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Laminated sheets with Ti2AlC/TiAl composite layers synthesized from the Ti–Al–TiC system and TC4 titanium alloy as the toughening layer were fabricated by spark plasma sintering. Their phase composition and microstructure were analyzed and flexural strength and fracture toughness measured. The composite layers mainly comprised Ti2AlC, TiC, TiAl, and Ti3Al phases. The flexural strength and fracture toughness of the sheets perpendicular to the laminated direction were 455.74 MPa and 21.65 MPa · m1/2, respectively. The TC4 layers provided a strengthening–toughening effect by changing the crack propagation model and weakening the fracture energy. Ti2AlC particles provided a strengthening effect. The synergistic effect of the two components enhanced the mechanical properties of these TiAl-based laminated composite sheets.

Mid-infrared laser materials with low phonon energy have significant applications. However, the development of available glass systems for high-power laser gain medium have posed a great challenge. Therefore, we investigated the 2.7 μm spectroscopic properties of Er3+/Yb3+-codoped oxyfluoride glass containing gallium, which were prepared by typically melting and quenching methods. The 2.7 μm luminescence properties of the Er3+/Yb3+-codoped oxyfluoride glass containing gallium were recorded by a 980 nm laser diode. The Judd–Ofelt parameters, decay curves, emission cross section, energy transfer efficiency and quantum efficiency were calculated. The maximum emission cross section of YbFGa-0.5 is 1.63 × 10−20 cm2by 980 nm excitation. The energy transfer efficiency is calculated to be 77.8% for the YbFGa-0.5 glass around 2700 nm. The quantum efficiency at 1530 nm is 65.6%. The result reveals that the best doping concentration ratio of Er3+:Yb3+ions is 1:0.5, and suggests an effective energy transfer from Yb3+to Er3+ions.

Glasses in the system xBi2O3–(100 – x)NaPO3were prepared using transitional melting–quenching and characterized using solid state nuclear magnetic resonance (SSNMR), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FT-IR). The addition of Bi2O3results in the depolymerization of the phosphorus chain and the formation of Q(n)(n= 0, 1, 2) phosphorus species, where nrepresents the number of P–O–P bonds that can be quantified using 31P magic angle spinning (MAS) NMR and constant-time double-quantum based dipolar recoupling effects nuclear alignment reduction (CT-DQ-DRENAR). The 23Na{31P}, 31P{23Na}, and XPS results consistently prove that both Na+and Bi3+ions are bounded by phosphorus tetrahedron [PO4]3–. Unlike other trivalent ions such as Ga3+and Al3+, which connect with the phosphorus tetrahedron by corner-sharing, Bi3+ions were first proved to share edge with the phosphorus tetrahedron by the analysis of 31P spectra, taking the charge balance and bond valence consideration into account. Such a difference in connectivity results in significant structural differences.

Yb:Lu3Al5O12(Yb:LuAG) nano powders were synthesized with the co-precipitation method from cation (Lu3+, Yb3+, Al3+) solution of different concentrations using NH4HCO3as the precipitant. The influence of cation concentration on the morphology and purity of the calcined powders was studied. Contrary to the conventional suggestion that recommends thin solution to obtain loosely agglomerated nano powders, results showed that thin cation (Lu+Yb+Al) concentration ≤0.08 mol/L led to formation of Al2O3and LuAP impurities in the obtained nano powders. By means of Tg/(DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), the cause was revealed to be re-dissolution of Lu at high pH value that resulted from the decomposition of NH4HCO3. (Lu+Yb+Al) concentration of ∼0.24 mol/L was recommended to achieve pure Yb:LuAG nano powders. Transparent Yb:LuAG ceramics were fabricated with the prepared Yb:LuAG nano powders. The transmittance around 800 nm was 77.5%.

Er^3+ doped CaF_2-fluorophosphate (FP) glass microcomposites were produced by heat-treating the mixture of Er^3+:CaF_2 precipitate and FP glass powder above the melting temperature of the FP glass. The appearance of CaF_2 crystallites in the resulting composites was confirmed by x ray diffraction. Despite the fact that the average diameter of the crystallites was around 10?μm as revealed by the micromorphology study, a transparent composite was obtained by matching the refractive index of FP glass to that of CaF_2. Intense IR fluorescence at around 2.7?μm was observed in the composite, implying the composite would be a promising candidate for IR lasers and amplifiers.

A tunable luminescence from red to blue in Eu-doped mesoporous AlPO4 glass is achieved by adjusting the annealing temperature. With increasing annealing temperature, the increased Eu3+ ions reduction changes the luminescence of the obtained glass. The abnormal reduction of Eu3+ to Eu2+ occurs in AlPO4 mesoporous glass at relative low annealed temperatures from 600 to 800 oC in air. The presence of Eu2+ ions, which are reduced from Eu3+ by hole-electron pairs, is revealed by XPS spectra. Our results indicate the mesoporous AlPO4 glass is a suitable matrix to incorporate Eu ions as the tunable luminescent light sources or LEDs.