共查询到20条相似文献,搜索用时 15 毫秒
1.
Mariana Ušáková Jozef Lukáč Rastislav Dosoudil Vladimír Jančárik Anna Grusková Elemír Ušák Jozef Sláma Jan Šubrt 《Journal of Materials Science: Materials in Electronics》2007,18(12):1183-1189
The paper is devoted to the preparation of NiZn ferrite with small substitutions of copper by means of ceramic technology.
The influence of small Cu substitution on the microstructural and magnetic properties of NiZn ferrites have been analysed
by means of various experimental methods and interpreted from the point of view of preparation technology optimisation and
possible applications of such materials. A strong correlation between the substituent content and resulting properties has
been observed, thus allowing preparation of material with the properties tailored for any particular application. 相似文献
2.
Zhen Liu Yang Feng Dongmei Jiao Na Zhang Huan Jiao 《Journal of Materials Science》2008,43(5):1619-1623
Al3+/Mg2+ doped Y2O3:Eu phosphor was synthesized by the glycine-nitrate solution combustion method. In contrast to Y2O3:Eu which showed an irregular shape of agglomerated particles (the mean particle size >10 μm), the morphology of Al3+/Mg2+ doped Y2O3:Eu crystals was quite regular. Al3+/Mg2+ substituting Y3+ in Y2O3:Eu resulted in an obvious decrease of the particle size. Meanwhile, higher the Al3+/Mg2+ concentration, smaller the particle size. In particular, the introduction of Al3+ ion into Y2O3 lattice induced a remarkable increase of PL and CL intensity. While, for Mg2+ doped Y2O3:Eu samples, their PL and CL intensities decreased. The reason that causes the variation of PL and CL properties for Al3+ and Mg2+ doped Y2O3:Eu crystals was concluded to be related to sites of Al3+ and Mg2+ ions inclined to take and the difference of ion charge. 相似文献
3.
E. V. Tret’yak G. P. Shevchenko T. A. Solomakha M. V. Korzhik 《Inorganic Materials》2017,53(3):307-312
BaI2:Eu2+,Eu3+ powders have been prepared by heat-treating BaCO3:Eu3+ precursor powders of various morphologies in an iodinating agent atmosphere and their structural properties, morphology, optical absorption, and luminescence have been studied. The results demonstrate that the powders thus prepared consist of a mixture of crystalline hydrates of various compositions, dominated by BaI2 ? 2Н2О (sp. gr. C2/c), and that the Eu2+: Eu3+ ratio in the powders is determined by the morphology of the precursor. 相似文献
4.
We report here on the development and spectral analysis of Cu2+ (0.5 mol%) and Mn2+ (0.5 mol%) ions doped in two new series of glasses. The visible absorption spectra of Cu2+ and Mn2+ glasses have shown broad absorption bands at 820 nm and 495 nm, respectively. For Cu2+ BFP glasses, excitation at 380 nm, a blue emission at 441 nm and also a weak emission at 418 nm ions have been observed.
For Mn2+ ions doped BFP glasses, excitation at 410 nm and a red shift at 605 nm emission have been observed. 相似文献
5.
Using citric acid as reducing agent and fuel, nitrate as a oxidant, boric acid as a flux material, red persistent phosphors
CaTiO3: Pr3+, Al3+ have been successfully synthesized by nitrate-citric acid combustion method. The best route is determined by studying influences
of the amount of citric acid and ammonium nitrate, pH value of the solution, initiating temperature of furnace, and the amount
of boric acid. The photoluminescence and crystallinity of persistent phosphors were investigated by using luminescence spectrometer
and X-ray diffractometer (XRD), respectively. The results show that the optimum molar ratio of citric acid to calcium nitrate
was about 0.8 and that of boric acid to calcium nitrate was about 0.4. Photoluminescence and decay curves show that the samples
exhibited the optimal luminous properties at pH value of 6 and at the initiating temperature of 700 °C. 相似文献
6.
Yuguo Yang Bing Liu Yuanyuan Zhang Xianshun Lv Lei Wei Jianhua Xu Huadi Zhang Xuping Wang Cong Zhang Jing Li 《Journal of Materials Science: Materials in Electronics》2018,29(20):17154-17159
Mg2+/Ga3+ doped Y3Al5O12:Ce3+ phosphors were synthesized through a solid state reaction. The phase and luminescent of the synthesized phosphors were investigated. For Ga3+ codoped Y2.96Ce0.04Al(5?x)GaxO12 phosphors, the emission intensity increases with the increase of Ga3+ concentration up to Y2.96Ce0.04Al4.80Ga0.20O12 and then decreases with a further increase of Ga3+ concentration, but the emission peak shifts to shorter wavelength continuously in the Ga3+ doping concentration range of 0.05–0.25. For Mg2+/Ga3+ codoped Y2.96Ce0.04Al(4.8?y)Ga0.20MgyO12 phosphors, the emission intensity decreases and the emission peak shifts to longer wavelength continuously in the Mg2+ doping concentration range of 0.02–0.12. The emission spectra of Y2.96Ce0.04Al(4.8?y)Ga0.20MgyO12 phosphors demonstrate that the codoped Mg2+/Ga3+ ions not only induce the enhancement of Y2.96Ce0.04Al5O12 emission intensity but also lead to the red shift of Y2.96Ce0.04Al5O12 emission peak. The decay lifetimes decrease in Mg2+/Ga3+ codoped Y2.96Ce0.04Al5O12 phosphors due to defects formed by substitutions of Y3+ by Mg2+/Ga3+. 相似文献
7.
Shivani Jindal Kamaldeep Kaur N. K. Verma Puneet Sharma 《Journal of Materials Science: Materials in Electronics》2018,29(1):86-90
Cd1?xTbxS (x?=?0.00, 0.05, 0.10, 0.15) nanoparticles were synthesized by hydrothermal technique. The effect of Tb-doping on structural, optical and magnetic properties were studied. The X-ray diffraction (XRD) confirmed wurtzite phase without any impurity. HR-TEM micrographs revealed the particle size of ~?18 nm with spherical morphology. Band gap calculated from UV–Visible absorption spectra showed an initial decrease from 2.49 eV (x?=?0) to 2.45 eV (x?=?0.10). Further, increasing Tb-doping to x?=?0.15 band gap increased to 2.54 eV. Photoluminescence emission spectra showed peaks at 430 and 490 nm for x?=?0 and 0.05 which corresponds to blue emission. Further increase in Tb doping, peaks found to be quenched. Peak at 530 nm is due to green emission and shifted to higher wavelength with Tb-doping. Magnetic analysis confirmed ferromagnetism in both undoped and Tb-doped nanoparticles. Saturation magnetization found to decrease upto x?=?0.10 and increased for x?=?0.15. 相似文献
8.
V. V. Yagodin A. V. Ishchenko M. N. Sarychev G. F. Babailova N. S. Akhmadullina A. S. Lysenkov Yu. F. Kargin B. V. Shul’gin 《Inorganic Materials》2018,54(5):446-453
Polycrystalline Al5O6N samples have been prepared by sol–gel synthesis followed by carbothermal reduction and nitridation. X-ray luminescence (XRL) spectra and thermoluminescence (TL) curves of Ce3+- and Eu2+-doped aluminum oxynitride have been measured in the temperature range 5–380 K and analyzed. Working TL peaks have been detected in the range 150–250 K for the Al5O6N:Ce3+ sample and in the range 140–200 K for the Al5O6N:Eu2+ samples. There are also lower temperature peaks: in the ranges 10–60 and 20–100 K. The XRL spectra of the samples have been measured at temperatures of 8 (for the first time) and 300 K. 相似文献
9.
A. N. Georgobiani B. G. Tagiev O. B. Tagiev S. A. Abushov G. Yu. Eiyubov 《Inorganic Materials》2008,44(1):1-5
Data are presented on the 300-K photoluminescence in GaS crystals doped with Er3+ or codoped with Er3+ and Yb3+. IR excitation (λex = 976 nm) gives rise to anti-Stokes luminescence in GaS:Er3+ (0.1 at %) and GaS:Er3+,Yb3+ (0.1 + 0.1 at %) and leads to an increased intensity of the emission due to the 4 I 11/2 → 4 I 15/2 transitions. The anti-Stokes luminescence is shown to result from consecutive absorption of two photons by one Er3+ ion, and the increased intensity of Er3+ luminescence in GaS: Er3+,Yb3+ is due to energy transfer from Yb3+ to Er3+. 相似文献
10.
Campus G Garcia-Godoy F Gaspa L Panzanelli A Piu PC Micera G Lugliè P Sanna G 《Journal of materials science. Materials in medicine》2007,18(8):1521-1527
The short term (up to 14 days after restoration) release of selected ions (i.e., Hg(2+), Cu(2+) and Zn(2+)) from Dispersalloy into artificial saliva has been evaluated in regards to the nature of the saliva (Fusayama and McCarty and Shklar's solutions), the amount of amalgam, the time of contact and the periodical renewal (every 48 h interval) of artificial saliva. The evaluation of the ionic fraction of such metals has been accomplished by using anodic stripping methods (i.e., Differential Pulse Anodic Stripping Voltammetry, DPASV) with a 7 microm graphite disk microelectrode as a working electrode. Data obtained in this work are almost unprecedented in the literature due the fact that such analytical method exclude metals in non-ionic forms (e.g., metals or organometallic compounds). The high concentrations measured in every experimental condition confirm the concern for the short-term release of metals from amalgam into saliva. 相似文献
11.
Ce3+/Mn2+ singly doped and codoped Mg2Al4Si5O18 phosphors were synthesized by a solid state reaction. The phase, luminescent properties and thermal stability of the synthesized phosphors were investigated. Ce3+ and Mn2+ singly doped Mg2Al4Si5O18 phosphors show emission bands locating in blue and yellow–red regions, respectively. In Ce3+ and Mn2+ codoped Mg2Al4Si5O18, tunable luminescence was obtained because of the energy transfer from Ce3+ to Mn2+. In Mg2Al4Si5O18:Ce3+/Mn2+ phosphors with a fixed Ce3+ concentration, energy transfer efficiency increases with the increasing Mn2+ concentration, which is confirmed by the continually decreasing intensity and shortening decay time of Ce3+ emission. Moreover, the luminescent properties and thermal stability provide a great significance on the applications in the field of light emitting diodes. 相似文献
12.
Haike Ren Fugui Yang 《Journal of Materials Science: Materials in Electronics》2018,29(18):15396-15403
The Mn2+, Yb3+, Er3+: ZnWO4 green phosphors are synthesized successfully through the high temperature solid state reaction method. The micro-structure and morphology have been investigated by means of XRD and EDS. The doped concentrations of Mn2+, Yb3+, Er3+ are measured by ICP. The absorption spectra and emission spectra with different doped concentrations of Mn2+ are presented to reveal the influence of Mn2+ on the green up-conversion performance. Excited with 970 nm LED, the up-conversion emission peak at 547 nm is obtained and the CIE spectra as well as the green light photo are also presented. The results indicate that the Mn2+ ions play the role of the luminescence adjustment in the up-conversion process, which can improve the up-conversion green emission intensity effectively. The luminescence adjustment mechanism of Mn2+ ions in Mn2+, Yb3+, Er3+: ZnWO4 green phosphors has been discussed. The crystal parameters of Dq, B and C are calculated to evaluate the energy level split effect. 相似文献
13.
Due to the inherent anisotropy of the system, gold nanorods behave differently in comparison to their spherical counterparts.
Reactivity of gold nanorods, in presence of cupric ions, was probed in an attempt to understand the chemistry of anisotropic
particles. The reaction progresses through a series of intermediates. It can be arrested at any stage to get nanorods of desired
dimension and therefore, can be used for their reshaping. The presence or absence of cetyltrimethylammonium bromide (CTAB)
on the nanorod surface was found to be determining the site of initiation of the reaction. When a large concentration of CTAB
is present in the system, selective etching of the tips of the nanorod occurs and when the nanorods are purified to reduce
the amount of CTAB in the solution, the side faces of the nanorod also get reacted. Gold nanorods are converted to particles
by further surface reconstructions in a systematic surface specific chemistry. 相似文献
14.
Devender Singh Vijeta Tanwar Anura P. Simantilleke Bernabe Mari Pratap Singh Kadyan Ishwar Singh 《Journal of Materials Science: Materials in Electronics》2016,27(3):2260-2266
BaAl2O4:Eu2+,RE3+ (RE3+=Y, Pr) down conversion nanophosphors were prepared at 600 °C by a rapid gel combustion technique in presence of air using boron as flux and urea as a fuel. A comparative study of the prepared materials was carried out with and without the addition of boric acid. The boric acid was playing the important role of flux and reducer simultaneously. The peaks available in the XPS spectra of BaAl2O4:Eu2+ at 1126.5 and 1154.8 eV was ascribed to Eu2+(3d 5/2) and Eu2+(3d 3/2) respectively which confirmed the presence of Eu2+ ion in the prepared lattice. Morphology of phosphors was characterized by tunneling electron microscopy. XRD patterns revealed a dominant phase characteristics of hexagonal BaAl2O4 compound and the presence of dopants having unrecognizable effects on basic crystal structure of BaAl2O4. The addition of boric acid showed a remarkable change in luminescence properties and crystal size of nanophosphors. The emission spectra of phosphors had a broad band with maximum at 490–495 nm due to electron transition from 4f 65d 1 → 4f 7 of Eu2+ ion. The codoping of the rare earth (RE3+=Y, Pr) ions help in the enhancement of their luminescent properties. The prepared phosphors had brilliant optoelectronic properties that can be properly used for solid state display device applications. 相似文献
15.
The spectral parameters of Er3+ in Yb3+/Er3+:KY(WO4)2 crystal with space group C2/c have been investigated based on Judd-Ofelt theory. The spectral parameters were obtained: the intensity parameters are: 2 = 6.33 × 10–20 cm2, 4 = 1.35 × 10–20 cm2, 6 = 1.90 × 10–20 cm2. The radiative lifetime and the fluorescence branch ratios were calculated. The emission cross section e (at 1536 nm) is 2.0 × 10–21 cm2. 相似文献
16.
17.
Absorption characteristics of Cu2+, Mn3+ and Cr3+ ions in ternary silicate (20Na2O·10RO·70SiO2, where R=Ca, Sr, Ba) glasses were investigated. The intensities of absorption bands due to Cu2+ ion was found to increase with increasing ionic radii of the alkaline earth ions whereas it was found to decrease in case
of Mn3+ and Cr3+ ions with increasing ionic radii of the alkaline earth ions. The results were discussed in the light of relation between
linear extinction coefficients of these ions and coulombic force of alkaline earth ions. The change in intensities of Cu2+, Mn3+ and Cr3+ ion is attributed due to change in silicate glass compositions. 相似文献
18.
E. K. Yukhno L. A. Bashkirov L. S. Lobanovsky S. V. Trukhanov S. V. Slonskaya 《Inorganic Materials》2016,52(2):218-224
Single-phase ceramic samples of La1–xNdxInO3 (0.007 ≤ x ≤ 0.05), LaIn0.99M0.01O3, and La0.95Nd0.05In0.995M0.005O3 (M = Cr3+ and Mn3+) solid solutions have been prepared by solid-state reactions, and their crystal structure, magnetic field dependences of their specific magnetization at 5 and 300 K, and temperature dependences of their molar magnetic susceptibility have been studied. It has been shown that the 300-K specific magnetization of the La1–xNdxInO3 (x = 0.02, 0.05), La0.95Nd0.05In0.995M0.005O3 (M = Cr3+ and Mn3+), and LaIn0.99Mn0.01O3 solid solutions increases linearly with increasing magnetic field strength up to 14 T and that the magnitude of the 300-K specific magnetization of the La0.993Nd0.007InO3 and LaIn0.99Cr0.01O3 solid solutions increases linearly, but they have diamagnetic magnetization. At a temperature of 5 K, the magnetization of all the indates studied here increases nonlinearly with increasing magnetic field strength, gradually approaching magnetic saturation, without, however, reaching it in a magnetic field of 14 T. In the temperature range where the Curie–Weiss law is obeyed (5–30 K), the effective magnetic moments obtained for the Nd3+ ion (\({\mu _{effN{d^{3 + }}}}\)) in the La1–xNdxInO3 solid solutions with x = 0.007, 0.02, and 0.05 are 2.95μB, 3.09μB, and 2.75μB, respectively, which is well below the theoretical value \({\mu _{effN{d^{3 + }}}}\)= 3.62μB. The effective magnetic moments of the Cr3+ and Mn3+ ions in the LaIn0.99Cr0.01O3 and LaIn0.99Mn0.01O3 solid solutions are 3.87μB and 5.11μB, respectively, and differ only slightly from the theoretical values \({\mu _{effC{r^{3 + }}}}\)= 3.87μB and \({\mu _{effM{n^{3 + }}}}\)= 4.9μB. 相似文献
19.
Pr3+/Ce3+:YAG precursors were co-precipitated using triethanolamine as dispersant and pH regulator. The different dosages of triethanolamine (D) vs. the properties of Pr3+/Ce3+:YAG phosphors were discussed. When D = 0.5 vol%, the pH of titration process was controlled in the range of ~7.94–8.16 to guarantee the uniform distribution of Al, Y, Ce and Pr in the precursors. The relatively higher pH could decrease the loss of Ce and Pr in the precursors and increase the particle size of the obtained powders, which was beneficial to the enhancement of luminescent intensity. Therefore, the precursors directly converted to pure-phase YAG at 900°C, and the phosphors calcined at 1000°C showed the best dispersity due to the dispersion effect of triethanolamine and the most excellent luminescent property. When D ≥ 2 vol%, although pure-phase YAG was detected, the emission intensity of the phosphors decreased due to the decrease of dispersity and purity. Moreover, the co-doped Pr3+ enhanced the red emission of Pr3+/Ce3+:YAG phosphors. 相似文献
20.
La2O3 doped nanocrystalline zirconia (ZrO2) has been prepared by chemical co-precipitation method for various dopant concentrations, varying from 3 to 30 mol%. Structural phases have been characterized by X-ray diffraction technique. All the as-synthesized samples were found to be in monoclinic phase. Annealing of the samples at different temperatures from 400 to 1000∘C stabilized ZrO2 either partially or fully the tetragonal/cubic phases. When they were annealed at 1200∘C, the monoclinic phase appeared again with a new cubic pyrochlore structured La2Zr2O7 at the expense of stabilized tetragonal phase. Formability of the tetragonal/cubic phase has been influenced by the dopant concentration and the annealing temperature. Sample with 8 mol% La2O3 has been stabilized completely in tetragonal/cubic phase after annealing at 900∘C for 1 h. Smallness of the grain in these nanocrystalline materials may also have assisted in the formation of La2O3-ZrO2 solid solution. 相似文献