Journal of Non-Crystalline Solids: X最新文献

We present comparison of spin-coated thin films prepared in traditional way from solution of dissolved bulk glass of particular ternary composition with films prepared from mixture of two separately dissolved binary bulk glasses targeting the same composition. The samples of five tie-line As-S-Se compositions ranging from As₃₃S₆₇ to As₃₃Se₆₇ were deposited in specular optical quality and thermal dependences of their optical properties, thickness, surface roughness, organic residual content, structure, and chemical resistance were studied. The deposited thin films were also structured by hot embossing at various temperatures to study the influence of source solution preparation on structuring process. Thin films prepared from solution mixtures show close physico-chemical properties to thin films prepared from solutions of corresponding bulk glasses.

The optimization of the oxide and fluoride content, crystallinity and rare earth ion concentration in oxyfluoride glass ceramics (GCs) are of great importance in obtaining high photoluminescence quantum yield (PLQY) for optical refrigeration applications. Presented herein are the important advancements in the development of a novel oxyfluoride GCS of the composition (SiO₂-Al₂O₃)_(100-a) (YLiF₄)_b: (YbF₃)_b (a = 35 and 40; in mol %, b = 1 and 2 mol%) with the corresponding parent glasses with an in-depth investigation on enhancing the optical performance for laser cooling. Depending on the oxide/fluoride (O/F) ratio and ytterbium content the internal quantum yield (iQY) varied between 70 and 99% in glass ceramics at several excitation wavelengths. The optical properties of GCs containing YLiF₄ and YF₃ nanocrystals obtained from the same initial composition (modulated by time and fusion temperature) were compared to find the optimal composition for optical refrigeration. Low fluorine content led to the generation of YLiF₄ as a major phase after ceramization and high fluorine content helped in the generation of the YF₃ phase. An increase in the radiative lifetime of YF₃ GCs compared to YLiF₄ GCs has been found to coincide with the enhancement of the PLQY, which is beneficial for laser cooling. The temperature change (ΔT) change measured using a fiber Bragg grating (FBG) in the glass and glass-ceramic samples with different pump wavelengths showed significant heat mitigation near ∼1030 nm. The observed enhanced PL intensity, iQY and lifetime after purification of YLiF₄ glasses imply that the purity of the material plays a paramount role in lowering the background absorption and enhancing the quantum yield. Looking ahead, we see a bright future for oxyfluoride GCs in applications requiring the ultimate levels of thermal, mechanical and optical performance, especially for the development of cryocooler devices, which are still technologically challenging and expensive. The usage of GCs will open up new possibilities in optical cooling technology, enabling cooling devices of any size and shape.

Glass surfaces play a critical role in several modern applications, and open questions remain as to how the bulk composition of a multicomponent glass informs its surface composition—particularly at the outermost monolayer. This has important implications for properties such as electrostatic charging, wetting, and adhesion. Here, we apply high-sensitivity low-energy ion scattering (HS-LEIS) to examine a systematic series of ternary CaO-Al₂O₃-SiO₂ glass compositions. Analyzed are fresh fracture surfaces created under high-vacuum conditions, giving rigorous attention to peak quantification details. Results indicate that the measured surface compositions are, within uncertainty, very close to analyzed bulk compositions. This finding runs contrary to many studies showing disagreement between surface and bulk composition in glass, and possible reasons are discussed. By providing an experimental foundation from relatively ideal fracture surfaces, these results pave the way for further studies on the outermost composition of realistic glass surfaces of commercial importance.

It has been a long-sought goal to explore the nature of amorphous formation. Investigate the role of interatomic potential can be a fascinating method to study this myth from bottom up. In this work, molecular dynamics is used to systematically study the glass forming processes of binary CuZr melts on both structural and dynamical evolutions. The strong repulsion between CuCu and the weak repulsion between ZrZr is found to determine the structural arrangement, and then affect the type, number and spatial correlation of clusters. The difference of melt dynamics is controlled by both the steep repulsion and the anharmonic attraction of potential. The increase of the anharmonic attraction in melts can also lead to a higher shear transformation zone density in the glass. Our findings provide deeper insights into the understanding of glass-forming processes and its connection to glassy performance controlled by interatomic potential.

This review is dedicated to recent advances in the study of bismuth-doped silica-based fibers, which are vital components for creating promising contemporary optical devices operating in the near IR region. The first part of the review summarizes features inherent to different types of bismuth active centers, such as photo- and thermally induced destruction and recovery, which are particularly of great interest with respect to the nature of luminescence in bismuth-doped fibers (BDFs). In addition, the review specifies the status and possible ways on how to improve the main characteristics of BDFs, moreover, the paper proposes the latest results regarding novel designs of BDFs and demonstrates recent progress in fiber lasers and amplifiers based on them, including bismuth lasers with record performance parameters, as well as compact and efficient broadband amplifiers. In conclusion, a short summary alongside with road-to-market perspectives of the developed active fibers are given.

PbS quantum dots (QDs) are appropriate for use in tunable optoelectronic devices such as optical amplifiers because of their large Bohr exciton radii (18 nm). Laser-assisted local heating around Ag NPs can provide an effective method for site selective precipitation and for controlling the size of QDs. Continuous wave (CW) laser irradiation has been applied on a Ag⁺-ion exchanged glass which lead to the precipitation of QDs PbS QDs of 5-nm diameter were precipitated after 3 min of CW laser illumination at 1.5 W. The PbS QDs showed a PL peak at λ ∼ 1490 nm, which shifted toward longer wavelength side as duration of Ag⁺ ion exchange and of laser illumination increased. This method was further applied to prepare a rod containing three sections with different diameters of PbS QDs to propose the possibility of developing broadband amplifiers to cover the 1.3–1.7 μm communication window using one glass fiber. Co²⁺ also absorbs 532 nm laser light and converts it to thermal energy that results in the precipitation of PbS QDs in the glass matrix. The emission peak of the QDs covers 1020 nm < λ < 1245 nm as laser power was increased from 6 to 7 W/cm². Temperature in the glass increased to ∼518 °C when it was illuminated at the intensity of 6 W/cm².