Synthesis and Characterization of the Pb5(PxAs1-xO4)3Cl Solid Solutions

A series of the Pb
₅
(P
_x
As
_1-x
O
₄
)
₃
Cl solid solutions were directly prepared through aqueous precipitation method. The results of the elemental analysis, XRD, FT-IR and SEM characterization have confirmed the forming of the mimetite/pyromorphite solid solutions. The XRD analysis indicated that the end-member components of the solid solutions were well matched respectively to card #01-080-2103 for mimetite and #00-019-0701 for pyromorphite, and their corresponding unit cell parameters. In FT-IR spectra, the stretching vibrational absorption band of AsO
₄
^3-
appeared around 788.71-820.00 cm
^-1
(γ
₃
), and the bending vibration absorption band was also visible at 418.00 cm-1 (γ
₄
). In addition, no vibrations of AsO
₄
^3-
appeared at 1407.82 cm
^-1
, 1563.44 cm
^-1
and 1733.26 cm
^-1
. There was a clear water peak of pyromorphite appeared at 3440.62 cm
^-1
and the antisymmetric stretching peak of PO
₄
^3-
appeared around 979.50-1050.05 cm
^-1
(γ
₃
) and the symmetrical peak appeared around 540.08-575.53 cm
^-1
(γ
₄
). Observed by SEM, the shape of crystals changed gradually from the fibrous, needle-like to the granular solid block as PO
₄
^3-
in the solids increased.