ChemInform Abstract: Well‐Defined Crystallites Autoclaved from the Nitrate/NH₄OH Reaction System as the Precursor for (Y,Eu)₂O₃ Red Phosphor: Crystallization Mechanism, Phase and Morphology Control, and Luminescent Property.

Abstract

Hexagonal platelets of Ln2(OH)5NO3·nH2O (Ln: Y, Eu), hexagonal prisms and microwires of Ln4O(OH)9NO3, square nanoplatelets of Ln2.94(NO3)0.06·nH2O, and spindle-like microrods of Ln(OH)3 are hydrothermally synthesized from aqueous solutions of Ln(NO 3 ) 3 (sometimes together with NH4NO3) and NH4OH (autoclave, pH 6-13, 120-200°C, 24 h). The samples are characterized by XRD, FESEM, TEM, and photoluminescence spectroscopy. The formation domains of the compounds are discussed. The compounds all convert to cubic (Y0.95Eu0.05)2O3 by annealing at 600°C for 4 h retaining their original crystal shapes. The resultant phosphors show optical properties dependent on particle size, but do not differ in the positions of the emission/excitation bands. -(ZHU, Q.; LI*, J.-G.; MA, R.; SASAKI, T.; YANG, X.; LI, X.; SUN, X.; SAKKA, Y.; J. Solid State Chem. 192 (2012) 229-237, http://dx.