solidification field of the BaFe$_2$As$_2$ phase. We found that the BaFe$_2$As$_2$ phase most likely melts congruently and primarily solidifies either in the FeAs excess or Ba$_{x}$As$_{100-x}$ excess liquid. Knowing the primary solidification field, we have performed the vertical Bridgman growth using the starting liquid composition of Ba$_{15}$Fe$_{42.5}$As$_{42.5}$. Large single crystals of the typical size 10x4x2 mm$^3$ were obtained and their quality was confirmed by X-ray Laue and neutron diffraction.