It could be mixture of various calcium phosphates and calcium hydroxide. You do XRD and check the phases. How did you get the Ca/P ratio?

thanks for your answer Shekhar Nath sir,

i gone XRD, FTIR and checked the phases. its hap only i have JCPDS number also . however i checked EDAX analysis but its showed ca/p ratio is 2.0-2.5.

EDAX will not show the correct value unless it is calibrated with the similar material. Do ICP-AES/AAS for accurate result. Also some amorphous gassy phase may contribute to the amount. The amorphous phase will not come in the XRD result. The best is as I said ICP-AES/AAS. 

thanks Shekhar Nath sir, i will do ICP.

I agree with Shekhar Nath. ICP is a good choice to help you in this case and in the characterization of Ca/P ratio of calcium ortophosphates in general.

thanks for your valuable suggestion Thales Rafael Machado.

Hydroxyapatite (HAp), (Ca10(PO5)6(OH)2), the [Ca]/[P] = 10/6 = 1.67.    Possibly your measurement offered the ratio data based on weight.  After converting them into molar base, you might get the meaningful outcomes! 

thanks sir jen-chang Yang, for your valuable answer.

it will useful for my studies.

Indeed, only chemical analysis is able to provide the correct values of the Ca/P ratio. ICP-AES/AAS is an option as well. Concerning the difference between molar and weight ratios, it is the shame for a Ph.D. student not to know the difference. Furthermore, prior start working on a new subject, one must learn the basics by reading the proper literature, in your case, on hydroxyapatite and other calcium phosphates.

Did You use buffer solution at pH9,0?? Yours solutions were correct?? Was  Calcium concentration 0.20mol/L and Phophate 0.12mol/L?? 

 What was the articleor references you using to produce your hydroxyapatite??

@Sérgio Yoshioka, using alkaline heat treatment and reference is supalak kongsri 2013 et al.,