Synthesis Conditions on the Nature of GdBO3 Phase Formed

Abstract Present study has been carried out to develop a facile synthetic methodology for preparing single phase monoclinic and triclinic forms of GdBO 3 , a potential phosphor material. This is achieved by varying annealing temperatures and annealing steps. Detailed structural studies, using X‐ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopic techniques confirmed that, Gd 3+ ‐boric acid complexes formed initially at low temperatures (300 °C or less) get converted to monoclinic and triclinic forms of GdBO 3 depending upon annealing temperatures, annealing steps and heating rates. Multiple steps with slow heating rates (∼3 °C/min) lead to the formation of single phase triclinic form of GdBO 3 . Two step heating with relatively faster heating rates (5 °C/min and above) results in single phase monoclinic GdBO 3 . FTIR and Raman studies also confirmed that boron exists only as BO 4 structural units (in the form of B 3 O 9 3− rings) in monoclinic GdBO 3 and as BO 3 structural units in triclinic GdBO 3 . Luminescence studies carried out with Eu 3+ as a probe species confirmed more covalent nature around Eu 3+ /Gd 3+ ions with improved red colour emission from triclinic form of GdBO 3 compared to the monoclinic form.