High-pressure self-flux growth and characterization of Li-deficient Li0.95FeAs single crystals.

• Li-deficient Li 0.95 FeAs crystals were grown by high-pressure self-flux method. • Grown crystals exhibit plate-like shape with dimensions up to 0.7 × 0.7 × 0.15 mm3. • For Li-deficient composition Li 0.95 FeAs a critical temperature T c is 16 K. Single crystals of LiFeAs were successfully grown by a self-flux method using the cubic anvil high-pressure and high-temperature technique. The reaction took place in a closed boron nitride crucible at a pressure of 1 GPa and a temperature of 1050 °C. The grown crystals, retrieved from solidified lump, exhibit plate-like shapes with sizes up to 0.7 × 0.7 × 0.15 mm3. Single-crystal x-ray diffraction refinement confirmed the high structural perfection of the grown crystals [space group P 4/ nmm , No 129, Z = 2, a = 3.77370(10) Å, c = 6.3468(6) Å, and V = 90.384(9) Å3] with the presence of a small deficiency on the Li site. The refined chemical composition of the produced crystals is Li 0.95 FeAs. Temperature-dependent magnetization measurements revealed bulk superconductivity with a superconducting transition T c = 16 K. A comparative analysis of LiFeAs, Li 1- x FeAs, and Li 1- y Fe 1+ y As systems reveal that superconductivity is less sensitive to the Li deficiency, although it may completely disappear in the presence of both Fe excess and Li deficiency. [ABSTRACT FROM AUTHOR]