Divalent europium-doped nitride phosphors, Ca 1-x Eu x AlSiN 3 (x ) 0-0.2), were successfully prepared by the self-propagating high-temperature synthesis (SHS) by using Ca 1-x Eu x AlSi alloy powder as a precursor. The Rietveld refinement analysis was carried out on the CaAlSiN 3 host lattice to elucidate the luminescence properties of dopant Eu 2+ on the tetrahedrally coordinated site. For the Eu 2+ doped samples, strong absorption peaking at about 460 nm was observed on the excitation spectra, which matched perfectly with the current blue light of InGaN/GaN light-emitting diodes (LEDs). The optimized sample, Ca 0.98 -Eu 0.02 AlSiN 3 , gave the red emission peaking at 649 nm of which the intensity was competitive with the sample prepared from the metal nitride raw materials (Ca 3 N 2 , AlN, Si 3 N 4 , and EuN). The CIE chromaticity index (0.647, 0.347) with high color saturation indicated that it was a promising candidate as a redemitting phosphor for the InGaN/GaN-based down-conversion white LEDs for general illumination or displays.

Eu 2 + -doped ternary nitride phosphor, Sr2Si5N8:Eu2+, was prepared by the carbothermal reduction and nitridation method. The Rietveld refinement analysis showed that the single phase products were obtained. Two main absorption bands were observed on the diffuse reflection spectra peaking at about 330 and 420nm, so that the resultant phosphor can be effectively excited by InGaN light-emitting diodes. The emission peak position of (Sr1−xEux)2Si5N8:Eu2+ series varied from 618to690nm with increasing Eu2+ ion concentration. The redshift behavior of the emission band was discussed on the basis of the configuration coordination model.

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Fe nanowires with 70–200nm in diameter and 20–50μm in length were synthesized by a chemical vapor deposition method for electromagnetic wave absorption application. The frequency dependences of relative permittivity (εr) and permeability (μr) were strongly dependent on the diameter of Fe wires. Compared with micrometer wires or flakelike samples, nanowires exhibited a magnetic resonance (μr″) peak in the range of 1–18GHz, suggesting that nanowires have significant effect for reducing the eddy current loss, therefore, the resin compacts of 29vol% Fe nanowires with thicknesses of 1.3–4.0mm provided good electromagnetic wave absorption performances in the range of 5.6–18GHz.

Eu2+ ion-doped nitride phosphor, Ca2Si5N8:Eu2+, was synthesized by the carbothermal reduction and nitridation (CRN) method and the photoluminescence properties were characterized. It showed a broad absorption band between 250 and 550 nm which was efficiently excited by blue LEDs (400–470 nm) and a strong emission band peaking at 600 nm with a FWHM of 80 nm. The obtained phosphor provided saturated color chromaticity (0.589, 0.407) to generate warm-white light in phosphor-converted white LEDs.

A series of ternary nitride solid solutions with a general formula of ͑Sr 1−x Ca x ͒ 2 Si 5 N 8 /Eu 2+ ͑2 atom %͒ were synthesized by the carbothermal reduction and nitridation ͑CRN͒ method. The structure and luminescence properties were characterized for practical applications as a potential red phosphor for the phosphor-converted white light-emitting diodes ͑LEDs͒. The solid solutions were formed as the uniformly single phases with orthorhombic ͑ Pmn2 1 ͒ and monoclinic ͑Cc͒ symmetry at each end of ͑Sr 1−x Ca x ͒ 2 Si 5 N 8 , while in the range of 0.5 Ͻ x Ͻ 0.75, such solid solution phases coexisted. All of the obtained phosphors were well crystallized and the grains grew from 5 to 20 m with increasing Ca 2+ content. These phosphors showed broadened excitation spectra originated from the 4f 7 → 4f 6 5d transition of Eu 2+ ions, so that the intense orange-red emission bands were observed under the excitation of 380-470 nm corresponding to the output lights of near-UV or blue LEDs.

Nanocomposite magnetic materials α-Fe∕C(a), Fe2B∕C(a), and Fe1.4Co0.6B∕C(a) were prepared by mechanically grinding α-Fe, Fe2B, or Fe1.4Co0.6B with amorphous carbon [C(a)] powders. Complex permittivity, permeability, and electromagnetic wave absorption properties of resin compacts containing 40-vol% composite powders of α-Fe∕C(a), Fe2B∕C(a), and Fe1.4Co0.6B∕C(a) were characterized according to a conventional reflection/transmission technique. The real part (εr′) and imaginary part (εr″) of the relative permittivity are low and almost independent of frequency between 0.05 and 40GHz. The Imaginary part (μr″) of the relative permeability exhibited wide peaks in the 1–9-GHz range for α-Fe∕C(a), in the 2–18-GHz range for Fe2B∕C(a), and in the 18–40-GHz range for Fe1.4Co0.6B∕C(a) owing to their different magnetocrystalline anisotropy field (HA) values. Consequently, the resin compacts of 40-vol% α-Fe∕C(a), Fe2B∕C(a), and Fe1.4Co0.6B∕C(a) powders provided good electromagnetic (em) wave absorption performances (reflection loss<−20dB) in ranges of 4.3–8.2GHz (G band), 7.5–16.0GHz (X band), and 26.5–40GHz (Q band) over absorber thicknesses of 1.8–3.3, 1.2–2.2, and 0.63–0.82mm, respectively. Our experimental results demonstrate that the amorphous-carbon-based magnetic nanocomposites are promising for the application to produce thin and light EM wave absorbers.

Reddish-orange long-lasting phosphorescence materials, various amounts of Eu2+ - and Tm3+ -co-doped phosphors (Ca2Si5normalN8:Eu2+,Tm3+) , were prepared by the conventional high temperature solid-state reaction method, and their luminescence properties were systematically investigated by photoluminescence spectra, afterglow spectra, afterglow decay curves, and thermoluminescence spectra. The Ca2Si5normalN8:Eu2+,Tm3+ materials exhibited strong reddish-orange emission bands in a wavelength range of 500–750 nm with peak positions at about 600 nm due to the 5d→4f transition of the Eu2+ ion. Furthermore, these phosphors emitted strong reddish-orange long-lasting phosphorescence with an afterglow time of more than 1 h after turning off the activating lamp in the light perception of the dark-adapted human eye (0.32mcd/normalm2) . Such afterglow of Ca2Si5normalN8:Eu2+,Tm3+ phosphors was attributed to the recombination of holes and electrons that were trapped within the lattice defect centers. The results of the thermoluminescence spectra indicated that the increase in the predominating band at 350 K, which was associated with the charge-trapping centers, was responsible for the enhancement of the afterglow properties of Ca2Si5normalN8:Eu2+,Tm3+ .