Luminescence enhancement of high temperature hexagonal phase of Ba0.99MgAl10O17: Eu0.01 nanophosphor synthesized at moderately low temperature

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2021-01, Vol.263, p.114791, Article 114791
• Main Authors: Jaiswal, Vishnu V., Chandar Rao, P., Sreelatha, C.J., Sai Prasad, A.S., Haranath, D.
• Format: Article
• Language: English
• Subjects: Chemical synthesis; Deflagration; Energy transfer; Europium; Gamma irradiation; Gel deflagration method; Hexagonal phase; High temperature; Low temperature; Morphology; Nanoparticles; Nanophosphors; Phosphors; Photoluminescence; Roasting; Thermal stability; Thermoluminescence
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2020.114791

The current paper is the one of the few known reports that depict the appearance of high temperature hexagonal phase for Ba0.99MgAl10O17: Eu0.01 (BAM:Eu2+) nanophosphor synthesized at relatively low (~600 °C) temperatures, which is otherwise possible at very high (>1500 °C) sintering temperatures. Comparison of photoluminescence (PL) properties of BAM:Eu2+ nanophosphor to its bulk counterpart has been thoroughly investigated. A drastic improvement in crystallanity, phase purity and PL intensities has been achieved by the presence of NH4F during post-calcination treatments. A highly crystalline, regular morphology and excellent PL of BAM:Eu2+ nanophosphor recommends its suitability in modern display applications. [Display omitted] •Hexagonal BAM has been prepared at lower (~600 °C) sintering temperatures.•Defect centres formed due to γ-irradiation in nanophosphors were studied in detail.•BaMgAl10O17:Eu2+ nanophosphor exhibits intense emission compared to its bulk. Photoluminescent (PL) properties of Eu2+-doped BaMgAl10O17 (BAM:Eu2+) phosphors are significantly influenced by its crystallanity, phase and regular morphology. To obtain a high brightness blue-emitting BAM:Eu2+ nanophosphor, a pH-controlled polymeric gel deflagration method was performed at ~ 600 °C followed by post calcination at 1300 °C for 3 h under mild reducing atmosphere. It is one of the very few reports that depicts the formation of hexagonal phase of BAM:Eu2+ nanophosphor at relatively lower (~600 °C) temperatures, which is otherwise possible at very high (>1500 °C) sintering temperatures. A drastic improvement in crystallanity, phase, morphology and PL intensities has been achieved in BAM:Eu2+ nanophosphors with the addition of ammonium fluoride (NH4F) during post-calcination treatment. The presence of NH4F benefitted the thermal stability of BAM:Eu2+ nanophosphors as well. X-ray diffraction studies confirmed the phase purity while the scanning electron microscopy revealed regular morphology with non-aggregated nanoparticles. The improvement in crystallanity of BAM:Eu2+ nanophosphors led to almost four times increase in PL intensity in comparison to its bulk counterpart synthesized by solid-state reaction method. Intentional gamma irradiation of the samples for the creation of F+ centres is another unique feature studied in the current work. The obtained results clearly indicate that BAM:Eu2+ nanophosphor prepared in the study would be an ideal candidate for enhancing the properties of