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In this paper, the effects of crystallization advance on the material structure and electrical properties of lithium-ion Na+super ionic conductor (NASICON) glass ceramics were investigated. Glasses with Li1.5Al0.5Ge1.5(PO4)3and Li1.5Sc0.17Al0.33Ge1.5(PO4)3compositions were crystallized in controlled conditions to obtain gradual increment of the volume crystallized fraction. The glass-to-crystal transformation was then monitored by differential scanning calorimetry analysis (DSC), X-ray diffractometry (XRD), Raman spectroscopy, solid-state nuclear magnetic resonance spectroscopy (MAS NMR), and electron microscopy, along with chemical analyses. Finally, the electrical properties of the specimens were evaluated by impedance spectroscopy to observe the changes in electrical properties according to the crystallization advance. Results revealed that glasses containing scandium are more stable against crystallization than their neat counterparts. Crystallization led to the formation of single-phase NASICON glass ceramics. Scandium induced a lattice expansion of the NASICON structure. Furthermore, crystallization induces remarkable structural changes in the materials as a whole, either in local order or in medium to long order. No important increase in conductivity was observed in earlier stages of crystallization. After the percolation of crystals, conductivity increases sharply and the remaining glassy phase has little impact on the total conductivity of the material. Scandium expands the rhombohedral structure but increases the glass stability and reduces the sizes of crystals for the fully crystallized glass ceramics. Glass ceramics with larger grains are more propitious for conductivity than the more refined ones. Therefore, this paper offers key information about the understanding of NASICON crystallization and its structural evolution, providing important insights into the crystallization of these electrolytes.

In this work we explored the fabrication of flexible and transparent hybrids of silk fibroin (SF) and epoxy-modified siloxane for photonic applications. It is well-known that regenerated SF solutions can form free-standing films with high transparency. Although SF has a restricted number of chemically reactive side groups, the main issues of as-cast pristine SF films regard the high solubility into aqueous media, brittleness, and low thermal stability. The design of SF films with enhanced functionality but high transparency triggers new opportunities on a broader range of applications in biophotonics. Here we present a simple, functional, yet remarkably versatile hybrid material derived from silica sol–gel process based on SF protein and (3-glycidyloxypropyl)trimethoxysilane (GPTMS), an organically modified silicon-alkoxide owning a reactive terminal epoxy group. Specifically, we investigated the effect of the addition of GPTMS into SF solutions on the processability, morphology, crystallinity, and mechanical and optical properties of the resulting hybrid films. Highly transparent (ca. 90%) and flexible free-standing hybrid films were achieved. Cell viability assays revealed that the hybrid films are noncytotoxic to rat osteoblast cells even at high GPTMS content (up to 70 wt %). The hybrid films showed enhanced thermal stability and were rich in organic (epoxy) and inorganic (silanol) functional groups according to the content of GPTMS. We also evaluated the successful preparation of high-quality optical red emissive SF hybrid films by loading YVO4:Eu3+nanoparticles at low concentration (<5 wt %). A meaningful description of the hybrid film structure is reported from the combination of scanning electron and atomic force microscopies, vibrational spectroscopy, solid-state NMR, and X-ray diffraction analyses.

Glass samples of composition 40AgI–(60–x)AgPO3–xAg2WO4(0 ≤ x≤ 25 mol %) have been prepared by the conventional melt-quenching method. These glasses receive renewed interest due to their ionic conductivity and transparency in the visible range. Because the physical and optical properties of these glasses are highly dependent on composition in this system, a comprehensive structural study has been carried out using Raman spectroscopy and 1D and 2D NMR of the 31P and 109Ag nuclei. With increasing Ag2WO4content, the network is modified from a 1D Q(2)-like chain structure to a topology in which Q(1)and Q(0)species linked to octahedrally coordinated tungsten species dominate. This structural transformation increases the glass rigidity and stability against hydrolysis reactions. The compositional evolution of the phosphate speciation (in terms of Q(n)mWunits) is consistent with maximum tungstate dispersion in glasses with x≤ 10, while for glasses with higher tungstate content the data are more consistent with a random distribution of P–O–P, P–O–W, and W–O–W linkages. The 109Ag NMR chemical shifts are independent of composition and suggest that mobile silver ions are situated within cluster regions, furnishing a constant mixed iodide/oxide local environment.