# Synthesis and Features of Luminescent Bromo- and Iodohectorite Nanolay Materials
## 5 Conclusions  
The synthesis and properties of the Br-Hec and I-Hec materials have been presented for the first time in the current work. The materials adopt the same crystal structure and chemical environment as hectorite clays. However, replacement with halogen ions gives these materials broader possibilities for application in the production of luminescent materials, thus making them potential candidates for a wide range of follow-up research. The X-Hec materials are candidates for generating luminescent materials by doping with rare earth ions. These materials could be used in the quantitative determination of bio-molecules, and bio-imaging in vitro, due to the high bio-compatibility of clay minerals. Also, up-convertor materials may be obtained through the co-doping of X-Hec materials with rare earth ions, e.g., Er\({}^{3+}\)-Tm\({}^{3+}\)-Yb\({}^{3+}\), Yb\({}^{3+}\)-Tm\({}^{3+}\), Tm\({}^{3+}\)-Er\({}^{3+}\), etc. Such materials could be used as light-converting elements, enhancing the efficiency of commercially available solar cell devices.  
The high specific surface area found in both materials could enable their further application in gas sensors or in electrochemical devices for charge storage. Br-Hec and I-Hec materials could also be used as heterogeneous catalysts in polymeric reactions: since they possess moderated thermal stability, easy structural modification, and nanosize along the 001 direction, they could generate a functionalized modifier of polymeric structures, thus enhancing the physical properties of the final product. Moreover, the production of the p-n type of solar cells having X-Hec materials as the n-type element can be studied because of the X-Hec materials' abundance in negative free-carriers in their negative layers.  
H.S.S. and J.H. acknowledge the Brazilian funding agency CNPq for the Ciencia sem Fronteiras scholarships and the UTUGS for further funding. H.S.S. and J.M.C. acknowledge the Academy of Finland--CNPq Finland-Brazil bilateral project (#490242/2012-0). H.S.S. also acknowledges [PERSON] of the Universidade de Sao Paulo-SP-Brazil for his collaboration on the application and extension of the research grant.  
[PERSON] conceived, designed and performed most of the experiments, analyzed the data and wrote the paper; [PERSON] and [PERSON] performed the \({}^{29}\)Si MAS NMR measurements and revised the interpretation of the data; [PERSON] helped with the interpretation of the data and revised the manuscript; [PERSON] measured the nitrogen sorption isotherms and revised the interpretation of the data; [PERSON] assisted in the interpretation of the titanium luminescence and revised the manuscript; [PERSON] helped with the FTIR measurements and revised the interpretation of the data; [PERSON] contributed on the revision of the manuscript; [PERSON] contributed on the elaboration of the project, interpretation of the data, and revision of the manuscript; [PERSON] supervised the research project, elaborated the experiments, provided the materials and apparatus needed, and co-wrote and revised the manuscript.  
The authors declare no conflict of interest.  
Figure 13: The XRF measurements of bromohectorite (**top**) and iodohectorite (**bottom**) after heating to 1000 \({}^{\circ}\)C.  
Figure 14: Emission spectra of iodohectorite recorded at several excitation wavelengths. The data are not corrected for the excitation source intensity at different wavelengths.