Enhancement of an Iron-Based Layered Compound Superconducting Properties by High Pressure Synthesis Technique

Abstract

Here we report the high pressure synthesis technique, physical properties and effect of Y substitution on the La-based iron oxypnictide LaFeAsO 0.6 superconductor. Replacement of La 3+ by Y 3+ in La 1- x Y x FeAsO 0.6 results in the decrease of lattice parameters, due to internal chemical pressure effect into the system. Superconducting transition temperature ( T c ) increases up to 43.1 K for x =0.5. The present results provide an alternative, much simpler way to achieve higher- T c in the La-based oxypnictide superconductors, as well as revealing that the lattice parameters are the dominating parameter to determine T c of these new high- T c superconductors. Also we report the new discovery of Ca 1- x Na x Fe 2 As 2 with T c =26 K.