Dear Negar Shokouhnejad thank you for your interesting technical question. A Figure showing the Powder X-ray diffraction pattern of synthetic Ca3(PO4)2 is depicted in the following relevant article:
X‐ray powder diffraction data of synthetic β‐Tricalcium Phosphate
Article X‐ray powder diffraction data of synthetic β‐Tricalcium Phosphate
Also please have a look at the following potentially useful articles:
Synthesis of Calcium Hydroxyapatite–Tricalcium Phosphate (HA–TCP) Composite Bioceramic Powders and Their Sintering Behavior
Crystal structure analysis of β-tricalcium phosphate Ca3(PO4)2 by neutron powder diffraction
Article Crystal Structure Analysis of ??-Tricalcium Phosphate Ca3(PO...
You can also search directly at the ICDD database (e.g. the sum formula Ca3P2O8, see attached screenshot), but the search results are not accessible for free: