Phase diagrams of the SrF2(Y, Ln)F3 systems part I.—X-ray characteristics of phases

First fluoride ceramics lasing at 605 nm at ambient temperature fabricated from chemically synthesized powders

Laser ceramics have emerged as promising candidates of solid-state laser gain media. However, most laser ceramics are currently focused on lasing in the infrared wavelength range. The very limited options of host materials and the increased optical scattering losses at shorter wavelengths within ceramics have greatly limited the development of visible laser ceramics. Here we report visible laser ceramics with a composition of 0.5%Pr3+,5%Y3+:SrF2, in which a visible (orange) laser oscillation at 605 nm has been successfully achieved at room temperature pumped by InGaN blue laser diodes with a maximum slope efficiency of 8.1%. The ceramics were fabricated by vacuum hot pressing (VHP) of wet-chemistry synthesized 0.5%Pr3+,5%Y3+:SrF2 powders, followed by hot isostatic pressing (HIP). It was found that the visible laser ceramics exhibited a lower optical scattering loss along the processing pressure direction of the VHP process, indicating a uniaxial anisotropy in optical transmission within the ceramics. To our best knowledge, the current work is the first report on visible laser ceramics lasing in the orange region at ambient temperature, fabricated from chemically synthesized powders, which could pave the way for future scientific research on and industrial applications of more sophisticated and cost-effective visible laser ceramics.

Nano metal fluorides: small particles with great properties

The recently developed fluorolytic sol–gel route to metal fluorides opens a very broad range of both scientific and technical applications of the accessible high surface area metal fluorides, many of which have already been applied or tested. Specific chemical properties such as high Lewis acidity and physical properties such as high surface area, mesoporosity and nanosize as well as the possibility to apply metal fluorides on surfaces via a non-aqueous sol make the fluorolytic synthesis route a very versatile one. The scope of its scientific and technical use and the state of the art are presented.

Sol–gel synthesis of Sr1−xYbxF2+x nanoparticles dispersible in acrylates

A new approach to prepare nanoparticles in SrF₂-YbF₃ systems via the fluorolytic sol–gel synthesis is presented.

The key role of the composition and structural features in fluoride ion conductivity in tysonite Ce1−xSrxF3−x solid solutions

Evolution with x of RT ionic conductivity of RE_1−xAE_xF_3−x showing that Ce_1−xSr_xF_3−x is the best F⁻ tysonite conductor is discussed.

Impurity doping: a novel strategy for controllable synthesis of functional lanthanide nanomaterials

Many technological nanomaterials are intentionally 'doped' by introducing appropriate amounts of foreign elements into hosts to impart electronic, magnetic and optical properties. In fact, impurity doping was recently found to have significant influence on nucleation and growth of many functional nanocrystals (NCs), and provide a fundamental approach to modify the crystallographic phase, size, morphology, and electronic configuration of nanomaterials. In this feature article, we provide an overview of the most recent progresses in doping-induced control of phase structures, sizes, shapes, as well as performances of functional nanomaterials for the first time. Two kinds of impurity doping strategies, including the homo-valence ion doping and hetero-valence ion doping, are discussed in detail. We lay emphases on impurity doping induced modifications of microstructures and optical properties of upconversion (UC) lanthanide (Ln(3+)) NCs, but do not limit to them. In addition, we also illustrate the control of Ln(3+) activator distribution in the core@shell architecture, which has recently provided scientists with new opportunities for designing and tuning the multi-color emissions of Ln(3+)-doped UC NCs. Finally, the challenges and future perspectives of this novel impurity doping strategy are pointed out.

Abnormal size-dependent upconversion emissions and multi-color tuning in Er3+-doped CaF2-YbF3 disordered solid-solution nanocrystals

A series of Er(3+)-doped (1 - x)CaF(2)-xYbF(3) (0 ≤ x ≤ 0.6) disordered solid-solution nanocrystals with various mean sizes were successfully prepared by a facile solvothermal route. Interestingly, abnormal size-dependent upconversion emissions were demonstrated in these nanocrystals for the first time. With increasing grain size, an obvious enhancement of red to green emission ratio was observed in the Er(3+) (2 mol%): 0.4CaF(2)-0.6YbF(3) nanocrystals, which is the opposite of the routine size-dependent upconversion emission behavior reported previously. Taking Eu(3+) ions as a structural probe, we investigated the influence of a disordered solid-solution structure on Ln(3+) luminescence, and proposed that Ln(3+) clusters formed in the host should play a key role to induce this unusual size-dependent upconversion emission phenomenon. As a consequence, multi-colors such as green, yellow, and red upconversion emissions can be easily realized by appropriately modifying the Yb(3+) content in the Er(3+)-doped (1 - x)CaF(2)-xYbF(3) nanocrystals. The reported results will deepen the understanding of size effects on the lanthanide upconversion in nanocrystals.

Modifying the size and shape of monodisperse bifunctional alkaline-earth fluoride nanocrystals through lanthanide doping

In this communication, a simple route for modifying the uneven size and shape of alkaline-earth fluoride nanophases to monodisperse ultrasmall nanospheres through lanthanide doping is offered. These nanospheres are found to exhibit bifunctionality, i.e., tunable upconversion emissions as well as proper paramagnetism, making them potentially applicable in the biological field. The synthesis strategy, which involves doping of an impurity with a different valence than the cation in the nanophase, might be useful for controlling the solution growth of some technologically important nanomaterials.