Photoluminescence properties of modified kaolin ceramic in response to UV irradiation

We introduce a new elective innovation involving the impregnation of activated nanoparticles into raw Algerian kaolin material. The process is based on the incorporation of AlPO₄ nanocrystals, firstly exposed to the UV irradiation, to advance intense light emission. Experimental results show that the modified kaolin (TK sample) exhibits superior performance, enabling broad and efficient light emission across the 376 to 760 nm range, with peak intensities reaching approximately ∼10⁷ counts/s. To monitor the evolution in the physical properties induced by AlPO₄ (NC), the structural and chemical compositions were caracterized using XRD, XRF, and FTIR techniques. Several substrates were prepared from different modified powders. The XRD analysis revealed that the achieved sample is composed by major kaolinite content showing a stoichiometric equilibrium between alumina (45 %) and silica (51 %). It crystallizes in the monoclinic system, space group Cc N° 9, with lattice parameters a = 5.14 Å, b = 8.90 Å, and c = 14.51 Å. In the analyses of ATR-FT-IR spectroscopy, the results show the appearance of wave number at ∼914 cm⁻¹ assigned to Al–Al–OH stretching. The characteristic peak at 675 cm⁻¹ is attributed to Al–O–Si deformation in kaolinite. Additionally, a weak Si–O stretching band at 750 cm⁻¹ of quartz, and a prominent band at 1050 cm⁻¹ associated with ${\text{PO}}_4^{3-}$ ions were observed. These findings suggest that, behind the UV irradiation, the presence of PO₄³⁻ ions is primarily responsible for the observed high-intensity photoluminescence emissions, while oxygen and hydroxyl vacancies within the clay matrix further contribute to the enhancement of the photoluminescence emission intensity. Overall, our results are consistent and disclose the successful synthesis of kaolinite, with high sensitivity to the UV irradiation, for its use as a material for exhaust gas photocatalyst.