Mixed valence effects in TbVO4: Y nanocrystals and diamagnetic materials: Structure, optical linear & nonlinear, magnetic and Faraday rotation properties

Diamagnetic Y3+ ions doped magneto-optical TbVO4 nanocrystals were synthesized and characterized, the influence of mixed valence effect in TbVO4: Y to structure and properties of diamagnetic glasses/ceramic was studied. 80-100 nm spherical TbVO4 nanocrystals were hydrothermally synthesized. The doping of 30% and 40% Y3+ into TbVO4 increased the grain size to 120-150 nm and transformed pure zircon-type to a combination of zircon-scheelite type structure. EDX, Raman and infrared spectra revealed that the Y3+ occupied the site of Tb3+ with chemical formula of Tb0.7Y0.3VO4 and Tb0.6Y0.4VO4 respectively. More than 40% Y3+ could not be incorporated into TbVO4 lattice. Y doped TbVO4 nanocrystals presented two absorption peaks at 266 nm and 301 nm and one broad emission peak centered at 468 nm. A quenching of emission was observed for 40%Y doped TbVO4 due to the non-radiation energy transfer between Tb3+ and Y3+. Three nanocrystals displayed EPR resonance signal at g = 1.98 for V4+ ions due to the ion (oxygen) vacancies and structure deformation. VSM and XPS results indicated that the Y3+ doping changed paramagnetic to diamagnetic due to the increase concentration of diamagnetic Y3+, V5+ and Tb4+ ions. Three nanocrystals doped diamagnetic glass/ceramic presented different transparency, homogeneity and structures because of multivalence states of Tb and V in glasses/ceramic. Pure TbVO4 and TbVO4:30%Y doped glasses exhibited transition F-7(0)-> D-5(2) of Tb3+ and B-2(2) g -> B-2(1) g of V4+ ions which resulted in the reduction of band gap energy and red-shifts of absorption edges. A quenching of D-5(4)-> F-7(5-2) transition of Tb3+ was observed in Tb0.6Y0.4VO4 doped ceramic. Closed and open-aperture Z-scan showed an enhancement of nonlinearity due to the increase of polarizability. The mixed valence states of Tb and V yielded different magnetization and magneto optical rotation performances in glasses/ceramic. TbVO4:30%Y doped glass exhibited remarkable third nonlinear susceptibility (7.66 x 10(-11) esu), magnetization and Verdet constant (0.2248 min/G.cm) at 633 nm. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, diamagnetic TbVO4 nanocrystals doped with Y3+ ions were synthesized and characterized, with a focus on the influence of mixed valence effect in TbVO4:Y on the structure and properties of diamagnetic glasses/ceramic. The doping of Y3+ into TbVO4 resulted in changes in grain size, crystal structure, and optical properties. The incorporation of Y3+ ions affected the absorption and emission peaks of the TbVO4 nanocrystals, as well as their magnetization and nonlinearity properties.