Augmenting cyan emission in vanadate garnets via Dy³⁺activation for light emitting devices and multi-mode optical thermometry

Abstract

Developing cyan-based phosphors is inevitable to bridge the cyan gap to generate white light with high color rendering index. Herein, the blue-green emission from VO43- center in the Sr2NaMg2V3O12 host...

Delving into the multifunctionality of Sr2NaMg2V3O12via RE3+ substitution for dual-mode temperature sensing, latent fingerprint detection and security inks

“…Compared with the Eu 3+ based SNMV system, 23 a red shift in the Raman modes is observed for the Sm 3+ system. For the SNMV:Sm 3+ system, it can be noted that from the Raman spectra shown in Fig.…”

“…Nevertheless, the maximum phonon energy of SNMV:Eu 3+ is 844 cm À1 . 23 The red shift of Raman modes in the Sm 3+ system might be due to the weaker ionic bond strength owing to the relatively lower electronegativity of Sm 3+ (1.377) compared to Eu 3+ (1.356) in eight coordination. 44 The reduced number of Raman modes might be due to the polycrystalline nature, overlap of modes and low resolution of the instrument.…”

“…3(b)), making it suitable for substituting activator ions in the host material, whereas SNMV:Eu 3+ and SNMV host phosphors possess bandgaps of 3.0 and 3.2 eV, respectively. 22,23 The slight decrease in the bandgap of SNMV:RE 3+ systems is due to the replacement of larger Sr 2+ with RE 3+ , occupying the dodecahedral site. The substitution of Sm 3+ introduces additional 4f energy states in the forbidden gap, which lowers the bandgap of the Sr 2 NaMg 2 V 3 O 12 :Sm 3+ system.…”

“…Vanadate-based hosts are known for their strong absorption and self-activated luminescence due to the 3 T 1,2 -1 A 1 transitions. 17,[19][20][21][22][23][24] RE ions possess a low absorbance in the UV region due to narrow excitation of forbidden 4f-4f transition. Hence, the RE-activated vanadate host structure helps in phonon-assisted energy transfer from VO 4 3À to RE 3+ .…”

“…Recently, our group has investigated the thermographic and thermochromic luminescence of the Eu 3+ -activated Sr 2 NaMg 2 V 3 O 12 system in detail. 23 Moreover, the study of optical temperature sensing based on vanadate garnets still needs to be improved. To figure out this gap in understanding the potentiality of vanadate garnets, Sr 2 NaMg 2 V 3 O 12 (SNMV) is selected as the host material due to its better luminescence properties.…”