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1.
Lipeng Jiang Xiyan Zhang Shiqi Zhu He Tang Qingxi Li Wenmin Zhang Xiaoyun Mi Liping Lu Hongwei Liu Xiuling Liu 《Journal of Materials Science: Materials in Electronics》2018,29(11):9045-9051
Y3?yAl5?xGaxO12:Ce3+y phosphors were prepared by high temperature solid state reaction method. The crystal structures, the influence of Ga3+ concentration on the photoluminescence (PL), cathodoluminescence, thermal stability and morphology of the phosphors were studied in detail. The results indicated that diffraction angle of the samples decreased gradually with the increase of Ga3+ ions content in XRD pattern. The emission peak of the spectra show a progressive blue-shift, the intensity increased first and then decreased and the optimal Ga3+ concentration in Y2.94Al5?xGaxO12:Ce3+0.06 phosphors is x?=?0.75. The critical concentration of Ce3+ in YAGG:Ce3+ phosphors is affected with the ratio of Ga3+ to Al3+ and the Y2.9Al4.25Ga0.75O12:Ce3+0.1 phosphor showed the best performance on PL. However, the optimum concentration of Y3?yAl5?xGaxO12:Ce3+y phosphors is x?=?1.5 and y?=?0.04 when they were excited by cathode ray. 相似文献
2.
Guo-Zhong Zang Li-Ben Li Xiu-Jie Yi Juan Du Yan Li 《Journal of Materials Science: Materials in Electronics》2012,23(5):977-980
Lead-free (K0.48Na0.52)(W2/3Bi1/3)xNb1−xO3 (KNN-WBi) piezoceramics with x ranging from 0.004 to 0.010 were synthesized by conventional ceramic processing. The sintered
KNN-WBi ceramics showed perovskite structure without detectable secondary phase containing W and Bi. With increasing x, the
orthorhombic-tetragonal phase transition temperature (T
O-T) decreased from 200 to 184 °C whereas, the tetragonal-cubic phase transition temperature (T
C) decreased slightly. With the doping of (W2/3Bi1/3), the piezoelectric properties were greatly improved and the piezoelectric constants d
33, k
p, Q
m exhibited maximum values of 136 pC/N, 43.3% and 175, respectively at x = 0.008. The KNN-WBi ceramics also exhibited good ferroelectric properties with remnant polarizations P
r higher than 25 μC/cm2 and coercive fields E
c lower than 1,000 V/mm. The results strongly suggest that the B site doping of constructed quinquevalent element is an effective
method for the investigation of potassium sodium niobate system. 相似文献
3.
Wenhao Ding Wen Sun Chengfu Deng Lixi Wang Qitu Zhang 《Journal of Materials Science: Materials in Electronics》2017,28(20):15050-15055
SmNixFe1?xO3 (0?≤?x?≤?0.5) with perovskite-type structure has been successfully prepared by conventional solid-state reaction as a microwave and laser multi-functional material. The optimized synthesis temperature and the effects of Ni doping on the reflectivity, electromagnetic loss properties were investigated in details. XRD results shown that synthesis temperature did not change the perovskite structure of SmFeO3. The reflectivity at 1.06 μm was about 0.33% at 1200–1300?°C. Doping Ni did not cause the change of perovskite structure. The incorporation of Ni in SmFeO3 contributed to the decrease of reflectivity at a wider wavelength, SmNi0.3Fe0.7O3 possessed the lowest reflectivity at 1.06 μm. Moreover, electromagnetic property was very sensitive to Ni content. The real and imaginary parts of complex permeability were enhanced remarkably at a certain frequency. The changes in magnetic performance provided possibility of choosing specific frequency of magnetic loss. The difference in electric and magnetic losses caused by Ni concentration could result in microwave absorption at different frequency. In a word, SmNixFe1?xO3 could be a promising candidate for a multi-functional material with compatible camouflage capability for radar and laser waveband. 相似文献
4.
T. Ramesh R. S. Shinde S. Senthil Kumar S. R. Murthy 《Journal of Materials Science: Materials in Electronics》2017,28(19):14138-14148
Gadolinium substituted yttrium iron garnet (Gd: YIG: Y3?xGdxFe5O12 where x?=?0, 0.25, 0.5, 0.75, 1, 1.25, 1.5) nanopowders were synthesized by microwave hydrothermal method. Phase structure of synthesized powders was examined using fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) which revealed a cubic garnet structure. Spherical-like morphology of synthesized powders was confirmed by field emission scanning electron microscopy (FESEM) studies. The synthesized powders were sintered at 1100?°C for 60 min using microwave furnace and characterized by using XRD and FESEM. Magnetic properties such as saturation magnetization and Curie temperature were measured using vibration sample magnetometer (VSM) and differential scanning calorimetry (DSC) studies respectively. Temperature stability of magnetization was measured using pulse magnetometer and complex permeability was measured over a frequency range of 100 kHz–1.8 GHz. The obtained results showed that the saturation magnetization as well as permeability decrease while curie temperature and temperature stability increase with Gd concentration. It is concluded that substitution of Gd makes the YIG better microwave magnetic material, which may be used in high power non-reciprocal microwave devices in the microwave region. 相似文献
5.
6.
Shyla Joseph James T. Joseph Annamma John J. K. Thomas Sam Solomon 《Journal of Materials Science: Materials in Electronics》2011,22(7):741-744
LnTiSbxNb1−xO6 (Ln = Ce, Pr) ceramics were prepared by the conventional solid state ceramic route for x = 0, 0.05, 0.1, 0.15, 0.2 and 0.25.
The structure of the materials was analyzed using X-ray diffraction techniques. The cell parameters and the theoretical densities
of the samples were calculated using least square methods. The samples are sintered to more than 90% of the theoretical density
at 1,325–1,350 °C. The microwave dielectric properties were measured using the cavity resonator method. The surface morphology
of the sintered sample was analyzed using Scanning Electron Microscopy. All the materials have good microwave dielectric properties
and are suitable for dielectric resonator applications. 相似文献
7.
A. G. Belous O. V. Ovchar D. O. Mishchuk A. V. Kramarenko B. Jancar J. Bezjak D. Suvorov 《Inorganic Materials》2007,43(4):412-417
The formation of the columbite-structure magnesium niobate MgNb2O6 is a multistep process. Single-phase material can only be obtained through long-term high-temperature heat treatment. Deviations from stoichiometry have a significant effect on the microwave quality factor Q of the material: magnesium-deficient ceramics contain small amounts of Nb2O5 and have relatively low Q values, whereas an excess of magnesium leads to the formation of Mg4Nb2O9 (alpha-alumina structure) as an impurity phase, thereby drastically increasing the electrical Q. 相似文献
8.
Ying Yuan Shuren Zhang Xiaohua Zhou Longcheng Xiang 《Journal of Materials Science: Materials in Electronics》2008,19(4):343-347
(Zn1−xMgx)TiO3 (x = 0.1–0.5) solid solutions were synthesized by solid-state reaction using ZnO, (MgCO3)4·Mg(OH)2·5H2O and TiO2 as raw materials. The influences of Zn: Mg ratio and calcining temperature on the properties of (Zn1−xMgx)TiO3 were studied. By adding CaTiO3 into (Zn1−xMgx)TiO3, the microwave properties and sintering behavior were improved. The ceramics could be sintered at 1150 °C, and the ceramics
with excellent microwave properties of τf ≈ ±10 ppm/°C, ε ≈ 24, Q × f > 45000 GHz (8 GHz) were obtained. 相似文献
9.
T. P. Dhanya P. S. Simna R. Ratheesh 《Journal of Materials Science: Materials in Electronics》2011,22(8):974-977
The ceramic compositions Ba3−xSrxLiM3Ti5O21[M=Nb and Ta, x = 0 to 3] were prepared through conventional solid state ceramic route. A detailed study has been carried
out to correlate the structure of Ba3−xSrxLiM3Ti5O21[M=Nb and Ta, x = 0 to 3] with respect to their dielectric properties. The structure and microstructure of ceramic samples
were studied using powder X-ray diffractometer and Scanning Electron Microscopic techniques. The dielectric properties of
the sintered ceramic compacts have been studied. The Ba-rich compositions were identified as promising candidates for high
frequency applications whereas the Sr-rich compositions were excellent ionic conductors and can be commercially exploited
for applications in solid-state batteries. 相似文献
10.
JiQiang Jia JianMin Li GaoYang Zhao 《Journal of Superconductivity and Novel Magnetism》2018,31(6):1733-1739
By the combined use of the sol-gel and pulsed laser deposition methods, the SrTiO3/YBa2Cu3O7?x (STO/YBCO) heterostructure was prepared on a LaAlO3 substrate. XRD results and φ scanning test showed that the prepared STO/YBCO heterostructure had good biaxial texture. Moreover, a Pt electrode was sputtered on the STO/YBCO heterostructure to investigate the current density-voltage (J ? V) characteristic curves of STO/YBCO in the 50–300 K temperature range. The results showed that the STO/YBCO heterostructure had good rectifying characteristics. With an applied positive bias voltage smaller than 3.7 V, the current density of the STO/YBCO heterostructure decreased with the decrease of temperature; for higher voltages, on the contrary, the current density increased with the decrease of temperature. When the YBCO experienced superconducting transition, the turn-on voltage (V t) changed suddenly due to the sudden opening of the superconducting energy gap of YBCO. The V t variation obtained from the experiment was essentially consistent with the known value of the YBCO superconducting energy gap. 相似文献
11.
L. V. Kokhanovskii Yu. G. Zonov O. P. Ol’shevskaya V. V. Pan’kov 《Inorganic Materials》2005,41(8):876-881
SrCo1 − x
FexO3 − δ solid solutions with 0.3 ≤ x ≤ 0.9 are shown to have the cubic perovskite structure. The unit-cell parameter and volume of the solid solutions are nonmonotonic functions of Fe content, with a minimum at x = 0.4. Dilatometric data are used to determine the thermal expansion coefficients of the solid solutions. At low oxygen partial pressures (
≤ 40 Pa), the high-temperature, disordered perovskite phase exists between 850 and 1000°C, which is the optimal temperature range for the effective use of SrCo1 − x
FxO3 − δ ceramics as oxygen membranes in oxygen partial pressure gradients of 104–105/10–100 Pa.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 8, 2005, pp. 998–1004.Original Russian Text Copyright © 2005 by Kokhanovskii, Zonov, Ol’shevskaya, Pan’kov. 相似文献
12.
Kalengay Mbela T. Moyo Nadir S.E. Osman 《Journal of Materials Science: Materials in Electronics》2016,27(9):8916-8922
Magnesium-iron chromium oxides (Mg0.2Cr1.8?x Fe x O3 with x varying from 0.3 to 0.9) produced by hydrothermal process in a stirred pressure reactor from pure metal chlorides have been annealed at 700 °C. Single phase corundum structure and nanophase structure of the as-synthesized samples were confirmed by X-ray diffraction (XRD). Instead of the correlation between H EB and D XRD observed at T A = 600 °C, we find significant changes. The H EB increases with decreasing particle size reaches a maximum at ~43 nm (x = 0.5) then decreases. 相似文献
13.
Gadolinium doped bismuth borate glasses containing up to 30 mol% Y2O3 were prepared by fast melt quenching method. The effect of yttrium on the local order in 3B2O3 · Bi2O3 and B2O3 · Bi2O3 glass matrices, particularly on the bismuth sites, was investigated by infrared (IR) spectroscopy and electron paramagnetic
resonance (EPR) of Gd3+ ions. The IR results show that the local structure is more ordered in the glass system with higher bismuth content and the
progressive addition of yttrium increases the local disorder in both bismuth–borate glass matrices. The EPR results indicate
that Gd3+ ions occupy both bismuth and yttrium sites and reflect the same structural disorder like that suggested by IR results. 相似文献
14.
Qiang Li Shengxiang Bao Yuanxun Li Lijie Song Wei Jiang Yongda Hu 《Journal of Materials Science: Materials in Electronics》2015,26(11):8887-8891
In this paper, Cr-doped Bi0.9Ba0.1Fe1?xCrxO3 (x = 0.00, 0.05, 0.10, 0.15, 0.20) ceramic materials were prepared by traditional state solid synthesized method, and the effects of Cr3+ ion on magnetic and dielectric properties were investigated. All samples showed BiFeO3 phase formation were successful synthesized. The SEM images showed the shape of samples changed from regular to irregular shape. With increasing of Cr2+ ions, Saturation magnetization (M s) increased from 5.24 to 8.6 emu/g, and then decreased to 7.31 emu/g, and coercivity (H c) increased from 110.66 to 256.49 Oe. All the samples showed high dielectric constants at low frequency and the values of dielectric constants decreased slightly with frequency increasing. Delectric loss (tanδ) values kept a steady in a wide range frequency of 10–600 MHz. They ranged in tanδ from 0.01 to 0.07, which was a low dielectric loss in Bi0.9Ba0.1Fe1?xCrxO3 ceramics. 相似文献
15.
A. N. Demina K. P. Polovnikova E. A. Filonova A. N. Petrov A. K. Demin E. Yu. Pikalova 《Inorganic Materials》2007,43(4):430-435
The thermal expansion and electrical conductivity of La0.7Sr0.3Mn1 ? y CryO3 (y = 0, 0.1, 0.3, 0.4) solid solutions have been studied at temperatures from 300 to 1270 K and oxygen partial pressures from 10?9 to 2.1 × 104 Pa. The solid solutions crystallize in rhombohedral symmetry (sp. gr. R3c). The lattice parameters of La0.7Sr0.3Mn1 ? y CryO3 decrease with increasing chromium content. Doping with chromium reduces the conductivity of lanthanum manganite, without changing the conductivity type. The charge transport in the solid solutions is due to small-polaron hopping. Disproportionation of the 3d transition metals is shown to play a key role in determining the electrical properties of the solid solutions. Partial chromium substitution for manganese reduces the thermal expansion coefficient of the manganite, improving its compatibility with yttria-stabilized zirconia, which is of practical importance. 相似文献
16.
Ajeet Kumar K. C. James Raju A. R. James 《Journal of Materials Science: Materials in Electronics》2018,29(16):13483-13494
In this work, (Pb1?xLax)(Zr0.60Ti0.40)O3 (PLZT x/60/40, x?=?at.%) ceramics were prepared by using high energy mechanical ball milling followed by cold isostatic pressing (CIP), investigated for their micro-structural, dielectirc, ferroelectric and piezoelectric properties. Mechanical activation results in the highly reactive nature of the nano size milled PLZT powders, which enables the partial perovskite phase formation, confirmed by room temperature XRD patterns. CIP leads to a higher density with a closely packed dense microstructure of sintered PLZT ceramics shown in SEM images. The grain size of PLZT x/60/40 ceramics was found to be decreasing with increasing La3+ content. The highest relative density of ~?97% was found to be for PLZT 8/60/40 ceramics with grain size of ~?1.35 µm. The PLZT 8/60/40 system also shows the highest dielectric constant of ~?1976, remnant polarization of 29.1 µC/cm2, piezoelectric coefficients (d33?\(~ \cong ~\)?570 pC/N, g33?\(~ \cong ~\)?28.03?×?10?3 Vm/N) and electromechanical coupling factors (kp?=?k33?=?64.1% and k31?=?54%). The elastic compliances for the PLZT x/60/40 ceramics were also obtained. 相似文献
17.
Nipaka Sukpirom Sirinoot Iamsaard Sumittra Charojrochkul Jinda Yeyongchaiwat 《Journal of Materials Science》2011,46(20):6500-6507
The synthesis of LaNi1−
x
Fe
x
O3−δ (LNF) perovskites with x = 0.0–1.0, for use as cathode materials for an IT-SOFC, was investigated using four combustion methods, Water Citrate (WC),
Modified Water Citrate (MWC), Nitric Citrate (NC), and Modified Nitric Citrate (MNC). The structures and homogeneities of
the synthesized powders were examined using an XRD, and the particle sizes were examined using an SEM and a particle size
analyzer. All four combustion methods gave the single phase perovskites with the same structure. The main difference was shown
in a particle size that the smallest to the largest sizes were obtained from MNC, MWC, NC, and WC, respectively. In this LNF
series, as x is 0–0.5, the crystal structure is cubic and rhombohedral at the calcination temperature of 700 and 900 °C, respectively.
Further investigation indicated that the cubic structure changed to rhombohedral structure at 900 °C, and was stable up to
1200 °C. As x is 0.6–1.0, the crystal structure is in orthorhombic phase when calcined between 700 and 1000 °C. This orthorhombic phase
decomposed above 1100 °C. From the XRD and SEM–EDX results, LaNi0.6Fe0.4O3−δ (LNF64) has a good chemical compatibility with 8YSZ from room temperature up to 900 °C. In addition, its thermal expansion
coefficient is 13.2 × 10−6 K−1 close to that of 8 mol% Y2O3 (8YSZ). Therefore, LNF64 also has a good physical compatibility with 8YSZ. 相似文献
18.
A. L. Podkorytov A. L. Timofeev I. A. Shevyakova V. O. Mal’tseva S. A. Shtin N. N. Zabolotskikh 《Inorganic Materials》2018,54(7):672-675
In this paper, we report the solid-state synthesis, characterization, and physicochemical properties of Pb4–xMxNb2O9 (M = Cu, Ni; x = 0–1.0) solid solutions. We have identified the stability limits of the solid solutions. Using the tolerance factor and relative electronegativities of the A- and B-site atoms (A4B2O9), we have identified the stability fields of the perovskite-related solid solutions. The materials have been characterized by X-ray diffraction, and the particle size composition of the synthesized powders has been determined. Their electrical conductivity has been measured as a function of temperature. We have studied the key electrochemical characteristics of solid-contact ion-selective electrodes fabricated using the synthesized materials: linear range and slope of the principal electrode function, working pH range, and response time. 相似文献
19.
J. Peng M. M. Wu F. L. Guo S. B. Han Y. T. Liu D. F. Chen X. H. Zhao Z. Hu 《Journal of Materials Science》2011,46(15):5160-5164
A new series of solid solutions Y2W3−x
Mo
x
O12 (0.5 ≤ x ≤ 2.5) were successfully synthesized by the solid state method. Their crystal structure and negative thermal expansion properties
were studied using high-temperature X-ray powder diffraction and the Rietveld method. All samples of rare earth tungstates
and molybdates were found to crystallize in the same orthorhombic structure with space group Pnca, and show the negative thermal expansion phenomena related to transverse vibration of bridging oxygen atoms in the structure.
Thermal expansion coefficients (TEC) of Y2W3−x
Mo
x
O12 were determined as −16.2 × 10−6 K−1 for x = 0.5 and −16.5 × 10−6 K−1 for x = 2.5 in the identical temperature range of 200–800 °C. High-temperature XRD data and bond length analysis suggest that the
difference between W–O and Mo–O bond is responsible for the change of TECs after the element substitution in this series of
solid solutions. 相似文献
20.
A continuous series of Bi2W1 − x
Mo
x
O6 solid solutions between the n = 1 Aurivillius phases Bi2WO6 and Bi2MoO6 with a polar orthorhombic structure (γ-phase) have been prepared by solid-state reactions at 850 (0 < x ≤ 0.3) and 530–640°C (0.3 ≤ x < 1), and their thermal and electrical properties have been studied throughout their stability region, between room temperature
and 960°C, with the aim of gaining detailed insight into their polymorphism. The results demonstrate that the tungsten-rich
(0 ≤ x ≤ 0.2) materials undergo a ferroelectric and a reconstructive phase transition like bismuth tungstate, Bi2WO6. The temperatures of both transitions decrease with increasing molybdenum content. The molybdenum-rich materials in the composition
range 0.9 ≤ x ≤ 1 are similar in properties to bismuth molybdate, Bi2MoO6. In the composition range 0.3 ≤ x ≤ 0.8, neither ferroelectric nor reconstructive phase transition was detected. 相似文献