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1.
Xiao-Yu Sun Zheng He Xuan Gu 《Journal of Materials Science: Materials in Electronics》2018,29(20):17217-17221
Zn2GeO4, Zn2GeO4:Mn2+, Zn2GeO4:Pr3+ and Zn2GeO4:Mn2+/Pr3+ phosphors were fabricated by a solid state reaction. The phase and luminescent properties of the fabricated phosphors were investigated. The XRD patterns show that all of the fabricated phosphors have an orthorhombic structure. The fabricated Zn2GeO4 shows an emission band in the range of 350–550 nm. The fabricated Zn2GeO4:Mn2+ and Zn2GeO4:Pr3+ phosphors show emission bands corresponding to Mn2+ and Pr3+ ions, respectively. The fabricated Zn2GeO4:Mn2+/Pr3+ phosphor shows the emission band results from Mn2+ and the codoped Pr3+ enhances the emission intensity of Mn2+. Moreover, Zn2GeO4:Mn2+/Pr3+ phosphor exhibits longer decay time than that of Zn2GeO4:Mn2+. The higher intensity and longer lifetime of Mn2+ emission are induced by the energy transfer from Pr3+ of various vacancies to Mn2+ in Zn2GeO4:Mn2+/Pr3+ phosphors. 相似文献
2.
A new efficient phosphor, Eu2+/Eu3+ and Ce3+ activated Na2Zn5(PO4)4 has been synthesized by solid-state reaction technique at high temperature. X-ray powder diffraction analysis confirmed the
formation of Na2Zn5(PO4)4 host lattice. Scanning electron microscopy indicated that the microstructure of the phosphor consisted of irregular fine
grains with a size of about 0·5–2 μm. Photoluminescence excitation spectrum measurements of Ce3+ activated Na2Zn5(PO4)4 show that the phosphor can be efficiently excited by UV-Vis light from 280 to 310 nm to realize emission in the visible (blue)
range due to the 5d-4f transition of Ce3+ ions which is applicable for scintillation purpose, whereas Eu2+/Eu3+ activated Na2Zn5(PO4)4 phosphor emits blue, green and red emission spectrum shows at 487 nm, 546 nm with a dominant peak at 611 nm respectively,
due to Eu2+/Eu3+ ions which is promising candidate for solid state lighting. Therefore, newly synthesised, by low cost and easy technique
prepared, novel phosphors may be useful as RGB phosphor for solid state lighting application. 相似文献
3.
S. S. Redozubov N. F. Kartenko I. M. Gaidamaka E. A. Nenasheva 《Inorganic Materials》2016,52(11):1166-1171
Ceramic samples based on ZnTa2O6 and ZnTa2O6–MO2 (M = Ti, Zr) systems have been obtained by the solid state ceramic route. The phase composition and microstructure of samples were investigated. The effect of the aliovalent substitution of ions Zn2+ and Ta5+ by M4+ (M = Ti, Zr) in the structure of ZnTa2O6 on microwave dielectric properties of ceramics was studied. The way of the compensation of the positive temperature coefficient of resonant frequency of dielectric resonators based on ZnTa2O6 ceramics with using the aliovalent substitution of cations was proposed. Dielectric resonators with the high temperature stability of the resonant frequency and high dielectric properties in the microwave range based on the ZnTa2O6–ZrO2 system were obtained for application in electronics. 相似文献
4.
A. N. Hapishah M. M. Syazwan M. N. Hamidon 《Journal of Materials Science: Materials in Electronics》2018,29(24):20573-20579
In this research work, magnetic and microwave absorption loss and other response characteristics in cobalt zinc ferrite composite has been studied. Cobalt zinc ferrite with the composition of Co0.5Zn0.5Fe2O4 was prepared via high energy ball milling followed by sintering. Phase characteristics of the as-prepared sample by using XRD analysis shows evidently that a high crystalline ferrite has been formed with the assists of thermal energy by sintering at 1250 °C which subsequently changes the magnetic properties of the ferrite. A high magnetic permeability and losses was obtained from ferrite with zinc content. Zn substitution into cobalt ferrite has altered the cation distribution between A and B sites in spinel ferrite which contributed to higher magnetic properties. Specifically, Co0.5Zn0.5Fe2O4 provides electromagnetic wave absorption characteristics. It was found that cobalt zinc ferrite sample is highly potential for microwave absorber which showed the highest reflection loss (RL) value of ??24.5 dB at 8.6 GHz. This material can potentially minimize EMI interferences in the measured frequency range, and was therefore used as fillers in the prepared composite that is applied for microwave absorbing material. 相似文献
5.
Bowen Zhang Mingming Shi Dongyun Zhang Yunyun Guo Chengkang Chang WeiJie Song 《Journal of Materials Science: Materials in Electronics》2017,28(16):11624-11630
This paper reports the comparison of photoluminescence and afterglow behavior of Dy3+ in CaSnO3 and Ca2SnO4 phosphors. The samples containing CaSnO3 and Ca2SnO4 were prepared via solid-state reaction. The properties have been characterized and analyzed by utilizing X-ray diffraction (XRD), photoluminescence spectroscope (PLS), X-ray photoelectron spectroscopy (XPS), afterglow spectroscopy (AS) and thermal luminescence spectroscope (TLS). The emission spectra revealed that CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors showed different photoluminescence. The Ca2SnO4:Dy3+ phosphor showed a typical 4F9/2 to 6Hj energy transition of Dy3+ ions, with three significant emissions centering around 482, 572 and 670 nm. However, the CaSnO3:Dy3+ phosphor revealed a broad T1 → S0 transitions of Sn2+ ions. The XPS demonstrate the existence of Sn2+ ions in CaSnO3 phosphor caused by the doping of Dy3+ ions. Both the CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors showed a typical triple-exponential afterglow when the UV source switched off. Thermal simulated luminescence study indicated that the persistent afterglow of CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors was generated by the suitable electron or hole traps which were resulted from the doping the calcium stannate host with rare-earth ions (Dy3+). 相似文献
6.
Yan-Hua Song Hai-Feng Zou Shu-Cai Gan Yue-Feng Deng Guang-Yan Hong Jian Meng 《Journal of Materials Science》2007,42(13):4899-4904
A red long lasting phosphor Zn3(PO4)2:Mn2+,Ga3+ (ZPMG) was prepared by ceramic method, and phase conversion and spectral properties were investigated. Results indicated
that the phase conversion from α-Zn3(PO4)2, β-Zn3(PO4)2 toγ-Zn3(PO4)2 occurs with different manganese concentration incorporated and sinter process. The structural change induced by the phase
transformation results in a remarkable difference in the spectral properties. The possible luminescence mechanism for this
red LLP with different forms has been illustrated. 相似文献
7.
S. A. Vladimirova M. N. Rumyantseva D. G. Filatova V. F. Kozlovskii A. S. Chizhov N. O. Khmelevskii A. V. Marchevskii Xiaogan Li A. M. Gaskov 《Inorganic Materials》2016,52(2):94-100
Nanocrystalline SnO2 has been synthesized and its surface has been modified with Au0 and Co(II, III). The distribution of the modifiers over the nanocomposites has been studied by X-ray diffraction, inductively coupled plasma mass spectrometry, and transmission electron microscopy. The effect of the modifiers on the hydrogen reduction of nanocrystalline SnO2 has been assessed. The CO sensing properties of the synthesized materials (10 ppm CO in air) have been studied in situ by electrical conductance measurements. The addition of both Au0 and Co(II, III) allows the working temperature of the SnO2-based semiconductor sensor to be lowered to 215°C. 相似文献
8.
R. A. Grigoryan 《Inorganic Materials》2007,43(11):1247-1251
The multicomponent refractory oxide system Zn2(TiaSnb)1 ? x ZrxO4 (a + b = 1; a: b = 1: 5, 1: 4, 1: 3, 1: 2, 1: 1, 1: 0, 2: 1, 3: 1, 4: 1; x = 0?1.0; Δx = 0.05) has been studied by x-ray diffraction, using samples prepared by melting appropriate oxide mixtures in a low-temperature hydrogen-oxygen plasma. Two phases, both with wide homogeneity ranges, have been identified: α-phase, with a cubic inverse spinel structure, and β-phase, with a tetragonal spinel structure. The phase boundaries in the system have been determined. Structural data are presented for about 100 solid solutions of different compositions. 相似文献
9.
We have studied the effect of codoping with CeO2 and SnO2 (2 to 3.5 wt %) on the microstructure and dielectric properties of BaTiO3. Doping with CeO2 and SnO2 inhibits grain growth in BaTiO3 and enables the fabrication of ceramic materials with a grain size below 1 μm. The temperature coefficient of permittivity
of the ceramics increases with CeO2 + SnO2 content, firing temperature, and firing time. 相似文献
10.
B. J. Madhu M. Gurusiddesh T. Kiran B. Shruthi H. S. Jayanna 《Journal of Materials Science: Materials in Electronics》2016,27(8):7760-7766
A conducting polymer, polyaniline (PANI)/Ni0.5Zn0.5Fe2O4 composites with high dielectric absorbing properties and electromagnetic shielding effectiveness at low frequencies were successfully synthesized through a simple in situ emulsion polymerization. PANI was doped with hydrochloric acid to improve its electrical properties and interactions with ferrite particles. PANI/Ni0.5Zn0.5Fe2O4 composites were characterized by X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analysis. Frequency dependence of dielectric and ac conductivity (σac) studies have been undertaken on the PANI/Ni0.5Zn0.5Fe2O4 composites in the frequency range 50 Hz–5 MHz. The electrical conduction mechanism in the PANI/Ni0.5Zn0.5Fe2O4 is found to be in accordance with the electron hopping model. Further, frequency dependence of electromagnetic interference (EMI) shielding effectiveness (SE) is studied. The EMI shielding effectiveness is found to decrease with an increase in the frequency. The maximum value 55.14 dB of SE at 50 Hz was obtained at room temperature for PANI/Ni0.5Zn0.5Fe2O4 composites in the 50 Hz–5 MHz frequency range. PANI/Ni0.5Zn0.5Fe2O4 composites were demonstrated as a promising functional material for the absorbing of electromagnetic waves at low frequencies because of a large amount of dipole polarizations in the polymer backbone and at the interfaces of the Ni–Zn ferrite particles and PANI matrix. 相似文献
11.
Zn2SiO4:Tb nanoparticles were prepared by sol-gel-microwave heating for the first time. X-ray powder diffraction (XRD) analysis confirmed
the formation of Zn2SiO4 in willemite structure. Field-emission scanning electron microscopy showed a narrow size distribution, small size (40–50 nm)
and spherical shape of the particles. Energy dispersive spectroscopy result indicated that the ratio of Tb3+/Zn2+ was in agreement with that of the feed. Photoluminescence measurement indicated that the phosphor emitted strong green light
centered at 545 nm under UV light excitation. The excitation spectra confirmed the energy transfer from the host material
to the Tb3+ ions. This is in favor of the effective green emission of Zn2SiO4:Tb nanoparticles. 相似文献
12.
Polycrystalline samples of gallium- and indium-doped Bi10Ti3W3O30 (mixed-layer Aurivillius phase with the Ti4+ and W6+ distributed at random over the perovskite-like slabs) have been prepared by solid-state reactions, and their polymorphism
and electrical properties have been studied. Doping with both In3+ and Ga3+ yields limited solid solutions and shifts the ferroelectric phase transition to lower temperatures. The heterovalent substitutions
of In3+ and Ga3+ for Ti4+ and W6+ increase the oxygen vacancy concentration and, accordingly, the conductivity of the material relative to the undoped compound. 相似文献
13.
The structure of Mg0.54Zn0.46Fe2O4 ferrites has been studied using x-ray diffraction techniques. It is established that high-temperature annealing (T = 1280°C, τ = 0.5–8.0 h) leads to a change in the crystal structure of samples, which is accompanied by their local amorphization. 相似文献
14.
The phase equilibria in the Tl2S-Tl2Te-Tl9BiTe6-TlBiS2 system have been studied by differential thermal analysis and x-ray diffraction. The results have been used to construct the T-x phase diagram along the Tl2S-Tl9BiTe6 ([TlBi0.333S0.5Te0.5]) and TlBiS2-Tl2Te(Tl9BiTe6) joins, the 500-K section of the phase diagram of the Tl2S-Tl2Te-Tl9BiTe6-TlBiS2 system, and its liquidus diagram. The invariant and univariant phase equilibria involved have been identified. The system has been shown to contain wide regions of Tl2Te-and Tl9BiTe6-based quaternary solid solutions. 相似文献
15.
P. Venkateswara Reddy S. Venkatramana Reddy N. Koteeswara Reddy 《Journal of Materials Science: Materials in Electronics》2017,28(18):13320-13327
The desired size of pure SnO2 and Co (1, 3, 5 mol%) with constant 5 mol% of Al co-doped into SnO2 nanoparticles are synthesized by chemical co-precipitation method. The raw materials used in synthesis are SnCl2.2H2O, AlCl3, Co (C2H3O2).4H2O, aqueous NH4OH and Polyethyleneglycol (PEG) from AR grade. The XRD pattern of pure and co-doped samples confirm the formation of tetragonal rutile phase of SnO2 nanoparticles with average particle size 25 and 20 nm respectively. Micrographs of scanning electron microscope (SEM) for pure and (Co, Al) co-doped into SnO2 show that the prepared nanoparticles are agglomerate and spherical in shape. The EDAX spectra of prepared nanoparticles indicate the presence of Co2+, Al3+, Sn4+ and O2+ and also confirm stoichiometric proportions of raw material in the formation of SnO2. Transmission electron microscope (TEM) reveals that the surface morphology of pure and co-doped samples are spherical, and average size of particles is ~20 nm. Magnetization measurements from M-H curves of VSM show that the ferromagnetism at low concentration of Co and at higher concentration of Co shows weak ferromagnetism due to super exchange coupling among neighboring ions. The bound magnetic polarons model supports the observed ferromagnetic behavior. 相似文献
16.
The piezoelectric/piezomagnetic composite, PZT/Ni0.284Zn0.549Cu0.183Fe1.984O4, was fabricated by the mixed oxide method. The phase assemblage, piezoelectric strain constant and saturation magnetization were investigated. The results indicate that the PZT phase is compatible with Ni0.284Zn0.549Cu0.183Fe1.984O4 phase, and dense diphasic ceramic composites were obtained. It is found that piezoelectric strain constant decreases exponentially as the amount of doped piezomagnetic materials in the composite increases. Correspondingly, saturation magnetization of the composite also decreases with the increasing weight fraction of piezoelectric materials. Three reasons cause the results. First, the grain growth of piezomagnetic phase at the co-sintering temperature reduces grain size and continuity of the piezoelectric phase. Second, the pore size and porosity in composite increase dramatically with increasing amount of piezomagnetic phase. Third, the low resistivity of the composite prevents the poling process and reduces the piezoelectric strain constant. The tailoring of microstructure to achieve a high performance piezoelectric/piezomagnetic composite is proposed based on the analysis. 相似文献
17.
SnO2/MoO3 nanocomposites are synthesized in a broad composition range through chemical precipitation from solution, and their phase composition and microstructure are investigated by x-ray diffraction. The gas sensitivity of the nanocomposites to lower alcohols (CnH2n + 1 OH, n=1–4) is studied by in situ conductance measurements. The results are interpreted in terms of the acid-base properties of the nanocomposite surface.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 4, 2005, pp. 442–449.Original Russian Text Copyright © 2005 by Makeeva, Rumyantseva, Gaskov. 相似文献
18.
The complete elastic modulus matrix of Li2Zn2(MoO4)3 single crystals has been measured for the first time. The sound velocity has been measured in different directions of the
crystals by a pulse-phase method. The measurement results have been used to calculate elastic moduli. The sound velocity has
been calculated in the three main crystallographic planes of the crystals. 相似文献
19.
A simple co-precipitation technique has been successfully applied for the preparation of pure single phase CaBi4Ti4O15 (CBT) powders. Ammonium oxalate and ammonium hydroxide were used to precipitate Ca2+, Bi3+ and Ti4+ cations simultaneously. No pyrochlore phase was found while heating powder at 600 C and pure CBT phase was found to be formed by X-ray diffraction. Particle size and morphology was studied by transmission electron microscopy (TEM). The room temperature dielectric constant at 1 kHz is 400. The ferroelectric hysteresis loop parameters of these samples were also studied. 相似文献
20.
The transport properties of Cs0.97Rb0.03H2PO4 have been studied using polycrystalline samples and single crystals. The mixed salt is isostructural with cesium dihydrogen phosphate and has slightly smaller unitcell parameters. The cation substitution increases the low-temperature ionic conductivity of the material by about two orders of magnitude but has an insignificant effect on the conductivity of the high-temperature phase. The low-temperature conductivity of single-crystal samples exhibits significant anisotropy, with σ a < σ b±c . The conductivity of the polycrystalline material is close to σ b±c . The substitution reduces the temperature of the superionic phase transition by 20°C and enhances the thermal stability of the high-temperature phase at low humidity (1 mol % H2O). 相似文献