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-CaFe2As2 is special among the 122 materials as due to its reduced unit cell volume and c lattice parameter, which is very close to collapsed tetragonal (CT) phase. So it is very sensitive to external pressure and chemical pressure (doping). Optimal Na doped (Ca0.34Na0.66)Fe2As2 shows a superconducting transition with Tc ~ 33 K at ambient pressure.