Lead(II) fluoride particles synthesized by a straightforward mechanochemical route

A low temperature mechanochemistry procedure was used to prepare lead(II) fluoride particles, with the objective of synthetizing pure alpha and beta phases. Lead acetate trihydrate was reacted with ammonium fluoride by hand-grounding, thus forming a white liquid mixture containing lead(II) fluoride, water and ammonium acetate. A further short thermal treatment, performed at a low temperature (ca. 100 degrees C), allowed the evaporation of by-products, giving directly a powder constituted by pure PbF2. According to XRD analysis, the obtained product involved mostly the cubic beta-PbF2 phase, with only traces of the orthorhombic alpha-PbF2 phase. SEM analysis indicated the formation of crystalline aggregates, without a well defined morphology. This synthetic strategy could be easily modified by adding small quantities of organic additives used to tune the crystalline phase. Hence, the addition of either citric acid or poly (acrylic acid-co-maleic acid) facilitated the production of the cubic phase (beta-PbF2), while the addition of selected amines strongly favored the crystallization of the orthorhombic phase (alpha-PbF2). (C) 2015 Elsevier B.V. All rights reserved.