New phosphates, Sr 1.9 Cu 4.1 (PO 4 ) 4 , Sr 2 Cu(PO 4 ) 2 , and Sr 9.1 Cu 1.4 (PO 4 ) 7 , were found in the Cu 3 (PO 4 ) 2 –Sr 3 (PO 4 ) 2 system at 900°C under air. Sr 1.9 Cu 4.1 (PO 4 ) 4 crystallizes in an orthorhombic system with a=15.3695(7) Å, b=10.3652(4) Å, and c=7.9425(4) Å. Crystal structures of Sr 9.1 Cu 1.4 (PO 4 ) 7 , Sr 2 Cu(PO 4 ) 2 , and the known phase, Sr 3 Cu 3 (PO 4 ) 4 , were refined by the Rietveld method from X-ray diffraction data: space group R3m, a=10.6119(1) Å, c=19.7045(2) Å, and Z=3 for Sr 9.1 Cu 1.4 (PO 4 ) 7 ; space group C2/m, a=11.5155(1) Å, b=5.07543(6) Å, c=6.57487(7) Å, β=106.3563(6)°, and Z=2 for Sr 3 Cu(PO 4 ) 2 ; and space group P2 1 /c, a=9.2010(1) Å, b=4.94104(4) Å, c=17.8998(3) Å, β=122.8952(9)°, and Z=2 for Sr 3 Cu 3 (PO 4 ) 4 . A second-harmonic generation study confirmed that the structures of all four compounds have the center of symmetry. Sr 3 Cu 3 (PO 4 ) 4 is isotypic with Ca 3 Cu 3 (PO 4 ) 4 . Copper cations in Sr 3 Cu 3 (PO 4 ) 4 have square planar and trigonal bipyramidal coordination and strontium cations have octahedral and ninefold coordination. Sr 2 Cu(PO 4 ) 2 is isotypic with Ba 2 Cu(PO 4 ) 2 . Copper cations in Sr 2 Cu(PO 4 ) 2 have square planar coordination and strontium cations have ninefold coordination. Sr 9.1 Cu 1.4 (PO 4 ) 7 is structurally related to β-Ca 3 (PO 4 ) 2 and Sr 3 (PO 4 ) 2 . A portion of copper cations in Sr 9.1 Cu 1.4 (PO 4 ) 7 fully occupies the trigonal-distorted octahedral site M5. The structure of Sr 9.1 Cu 1.4 (PO 4 ) 7 has some disordered elements: (1) strontium cations in the M3 site statistically occupy four positions near the center of symmetry; (2) orientation disordering of the P1O 4 tetrahedra is observed; (3) the M4 site is occupied by 0.05Sr 2+ +0.2Cu 2+ +0.75□; and (4) copper cations in the M4 site are slightly displaced from the threefold axis with distances between positions about 0.94 Å. Formation of solid solutions Sr 9.1−x Ca x Cu 1.4 (PO 4 ) 7 (0≤x≤9.1), Sr 2−x Ba x Cu(PO 4 ) 2 (0≤x≤2), and Sr 3−x Ba x Cu 3 (PO 4 ) 4 (0≤x≤1.5) was shown.