Energy Manipulation in Lanthanide-Doped Core-Shell Nanoparticles for Tunable Dual-Mode Luminescence toward Advanced Anti-Counterfeiting.

Developing advanced luminescent materials and techniques is of significant importance for anti-counterfeiting applications, and remains a huge challenge. In this work, a new and efficient approach for achieving efficient dual-mode luminescence with tunable color outputs via Gd3+ -mediated interfacial energy transfer, Ce3+ -assisted cross-relaxation, and core-shell nanostructuring strategy is reported. The introduction of Ce3+ into the inner core not only serves the regulation of upconversion emission, but also facilitates the ultraviolet photon harvesting and subsequent energy transfer to downshifting (DS) activators in the outer shell layer. Furthermore, the construction of the core@shell nanoarchitecture enables the spatial separation of upconverting activators and DS centers, which greatly suppresses their adverse cross-relaxation processes. Consequently, efficient and multicolor-tunable dual-mode emissions can be simultaneously observed in the pre-designed NaGdF4 :Yb/Ho/Ce@NaYF4 :X (X = Eu, Tb, Sm, Dy) core-shell nanostructures under 254 nm ultraviolet light and 980 nm laser excitation. The proof-of-concept experiment demonstrates that 2D-encoded patterns based on dual-mode emitting nanomaterials are very promising for anti-counterfeiting applications. It is believed that this preliminary study will advance the development of the fluorescent materials for potential applications in anti-counterfeiting and optical multiplexing.

Efficient dual-mode luminescence from lanthanide-doped core-shell nanoarchitecture for anti-counterfeiting applications.

Fluorescent anti-counterfeiting technique is generally based on the development of luminescent materials, which generally exhibit single-mode emissions under single-wavelength excitation, thus resulting in a poor anti-fake effect. To improve the anti-forgery performance of fluorescent anti-counterfeiting approaches, dual-mode luminescent nanoparticles with the form of a ß-NaGdF4:Yb/Ho/Ce@ß-NaYF4:Tb/Eu core-shell structure have been skillfully designed and synthesized by a co-precipitation strategy. Through the cross-relaxation process between Ce3+ and Ho3+ ions in the inner core region, the up-conversion luminescence colors of the as-synthesized samples can be turned from green to yellow and finally to red when adjusting the dopant concentration of Ce3+ in the core. By selecting Ce3+ as the sensitizer for harvesting the energy of incident ultraviolet (UV) light and introducing Gd3+ as the ideal intermediate for subsequent energy migration, the down-converting emission colors of the as-obtained samples are also regulated from green to red via a Gd3+-assisted interface energy transfer processes (Ce3+ → Gd3+ → Tb3+, Ce3+ → Gd3+ → Tb3+ → Eu3+). Consequently, dual-mode luminescence with multi-color outputs can be achieved in the pre-designed core-shell nanostructure under the excitation of a 980 nm near-infrared laser and 254 nm UV light. The designed nanoarchitecture with bright dual-mode emissions and tunable colors greatly improves the ability of modern anti-counterfeiting, demonstrating its promising applications in anti-fake and optical multiplexing.

Schottky junction effect enhanced plasmonic photocatalysis by TaON@Ni NP heterostructures.

We chemically deposited amorphous Ni(OH)2 layers over TaON particles with irregular surface morphology, and subsequently in situ reduced them to Ni (10-20 nm) nanoparticles, to construct a TaON@Ni photocatalyst. Such a hierarchical hybrid aims to combine the enhanced light absorption by the metal Ni plasmonic effect with accelerated charge separation by a Schottky barrier, and herein, achieves a higher photocatalytic activity in CO2 reduction than TaON.

Ta3N5 nanorods encapsulated into 3D hydrangea-like MoS2 for enhanced photocatalytic hydrogen evolution under visible light irradiation.

Tantalum nitride (Ta3N5) with an appealing band gap (∼2.1 eV) has emerged as a promising catalyst in the photocatalysis field. However, Ta3N5 application in the photocatalytic hydrogen evolution reaction (HER) is limited due to disadvantages such as unsatisfactory separation and transfer of photogenerated carriers. Here we utilize MoS2 as co-catalysts to promote the kinetics of photocatalytic H2 evolution over Ta3N5. The Ta3N5 nanorods were encapsulated into 3D hydrangea-like MoS2 for maximizing the contact areas between Ta3N5 and MoS2 and offering rich active sites. More importantly, spectroscopic analysis and theoretical calculations consistently reveal that the unique interfacial interaction, as well as the matching band alignment between Ta3N5 and MoS2, accelerates the photogenerated charge extraction from Ta3N5 to MoS2, reducing charge recombination losses in Ta3N5. Thus, the optimized Ta3N5/MoS2 hybrid exhibits a substantially enhanced hydrogen evolution rate (56.5 µmol h-1), over 22 times higher than that of pristine Ta3N5. This work may provide a general strategy to overcome the low photocatalytic activity of nitrides for hydrogen evolution.

Low-temperature pseudomorphic transformation of polyhedral MIL-88A to lithium ferrite (LiFe3O5) in aqueous LiOH medium toward high Li storage.

The ability to develop novel nanomaterials, and to precisely manufacture their functional structures at the nano- and microscales would benefit many emerging device applications. Herein, as a first example, we describe the exploration of feasibility for the morphological replacement of an iron-based MOF bearing trimeric FeIII-O clusters, MIL-88A preform, with a polyhedral architecture of around 0.4 × 1.2 µm by a lithium ferrite (LiFe3O5) phase via solid-liquid pseudomorphic transformation reactions in biologically and environmentally favourable aqueous lithium hydroxide (LiOH). The reaction proceeds at 170 °C, and the overall reaction can be described as Fe3O(H2O)2(FMA)3(OH)·nH2O (MIL-88A) + 7OH- + Li+ → LiFe3O5 + 3FMA2- + (n + 6) H2O (FMA = fumarate). It was proposed that through the coordination substitution of a MOF ligand by OH-, follow-up dehydration and dehydroxylation, and final H+/Li+ ionic exchange, the monolithiated iron oxides formed thermodynamically at comparatively low temperatures, which transcribe the global nanostructure morphologies of the polyhedral MOF preforms with the hexagonal symmetry, but were composed of interconnected LiFe3O5 particles (about 16 nm) that crystallize in a typical magnetite-type cubic (Fd3[combining macron]m) structure. Given the characteristic texture and structure of the Li-Fe oxide replica, cubic LiFe3O5 was preferentially employed as a new type of electrode material in rechargeable lithium cells. Notably, from the electrochemical evaluation, this metal oxide system exhibits decent anodic performances by undergoing a nine-electron conversion reaction, showing a substantially high specific capacity with an average potential of 0.8 V versus lithium metal, a long service life (700 cycles), and exceptional high-rate capability (up to 2.0 A g-1). The synthetic paradigms demonstrated that the MIL-88A to LiFe3O5 conversion may be transferable to other advanced inorganic-based electrodes from the parent metal compound such as LiFeO2, LiMn2O4 or LiCoO2 toward sustainable energy fields.

Tailoring frequency-insensitive large field-induced strain and energy storage properties in (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3-modified (Bi0.5Na0.5)TiO3 lead-free ceramics.

Lead-free (Bi0.5Na0.5)TiO3-based relaxor ferroelectrics are attracting growing research interest due to their very large field-induced strain response and excellent energy storage performance. While extensive explorations have been made of these performances separately, being able to optimize both field-induced strain and energy storage performance of polycrystalline materials together, and hence achieve a synergistic result, would also be highly desirable for their practical applications. Herein, lead-free relaxor-ferroelectric (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3-modified (Bi0.5Na0.5)TiO3 (BNT-BCZT) ceramics were designed and demonstrated to be feasible candidates for both actuator and pulsed power capacitors. Optimal field-induced strain performances were realized in 0.92BNT-0.08BCZT ceramics with not only a high strain of 0.46% but also an impressive frequency stability (0.5 Hz-100 Hz), superior to those of other reported BNT-based materials under a similar frequency range. Moreover, the 0.5BNT-0.5BCZT compositions in the complete ER region delivered a relatively high Wrec of 0.95 J cm-3 and η of 69%, while still remaining insensitive to changes in temperature, frequency, and cycle number. More importantly, a short discharge time (of ∼0.41 µs) was also measured for this composition. Introducing BCZT into the composition was found to promote a non-ergodic-to-ergodic relaxor (NR-ER) phase transition and the formation of dynamic polar nanoregions (PNRs), generating the high strain responses and superior energy storage performances of the given compositions. These features may offer a new strategy to simultaneously tailor lead-free relaxor ferroelectrics toward high field-induced strain and superior energy storage performance for ceramics actuators and capacitor applications.

In-situ synthesis of Ni-Co-S nanoparticles embedded in novel carbon bowknots and flowers with pseudocapacitance-boosted lithium ion storage.

We design a facile approach to prepare a bimetallic transition-metal-sulphide-based 3D hierarchically-ordered porous electrode based on bimetallic metal-organic frameworks (Ni-Co-MOFs) by using confinement growth and in-situ sulphurisation techniques. In the novel resulting architectures, Ni-Co-S nanoparticles are confined in bowknot-like and flower-like carbon networks and are mechanically isolated but electronically well-connected, where the carbon networks with a honeycomb-like feature facilitate electron transfer with uninterrupted conductive channels from all sides. Moreover, these hierarchically-ordered porous structures together with internal voids can accommodate the volume expansion of the embedded Ni-Co-S nanoparticles. The pseudocapacitive behaviours displayed in the NCS@CBs and NCS@CFs occupied a significant portion in the redox processes. Because of these merits, both the as-built bowknot and flower networks show excellent electrochemical properties for lithium storage with superior rate capability and robust cycling stability (994 mAh g-1 for NCS@CBs and 888 mAh g-1 for NCS@CFs after 200 cycles). This unique 3D hierarchically-ordered structural design is believed to hold great potential applications in propagable preparation of carbon networks teamed up with sulphide nanocrystals for high energy storage.

Electrical switching properties and structural characteristics of GeSe-GeTe films.

Germanium chalcogenides, especially GeSe and GeTe alloys, have recently gained popularity because of their Ovonic threshold (volatile) and memory (non-volatile) switching properties, with great potential for electric storage applications. Materials designed in a pseudo-binary way may possess superior properties in their phase transition, e.g. GeTe-Sb2Te3 materials, and bring about revolutionary advances in optical storage. However, to date, the electrical switching behaviors of films of pseudo-binary GeSe-GeTe have not yet been studied, and neither have the structural characteristics. Herein, we present both the thermally and electrically induced switching behaviors of GeSe-GeTe film, as well as the structural evolution due to composition tuning. The crystallization temperature of GeSe-GeTe films increases with GeSe content quite sensitively. An atom-resolved picture of the GeSe-GeTe alloy with a state-of-the-art atomic mapping technology has been presented, where a randomly mixed arrangement of Se and Te atoms is determined unambiguously in Ge50Se13Te34 with a GeTe-like rhombohedral structure. The local structural motifs in GeSe-GeTe, more specifically, sixfold coordinated octahedra with a distinguished degree of Peierls distortion and geometric variety, are essential to understand its electric properties. GeSe-GeTe alloy, Ge50Se13Te34, based memory cells have been fabricated, showing a fast memory switching behavior and excellent retention of 10 years at 208 °C.

In situ synthesis of carbon doped porous silicon nanocomposites as high-performance anodes for lithium-ion batteries.

We demonstrate the in situ synthesis of carbon doped porous silicon (Si/C) nanocomposites by a simple thermal displacement process between Mg2Si and inorganic gas CO2 in one-step. Via the decomposition of Mg2Si, the reduction process occurred between Mg and CO2, leading the uniform doping of many distributed tiny carbon nanoparticles into Si. Meanwhile, the porous structure was formed after an acid treatment. When worked as anodes for lithium-ion batteries, the as-prepared s-porous Si/C nanocomposites exhibited good cycling stability and high-rate capability, which were superior to the porous Si and porous Si/C nanocomposites. It was revealed that the enhanced electrochemical properties could be ascribed to the novel porous structure and doped carbon nanoparticles that can buffer the volume expansion, as well as enhance the electronic conductivity of Si. The reaction mechanism was well investigated by studying the influence of reaction temperature and raw Mg2Si particle size on the morphology and component of the porous Si/C nanocomposites.

Tunable Optical Properties and Enhanced Thermal Quenching of Non-Rare-Earth Double-Perovskite (Ba1- xSr x)2YSbO6:Mn4+ Red Phosphors Based on Composition Modulation.

Non-rare-earth Mn4+-doped double-perovskite (Ba1- xSr x)2YSbO6:Mn4+ red-emitting phosphors with adjustable photoluminescence are fabricated via traditional high-temperature sintering reaction. The structural evolution, variation of Mn4+ local environment, luminescent properties, and thermal quenching are studied systematically. With elevation of Sr2+ substituting content, the major diffraction peak moves up to a higher angle gradually. Impressively, with increasing the substitution of Ba2+ with Sr2+ cation from 0 to 100%, the emission band shifts to short-wavelength in a systematic way resulting from the higher transition energy from excited states to ground states. Besides, this blue-shift appearance can be illuminated adequately using the crystal field strength. The thermal quenching of the obtained solid solution is dramatically affected by the composition, with the PL intensity increasing 16% at 423 K going from x = 0 to 1.0. The w-LEDs component constructed by coupling the UV-LED chip with red/green/blue phosphors demonstrate an excellent correlated color temperature (CCT) of 3404 K, as well as color rendering index (CRI) of 86.8.

Enhanced luminescence of a Ba2GdSbO6:Mn4+ red phosphor via cation doping for warm white light-emitting diodes.

With admirable luminescence performance and a cheap price, non-rare-earth-based oxide red phosphors are a potential competitor of rare-earth-doped phosphors for warm white LEDs (WLEDs). Herein, a novel double-perovskite Ba2GdSbO6:Mn4+ phosphor, demonstrating strong red emission ascribed to a spin-forbidden Mn4+:2Eg → 4A2g transition in the region of 620-750 nm, has been synthesized via a solid-state reaction route. The microstructure and luminescence properties are investigated in detail. The concentration quenching mechanism and thermal stability based on thermal quenching characteristics are also discussed. Importantly, Li+, Mg2+, Zn2+, Si4+, Ti4+ and Ge4+ dopants are discovered to be beneficial for enhancing Mn4+ luminescence, and the related mechanisms are comprehensively described. In addition, by combining red-emitting Ba2GdSb0.994O6:0.003Mn4+,0.003Mg2+ with the commercial blue-emitting BaMgAl10O17:Eu2+ and green-emitting Ba3La6(SiO4)6:Eu2+ phosphors in various ratios, a series of WLED devices with a tunable correlated color temperature (CCT) evolving from 6256 to 3486 K and a color rendering index (CRI) increasing from 72.1 to 88.3 are achieved.

Efficient rare-earth free red-emitting Ca2YSbO6:Mn4+,M(M = Li+, Na+, K+, Mg2+) phosphors for white light-emitting diodes.

Owing to its low-cost and satisfactory luminescent-emission performance in warm white light-emitting diodes (w-LEDs), the non-rare-earth Mn4+-activated red phosphor has become a promising competitor of commercial rare-earth doped phosphor. In this study, a series of novel red-light emitting phosphors based on Ca2YSbO6:Mn4+ have been developed successfully by a conventional solid-state reaction. The structural and luminescent properties of these phosphors are systematically investigated. The as-prepared Ca2YSbO6:Mn4+ product exhibits a broad excitation band ranging from 250 to 600 nm and an abnormal intense deep-red emission centered at 680 nm with a full width at half maximum (FWHM) of ∼46 nm. The optimal Mn4+ doping concentration is about 0.3 mol%, and the concentration quenching mechanism is determined to be a dipole-dipole interaction. Impressively, the Ca2YSbO6:0.003Mn4+ phosphor shows an outstanding quantum efficiency of 62.6% and an excellent thermal stability. In addition, the effect of Li+, Mg2+, Na+ and K+ dopants on the luminescent properties of Mn4+-doped Ca2YSbO6 phosphors is elucidated. Furthermore, by employing the as-prepared Ca2YSbO6:Mn4+ as a red component, a warm w-LED with high color rendering index (Ra = 87.5) and low correlated color temperature (CCT = 3255 K) can be acquired. It is believed that the present phosphor has a potential application as a supplement of the red component for warm w-LEDs.

Synchrotron radiation in situ X-ray absorption fine structure and in situ X-ray diffraction analysis of a high-performance cobalt catalyst towards the oxygen reduction reaction.

Transition metal-based composites are one of the most important electrocatalysts because of their rich redox chemistry. The reaction kinetics of a redox couple is dependent on the chemical valence and is a key issue in electrocatalytic performance. In this study, a metallic Co catalyst was synthesized by pyrolyzing Co(OH)2. The effect of the chemical valence of Co on the oxygen reduction reaction (ORR) was investigated by comparing the electrocatalytic properties of three Co-based catalysts containing Co0, Co2+, and Co3+. The electrocatalytic properties were evaluated mainly by linear scan voltammetry (LSV) and a direct borohydride fuel cell (DBFC) where the Co-based catalysts were used as cathodes. The LSV results show that the ORR peak current density increases with a decrease in chemical valence. The DBFC with the Co0 cathode exhibits highest power density and good durability. In situ X-ray diffraction combined with in situ X-ray absorption fine structure tests was carried out to reveal the dynamic microstructure evolution of the Co0 cathode during ORR. The in situ results clearly demonstrate the evolution of metallic Co to Co(OH)2 and then to CoOOH during the ORR.

Lead-free BNT-based composite materials: enhanced depolarization temperature and electromechanical behavior.

The development of (Bi0.5Na0.5)TiO3-based solid solutions with both high depolarization temperature Td and excellent piezoelectric and electromechanical properties for practical application is intractable because improved thermal stability is usually accompanied by a deterioration in piezoelectric and electromechanical performance. Herein, we report a 0-3 type 0.93(Bi0.5Na0.5)TiO3-0.07BaTiO3 : 30 mol%ZnO composite (BNT-7BT : 0.3ZnO), in which the ZnO nanoparticles exist in two forms, to resolve the abovementioned long-standing obstacle. In this composite, Zn ions fill the boundaries of BNT-7BT grains, and residual Zn ions diffuse into the BNT-7BT lattice, as confirmed by XRD, Raman spectroscopy, and microstructure analysis. The BNT-7BT composite ceramics with a 0-3 type connectivity exhibited enhanced frequency-dependent electromechanical properties, fatigue characteristics, and thermal stabilities. More importantly, low poling field-driven large piezoelectric properties were observed for the composite ceramics as compared to the case of the pure BNT-7BT solid solution. A mechanism related to the ZnO-driven phase transition from the rhombohedral to tetragonal phase and built-in electric field to partially compensate the depolarization field was proposed to explain the achieved outstanding piezoelectric performance. This is the first time that the thermal stability, electromechanical behavior, and low poling field-driven high piezoelectric performance of BNT-based ceramics have been simultaneously optimized. Thus, our study provides a referential methodology to achieve novel piezoceramics with excellent piezoelectricity by composite engineering and opens up a new development window for the utilization of conventional BNT-based and other lead-free ceramics in practical applications.

Control of bulk homochirality and proton conductivity in isostructural chiral metal-organic frameworks.

We have demonstrated for the first time that isostructural homochiral metal-organic frameworks (MOFs) can be synthesized directly from chiral ligands and indirectly from achiral ligands via spontaneous resolution combined with cooperative chirality induction, respectively. Moreover, the usage of different ligands leads to distinct proton conduction behaviors.

Reconstruction of TiO2/MnO2-C nanotube/nanoflake core/shell arrays as high-performance supercapacitor electrodes.

Construction of electrodes with fast reaction kinetics is of great importance for achieving advanced supercapacitors. Herein we report a facile combined synthetic strategy with atomic layer deposition (ALD) and electrodeposition to rationally fabricate nanotube/nanoflake core/shell arrays. ALD-TiO2 nanotubes are used as the skeleton core for assembly of electrodeposited MnO2-C nanoflake shells forming a core/shell structure. Highly porous architecture and good electrical conductivity are combined in this unique core/shell structure, resulting in fast ion/electron transfer. In tests of electrochemical performance, the TiO2/MnO2-C core/shell arrays are characterized as cathode for asymmetric supecapacitors and exhibit high specific capacitance (880 F g-1 at 2.5 A g-1), excellent rate properties (735 F g-1 at 30 A g-1) and good long-term cycling stability (94.3% capacitance retention after 20 000 cycles). The proposed electrode construction strategy is favorable for fabrication of other advanced supercapacitor electrodes.

Composition- and temperature-driven phase transition characteristics and associated electromechanical properties in Bi0.5Na0.5TiO3-based lead-free ceramics.

In this study, a lead-free ceramic system comprising (0.94 - x)Bi0.5Na0.5TiO3-0.06BaTiO3-xBi(Zn0.5Ti0.5)O3 (BNT-BT-BZT) was designed and prepared by a conventional solid-state reaction method. The effect of the addition of BZT on the phase transition characteristics and associated electromechanical properties of BNT-BT was systematically discussed and a schematic phase diagram was established. The addition of BZT had a strong impact on the phase transition as well as the strain and piezoelectric activity. The phase coexistence, which involves ferroelectric rhombohedral-relaxor pseudocubic phases, can be driven by modification with BZT and increases in temperature and can be confirmed by XRD measurements, analysis of Raman spectra and temperature-dependent changes in polarization and strain hysteresis loops. Accompanied by a shift in the ferroelectric-to-relaxor temperature TF-R to below room temperature on the addition of BZT, a compositionally induced ferroelectric-to-relaxor phase transition occurred, which gave rise to a large strain of 0.33% with a normalized strain Smax/Emax of 550 pm V(-1) at the critical BZT content x of 0.0275. The results were closely correlated with the composition and dependence on temperature of the phase transition, which significantly influenced the electromechanical properties, and the origin of the large strain observed in the present system was also addressed in detail. As a result, the design principles provided in this study open the possibility of obtaining BNT-based lead-free ceramics with enhanced electromechanical properties for actuator applications.

New Eu(3+)-activated perovskite La(0.5)Na(0.5)TiO3 phosphors in glass for warm white light emitting diodes.

With an increasing demand for high-power warm white light emitting diodes (w-LEDs), the discovery of efficient red-emitting inorganic color converters is in great demand. Herein, a novel perovskite La0.5Na0.5TiO3:Eu(3+) red-emitting phosphor with excellent thermal stability and high quantum efficiency has been successfully synthesized by a traditional solid-state reaction. Then, the developed La0.5Na0.5TiO3:Eu(3+) red phosphor and commercial YAG:Ce(3+) yellow phosphor were incorporated into an innovatively designed low-melting glass. Impressively, the destruction of La0.5Na0.5TiO3:Eu(3+) and YAG:Ce(3+) phosphor particles during glass melting was quite low. Remarkably, the fabricated w-LEDs using an InGaN-based blue chip combined with Phosphor in Glass (PiG) plates exhibited an improved chromaticity feature and superior optical performance. Through simply adjusting the content of red phosphors in the PiG, the correlated color temperature of the PiG-based w-LEDs evolved from cool white (6771 K) to warm white (4417 K) and the color rendering index increased from 73.4 to 86.4. Moreover, the PiG-based warm w-LEDs presented superior thermal stability.

Tuning the Upconversion Luminescence Lifetimes of KYb2 F7 :Ho(3+) Nanocrystals for Optical Multiplexing.

Conventional luminescent color coding is limited by spectral overlap and the interference of background fluorescence, thus restricting the number of distinguishable identities that can be used in practice. Here, we demonstrate the possibility of generating diverse time-domain codes, specially designed for a single emission band, using lanthanide-doped upconversion nanocrystals. Based on the knowledge of concentration quenching, the upconversion luminescence kinetics of KYb2 F7 : Ho(3+) nanocrystals can be precisely controlled by modifying the dopant concentration of Ho(3+) ions, resulting in a tunable emission lifetime from 75.8 to 1944.5 µs, which suggests the practicality of these time-domain codes for optical multiplexing.

Nd(3+)-Sensitized Ho(3+) Single-Band Red Upconversion Luminescence in Core-Shell Nanoarchitecture.

A strategy to achieve 808 nm excited single-band red upconversion luminescence of Ho(3+) via the core-shell nanoarchitecture design was provided. Specifically, the synthesized Yb/Ho/Ce: NaGdF4@Yb/Nd: NaYF4 active-core@active-shell nanoparticles were evidenced to enable high-content doping of Nd(3+) (∼10 mol %) in the shell layer and, thus, markedly enhance red upconversion emission from Ho(3+) activators in the core with the assistance of spatially confined doping of Nd(3+) ions and efficient energy transfer of Nd(3+) → Yb(3+)(shell) → Yb(3+)(core) → Ho(3+). Importantly, introducing Ce(3+) into the core was beneficial to the competition of radiation transitions from the two intermediate excited states of Ho(3+): (5)S2,(5)F4 (green-emitting) and Ho(3+): (5)F5 (red-emitting), which induced great enhancement in the red to green intensity ratio and ultimately intense single-band red upconversion emission. We believe that this preliminary study will provide an important advance in developing luminescent markers suitable for biolabeling applications.