Vol. 337 No. 4 (2026)
DOI https://doi.org/10.18799/24131830/2026/4/5553
Boric acid effect on phase formation in a calcium hydroxide – aluminum nanopowder system in situ
Relevance. Calcium dialuminate CaAl4O7 is of interest to both the construction industry and the production of LEDs and decorative coatings due to its excellent luminescent properties when doped with rare-earth and transition metal ions. Solid-phase synthesis in Ca(OH)2/CaCO3-Al2O3 systems with the addition of an H3BO3-based flux has become widely used for synthesizing aluminates. The transition from Al2O3 to metallic Al in such systems increases the reaction rate due to additional heating of the system during Al oxidation. Nanosized Al powders also increase the reactivity of the system due to their large specific surface area. However, the addition of a flux to such systems can have both a positive (liquid-phase synthesis) and a negative (hindrance to Al oxidation) effect. Therefore, assessing the effect of a flux on aluminate synthesis in systems with metallic aluminum powder requires separate study. Aim. To study H3BO3 (flux) effect on phase formation of calcium aluminate in the Ca(OH)2–Alnp system. Methods. Investigation in situ X-ray phase analysis using synchrotron radiation. Heating of powder compositions was carried out in an air atmosphere using a platinum heater in the temperature range of 25–1350°C at a rate of 30 °C/min. Results and conclusions. Boric acid acts as an inhibitor of calcium carbonate (CaCO3) formation in the temperature range of 25–900°C. The flux also helps to reduce the formation temperature of calcium monoaluminate (CaAl2O4) from 1149 to 1110°C and calcium dialuminate (CaAl4O7) from 1330 to 1245–1260°C. It was established that the intermediate phase Ca3B2O6 in the boron-containing system is formed at 680–900°C. This phase disappears upon completion of the synthesis. The authors proposed mechanism of action of the flux, suggesting improved contact between the solid phases in the liquid melt B2O3 and better diffusion of oxygen in the intermediate phase Ca3B2O6. The obtained results are of practical importance for optimizing the synthesis of luminescent materials based on calcium aluminates and calculating the initial composition of components using the solid-phase synthesis method.
For citation: Tokarev D.S., Mostovshchikov A.V., Sharafutdinov M.R., Syrtanov M.S., Kargin A.E. Boric acid effect on phase formation in a calcium hydroxide – aluminum nanopowder system in situ. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 4, pp.115-126.
Keywords:
calcium aluminate, boric acid, flux, phase formation, synchrotron radiation, luminescent materials, in situ X-ray diffraction
References:
1. Hou Q., Zhang Z., Zhao Y., Ye K., Tian J., Mu Y., He J., Ye G. The effect of alumina-rich spinel exsolution on the mechanical property of calcium aluminate cement-bonded corundum castables. Materials, 2025, vol. 18, no. 2, pp. 405. DOI: 10.3390/ma18020405.
2. Gollapalli V., Jana P., Önal M.A.R., Borra C.R., Babu N.K. Valorization of aluminium dross and ladle furnace slag for sustainable production of calcium aluminate for steel refining. Journal of Sustainable Metallurgy, 2025, vol. 11, pp. 2780–2793. DOI: 10.1007/s40831-025-01165-5.
3. Trubitsyn M.A., Furda L.V., Yapryntsev M.N., Volovicheva N.A., Mikhailyukova M.O. Impact of precursor granulometry on the synthesis of calcium-aluminate phases. Russian Journal of Applied Chemistry, 2023, vol. 96, no. 3, pp. 297–309. DOI: 10.1134/S1070427223030059.
4. Li S., Chen D., Gu H., Huang A., Fu L. Investigation on application prospect of refractories for hydrogen metallurgy: the enlightenment from the reaction between commercial brown corundum and hydrogen. Materials, 2022, vol. 15, no. 19, pp. 7022. DOI: 10.3390/ma15197022.
5. Yin X.L., Zhang B., Wang H.F., Li X. W., Feng Q. Enhancement of sintering and mechanical properties of alumina-rich Al2O3–MgO–CaO refractory composite by doping La2O3. Ceramics International, 2024, vol. 50, no. 22, pp. 47494–47500. DOI: 10.1016/j.ceramint.2024.08.492.
6. Zhang Y., Yu Y., Zhao Q. A three-mode optical thermometer based on Cr3+ doped CaAl12O19 phosphors. Ceramics International, 2025, vol. 51, no. 6, pp. 7321–7329. DOI: 10.1016/j.ceramint.2024.12.168.
7. Altunal V., Yegingil Z. Luminescence properties and optically stimulated luminescence characteristics of CaAl12O19: Tm, Be phosphor for dosimetry applications. Radiation Physics and Chemistry, 2025, vol. 233, pp. 112733. DOI: 10.1016/j.radphyschem.2025.112733.
8. Botvina T.M., Botvin V.V., Selyunina L.A., Mishenina L.N. Influence of phase composition and crystal structure on the luminescent properties of calcium aluminates (CaAl2O4, CaAl4O7, CaAl12O19) activated by Eu3+ ions. Journal of Luminescence, 2024, vol. 267, pp. 120344. DOI: 10.1016/j.jlumin.2023.120344.
9. Panda R., Behera M., Hegde M., Woźny P., Padhi R.K., Kumar K., Mishra N.K., Kumar R.A., Runowski M. Robust luminescent material with superior color purity: Sm3+ ion-doped CaAl4O7 phosphor synthesized in a cost-effective approach for solid-state lighting applications. Journal of Molecular Liquids, 2024, vol. 409, pp. 125441. DOI: 10.1016/j.molliq.2024.125441.
10. Singh V., Seshadri M., Saravanakumar S., Joo J.B. Study of energy transfer process and radiative properties of CaAl4O7: Ho3+ phosphor for green light emission. Physica Scripta, 2024, vol. 99, no. 2, pp. 025513. DOI: 10.1088/1402-4896/ad1911.
11. Panda R., Behera M., Hegde M., Kumar R.A., Padhi R.K., Ashok A.M., Mishra N.K., Kumar K. Development of thermally stable, single-phased CaAl4O7: Dy3+ phosphor and a study on their down-conversion features for lighting applications. Advanced Powder Technology, 2024, vol. 35, no. 11, pp. 104672. DOI: 10.1016/j.apt.2024.104672.
12. Kemere M., Antuzevics A., Rodionovs P., Rogulis U., Sarakovskis A. Photoluminescence and electron paramagnetic resonance studies of Mn2+ doped CaAl4O7. Optical Materials, 2022, vol. 127, pp. 112352. DOI: 10.1016/j.optmat.2022.112352.
13. Piotrowski W.M., Szymanski D., Crozzolin M., Back M., Marciniak L. Improving the luminescent properties of Fe3+ in CaAl4O7 by co-doping with Bi3+ ions. Materials Research Bulletin, 2025, vol. 181, pp. 113081. DOI: 10.1016/j.materresbull.2024.113081.
14. Vasylechko L., Stadnik V., Hreb V., Zhydachevskyy Y., Luchechko A., Mykhaylyk V., Kraus K., Suchocki A. Synthesis, crystal structure and photoluminescent properties of red-emitting CaAl4O7: Cr3+ nanocrystalline phosphor. Inorganics, 2023, vol. 11, no. 5, pp. 205. DOI: 10.3390/inorganics11050205.
15. Liu S.X., Xiong F.B., Lin H.F., Meng X.G., Lian S.Y., Zhu W.Z. A deep red-light-emitting phosphor Mn4+: CaAl4O7 for warm white LEDs. Optik, 2018, vol. 170, pp. 178–184. DOI: 10.1016/j.ijleo.2018.05.127.
16. Chen Z., Zhu H., Qian J., Li Z., Hu X., Guo Y., Fu Y., Zhu H., Nai W., Yang Z., Li D., Zhou L. Rare earth ion doped luminescent materials: a review of up/down conversion luminescent mechanism, synthesis, and anti-counterfeiting application. Photonics, 2023, vol. 10, no. 9, pp. 1014. DOI: 10.3390/photonics10091014.
17. Singh S., Singh D., Siwach P., Gupta I., Kumar P. Synthesis strategies for rare earth activated inorganic phosphors: a mini review. Applied Research, 2025, vol. 4, no. 1, pp. e202400190. DOI: 10.1002/appl.202400190.
18. Tokarev D.S., Mostovshchikov A.V., Gubarev F.A. The perspectives of metal nanopowders application for luminescent material production. 2024 IEEE 25th International Conference of Young Professionals in Electron Devices and Materials (EDM). Altai, Russian Federation, 2024. pp. 90–94. DOI: 10.1109/EDM61683.2024.10615045.
19. Tokarev D., Mostovshchikov A., Nikolaeva A., Nazarenko O. Regularities of calcium dialuminate synthesis in the process of solid-phase synthesis from aluminum micro-and nanopowders. Ceramics International, 2025, vol. 51, no. 30, pp. 62667–62673. DOI: 10.1016/j.ceramint.2025.10.425.
20. Aul'chenko V.M., Bessergenev A.V., Evdokov O.V., Gerasimov V.S., Gaponov Y.A., Korneev V.N., Mezentsev N.A., Sergienko P.M., Sharafutdinov M.R., Sheromov M.A., Titov V.M., Tolochko B.P., Vazina A.A. The station for time-resolved investigation in wide and small angles of diffraction. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1998, vol. 405, no. 2, pp. 487–493. DOI: 10.1016/S0168-9002(98)00005-9.
21. Aulchenko V.M., Bukin M.A., Velikzhanin Y.S., Gaponenko Y.V., Dubrovin M.S., Titov V.M., Ancharov A.I., Gaponov Y.A., Evdokov O.V., Tolochko B.P., Sharafutdinov M.R. Fast, parallax-free, one-coordinate X-ray detector OD3. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1998, vol. 405, no. 2, pp. 269–273. DOI: 10.1016/S0168-9002(97)00169-1.
22. Criado Y.A., García R., Abanades J.C. Experimental demonstration of an air contactor to capture CO2 from the atmosphere using Ca(OH)2 solid forms. Chemical Engineering Journal, 2025, pp. 166077. DOI: 10.1016/j.cej.2025.166077.
23. Yao Y., Watanabe T., Yano T., Iseda T., Sakamoto O., Iwamoto M., Inoue S. An innovative energy-saving in-flight melting technology and its application to glass production. Science and Technology of Advanced Materials, 2008, vol. 9, no. 2, pp. 025013. DOI: 10.1088/1468-6996/9/2/025013.
24. Liu J., Liang D., Xiao J., Chen B., Zhang Y., Zhou J., Cen K. Composition and characteristics of primary combustion products of boron-based propellants. Combustion, Explosion, and Shock Waves, 2017, vol. 53, no. 1, pp. 55–64. DOI: 10.1134/S0010508217010099.
25. Sadaf S., Wu T., Zhong L., Liao Z.Y., Wang, H.C., Wang W.L. Effective mechanism of B2O3 on the structure and viscosity of CaO–SiO2–B2O3‐based melts. Steel research international, 2021, vol. 92, no. 4, pp. 2000531. DOI: 10.1002/srin.202000531.
26. Wang M., Chen L., Zhang Y., Tao W.Q. Numerical study of the dehydration and hydration processes of the Ca(OH)2/CaO system in an indirect-direct reactor. Journal of Energy Storage, 2023, vol. 71, pp. 108119. DOI: 10.1016/j.est.2023.108119.
27. Feng H., Wang H., Ma Z., Wang S., Li P. Quantification of surface orientation effect on the thermal stability of γ-Al2O3 with different morphologies. Applied Surface Science, 2022, vol. 594, pp. 153509. DOI: 10.1016/j.apsusc.2022.153509.
28. Kovarik L., Bowden M., Khivantsev K., Kwak J.H., Szanyi J. Structural complexity of γ-Al2O3: The nature of vacancy ordering and the structure of complex antiphase boundaries. Acta Materialia, 2024, vol. 266, pp. 119639. DOI: 10.1016/j.actamat.2023.119639.
29. Shevchenko V.G., Eselevich D.A., Krasilnikov V.N., Konyukova A.V. Methods of TG, DSC, and synchrotron analysis for enhancing the reactivity of aluminum-based metallic fuels. From Chemistry towards Technology Step-by-Step, 2025, vol. 6, no. 3, pp. 39–66. DOI: 10.52957/2782-1900-2025-6-3-39-66.
30. Park J., Kim G., Kim Y.J. Luminescent properties of CaAl4O7 powders doped with Mn4+ ions. Ceramics International, 2013, vol. 39, pp. S623–S626. DOI: 10.1016/j.ceramint.2012.10.149.
31. German R.M., Suri P., Park S.J. Liquid phase sintering. Journal of materials science, 2009, vol. 44, no. 1, pp. 1–39. DOI: 10.1007/s10853-008-3008-0.
32. Li C., Li Y., Zhang C., Chu Z., Fang Y. Ca3B2O6-modified papermaking white mud for CaCO3/CaO thermochemical energy storage. Chemical Engineering Journal, 2023, vol. 461, pp. 142096. DOI: 10.1016/j.cej.2023.142096.
33. El Hayek R., Ferey F., Florian P., Pisch A., Neuville D. R. Structure and properties of lime alumino-borate glasses. Chemical Geology, 2017, vol. 461, pp. 75–81. DOI: 10.1016/j.chemgeo.2016.11.025.
34. Ferey F., Briaud V., Violet P., Pisch A. Experimental and theoretical contribution to the phase equilibria in the ternary CaO–Al2O3–B2O3 system. Journal of Phase Equilibria and Diffusion, 2020, vol. 41, no. 4, pp. 443–456. DOI: 10.1007/s11669-020-00803-7.
35. Pisch A., Ferey F., Briaud V. Phase equilibria and thermodynamics in the CaO–Al2O3–B2O3 ternary system in air. GTT Annual Workshop. Aachen, Germany, 2012. 11 p.
36. Haranath D., Sharma P., Chander H., Ali A., Bhalla N., Halder S.K. Role of boric acid in synthesis and tailoring the properties of calcium aluminate phosphor. Materials Chemistry and Physics, 2007, vol. 101, no. 1, pp. 163–169. DOI: 10.1016/j.matchemphys.2006.03.003.
