Glowing synthetic chlorohectorite: The luminescent features of a trioctahedral clay mineral

• Published in: Journal of luminescence Vol. 192; pp. 567 - 573
• Main Authors: Santos, Hellen S., Carvalho, José M., Viinikanoja, Antti, Hyppänen, Iko, Laihinen, Tero, Romani, Eric C., Larrudé, Dunieskys G., Tuominen, Marjukka, Laukkanen, Pekka, Swart, Hendrik C., Brito, Hermi F., Hölsä, Jorma, Lastusaari, Mika
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2017
• Subjects: Chlorohectorites; Emission; Layered silicates; Persistent luminescence; Titanium; Traps; Titanium; Emission; Layered silicates; Chlorohectorites; Traps; Persistent luminescence
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2017.07.017

Clay minerals are versatile materials with numerous industrial applications. Their unique layered structure can act as a host for many optically active species. The synthesis and luminescence properties of chlorohectorite clays are now reported for the first time. The synthesized clays are composed of quasi-circular nanoparticles with diameters around 20–30nm showing blue/green emission and persistent luminescence with a duration of ca. 5s. The luminescence features are associated with titanium impurities in the chlorohectorite structure. It is shown that Ti can act as activator ion even at low concentrations: the XRF and ICP-MS measurements of the chlorohectorite materials indicate a Ti concentration around 60 ppm originating from the precursors. The XPS measurements of the clay materials showed the Ti 2p3/2 signals at 457.8 and 458.9eV associated with Ti3+ and TiIV, respectively. The excitation spectra confirm Ti3+ as the luminescent center in the chlorohectorites through the bands at 287 and 370nm, related to the e−(O2−(2p))→TiIV charge transfer and the electronic transitions from the t2g to eg levels of Ti3+, respectively. The persistent luminescence properties are due to structural defects common for layered silicates. [Display omitted]