  The Ca10(PtnAs8)(Fe2As2)5 (n=3,4) compounds are a new type of iron pnictide
superconductors whose structures consist of stacking Ca-PtnAs8-Ca-Fe2As2 layers
in a unit cell. When n=3 (the 10-3-8 phase), the undoped compound is an
antiferromagnetic (AFM) semiconductor, while, when n=4 (the 10-4-8 phase), the
undoped compound is a superconductor with the transition temperature of 26K.
Here we report the results of high-pressure studies on the 10-3-8 compound
obtained through a combination of in-situ resistance, magnetic susceptibility,
and Hall coefficient measurements. We find that its AFM order can be suppressed
completely at 3.5 GPa and then superconducting state appears in the pressure
range of 3.5-7 GPa. The pressure dependence of superconducting transition
temperature displays a dome-like shape.
