PECULIARITIES OF CALCIUM PHOSPHATES DOPING WITH TRACE ELEMENTS

The calcium phosphate formation Сa2+-Mg2+-Na+-PO43--NO3- at the molar ratios Сa2+: Mg2+: Na+: PO43-= (10-х-y/2) : х : y : 6, (x = 0.1, 0.25, 0.5, 0.75; у = 0.25, 0.5, 0.75, 1.0) at temperature 25°С and further heating to 600 °С has been investigated. The conditions for formation of apatite-related calcium phosphate that contains trace elements magnesium and sodium (0.5 wt% of both) in the system with molar ratio Сa2+ : Mg2+ : Na+ : PO43- -= (10-х-y/2) : 0.1 : 0.25 : 6 as well as biphasic calcium phosphates (mixture of phases based on Са10(РО4)6(ОН)2 – hexagonal system, space group Р63/m and β-Са3(РО4)2 – trigonal system, space group R-3c) at molar ratio Сa2+ : Mg2+ : Na+ : PO43-= (10-х-y/2) : х : 0.25 : 6, (x = 0.25, 0.5, 0.75) have been established. It was found, that amount of phase based on β-Са3(РО4)2 in the composition of biphasic calcium phosphates increased (from 10 wt % to 45 wt %) at growing of magnesium quantity in the initial solution. In the case of system with different sodium amount the biphasic calcium phosphates also formed, but the weight ratio of phases based on Са10(РО4)6(ОН)2 and β-Са3(РО4)2 less depend on sodium amount in the initial solution and vary in the range 10–15 wt% for values of molar ratio Сa2+: Mg2+: Na+: PO43-= (10-х-y/2) : 0.25 : y : 6, ( у = 0.25, 0.5, 0.75). Attempt of preparing of apatite-related calcium phosphate containing 0.5 wt% of magnesium and 2.2 wt% of sodium resulted in formation of mixture of phases based on Са10(РО4)6(ОН)2 and double orthophosphate NaCaPO4. According calculation using Shererra equation the particles size is in the range 30–50 nm.FTIR spectroscopy results confirmed the presence of orthophosphate anions as well as OH-group in the composition of synthesized calcium phosphates. Established conditions of calcium phosphate formation can be used at creation of biomaterials based on biphasic calcium phosphates which contain different amount of trace elements (from 0.5 to 2.2 wtс%).