As human lifespan increases with societal development, tumors have become one of the major diseases threatening public health. However, traditional cancer therapies face inevitable limitations and side effects. Consequently, minimally invasive alternatives, such as photodynamic therapy (PDT) and photothermal therapy (PTT), have attracted significant research interest. This comprehensive review summarizes the application of rare-earth-doped and rare-earth-containing nanomaterials in PDT and PTT for cancer therapy. We first introduce the fundamental principles of both therapies and the critical role of rare earth (RE) components, followed by a discussion of four major material categories: carbon-based nanomaterials, upconversion nanomaterials, sulfide/oxide nanoparticles, and metal nanocomposites. Furthermore, the review discusses the phototherapeutic applications of these materials from a mechanism-guided perspective, with emphasis on PDT, PTT, and synergistic combined therapy. Finally, we address the current challenges, proposed solutions, and future prospects of this rapidly developing field. Rather than functioning as universal performance enhancers, RE components regulate phototherapy through ion-specific mechanisms, including Near-infrared (NIR)-to-visible/Ultraviolet (UV) conversion, photosensitizer activation, oxygen/reactive oxygen species modulation, magnetic or optical imaging, and temperature-feedback monitoring. These multifunctional roles provide a promising but still preclinical foundation for next-generation tumor phototherapy, provided that biosafety, irradiation parameters, metabolism, and scalable synthesis are carefully evaluated.

High-radiant-intensity broadband near-infrared (NIR) emitters are highly desirable for nondestructive testing, night-vision imaging, and information encryption. However, the exploration of phosphors that possess both high luminous efficiency and outstanding thermal stability continues to pose significant difficulties. Among various NIR phosphor systems, Cr3+-doped MgGa2O4 (MGO:Cr3+) exhibits characteristic broadband emission. Herein, Bi3+ ions were incorporated as sensitizers into the MGO:Cr3+ phosphor system, resulting in substantial enhancements in photoluminescence (PL), mechanoluminescence (ML), and thermal stability. The Bi3+ co-doping enhanced the NIR PL intensity to 4.0 times and the ML output to 1.45 times those of the Cr3+ singly doped reference, indicating a pronounced sensitization effect and improved energy transfer efficiency. Furthermore, the emission-intensity retention at 423 K improved from 49.29 to 82.88%, confirming a significant enhancement in the thermal stability of the NIR emission. A broadband NIR phosphor-converted light-emitting diode (pc-LED) assembled by coupling the Bi3+, Cr3+-co-doped MGO with a blue LED further demonstrated the material's potential for nondestructive testing, night-vision imaging, and anti-counterfeiting.

Luminescent ion-doped materials have gained extensive attention and application in both scientific research and practical fields. The integration of luminescent ions with nano-structured semiconductors has emerged as a highly promising development trend to meet the growing demands for advanced functional systems. This review focuses on luminescent ion-doped nano-structured semiconductors, including 0D, 1D, and 2D systems. It elaborates on the pivotal roles that luminescent ions play within these materials. Subsequently, the article offers a comprehensive overview of the application scenarios and effects of various luminescent ions doped into nano-structured semiconductors. Additionally, the article systematically discusses the coupling mechanisms between luminescent ions and nano-structured semiconductors, as well as the synergistic effects of codoping. We also present the specific applications of these materials in the information and functional materials fields. Lastly, this work addresses the current challenges faced in this research area and outlines the frontier development directions, providing valuable insights for future exploration.

Lanthanide-doped fluorides are promising materials for advanced photonic and quantum applications due to their wide bandgap, low phonon energy, and chemical stability. In this work, we present a systematic comparative study of ytterbium incorporation at low doping levels (0.05-0.2 mol%) in BaF2 and CaF2 single crystals, focusing on the interplay between host lattice properties, charge-state stabilization, and defect formation mechanisms. Using a combination of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), transmittance, and infrared photoluminescence (IR PL), we explore how host lattice properties affect the stabilization of Yb3+ and Yb2+ ions. XRD confirmed cubic phase purity and lattice parameter stability in both hosts, while XPS revealed surface chemical composition variations associated with charge-compensating defects and trace impurities. EPR spectra indicated that BaF2 favored perturbed Yb3+ environments with increasing dopant levels, while CaF2 maintained predominantly unperturbed sites, suggesting a more favorable ionic match for Yb2+. Photothermal deflection spectroscopy (PDS) and IR PL results showed host-specific optical responses, with CaF2 exhibiting crystal-field splitting and broader local field effects. These results reveal a clear decoupling between long-range structural stability and local lattice perturbations, and demonstrate that host cation identity governs the balance between Yb2+ and Yb3+ stabilization as well as defect-driven optical behavior. This offers valuable insights for optimizing rare-earth-doped fluoride crystals in laser, scintillator, and quantum device applications.

Lanthanide-doped double perovskites have emerged as promising candidates for remote optical thermometry owing to their exceptional photoluminescence properties. However, pronounced luminescence quenching at elevated temperatures remain a critical bottleneck for application in high-precision temperature measurements. Herein, we report Yb3+/Ho3+-doped Cs2NaYCl6 double perovskites synthesized via a solid-phase synthesis method, exhibiting thermally enhanced upconversion luminescence (UCL) and controllable color conversion. By tailoring the lanthanide doping concentration and temperature, the emission color gradually transitions from green to orange. Remarkably, this pattern remains consistent over a wide temperature range of 303-573 K, delivering a maximum relative sensitivity of 1.34% K- 1 at 303 K. These features enable thermometers based on fluorescence intensity ratio (FIR) with excellent stability, high sensitivity and visualization capability. More importantly, the system simultaneously realizes thermochromic upconversion switch, opening an opportunity for multifunctional optical devices in sensing, imaging, and smart photonics.

Abstract Controlled melt nonstoichiometry was investigated as a processing parameter governing secondary-phase formation and functional properties of Ce3+-doped (Tb,Y)3Al5O12 single crystals grown by micropulling-down. Crystals were grown from melts with 0, 3, 6, 9, and 11 mol % Y2O3 deficiency. X-ray diffraction, electron probe microanalysis, and Raman spectroscopy revealed phase-pure garnet up to 3 mol % deficiency, rim-localized α-Al2O3 inclusions at 6 and 9 mol %, and core-localized perovskite-type inclusions at 11 mol %. Secondary-phase formation modified Tb/Y partitioning in the garnet matrix, affecting Ce3+ emission kinetics, Tb3+↔Ce3+ energy transfer, trap depth, and scintillation properties. The 11 mol % deficient crystal showed the highest thermal stability, with the Ce3+ thermal-quenching onset shifting from 375 to 425 K. The 9 mol % deficient crystal reached a luminous efficacy of 158 lm/W and a scintillation light yield of 33,600 photons/MeV. X-ray radiography using the 9 mol % Y2O3-deficient crystal showed clear images of an SD card. These results indicate that melt nonstoichiometry can tune the balance between photoconversion and scintillation performance in rare-earth garnets.

The exposure of luminescent materials to X-ray radiation and high-power laser excitation results in significant heating, leading to thermal quenching and a corresponding reduction in phosphor efficiency. This study aimed to address this limitation by enhancing material efficiency while maintaining high thermal stability. YAG:Ce,Tb transparent ceramics were successfully fabricated via vacuum reactive sintering method, with moderate concentrations of Tb3+ ions (1, 5 and 10 at%) codopants. These ceramics exhibited a dense microstructure without micropores, achieving high transparency of 77-80% at 900 nm. The incorporation of Tb3+ ions, is evidenced by the systematic increase in lattice constants from 12.608 & Aring; (YAG:Ce) to 12.615 & Aring; (YAG:Ce,Tb10%) in accordance with Vegard's law. The phonon-assisted Ce3+ <-> Tb3+ bidirectional resonance mechanism, which facilitated energy transfer between Ce3+ and Tb3+ ions, was observed. The optimal transfer rate was observed at approximately 480 K. Beyond this temperature, the rate progressively accelerated, leading to accelerated decay times. Notably, YAG:Ce,Tb10% ceramics demonstrated a two-fold increase in radioluminescence intensity compared to uncodoped YAG:Ce ceramics. This substantial improvement in luminescence performance highlights the potential of YAG:Ce,Tb ceramics as highly efficient phosphors for X-ray imaging applications, offering enhanced brightness and energy transfer efficiency under high-temperature operating conditions. The Tb3+ codoping also enhanced Ce3+ emission, allowing for tuning of the correlated color temperature to a maximum of 6013 K, while maintaining a stable color rendering index of 69-73 and luminous efficacy of similar to 123 lm W-1. It was shown that the luminous efficacy was not a constant parameter, but depended on the excitation laser power, initially increasing with power up to 0.5 W and then saturating. These results establish YAG:Ce,Tb transparent ceramics as highly promising materials for white LEDs due to their good thermal stability, tunable optical properties, and enhanced luminescence performance.

The exposure of luminescent materials to X-ray radiation and high-power laser excitation results in significant heating, leading to thermal quenching and a corresponding reduction in phosphor efficiency.

A high-performance Ce3+-doped (Gd, Tb)3(Ga, Al)5O12 (GTAGG: Ce) single crystal was engineered and characterized, demonstrating a high application potential for advanced X-ray imaging. A transparent 1-inch diameter single crystal was grown using the Czochralski method, demonstrating a significant advancement in large-scale scintillator production. Comprehensive characterization using X-ray diffraction and electron probe micro-analysis confirmed the crystal’s structural integrity. Photoluminescence and radioluminescence spectroscopy demonstrated efficient bidirectional energy transfer between Ce3+ and Tb3+ ions, a critical mechanism enhancing the performance of the scintillator. X-ray imaging tests were performed using crystals with a thickness of 100 μm at the Aichi Synchrotron Radiation Center. Comparison with the industry-standard LuAG: Ce scintillator showed that the GTAGG: Ce crystal produced 2.4 times higher light output and achieved a high spatial resolution of 0.85 μm. The results indicated that GTAGG: Ce is suitable for the next generation of high-performance X-ray imaging detectors in scientific and medical imaging applications.

This study explored the influence of Sc3+ ions incorporation on the structural, vibrational, luminescent, and scintillation properties of Pr3+-doped Lu3(Al, Sc)2.5Ga2.5O12 garnet crystals. Addressing the limited research on Sc-admixed and Pr3+ doped garnet systems, this work successfully demonstrated the crystallization of garnet crystals from the melt, overcoming the substantial atomic mismatch between Sc and Al while preserving the thermodynamic stability of the garnet phase. Importantly, Sc-admixing enhanced atomic homogeneity and allowed for increased doping concentrations of Pr3+ ions, which is crucial for tailoring the functional properties of advanced optical materials. The trap depths ranged from 1.63 eV (deep traps) to 0.22 eV (shallow traps) across all samples, with frequency factors predominantly between 1 × 107 and 1 × 1011 s-1, consistent with first-order thermoluminescent kinetics. From a materials design perspective, Sc3+ ions substitution induced beneficial host lattice disorder, enhancing the emission intensity of 4f15d1 1 → 4f2 interconfigurational and 4f2 → 4f2 intraconfigurational transitions. This effect highlighted the potential of Sc as a promising substituent for enhancing the luminescence intensity of rare earth elements. Synchrotron radiation experiments provided insights into the impact of Sc on band gap energy and energy transfer efficiency toward Pr3+ ions offering new opportunities for engineering scintillators and phosphors with tunable optical properties.

A next-generation class of dual-phase, multifunctional photoconversion and thermal sensing materials has been developed using Ce3+-doped YAG-YAP eutectic crystals, synthesized via directional solidification at variable rates (0.1-0.9 mm/min) to precisely tailor phase morphology and dopant distribution. Structural and compositional analyses revealed a lamellar microstructure comprising alternating garnet (Y3Al5O12, YAG) and perovskite (YAlO3, YAP) domains, with Ce3+ ions preferentially partitioned into the garnet phase at elevated solidification rates. Systematic control of domain sizes was achieved by modulating the growth rate. Slower growth resulted in larger domains that enabled near-complete transmission of blue light through YAP, whereas faster growth produced finer structures that led to increased scattering and absorption of blue light. This morphology-driven optical tunability enabled dynamic control over the correlated color temperature (CCT), ranging from cool to warm white emissions. Beyond structural engineering, the eutectics demonstrated dual-mode thermal sensing via ratiometric luminescence thermometry under both photoluminescence (PL) and X-ray-induced scintillation excitation. Excitation modality significantly affected thermal sensitivity due to distinct charge transport and energy transfer dynamics. Under PL, the relative sensitivity reached 0.47% K-1, while scintillation-based excitation achieved an enhanced sensitivity up to 1.1% K-1. Crucially, the scintillation mode permits passive, remote temperature monitoring without external optical excitation, activated solely by ambient ionizing radiation. These capabilities position Ce3+-doped YAG-YAP eutectics as promising candidates for advanced thermal sensing in extreme environments, including nuclear reactors, aerospace systems, and high-energy particle detectors.

Substituting Sc 3+ for Al 3+ in Pr 3+ -doped Lu 1.5 Y 1.5 Al 5− x Sc x O 12 crystals enhances the Pr 3+ emission across the UV-Vis-NIR spectral range. This enhancement is attributed to an efficient Sc 3+ → Pr 3+ energy transfer and increased structural disorder.

In this study, the photoluminescence wavelength and decay constant of Cr:Gd3Ga5O12 garnet oxide were modified by substituting Gd3+/Ga3+ cations with a Ca2+/Si4+ cation pair. The primary objective of this study was to shift the emission wavelength to the near-infrared (NIR) region and accelerate decay of Cr:Gd3Ga5O12 for its potential use as a scintillation detector in medical applications. The incorporation of Ca2+ and Si4+ ions in site of Gd3+/Ga3+ ions resulted in a significant redshift in the photoluminescence wavelength of Cr3+ ions and an acceleration of decay. The results clearly demonstrated that Ca2+/Si4+ cation pair substitution is a clearly effective strategy for modulating the optical properties of Cr:Gd3Ga5O12, with the potential to develop a NIR garnet scintillator

Driven by the pursuit of optimizing the luminescent properties of garnet-based single crystals for X-ray imaging applications, this work reports on the successful synthesis and in-depth characterization of GYAGG crystals doped with Ce³⁺ or Tb³⁺ ions, and doubly-doped with both of them. Micro-pulling down synthesis yielded crystals with a single cubic phase confirmed by X-ray diffraction. Photoluminescence (PL) and radioluminescence (RL) measurements on Ce³⁺,Tb³⁺ co-doped GYAGG revealed bidirectional energy transfer processes. Characteristic broadband 5d1→4f emission of Ce³⁺ centres peaking at 530 nm and narrow 4f→4f emission lines of Tb³⁺ ions starting from 5D4 level within 480-630nm were observed. At higher doping levels, cross-relaxation in Tb³⁺ pairs resulted depleted 5D3 state and only the emission from 5D4 one was observed in the spectra. Analysis of PL decay characteristics corroborated the spectral observations, confirming progressively decreasing Ce³⁺ decay time (down to 40 ns at 15% Tb3+) due to enhanced Ce³⁺→Tb³⁺ energy transfer. Similarly, the Tb³⁺ decay time accelerated by more than 60% after the Ce³⁺ co-doping. Notably, co-doping with 0.5% Ce³⁺ and 10-15% Tb³⁺ doubled the luminescence intensity of RL spectra compared to 0.5% Ce³⁺-doping alone, attributed to the increased density of emitting centres.

The luminescence, scintillation and photoconversion properties of Ce3+-doped Lu0.6Gd2.4(Al5-xScx)O-12 (x = 1.2, 1.5, 2) garnet crystals grown by micro-pulling-down method were investigated. Increasing Sc3+ concentration induced lattice strain and cracking due to ionic radius mismatch. At low Sc3+ concentration, the strain caused core-concentrated cracks and radial inhomogeneity. At higher Sc3+ concentration, extensive cracking occurred throughout crystals, improving radial homogeneity. With the increase of Sc3+ concentration, the Ce3+ 5d(1) -> 4f luminescence was slightly blue-shifted due to the decrease in crystal field splitting of the 5d levels. At room temperature (RT), the increase of light yield with increasing Sc3+ concentration was attributed to the decrease in the bandgap value. Above RT, the decrease of photo- and radio-luminescence for all samples was due to the thermal ionization process. The decrease of radioluminescence at low-temperature regions can be caused by the localization of electrons at intrinsic shallow traps. Photoluminescence measurements disclosed that variations in scandium concentration can effectively modulate the correlated color temperature (CCT), color rendering index (CRI), and luminous efficiency (LE) of these luminescent materials. The incorporation of a micro-perovskite phase in the Lu0.6Gd2.4(Al3.8Sc1.2)O-12:Ce crystal resulted in a notable enhancement of the luminous efficiency, exhibiting a 38 % increase when compared to the sample devoid of micro-inclusions (e.g. x = 2.0).

In this study, the photoluminescence wavelength and decay constant of Cr:Gd3Ga5O12 garnet oxide were modified by substituting Gd3+/Ga3+ cations with a Ca2+/Si4+ cation pair. The primary objective of this study was to shift the emission wavelength to the near-infrared (NIR) region and accelerate decay of Cr:Gd3Ga5O12 for its potential use as a scintillation detector in medical applications. The incorporation of Ca2+ and Si4+ ions in site of Gd3+/Ga3+ ions resulted in a significant redshift in the photoluminescence wavelength of Cr3+ ions and an acceleration of decay. The results clearly demonstrated that Ca2+/Si4+ cation pair substitution is a clearly effective strategy for modulating the optical properties of Cr:Gd3Ga5O12, with the potential to develop a NIR garnet scintillator.

This study provided the first in-depth investigation of the effects of large dopant incompatibility (Pr3+ and La3+ ions) on the small host lattice element (Lu3+) in Lu3Al5O12 (LuAG) single crystal. The growth of such complex crystals from the melt presented many challenges. By engineering the ionic radius ratio of RE- and M-site cations, a single-crystal phase stabilized by configurational entropy was achieved. This investigation elucidated the crystallization behavior of configurationally disordered rare-earth aluminum garnet oxide (Lu1−x−yPrxLay)3Al5O12 from the melt and characterized its functional properties, including microstructural, optical, photoluminescence, and scintillation properties, between 5 and 300K. Relaxation of the imposed strain energy led to local perturbations and destabilization of the garnet structure. Multielemental EDS mapping, micro-Raman spectroscopy, and thermoluminescence revealed the mechanism by which atomic size mismatch drove a smooth transition from the garnet to the perovskite phase in high entropy garnets. The optical, photoluminescence, and scintillation measurements provided fundamental insights into property changes driven by incompatibility doping. Standard and modified Judd-Ofelt theory analysis of absorption spectra determined the phenomenological Judd-Ofelt parameters Ωλ and radiative lifetimes. Atomic size mismatch engineering offers a promising approach to overcoming the limitations of conventional eutectic synthesis methods.

Aluminum garnets display exceptional adaptability in incorporating mismatching elements, thereby facilitating the synthesis of novel materials with tailored properties. This study explored Ce3+-doped Tb3Al5−xScxO12 crystals (where x ranges from 0.5 to 3.0), revealing a novel approach to control luminescence and photoconversion through atomic size mismatch engineering. Raman spectroscopy confirmed the coexistence of garnet and perovskite phases, with Sc substitution significantly influencing the garnet lattice and induced A1g mode softening up to Sc concentration x = 2.0. The Sc atoms controlled sub-eutectic inclusion formation, creating efficient light scattering centers and unveiling a compositional threshold for octahedral site saturation. This modulation enabled the control of energy transfer dynamics between Ce3+ and Tb3+ ions, enhancing luminescence and mitigating quenching. The Sc admixing process regulated luminous efficacy (LE), color rendering index (CRI), and correlated color temperature (CCT), with adjustments in CRI from 68 to 84 and CCT from 3545 K to 12,958 K. The Ce3+-doped Tb3Al5−xScxO12 crystal (where x = 2.0) achieved the highest LE of 114.6 lm/W and emitted light at a CCT of 4942 K, similar to daylight white. This approach enables the design and development of functional materials with tailored optical properties applicable to lighting technology, persistent phosphors, scintillators, and storage phosphors.