“…Fundamental luminescence properties of sixcoordinated Ni 2+ illustrate by the energy levels diagram depict the possibility of NIR-II emission. Ni 2+ mainly contains three excited bands at UV, and the orange-red region ascribes to 3 [75] Excited electrons relax to the lowest excited state of 3 T 2 ( 3 F) or 1 E ( 1 D) depending on the crystal strength and then return to the ground state by radiative process…”
Section: Ni-dopedmentioning
confidence: 99%
“…Generally, Mg 2+ and Zn 2+ are two common choices of the divalent source in the Ni 2+ -activated spinel host structure because the similar ionic radius of six-coordinated Mg 2+ (r = 0.72 Å), Zn 2+ (r = 0.74 Å) with the Ni 2+ (r = 0.69 Å) cause the favorable substituting tendency and have the advantage of the less lattice defect and distortion. [72][73][74][75][76][77][78][79][80][81][82][83][84] Also, the trivalent cations in spinel structure are the other factor to influences the properties of Ni 2+ emission as they might randomly occupy both tetrahedral and octahedral to control the crystal fields. For example, if the larger cations are selected, the redshift of the spectra will present compared with the smaller one due to the weaker crystal field when lattice expansion.…”
Section: Ni-dopedmentioning
confidence: 99%
“…Until now, seldom research has been mainly about the Ni 2+activated phosphor. The common systems of Ni 2+ -activated spinel-structured NIR-II materials, including phosphor, glassceramic, and nanoparticles, are listed in [72,[74][75][76][77][78][79][80] Ni 2+ ions are forced to substitute the trivalent cations on the octahedral sites to create the NIR-II emission at the expense of charge imbalance, since the higher crystal field Adapted with permission. [72] Copyright 2021 Elsevier B.V. c) PLE spectra and d) PL spectra of ZGO:xNi excited by 310 nm.…”
Applications in near‐infrared (NIR) have been explored significantly in many fields, including bioimaging, night vision, plant growth, and chemical analysis. Different emission profiles are required within the same industry. Developing luminescent materials with different tuning methods is reliable for controlling the NIR regions (NIR‐I, 700–1000 nm; NIR‐II, 1000–1700 nm). Spinel phosphors are promising candidates due to their ability to modulate the crystal field. Understanding the parameters that influence the degree of inversion in spinel compounds is crucial to harness the variability of the spinel structure. Cr3+ and Ni2+ are ideal activators for NIR‐I and NIR‐II emissions, respectively. However, there is a need for phosphors that emit in the NIR‐II region when excited by visible light. Although the energy transfer method combining two activators is considered, this review focuses on different types of spinel structures, discussing their types and common strategies to tune the host structure. The goal is to achieve desired shift and broadness of the entire NIR spectrum, highlighting the importance of spectrum tuning for practical applications.
“…Fundamental luminescence properties of sixcoordinated Ni 2+ illustrate by the energy levels diagram depict the possibility of NIR-II emission. Ni 2+ mainly contains three excited bands at UV, and the orange-red region ascribes to 3 [75] Excited electrons relax to the lowest excited state of 3 T 2 ( 3 F) or 1 E ( 1 D) depending on the crystal strength and then return to the ground state by radiative process…”
Section: Ni-dopedmentioning
confidence: 99%
“…Generally, Mg 2+ and Zn 2+ are two common choices of the divalent source in the Ni 2+ -activated spinel host structure because the similar ionic radius of six-coordinated Mg 2+ (r = 0.72 Å), Zn 2+ (r = 0.74 Å) with the Ni 2+ (r = 0.69 Å) cause the favorable substituting tendency and have the advantage of the less lattice defect and distortion. [72][73][74][75][76][77][78][79][80][81][82][83][84] Also, the trivalent cations in spinel structure are the other factor to influences the properties of Ni 2+ emission as they might randomly occupy both tetrahedral and octahedral to control the crystal fields. For example, if the larger cations are selected, the redshift of the spectra will present compared with the smaller one due to the weaker crystal field when lattice expansion.…”
Section: Ni-dopedmentioning
confidence: 99%
“…Until now, seldom research has been mainly about the Ni 2+activated phosphor. The common systems of Ni 2+ -activated spinel-structured NIR-II materials, including phosphor, glassceramic, and nanoparticles, are listed in [72,[74][75][76][77][78][79][80] Ni 2+ ions are forced to substitute the trivalent cations on the octahedral sites to create the NIR-II emission at the expense of charge imbalance, since the higher crystal field Adapted with permission. [72] Copyright 2021 Elsevier B.V. c) PLE spectra and d) PL spectra of ZGO:xNi excited by 310 nm.…”
Applications in near‐infrared (NIR) have been explored significantly in many fields, including bioimaging, night vision, plant growth, and chemical analysis. Different emission profiles are required within the same industry. Developing luminescent materials with different tuning methods is reliable for controlling the NIR regions (NIR‐I, 700–1000 nm; NIR‐II, 1000–1700 nm). Spinel phosphors are promising candidates due to their ability to modulate the crystal field. Understanding the parameters that influence the degree of inversion in spinel compounds is crucial to harness the variability of the spinel structure. Cr3+ and Ni2+ are ideal activators for NIR‐I and NIR‐II emissions, respectively. However, there is a need for phosphors that emit in the NIR‐II region when excited by visible light. Although the energy transfer method combining two activators is considered, this review focuses on different types of spinel structures, discussing their types and common strategies to tune the host structure. The goal is to achieve desired shift and broadness of the entire NIR spectrum, highlighting the importance of spectrum tuning for practical applications.
“…In addition, NIRF imaging in the second biological window (1000—1400 nm), also named over-thousand near-infrared (OTN) imaging, has attracted significant attention in in vivo imaging applications due to its even deeper tissue penetration, higher image contrast, and reduced phototoxicity and photobleaching 22 . OTN fluorescence imaging agents include Ag 2 S quantum dots 23 , rare-earth doped materials 24 , Ni-doped magnetic nanocrystals 25 , and single-wall carbon nanotube 26 . Figure 1 Representative NIRF dyes used in dual-modality optical fluorescence imaging.…”
Section: Brief Overview Of Different Imaging Modalitiesmentioning
Multimodality optical imaging probes have emerged as powerful tools that improve detection sensitivity and accuracy, important in disease diagnosis and treatment. In this review, we focus on recent developments of optical fluorescence imaging (OFI) probe integration with other imaging modalities such as X-ray computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and photoacoustic imaging (PAI). The imaging technologies are briefly described in order to introduce the strengths and limitations of each techniques and the need for further multimodality optical imaging probe development. The emphasis of this account is placed on how design strategies are currently implemented to afford physicochemically and biologically compatible multimodality optical fluorescence imaging probes. We also present studies that overcame intrinsic disadvantages of each imaging technique by multimodality approach with improved detection sensitivity and accuracy.
“…ZnAl 2 O 4 -doped nickel and cobalt are widely used as blue and green-blue pigments in glass and ceramics. 18 Therefore, the main objective of this contribution is to study the optical and dielectric properties of the Ag + doped ZnAl 2 O 4 compounds.…”
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