SYNTHESIS AND OPTICAL PROPERTIES OF NOBELIUM-ACTIVATED STRONIUM ALUMINATE (SR_4-X-Y CA_YAL₁₄O₂₅:NO _X )

Nobelium-activated strontium aluminate (Sr_4-x-y Ca_yAl₁₄O₂₅:No_x)was synthesized using boric acid by the solgel method in different concentrations. The samples obtained were heated in air at various temperatures, using the results of X-ray diffraction (XRD) analysis, it was found that Sr₄Al₁₄O₂₅ is single-phase at 1300°C. For partial replacement of strontium ions with calcium ions, the same strontium aluminate containing 0.04 mol/g of Nobelium was selected, and single-phase samples were obtained from a calcium concentration up to x_Ca=0,9. The highest relative intensity of the luminescence of Ho₃₊ ions in all samples was in the red zone of the spectrum, corresponding to the passage of these ions ⁵F₅→⁵I₈. In photoluminescence studies of samples, when excited by radiation with wavelengths of 465 nm and 560 nm, the maximum light emission of ~652 nm,~692 nm, and ~694 nm were formed. In all series of synthesized single-phase materials, the most intense light emission peaks are in the compound that exchanges Sr²⁺ strontium ions with Ca²⁺ ions. From the images taken using a scanning electron microscope (SEM), it can be seen that Sr_4-xAl₁₄O₂₅:Ho_x particles are stuck together in monolithic blocks due to the use of extremely high heating temperatures. Although the synthesis of strontium replacement with calcium was carried out at the same temperature, changes in morphology were observed, and the hexagonal shape of aluminate particles partially replaced by Ca²⁺ ions was clearly visible.

1. Thompson N., Murugaraj P., Rix C., Mainwaring D.E. Role of oxidative pre-calcination in extending blue emission of Sr4Al14O25 nanophosphors formed with microemulsions // J. Alloys Compd. – 2012. – Vol. 537. – P. 147–153. https://doi.org/10.1016/j.jallcom.2012.04.112

2. Sharma S.K., Pitale S.S., Manzar Palik M., Dubey R.N., Qureshi M.S. Luminescence studies on the blue–green emitting Sr4Al14O25:Ce3+ phosphor synthesized through solution combustion route // Lumin J. – 2009. – Vol. 129. – P. 140–147. https://doi.org/10.1016/j.jlumin.2008.09.002

3. Sang H.H., Young K.J. Luminescent properties of Ce and Eu doped Sr4Al14O25 phosphors // Opt.Mat. – 2006. – Vol. 28. – P. 626–630. https://doi.org/10.1016/j.optmat.2005.09.031

4. Capron M., Fayon F., Massiot D., Douy A. Sr4Al14O25: Formation, Stability, and 27Al High-Resolution NMR Characterization // Chem. Mater. – 2023. – Vol. 15. – No. 575. https://doi.org/10.1021/cm0213265

5. Nagamani S., Panigrahi B.S. Luminescence Properties of SrO–Al2O3:Eu2+,Dy3+ Prepared at Different Temperatures // J. Am. Ceram. Soc. – 2010. – Vol. 93. – P. 3832–3836. https://doi.org/10.1111/j.1551-2916.2010.03938.x

6. Blasse G., Grabmaier B.C. Luminescent Materials. – Berlin, Springer, 1994. – P. 123. https://doi.org/10.1007/978-3-642-79017-1

7. Wang X., Jiang Q., Wang Z., Song B., Hou H., Xu L. and L. Xia. High performance

8. Sr4Al14O25:Mn4+ phosphor: structure calculation and optical properties // J. Mater. Chem. C. – 2022. – Vol. 10. – P. 7909–7916. https://doi.org/10.1039/D2TC00795A

9. Wang Z., Hou X., Liu Y., Hui Z., Huang Z., Fang M., Wu X. Luminescence properties and energy transfer behavior of colour-tunable white-emitting Sr4Al14O25 phosphors with co-doping of Eu2+, Eu3+ and Mn4+ //RSC Adv. – 2017. – Vol. 7. – No. 83. – P. 52995–53001. https://doi.org/10.1039/C7RA07970B

10. Chang C., Mao D., Shen J., and C. Feng. Preparation of long persistent SrO·2Al2O3 ceramics and their luminescent properties // J.of Alloys and Compounds. – 2003. – Vol. 348. – No. 1–2. – P. 224–230. https://doi.org/10.1016/S0925-8388(02)00836-8

11. Aitasalo T., H¨ols¨a J., Jungner H., Lastusaari M., and J. Niittykoski. J. Lumin. – 2001. – V. 94–95. – P. 59–63. https://doi.org/10.1155/2009/475074

12. Zhong R., J. Zhang, X. Zhang, S. Lu, and X.-J. Wang. Red phosphorescence in Sr4Al14O25: Cr3+, Eu2+, Dy3+ through persistent energy transfer // Applied Physics Letters. – 2006. – V. 88. – No. 20. https://doi.org/10.1063/1.2205167

13. Shankar H. Chander H. Divi, and P.K. Ghosh. Long decay luminescent powder and process for preparation thereof, USpatent no. 0183807 A1, October 2003.

14. Lin Y., Zhang Z., Zhang F., Tang Z., and Q. Chen. Preparation of the ultrafine SrAl2O4:Eu,Dy needlelike phosphor and its optical properties // Materials Chemistry and Physics. – 2000. – Vol. 65. – No. 1. – P. 103–106. https://doi.org/10.1016/S0254-0584(00)00222-4

15. Nag A. and T.R.N. Kutty. Role of B2O3 on the phase stability and long phosphorescence of SrAl2O4:Eu, Dy // J. of Alloys and Compounds. – 2003. – Vol. 354. – No. 1–2. – P. 221–231. https://doi.org/10.1016/S0925-8388(03)00009-4

16. Yuan Z.-X., Chang C.-K., Mao D.-L., and W. Ying. Effect of composition on the luminescent properties of Sr4Al14O25: Eu2+, Dy3+ phosphors // J. of Alloys and Compounds. – 2004. – Vol. 377. – No. 1–2. – P. 268–271. https://doi.org/10.1016/j.jallcom.2004.01.063

17. Wu Zh., Gong M., Shi J., and Q. Su. Comparative investigation on synthesis and luminescence of Sr4Al14O25:Eu2+ applied in InGaN LEDs // Journal of Alloys and Compounds. – 2008. – Vol. 458. – No. 1–2. – P. 134–137. https://doi.org/10.1016/j.jallcom.2007.03.139

18. Douy A., Capron M. Crystallisation of spray-dried amorphous precursors in the SrO–Al2O3 system: a DSC study // J. Eur. Ceram. Soc. – 2003. – Vol. 23. – P. 2075–2076. https://doi.org/10.1016/S0955-2219(03)00015-3.

19. Misevicius M., Scit O., Grigoraviciute-Puroniene I., Degutis G., Bogdanoviciene I., Kareiva A. Solgel synthesis and investigation of un-doped and Ce-doped strontium aluminates // Ceram. Int. – 2012. – Vol. 38. – P. 5915–5924. https://doi.org/10.1016/j.ceramint.2012.04.042.

20. Avdeev M., Yakovlev S., Yaremchenko A.A., Kharton V.V. Transitions between P21, P63(3A), and P6322 modifications of SrAl2O4 by in situ high-temperature X-ray and neutron diffraction // J. Solid State Chem. – 2007. – Vol. 180. – No. 12. – P. 3535–3544. https://doi.org/10.1016/j.jssc.2007.10.021

21. Lin Y.H., Tang Z.L., Zhang Z.T. Preparation of long-afterglow Sr4Al14O25-based luminescent material and its optical properties // Mater. Lett. – 2001. – Vol. 51. – P. 14. https://doi.org/10.1016/S0167-577X(01)00257-928

22. Nadzhina T.N., Pobedimskaya E.A. and N.V. Belov. Kristallografiya. – 1980. – Vol. 25. – P. 938.

23. Yuan Z.X., Chang C.K., Mao D.L., Ying W.J. Effect of composition on the luminescent properties of Sr4Al14O25: Eu2+, Dy3+ phosphors // J. Alloys Compd. – 2004. – Vol. 377. – P. 268. https://doi.org/10.1016/j.jallcom.2004.01.063.

24. Chang C.K., Jiang L., Mao D.L., Feng C.L. Photoluminescence of 4SrO·7Al2O3 ceramics sintered with the aid of B2O3 // Ceram. Int. – 2004. – Vol. 30. – P. 285. https://doi.org/10.1016/S0272-8842(03)00101-9.

25. Sakirzanovas S., Katelnikovas A., Dutczak D., Kareiva A., Justel T. Synthesis and Sm2+/Sm3+ doping effects on photoluminescence properties of Sr4Al14O25 // J. Lumin. – 2011. – Vol. 131. – P. 2255–2262. https://doi.org/10.1016/j.jlumin.2011.05.060

26. Vistorskaja D., Laurikenas A., Montejo de Luna A., Zarkov A., Pazylbek S. and A. Kareiva. SolGel Synthesis and Characterization of Novel Y3-xMxAl5-yVyO12 (M—Na, K) Garnet-Type Compounds. Inorganics. – 2023. – Vol. 11. – No. 2. – P. 58. https://doi.org/10.3390/inorganics11020058

27. Hans-R Hagemann H., Afshani J. Chapter 321 – Synthesis, luminescence and persistent luminescence of europium-doped strontium aluminate // Physics and Chemistry of Rare Earths. – 2021. – Vol. 60. – P. 163–225. https://doi.org/10.1016/bs.hpcre.2021.06.001

28. Kadyana S., Singha S., Sheorana S., Samantillekeb A., Maric B., Singh D. Synthesis, luminescent and structural characteristics of Sr4Al14O25:Eu2+ and Sr4Al14O25:Eu2+, RE3+ (RE=Nd, Dy) long persistent nanophosphors for solid state lighting // Optik. – 2020. – Vol. 204. – P. 164159. https://doi.org/10.1016/j.ijleo.2019.164159