  The magnetic and iron vacancy orders in superconducting (Tl,Rb)2Fe4Se5
single-crystals are investigated by using a high-pressure neutron diffraction
technique. Similar to the temperature effect, the block antiferromagnetic order
gradually decreases upon increasing pressure while the Fe vacancy
superstructural order remains intact before its precipitous disappearance at
the critical pressure Pc = 8.3 GPa. Combined with previously determined Pc for
superconductivity, our phase diagram under pressure reveals the concurrence of
the block AFM order, the iron vacancy order and superconductivity for the 245
superconductor. A synthesis of current experimental data in a coherent physical
picture is attempted.
