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Porous graphene materials show outstanding performance in energy storage field due to their unique microstructure and properties. To construct 3D hierarchical porous graphene and combine with conductive polyaniline is an effective way to realize high energy density and good cycling stability. The interlamellar macroporous structure of 3D graphene was constructed by polystyrene (PS) microspheres and nickel foam as double templates. The mesoporous structure was etched in 3D macroporous graphene sheets by potassium hydroxide (KOH) chemical activation. And 3D hierarchical porous graphene (3D-hpGr) composited with polyaniline (PANI) by in situ chemical oxidative polymerization to obtain 3D-hpGr/PANI composites. The effect of the introduction of 3D-hpGr on microstructure, morphology and electrochemical performance of the composites was investigated. PANI nanowire arrays successfully decorate the surface of the 3D-hpGr sheets when the amount of 3D-hpGr reaches 40% (wt%). The specific capacitance of 3D-hpGr/PANI40 reaches 573 F g−1 at 0.5 A g−1, much higher than that of pure PANI (419 F g−1). The retention ratio of 3D-hpGr/PANI40 retains 84% of its initial specific capacitance after 1000 cycles at 1.0 A g−1, and the cycling stability of all composites is higher than that of pure PANI (69%). The potential drop of 3D-hpGr/PANI composites decreases from 0.339 V to 0.139 V, and the energy density increases consequently. The energy density of 3D-hpGr/PANI40 reaches 31.2 W h kg−1 at the power density of 0.709 kW kg−1.

As the rapid growth of supercapacitor industry, there are increasing demands for aqueous dispersible and environmentally friendly polymer binders to manufacture graphene electrodes with high capacitance, long lifetime, and great mechanical flexibility. Here, four different binders were selected to study the effect on structural and electrochemical performance of the reduced graphene oxide (rGO) thin film electrodes. The four binders include two fluorinated polymers, a conductive binder formulation, and a water-based elastomeric binder. The morphology, crystallinity, thermal stability, and hydrophilicity of the electrode films were characterized. Electrochemical measurements were carried out to compare capacitance, resistance, and frequency response of the electrodes with various binders. Results reveal that the rGO with conductive binders showed the highest capacitance with low internal resistance in both aqueous and organic electrolytes; while the rGO bound by elastomeric binder exhibited excellent cycling stability, low charge transfer resistance, and low relaxation time constant in aqueous electrolyte. Moreover, it was found that that binders with high conductivity and enhanced compatibility with electrolytes can facilitate ionic diffusion within the porous structure of electrodes, which leads to faster frequency response and better capacitive properties.

Over the past few years, supercapacitors based on graphene/polyaniline (rGO/PANI) composites have gained immense attention. The electrochemical performance of rGO/PANI composites can be improved by controlling their morphology and structure. However, very few studies have been carried out on amine-functionalized graphene/polyaniline (F-rGO/PANI) composites. In this study, amine-functionalized graphene (F-rGO) and mesoporous graphene (PF-rGO) were composited with PANI. The results showed that the specific capacitance of the F-rGO/PANI composites could be improved by controlling their morphology. The mesoporous structure of F-rGO contributed to the improvement in the cycling stability and energy density of the composites. At a current density of 0.5 A g−1, the specific capacitances of F-rGO/PANI20–0.5h and PF-rGO/PANI are 597 F g−1 and 489 F g−1, respectively; these values are remarkably higher than that of pure PANI (400 F g−1). F-rGO/PANI20-0.5th and PF-rGO/PANI maintained specific capacitances of 75% and 89%, respectively, which were significantly higher than that of pure PANI; this was observed even after 2000 cycles of charge and discharge had been completed at a current density of 1 A g−1. The energy density of PF-rGO/PANI reaches 34.9 W h kg−1 at the power density of 1.27 kW kg−1. This study is expected to provide an effective basis for the future research of graphene-based composite electrode materials for supercapacitors.

Oxyfluoride tellurite glasses with compositions of TeO2–Al2O3–CaF2/BaF2–NaF–YbF3–xHoF3 (x = 0.1, 0.3, 0.5, 1.0, 1.5, 2.0 mol%) were prepared by conventional melt-quenching method. Effect of heat-treatment schedules on crystallization behavior and microstructure were analyzed by differential scanning caborimetry, X-ray diffraction, infrared spectra and scanning electron microscopy. Cubic CaF2 and BaF2 nano-crystal phases were formed by controlling heat-treatment schedules. Up-conversion emission properties and mechanism of Yb3+ and Ho3+ ions in glasses and glass–ceramics were investigated. The green and red up-conversion emissions were observed under 980 nm LD excitation. Up-conversion luminescence intensity in glasses was obvious higher than that in glass–ceramics. And there existed concentration quenching effect among Ho3+ ions resulted from cross-relaxation.

Graphite oxide was prepared via the modified Hummers’ method and graphene via chemical reduction. Deoxygenation efficiency of graphene oxide was compared among single reductants including sodium borohydride, hydrohalic acids, hydrazine hydrate, and vitamin C. Two-step reduction of graphene oxide was primarily studied. The reduced graphene oxide was characterized by XRD, TG, SEM, XPS, and Raman spectroscopy. Square resistance was measured as well. Results showed that films with single-step N2H4 reduction have the best transmittance and electrical conductivity with square resistance of ~5746 Ω/sq at 70% transmittance. This provided an experimental basis of using graphene for electronic device applications.

Transparent oxyfluoride tellurite glasses with composition of TeO2–SiO2–AlF3–CaO–NaF–ErF3–HoF3 were prepared by a conventional melt-quenching method. Hexagonal β-NaCaAlF6 nano-crystal phase was formed after heat-treatment. Er3+ and Ho3+ ions remain in the residual glass phase after crystallization. Luminescence properties and up-conversion emission mechanism were investigated. Luminescence intensity of Er3+ at 1.53 μm reduced gradually along with the increase of Ho3+ ions concentration both for glasses and glass–ceramics. The green and red up-conversion emissions were observed under 980 nm excitation. With the increase of the Ho3+ ions concentration, the green emission intensity decreased monotonously and the red emission intensity increased obviously, there existed energy transfer between Er3+ and Ho3+ ions, (1) Ho3+(5I8) + Er3+(4I11/2) → Ho3+(5I6) + Er3+(4I15/2), (2) Ho3+(5I6) + Er3+(4I11/2) → Ho3+(5F3) + Er3+(4I15/2), (3) Ho3+(5I6) + Er3+(4I13/2) → Ho3+(5F5) + Er3+(4I15/2). The decrease of red emission intensity at 3.0 mol% of Ho3+ ions was mainly due to the cross-relaxation among Ho3+ ions, Ho3+(5F3) + Ho3+(5I8) → Ho3+(5F5) + Ho3+(5I6).

Nano-Cordierite powders used for high frequency chip inductors (MLCIs) were prepared by sol–emulsion–gel method. Effects of precursor concentration and [H 2 O]/[Si] molar ratio on this material were studied. The sol–emulsion–gel processing of Mg 2 Al 4 Si 5 O 18 as well as its dielectric property were investigated. Owing to the better packing efficiency and therefore higher surface energy of the freestanding nano-powder, the pressed pellets made by cordierite powder showed 98.6% theoretical density at 900 °C for 2 h. The additive Bi 2 O 3 was utilized to promote the crystallization or transformation to α-cordierite and sintering. The sol–emulsion–gel-derived cordierite ceramics have low dielectric constant ( e =3.0∼4.0; 18 GHz) and low dielectric loss ( tgδ

Transparent glass–ceramics in TeO 2 –SiO 2 –AlF 3 –CaO–NaF–ErF 3 system were prepared. Effect of heat-treatment schedules on crystallization behavior and microstructure were analyzed by differential scanning caborimetry, X-ray diffraction, infrared spectrum and scanning electron microscopy. The sole CaF 2 nanocrystal phase was confirmed, grains were spherical and distributed uniformly. Te and Si atoms existed in [TeO 3 ] and [SiO 4 ] forms. The full width at half maximum at 1533 nm emission increased from 39.16 nm to 43.37 nm after crystallization. Er 3+ ions were incorporated into CaF 2 nanocrystals with low phonon energies. The transmittance of glass–ceramics reached 78% at 780 nm and 90% at 1017 nm.

Lithium aluminosilicate (LAS) glasses are generally difficult to prepare because of their high melting temperature. In this study, the preparation of LAS glasses was achieved at a relatively low melting temperature. The batch containing MgO-ZnO-Li2O-Al2O3-SiO2 was melted in a platinum crucible at 1550°C for 2 h and was then followed by two- or three-step heat treatment processes for nucleation and crystal growth. The characterizations were carried out by differential thermal analysis, X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and UV-Vis-NIR scanning spectrophotometry. The hexagonal stuffed β-eucryptite solid solution crystallized at 840–960°C. Most of the hexagonal β-eucryptite solid solution transformed into the tetragonal β-spodumene solid solution at 1100°C. Almost all the aluminum atoms entered into the tetrahedral sites in the aluminosilicate network of the β-eucryptite/β-quartz solid solution. All of the Al atoms did not belong to the aluminosilicate network of the β-spodumene solid solution. The glass ceramic with a mean grain size of 10–20 nm is transparent, the transmittance reaches ∼85% in the visible light wavelength.

Generally the preparation of lithium aluminosilicate (LAS) glasses is difficult on account of their high melting temperature. This research managed to prepare LAS glasses doped with Nd3+ ions by the conventional melting and quenching technique, at a relatively low melting temperature and by the use of some additives. Lithium aluminosilicate glasses were transformed to glass-ceramics by controlled nucleation and the crystallization process. The characterizations were performed by differential thermal analysis, X-ray diffraction, UV-Vis-NIR scanning spectrophotometry, and fluorescence spectrometry. The research focused on the photoluminescence spectra of the initial glass and the glass-ceramics under different heat-treatment schedules. Three main fluorescence bands centering at about 890, 1065, and 1330 nm were observed, which corresponded to the transitions of 4F3/2→4I9/2, and 4F3/2→4I11/2, and 4F3/2→4I13/2, respectively. Phase compositions of glass-ceramics were found to affect their fluorescent characteristics considerably. The fluorescent intensity increased markedly when Nd3+ ions entered the LixAlxSi1-xO2 β-eucryptite solid solution (SS). Quenching occurred when Nd3+ ions located at LixAlxSi3-xO6 β-eucryptite SS. Quenching disappeared after LixAlxSi3-xO6 β-eucryptite SS recrystallized into β-spodumene SS. The effectively induced cross section σin of Nd3+ ions located at the LixAlxSi1-xO2 β-eucryptite SS was 1.931 × 10−21 cm2 at 1065 nm.