Single-crystalline and near-monodispersed NaMF3 (M = Mn, Co, Ni, Mg) and LiMAlF6 (M = Ca, Sr) nanocrystals from cothermolysis of multiple trifluoroacetates in solution

Precisely synthesized LiF-tipped CoF2-nanorod heterostructures improve energy storage capacities

CoF2, with a relatively high theoretical capacity (553 mA h g-1), has been attracting increasing attention in the energy storage field. However, a facile and controllable synthesis of monodispersed CoF2 and CoF2-based nano-heterostructures have been rarely reported. In this direction, an eco-friendly and precisely controlled colloidal synthesis strategy to grow uniformly sized CoF2 nanorods and LiF-tipped CoF2-nanorod heterostructures based on a seeded-growth method is established. The unveiled selective growth of LiF nanoparticles onto the two end tips of the CoF2 nanorods is associated with the higher energy of tips, which favors the nucleation of LiF nanocrystals. Notably, it was found that LiF could protect CoF2 from corrosion even after 9 months of aging. In addition, the as-obtained heterostructures were employed in supercapacitors and lithium sulfur batteries as cathode materials. The heterostructures consistently exhibited higher specific capacities than the corresponding two single components in both types of energy storage devices, making it a potential electrode material for energy storage applications.

Microwave-assisted synthesis of NaMnF3 particles with tuneable morphologies

Here, the synthesis of sub-micron MMnF₃ (M = Na or K) particles by a rapid microwave-assisted approach is reported. Adjustment of the Na⁺-to-Mn²⁺ ratio in the reaction mixture yielded tuneable morphologies, i.e., rods, ribbons, and plates. Relaxometric results indicated that poly(acrylic acid)-capped MMnF₃ particles exhibited characteristic magnetic properties, which endows them with potential T₁-weighted contrast agent capabilities.

Synthesis, characterization, and luminescence studies of rare-earth-activated NaMgF3

NaMgF₃ -based phosphors have been described frequently in the literature. Their synthesis faces difficulties typical of fluoride materials. A simple precipitation synthesis for NaMgF₃ -based phosphors is described in this paper. This consisted of mixing aq. NaF and MgCl₂ /MgSO₄ solutions. Various activators could be incorporated by adding the required salts during this process. Characteristic emission of the activators was observed in the prepared phosphors. As-prepared samples exhibited predominantly trivalent lanthanide emission. After thermal treatment in a reductive atmosphere, europium-doped samples showed the intense emission of Eu²⁺ . By virtue of the intense nature of the emission, lifetime measurements could be made for this sample. Notably, intense thermoluminescence and optically stimulated luminescence were observed in NaMgF₃ :Eu. A simple, fast method for the synthesis of NaMgF₃ was therefore developed.

Rare-earth-containing perovskite nanomaterials: design, synthesis, properties and applications

As star material, perovskites have been widely used in the fields of optics, photovoltaics, electronics, magnetics, catalysis, sensing, etc. However, some inherent shortcomings, such as low efficiency (power conversion efficiency, external quantum efficiency, etc.) and poor stability (against water, oxygen, ultraviolet light, etc.), limit their practical applications. Downsizing the materials into nanostructures and incorporating rare earth (RE) ions are effective means to improve their properties and broaden their applications. This review will systematically summarize the key points in the design, synthesis, property improvements and application expansion of RE-containing (including both RE-based and RE-doped) halide and oxide perovskite nanomaterials (PNMs). The critical factors of incorporating RE elements into different perovskite structures and the rational design of functional materials will be discussed in detail. The advantages and disadvantages of different synthesis methods for PNMs will be reviewed. This paper will also summarize some practical experiences in selecting suitable RE elements and designing multi-functional materials according to the mechanisms and principles of REs promoting the properties of perovskites. At the end of this review, we will provide an outlook on the opportunities and challenges of RE-containing PNMs in various fields.

Transition metal trifluoroacetates (M = Fe, Co, Mn) as precursors for uniform colloidal metal difluoride and phosphide nanoparticles

We report a simple one-pot synthesis of uniform transition metal difluoride MF₂ (M = Fe, Mn, Co) nanorods based on transition metal trifluoroacetates (TMTFAs) as single-source precursors. The synthesis of metal fluorides is based on the thermolysis of TMTFAs at 250–320 °C in trioctylphosphine/trioctylphosphine oxide solvent mixtures. The FeF₂ nanorods were converted into FeF₃ nanorods by reaction with gaseous fluorine. The TMTFA precursors are also found to be suitable for the synthesis of colloidal transition metal phosphides. Specifically, we report that the thermolysis of a cobalt trifluoroacetate complex in trioctylphosphine as both the solvent and the phosphorus source can yield 20 nm long cobalt phosphide nanorods or, 3 nm large cobalt phosphide nanoparticles. We also assess electrochemical lithiation/de-lithiation of the obtained FeF₂ and FeF₃ nanomaterials.

Synthesis and X-ray absorption spectroscopy of potassium transition metal fluoride nanocrystals

Nanocrystals of KMF₃ (M = Mn–Ni) and K₃MF₆ (M = V, Fe) were synthesized via non-aqueous routes based on colloidal chemistry.

Tuning the morphology, luminescence and magnetic properties of hexagonal-phase NaGdF4: Yb, Er nanocrystals via altering the addition sequence of the precursors

Hexagonal-phase NaGdF₄: Yb, Er upconversion nanocrystals (UCNCs) with tunable morphology and properties were successfully prepared via a thermal decomposition method. The influences of the adding sequence of the precursors on the morphology, chemical composition, luminescence and magnetic properties were investigated by transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectrometry (ICP-AES), upconversion (UC) spectroscopy, and a vibrating sample magnetometer (VSM). It was found that the resulting nanocrystals, with different sizes ranging from 24 to 224 nm, are in the shape of spheres,  hexagonal plates and flakes; moreover, the composition percentage of Yb³⁺-Er³⁺ and Gd³⁺ ions was found to vary in a regular pattern with the adding sequence. Furthermore, the intensity ratios of emission colors (f _g/r, f _g/p), and the magnetic mass susceptibility of hexagonal-phase NaGdF₄: Yb, Er nanocrystals change along with the composition of the nanocrystals. A positive correlation between the susceptibility and f _g/r of NaGdF₄: Yb, Er was proposed. The decomposition processes of the precursors were investigated by a thermogravimetric (TG) analyzer. The result indicated that the decomposition of the resolved lanthanide trifluoroacetate is greatly different from lanthanide trifluoroacetate powder. It is of tremendous help to recognize the decomposition process of the precursors and to understand the related reaction mechanism.

Colloidal BiF3 nanocrystals: a bottom-up approach to conversion-type Li-ion cathodes

A facile colloidal synthesis of BiF3 nanocrystals (NCs) via thermal decomposition of bismuth(III) trifluoroacetate in oleylamine is reported. The NC size can be tuned from 6 to 40 nm by the adjustment of synthesis parameters. After removal of the capping surfactant molecules, BiF3 NCs were tested as a cathode material for Li-ion batteries. Close to theoretical Li-ion storage capacities of up to 300 mA h g(-1) at an average voltage of 3 V were obtained at a current density of 50 mA g(-1).

Energy transfer in lanthanide upconversion studies for extended optical applications

In this review, the various energy transfer pathways involved in lanthanide-related upconversion emissions are comprehensively discussed.

Nanoparticles for Improving Cancer Diagnosis

Despite the progress in developing new therapeutic modalities, cancer remains one of the leading diseases causing human mortality. This is mainly attributed to the inability to diagnose tumors in their early stage. By the time the tumor is confirmed, the cancer may have already metastasized, thereby making therapies challenging or even impossible. It is therefore crucial to develop new or to improve existing diagnostic tools to enable diagnosis of cancer in its early or even pre-syndrome stage. The emergence of nanotechnology has provided such a possibility. Unique physical and physiochemical properties allow nanoparticles to be utilized as tags with excellent sensitivity. When coupled with the appropriate targeting molecules, nanoparticle-based probes can interact with a biological system and sense biological changes on the molecular level with unprecedented accuracy. In the past several years, much progress has been made in applying nanotechnology to clinical imaging and diagnostics, and interdisciplinary efforts have made an impact on clinical cancer management. This article aims to review the progress in this exciting area with emphases on the preparation and engineering techniques that have been developed to assemble "smart" nanoprobes.

Upconversion nanoparticles: synthesis, surface modification and biological applications

New generation fluorophores, also termed upconversion nanoparticles (UCNPs), have the ability to convert near infrared radiations with lower energy into visible radiations with higher energy via a nonlinear optical process. Recently, these UCNPs have evolved as alternative fluorescent labels to traditional fluorophores, showing great potential for imaging and biodetection assays in both in vitro and in vivo applications. UCNPs exhibit unique luminescent properties, including high penetration depth into tissues, low background signals, large Stokes shifts, sharp emission bands, and high resistance to photobleaching, making UCNPs an attractive alternative source for overcoming current limitations in traditional fluorescent probes. In this article, we discuss the recent progress in the synthesis and surface modification of rare-earth doped UCNPs with a specific focus on their biological applications.

FROM THE CLINICAL EDITOR

Upconversion nanoparticles - a new generation of fluorophores - convert near infrared radiations into visible radiations via a nonlinear optical process. These UCNPs have evolved as alternative fluorescent labels with great potential for imaging and biodetection assays in both in vitro and in vivo applications.

NIR-responsive silica-coated NaYbF(4):Er/Tm/Ho upconversion fluorescent nanoparticles with tunable emission colors and their applications in immunolabeling and fluorescent imaging of cancer cells

NaYbF(4): RE upconversion (UC) fluorescent nanoparticles (NPs) were synthesized with variable rare-earth dopants (RE= Er(3+), Tm(3+), or Ho(3+), or a combination of these ions), from rare-earth stearate precursors in a water-ethanol-oleic acid system by using a two-phase solvothermal method. The NPs were shown to emit visible light such as orange, yellow, green, cyan, blue or pink light in response to near infrared (NIR) irradiation, and their emission colors could be simply tuned by changing either the co-dopant concentration or dopant species. The UC NPs were well-dispersed and spherical with an average size of 15~35 nm. They emitted strong UC fluorescence under the 980 nm NIR excitation. The effects of solvothermal reaction time and temperature on nanoparticle size and phase structure as well as UC fluorescence intensity were systematically studied. Water dispersibility was achieved by forming a silica coat on the surface of the UC NPs. After animo-functionalization, the silica-coated UC NPs were chemically conjugated with the rabbit anti-CEA8 antibody and then used as fluorescent biolabels for the immunolabeling and imaging of HeLa cells. The NIR-responsive multicolor visible light emission of these UC NPs will enable potential applications in biolabeling and multiplexed analysis because NIR light can penetrate tissue as deep as several inches and is safe to human body.