Luminescence properties of neodymium, samarium, and europium niobate and tantalate thin films

Thin films of lanthanide orthoniobate LnNbO(4) (LnNO) and orthotantalate LnTaO(4) (LnTO), (Ln = Nd, Sm, Eu) were fabricated using the sol-gel method with subsequent spin-coating on the PbZrO3/Al2O3 substrate and annealing at 1000 degrees C. X-ray diffraction patterns showed monoclinic M-LnNbO(4) or M '-LnTaO(4), which coexists with the orthorhombic or tetragonal phase. X-ray photoelectron spectroscopy demonstrated the presence of Nd3+, Sm3+/Sm2+ and Eu3+/Eu2+ ions. The luminescence properties of polymorphic films were investigated. Excitation spectra of PbZrO3 interlayer represented broad bands at 410 and 550 nm that were assigned to charge transfer bands (CTB). In all films, the CTB broad band at similar to 275 nm related to charge transfer transition of Ln(3+)-> O2- and NbO43- or TaO43- groups. In excitation spectra, I-4(9/2)->(4)G(5/2) (Nd3+), H-6(5/2)-> P-6(3/2) (Sm3+) and F-7(0)-> L-5(6) (Eu3+) transitions (at 585, 402 and 395 nm), respectively were found to be more intense than any other Ln(3+) transition. The emission spectra showed narrow and intense bands at 1065, 600, and 614 nm that were ascribed to Nd3+, Sm3+, and Eu3+ 4f-f intraconfigurational transitions F-4(3/2)-> I-4(11/2), (4)G(5/2)-> H-6(7/2), and D-5(0)-> F-7(2), respectively. The excellent luminescence properties of films make them new potential groups for visible and/or near-infrared applications such as sensors and imaging equipment.

Automated summary

Thin films of lanthanide orthoniobate LnNbO(4) and orthotantalate LnTaO(4) (Ln = Nd, Sm, Eu) were successfully fabricated using the sol-gel method and exhibited excellent luminescence properties, making them promising candidates for applications in sensors and imaging equipment.