  Recently a new family of Cr-based A2Cr3As3 (A = K, Rb, Cs) superconductors
were reported, which own a rare quasi-one-dimensional (Q1D) crystal structure
with infinite (Cr3As3)2- chains and exhibit intriguing superconducting
characteristics possibly derived from spin-triplet electron pairing. The
crystal structure of A2Cr3As3 is actually a slight variation of the hexagonal
TlFe3Te3 prototype although they have different lattice symmetry. Here we
report superconductivity in a 133-type KCr3As3 compound that belongs to the
latter structure. The single crystals of KCr3As3 were prepared by the
deintercalation of K ions from K2Cr3As3 crystals which were grown from a
high-temperature solution growth method, and it owns a centrosymmetric lattice
in contrast to the non-centrosymmetric K2Cr3As3. After annealing at a moderate
temperature, the KCr3As3 crystals show bulk superconductivity at 5 K revealed
by electrical resistivity, magnetic susceptibility and heat capacity
measurements. The discovery of this KCr3As3 superconductor provides a different
structural instance to study the exotic superconductivity in these Q1D Cr-based
superconductors.
