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

• Published in: Journal of alloys and compounds 2021-06, Vol.867, p.159065, Article 159065
• Main Authors: Chen, Qiuling, Chen, Weihao, Li, Zhuangzhuang, Miao, Baoji
• Format: Article
• Language: English
• Subjects: Absorption; Ceramics; Diamagnetism; Doping; Emission; Energy gap; Energy transfer; EPR; Faraday effect; Faraday rotation; Glass; Grain size; Homogeneity; Infrared spectra; Lattice vacancies; Magnetic; Magnetic properties; Magnetization; Nanocrystals; Nonlinear; Nonlinearity; Optical properties; Optical rotation; Quenching; Scheelite; Valence; Verdet constant; Y: TbVO4; Zircon
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.159065

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 7F0→5D2 of Tb3+ and 2B2 g→2B1 g of V4+ ions which resulted in the reduction of band gap energy and red-shifts of absorption edges. A quenching of 5D4→7F5–2 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 × 10−11 esu), magnetization and Verdet constant (0.2248 min/G.cm) at 633 nm. •Diamagnetic Y3+ doped ~100 nm spherical magneto-optical TbVO4 were synthesized, characterized.•Tb0.7Y0.3VO4/Tb0.6Y0.4VO4 show lower band gap, modified magnetization and zircon-scheelite structure.•Glasses/ceramic with different homogeneity, transparency and structure were obtained.•Multivalence of Tb and V in diamagnetic matrix contributed to linear and nonlinearity improvement.•TbVO4:30%Y doped glass show giant magnetization a