Citric sol–gel synthesis and luminescence characteristics of Ca1−y Sr y La2−x Eu x ZnO5 phosphors

Abstract

The emission-tunable CaLa 2-x Eu x ZnO 5 phosphors were synthesized by citric sol-gel method. The products were characterized by X-ray diffractometer, scanning electron microscope, energy dispersive spectroscopy and photoluminescence spectrometer. Through adjusting the dopant concentration of Eu 3? in CaLa 2 ZnO 5 phosphor, blue-green to orange-red emission with the 467 nm excitation could be obtained, which matches well with the emission of blue LED chip. Luminescence properties of Ca 1-y Sr y La 1.9 Eu 0.1 ZnO 5 (0 B y B 1) indicated that increasing Sr 2? content enhances not only the emission intensity of 5 D 0 ? 7 F 2 transition but also the emission intensity ratio of 5 D 0 ? 7 F 2 to 5 D 0 ? 7 F 1 (asymmetry ratio). The Ca 0.6 Sr 0.4 La 1.9 Eu 0.1 ZnO 5 phosphors possess optimal integrated emission intensity, which is 20 % higher than that of CaLa 1.9 Eu 0.1 ZnO 5 phosphors, and the Commission International de L'Eclairage chromaticity coordinate is (0.658, 0.341). Ca 1-y Sr y La 2-x Eu x ZnO 5 phosphors may have potential applications in field emission displays based on their particle size, low-cost synthetic route, and diverse luminescent properties.

Enhanced magnetic behavior, exchange bias effect, and dielectric property of BiFeO3 incorporated in (BiFeO3)0.50 (Co0.4Zn0.4Cu0.2 Fe2O4)0.5 nanocomposite

“…This is quite likely due to the enhanced magnetization in the nanocomposite sample of BFO-CZCF. This sort of behavior is also observed in other cases, 45,62 where the magnetization has been enhanced. BFO-CZCF exhibits the dispersion at low frequencies with a sharp variation of the permittivity and dielectric loss.…”

Molybdenum, Tungsten, and Aluminium Substitution for Enhancement of the Thermoelectric Performance of Higher Manganese Silicides

“…This observation is in agreement with other reports on Al, Mo, and Cr-doped HMS. [6][7][8]10 Liu et al 9 however, reported a contrast observation for chromium-doped polycrystalline HMS prepared by ball milling and in-situ SPS, but were not able to explain the reason for this unusual behavior. Comparison with chromium as dopant is because of the lack of a similar investigation for molybdenum and tungsten, all of which belong to the same group in the periodic table.…”

“…They adopt Nowotny chimney-ladder structures whose unit cells consist of Mn sublattices arranged as chimneys in which the Si sublattices form coupled helices spiraling as ladders. 1 A variety of work has been conducted on tuning the transport properties of HMS by substitution or doping, [4][5][6][7][8][9][10][11][12][13][14] compositing, [15][16][17] and nanostructuring. 18,19 For substitution at Si sites, the highest ZT values obtained were 0.6 at 833 K and 0.65 at 850 K for Ge and Al-doped polycrystalline HMS, respectively.…”

“…Improvement of thermoelectric performance by doping with different amounts of Ge has been widely reported by several groups; [4][5][6]8,11 the Ge contents were well below the experimentally determined solubility limit of approximately 1.0 at.%. 4 Therefore, a nominal composition of MnSi 1.75 Ge 0.02 , corresponding to 0.7 at.% Ge, was chosen in this work as the base material for further substitution with Al, Mo, and W. Similar to chromium substitution, [9][10][11][12][13][14] molybdenum and tungsten, which belong to the same group as chromium in the periodic table, were expected to have similar electronic effects on HMS-based compounds, and possibly reduce the lattice thermal conductivity by creating large mass fluctuations and lattice distortion owing to their size differences compared with the matrix element Mn.…”

Evaluation of the magnetocaloric response of nano-sized La0.7Ca0.3Mn1-xNixO3 manganites synthesized by auto-combustion method

“…13 Partial substitution of Mn 3+ by Ni 2+ ions in manganites synthesized by solid state reaction (grain sizes ∼1 µm), has previously been studied in connection with the magnetoresistive behavior. 14,15 The dimensionality strongly impacts the magnetic and magnetocaloric response of LCMO. 9,16 In the present work, results of a study of the MCE on LCMO manganites, synthesized by auto-combustion method and substituted at the Mn site by Ni 2+ are presented.…”