  We report the synthesis and basic physical properties of single crystals of
CaFe2As2, an isostructural compound to BaFe2As2 which has been recently doped
to produce superconductivity. CaFe2As2 crystalizes in the ThCr2Si2 structure
with lattice parameters a = 3.907(4) A and c = 11.69(2) A. Magnetic
susceptibility, resistivity, and heat capacity all show a first order phase
transition at T_0 171 K. The magnetic susceptibility is nearly isotropic from 2
K to 350 K. The heat capacity data gives a Sommerfeld coefficient of 8.2 +- 0.3
mJ/molK2, and does not reveal any evidence for the presence of high frequency
(> 300 K) optical phonon modes. The Hall coefficient is negative below the
transition indicating dominant n-type carriers.
