Mossbauer and XRD studies on the effect of doping iron in KCaY(PO sub(4)) sub(2)

The effect of doping iron at the yttrium site in hexagonal KCaY(PO sub(4)) sub(2) is studied for various concentrations of x (0 less than or equal to x less than or equal to 1), of iron using Mossbauer and X-ray diffraction methods. For low iron concentrations, very little changes in structure are seen but at x approximately 0.1, onset of new peaks in the XRD pattern is observed. The Mossbauer study of the doped samples reveals that iron has a solubility of up to 2.5% in the parent phase with any excess iron precipitating out to form a new and unknown phase. From a detailed analysis of the X-ray diffraction pattern (corresponding to x=1) of the latter phase, it is found that this phase is rhombohedral with the possible space group R3.