TY - JOUR
T1 - Effect of Zn substitution in Cr3+ doped MgAl2O4 mixed spinel nanoparticles on red/NIR emission properties
AU - Karthik H.G., Shreekrishna
AU - Menon, Samvit G.
AU - Hebbar N., Deepak
AU - Choudhari, K. S.
AU - Santhosh, C.
AU - Kulkarni, Suresh D.
PY - 2019/3/1
Y1 - 2019/3/1
N2 - Red/Near-infrared (NIR) emitting Mg1-xZnxAl1.98Cr0.02O4 nanoparticles were synthesized by co-precipitation followed by firing(1200 °C). Gradual shift of XRD peaks with Zn-content confirmed complete solid-solution formation. HRTEM revealed hexagonal sheet-like structures and lattice fringes revealed their single-crystallinity. Owing to refractory nature of MgAl2O4, particles were smaller(∼38 nm) in Mg-rich samples and gradually increased(∼58 nm) with Zn-substitution. Due to trigonal distortion, the fine splitting of the 4T1g level of Cr3+ manifests as asymmetric band(400 nm) in the excitation spectrum. Cr3+ emission was clearly observed, comprising of R-line and multi-phonon side-bands on either side, with maximum R-line intensity for x = 0.5. With increasing x, side-bands were more pronounced probably due to the band-gap difference of end members. High Dq/B (3.5–3.9), suggested Cr3+ in a strong crystal-field. Racah-parameter(B) variations suggest increased electron delocalization over molecular orbitals for higher Mg2+ substitutions. Longer lifetimes (23–34 ms) are well-suited for bioimaging and optoelectronic applications. Such a simple synthesis can be easily extended to other important phosphors.
AB - Red/Near-infrared (NIR) emitting Mg1-xZnxAl1.98Cr0.02O4 nanoparticles were synthesized by co-precipitation followed by firing(1200 °C). Gradual shift of XRD peaks with Zn-content confirmed complete solid-solution formation. HRTEM revealed hexagonal sheet-like structures and lattice fringes revealed their single-crystallinity. Owing to refractory nature of MgAl2O4, particles were smaller(∼38 nm) in Mg-rich samples and gradually increased(∼58 nm) with Zn-substitution. Due to trigonal distortion, the fine splitting of the 4T1g level of Cr3+ manifests as asymmetric band(400 nm) in the excitation spectrum. Cr3+ emission was clearly observed, comprising of R-line and multi-phonon side-bands on either side, with maximum R-line intensity for x = 0.5. With increasing x, side-bands were more pronounced probably due to the band-gap difference of end members. High Dq/B (3.5–3.9), suggested Cr3+ in a strong crystal-field. Racah-parameter(B) variations suggest increased electron delocalization over molecular orbitals for higher Mg2+ substitutions. Longer lifetimes (23–34 ms) are well-suited for bioimaging and optoelectronic applications. Such a simple synthesis can be easily extended to other important phosphors.
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U2 - 10.1016/j.materresbull.2018.11.035
DO - 10.1016/j.materresbull.2018.11.035
M3 - Article
AN - SCOPUS:85057471465
SN - 0025-5408
VL - 111
SP - 294
EP - 300
JO - Materials Research Bulletin
JF - Materials Research Bulletin
ER -