I had this problem with my standard XF.

I had put "Red Stuff" pads on it & they squeeked like hell when bedded in.....

Do as our friend says below..... put a dob of anti squeel compound between the piston and the pad & between the caliper face & pad, + de-burr the edges of the pads by trimming the sharp 90' edges off the pads too.

NOTE, do NOT get grease or finger marks on the friction faces, and ensure you put the pads back in the same places they each came from.
Ensure the disks are grime and finger mark / grease free before re-fitting the pads too.

This should solve the problem.

Grant B