“…Due to their attractive optical, electrical, and magnetic properties, lanthanides have found numerous applications as catalysts, 1,2 semiconductors, 3 sensors, 4 high-quality phosphors, 5,6 and timeresolved uorescence (TRF) biological labels. 7,8 More recently, rare earth-doped optoelectronic materials 9,10 have been used in the design of high-performance luminescent devices, 11,12 made possible because of the fascinating up-conversion properties of lanthanides. 13,14 Lanthanum, being the lightest representative of the lanthanides series, has been widely studied in its hydroxide, oxide, oxalate, phosphate, and oxychloride forms.…”