Tartrate promoted hydrothermal growth of highly [001] oriented (La_(0.95-x)Bi_xEu_(0.05))PO_4 (x = 0-0.01) nanowires with enhanced photoluminescence

摘要

Monoclinic (La0.95 - xBixEu0.05)PO4 nanowires with lengths of similar to 1.5 mu m and diameters of similar to 20-50 nm (aspect ratio up to the high value similar to 75) have been synthesized via hydrothermal crystallization in the presence of sodium tartrate (Tar(2-)). Detailed characterizations of the materials were achieved by the combined techniques of XRD, FE-SEM, TEM, FT-IR, and optical spectroscopies, and the formation mechanism of the nanowires was expatiated. It was found that Tar(2-) as a shape modifier can cap the growth of {012} facets and thus led to nanowires of high [001] orientation. The effects of experimental parameters such as Tar(2-)/M3+ (M = total cation) and PO43-/M3+ molar ratios, hydrothermal temperature and reaction time on phase and morphology evolution of the nanowires were unveiled. The effects of shape anisotropy, calcination and Bi3+ doping on the photoluminescence properties of the (La0.95 - xBixEu0.05)PO4 nanowire phosphors were also investigated in detail, including excitation, emission, fluorescence lifetime, and CIE chromaticity coordinates. The optimal Bi3+ content was determined to be similar to 0.7 at%.