Role of boric acid in synthesis and tailoring the properties of calcium aluminate phosphor

• Published in: Materials chemistry and physics 2007-01, Vol.101 (1), p.163-169
• Main Authors: Haranath, D., Sharma, Pooja, Chander, Harish, Ali, Anwar, Bhalla, Nitesh, Halder, S.K.
• Format: Article
• Language: English
• Subjects: Aluminates; Luminescence; Persistence; Phosphors
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2006.03.003

In the present work related to the development of high-luminous blue-emitting calcium aluminate phosphor, the active role of boric acid (H 3BO 3) as a chemical additive is identified. The appropriate usage of H 3BO 3 in defining the crystal structure, morphology and momentous variation in luminescent properties of calcium aluminate long persisting (LP) phosphor is systematically studied and presented. The results attribute two major roles for H 3BO 3; as a flux for promoting the formation of required crystalline phase, when added in the amounts less than 10 mol% and as one of the precursors for the formation of aluminoborate complex when added above 10 mol%. This amount could be treated as a threshold for aluminoborate complex formation. Luminescent studies revealed that out of all phases identified, CaAl 2O 4 is the only phase contributing for maximum photoluminescence (PL) augmentation and long persistence (10–12 h) from Eu 2+ and Nd 3+ ions, respectively. The relevant chemistry and reaction mechanism involved during solid-state synthesis of rare-earth doped calcium aluminate LP phosphor system have been discussed with greater emphasis on the luminescent properties affected with the addition of boric acid.