共查询到20条相似文献,搜索用时 15 毫秒
1.
V. V. Ivanova V. V. Gagulin S. K. Korchagina Yu. A. Shevchuk V. V. Bogatko 《Inorganic Materials》2003,39(7):745-748
(1 – x)BiFeO3–xDyMnO3 solid solutions with x= 0.03–0.30 are synthesized for the first time, and their dielectric and magnetic properties are studied. The solid solutions with x 0.08 have a rhombohedrally distorted perovskite structure, and those with x = 0.10–0.30 have an orthorhombically distorted structure. The 1-kHz electrical conductivity of the solid solutions exhibits semiconducting behavior and rises exponentially with temperature. The dielectric properties of the solid solutions are investigated in the microwave range (0.5–2.5 GHz) between room temperature and 250°C. The real part of their room-temperature dielectric permittivity reaches a maximum at x= 0.20, while the largest tan is observed at x = 0.03. The solid solutions with x= 0.03–0.08 exhibit high dielectric losses and are, therefore, candidate microwave absorbing materials. The magnetic and electrical ordering temperatures in the composition range studied exceed room temperature; that is, these solid solutions are new high-temperature seignettomagnetic materials. 相似文献
2.
E. M. Godzhaev A. M. Nazarov Kh. S. Khalilova A. M. Suleimanova 《Inorganic Materials》2002,38(9):876-879
TlIn1 – x
Nd
x
Se2(0 < x 0.1) solid solutions were characterized by x-ray diffraction and temperature-dependent electrical conductivity, Hall effect, thermoelectric power, and heat capacity measurements. With increasing Nd content, the lattice parameters of the solid solutions increase almost linearly, and their band gap decreases. 相似文献
3.
R. Z. Mekhtieva 《Inorganic Materials》2002,38(8):831-833
The effect of gamma irradiation on the dielectric (
33/0, tan) and piezoelectric (d
31, g
31, K
p, Q
m) properties of 2Sr4Nb10O30–K6Li4Nb10O30 solid solutions (tetragonal tungsten bronze structure) was studied as a function of K6Li4Nb10O30 content. The results demonstrate that increasing the gamma dose to 9 × 105 Gy reduces
33/0 and tan. With increasing Li+ content (filling of triangular channels), d
31, g
31, K
p, and Q
m increase. The results are interpreted in terms of the generation of stable defects and effective redistribution of the energy of gamma radiation over the ceramic sample. 相似文献
4.
The T–x phase diagram of the CdTe–MnTe system is mapped out. The CdTe–MnTe join is shown to be nonpseudobinary. The system contains an extended series of CdTe-based solid solutions (0–71.4 mol % MnTe at 1070 K). At 1070 K, -MnTe dissolves up to 0.3 mol % CdTe. Data are presented on the composition dependences of lattice parameters for the solid solutions studied and the luminescent properties of Cd1 – x
Mn
x
Te single crystals annealed in cadmium or tellurium vapor. 相似文献
5.
Yu. A. Shevchuk V. V. Gagulin S. K. Korchagina V. V. Ivanova 《Inorganic Materials》2001,37(8):836-838
Pb(Fe1/2Nb1/2)O3–Pb(Fe2/3W1/3)O3solid solutions were characterized by dielectric measurements at low frequencies and in the microwave range and magnetic measurements at high frequencies. The observed microwave dispersion was tentatively attributed to the domain mechanism of polarization. The obtained results suggest that the solid solutions studied are potential microwave-absorbing materials. 相似文献
6.
A. G. Belous E. V. Pashkova A. N. Makarenko V. P. Ivanitskii O. I. V'yunov A. V. Ragulya 《Inorganic Materials》2004,40(11):1196-1203
Tetragonal Zr0.886Y0.057Fe0.057O2 – solid solutions prepared by calcining coprecipitated and successively precipitated hydroxide mixtures were studied by Mössbauer spectroscopy immediately after calcination and after long-term storage. The results indicate that the solid solutions prepared via coprecipitation and successive precipitation contain Fe3+ in two (octahedral coordination) and three (octahedral, fivefold, and tetrahedral coordinations) inequivalent sites, respectively. Partial Fe3+ substitution for Y3+ is shown to prevent or substantially slow down the low-temperature structural degradation of stabilized zirconia. 相似文献
7.
Data are presented on K3Nb3O6(B2O6)1–x
(Si2O7)
x
solid solutions in the K3Nb3B2O12–K3Nb3Si2O13 system. The system is shown to contain two partial solid-solution series in the composition ranges 0 < x< 0.2 (KNB:Si) and 0.8 < x< 1 (KNS:B). KNB:Si crystals are grown from off-stoichiometric melts, and their polymorphism and physical properties are studied. Similar to K3Nb3B2O12, KNB:Si crystals exhibit a complex polymorphism and combine ferroelectric, ferroelastic, and superionic properties. Si substitution for B is shown to have a significant effect on the phase-transition temperatures and electrical properties of K3Nb3B2O12 crystals. The results obtained for K3Nb3Si2O13 crystals demonstrate that, in spite of their hexagonal habit, their room-temperature structure possesses orthorhombic or lower symmetry. The room-temperature dielectric permittivity 33 of K3Nb3Si2O13 crystals is as high as 4000. 相似文献
8.
Chunchun Li Xiaoyong Wei Haixue Yan Michael J. Reece Hongjun Ye 《Journal of Materials Science: Materials in Electronics》2013,24(6):1947-1954
A series of ceramics with a general formula Ca1+xLa4?xNbxTi5?xO17 (0 ≤ x ≤ 4) were fabricated using the solid-state ceramic route. The phase, microstructure, and microwave dielectric properties varied distinctly with composition or the value of x. X-ray diffraction results showed that the two end member phases, CaLa4Ti5O17 and Ca5Nb4TiO17, crystallized into single phases with orthorhombic and monoclinic crystal structure, respectively. For intermediate compounds with x = 1, 2, and 3, mixture phases CaLa4Ti5O17 and Ca5Nb4TiO17 coexisted and a trace amount of second phase was detected. The ceramics showed high ε r in the range of 45–52, relatively high quality factors with Q × f in the range of 9,870–15,680 GHz and τ f value in the range between ?38 and ?126.4 ppm/°C. τ f of CaLa4Ti5O17 can be tuned to a near-zero value by addition of suitable amount of TiO2. 相似文献
9.
The homogeneity range of La2/3–x
Li3x
4/3 – 2x
Ta2O6 perovskite-like solid solutions was determined. The transport properties of the La2/3–x
Li3x
4/3 – 2x
Ta2O6 oxides were shown to correlate with their lattice parameters and composition. Lithium-doped lanthanum metatantalate with an orthorhombically distorted perovskite-like structure is a good solid electrolyte with high lithium ion conductivity. 相似文献
10.
Low-temperature plasma synthesis was used to prepare solid solutions ( and ) in the ZnFe2O4–Zn2ZrO4pseudobinary system. The Zn2 – x
Zr1 – x
Fe2x
O4solid solutions were found to have a tetragonal spinel structure (a= 8.607–8.740 Å, c= 8.798–9.120 Å) in the composition range x= 0–0.55 and a cubic spinel structure (a= 8.447–8.539 Å) at x= 0.75–1.0. The tetragonal lattice distortion is attributed to a pseudo-Jahn–Teller effect. The electrical conductivity of the solid solutions shows semiconducting behavior and rises by a few orders of magnitude with increasing Fe3+content. 相似文献
11.
The fine structure of solid solutions between isomorphic p-block and 3dtransition-metal oxides was investigated experimentally and theoretically in the technologically important systems -Al2O3–M2O3(M = Ti, V, Cr, Fe). It was shown that the thermodynamic theory of isomorphic miscibility and conventional approaches to estimating solubility limits fail to explain and, at best, only predict the phase relations in the systems examined. The proposed magnetochemical method offers the possibility of studying in detail the M–M interactions in first-row oxides M2O3and (M
x
Al1 – x
)2O3solid solutions, probing their homogeneity, and revealing their salient structural features. The marked difference in the solubilities of isomorphic M2O3oxides in -Al2O3is interpreted in terms of the magnetic structure of the oxides. 相似文献
12.
A. L. Podkorytov M. I. Pantyukhina S. A. Shtin V. M. Zhukovskii 《Inorganic Materials》2000,36(12):1282-1284
(Sr1 – x
M
x
)2Nb2O7 (M = Cu, Ni) layered perovskite solid solutions were synthesized, and their stoichiometry ranges were determined. The electrical properties of the solid solutions were compared with those of Sr2Nb2O7. 相似文献
13.
14.
The anisotropic thermal expansion of Cu1 – x
Ag
x
InS2chalcopyrite solid solutions was studied by x-ray diffraction from 80 to 650 K. Over the entire temperature range studied, the thermal expansion of the solid solutions was found to be anisotropic: thec-axis thermal expansion is considerably smaller than thea-axis thermal expansion. The solid solutions with 0.55 <x< 1.0 exhibit negative c-axis thermal expansion. The composition dependences of the thermal expansion coefficients and anisotropy parameters are nonlinear. The anisotropy parameters rise monotonically with increasing x. The correlation between the thermal expansion anisotropy and tetragonal distortion = 2 – c/ais considered. Directions of zero thermal expansion are identified. 相似文献
15.
Ricardo Guido Follador Neto Eder Carlos Ferreira de Souza André Vitor Chaves de Andrade Sandra Regina Masetto Antunes Augusto Celso Antunes 《Journal of Materials Science: Materials in Electronics》2013,24(3):938-944
This work investigated the influence of Nb2O5 dopant on the varistor behavior of the ternary system (99.95 ? x)%TiO2, 0.05 %Cr2O3, x%Nb2O5, where x = 0.10; 0.15; 0.20; 0.25 % in mol. The processing was carried out using the conventional oxide mixture method. The initial oxides were homogenized in alcoholic media in a ball mill, for 3 h, dried in oven and isostatically pressed at 210 MPa and sintered at 1,400 °C for 2 h in air atmosphere and cooled at 5 °C/min cooling rate, resulting in pellets with high densification. Electrical measurements in continuous current at different temperatures revealed that for the lowest Nb2O5 concentration the breakdown electric field, EB = 4.41 V/cm and non-linear coefficient, α = 4.6 were obtained, and for the highest Nb2O5 concentration the breakdown electric field, EB = 9.71 V/cm and non-linear coefficient, α = 15.3 were obtained. These low values in the breakdown electric field enable these varistor systems to be used in protection systems for low-voltage energy grids. Changes in the potential barrier present in the grain–grain boundaries could also be observed, in which the height increased and the width decreased with the increase in the dopant concentration. However, for x = 0.25 % in mol Nb2O5, a significant reduction in the potential barrier height and the voltage per barrier was obtained. Furthermore, the tendency to increase the volume of the unitary cell with the increase of dopant concentration, which was interrupted in the system with 0.25 % Nb2O5, was another evidence that suggested the occurrence of Nb2O5 segregation in the grain boundaries, or even that the reduction in the average grain size could possibly dilute Nb2O5 concentration in the grain boundaries. The average grain size was calculated through SEM micrographs and ranged from 7 to 16 μm, with larger sizes occurring for lower dopant concentrations and presenting higher porosity and lower uniformity in the grains shape. 相似文献
16.
Huanfu Zhou Hong Wang Xiaoyan Ding Xi Yao 《Journal of Materials Science: Materials in Electronics》2009,20(1):39-43
A new Li2O–Nb2O5–TiO2 (LNT) ceramic with the Li2O:Nb2O5:TiO2 mole ratio of 3:1:3 has been investigated. The compound is composed of two phases, the Li2TiO3 and “M-phase” solid solution phase. The microwave dielectric ceramic has low sintering temperature (∼1100 °C) and good microwave
dielectric properties of a relatively high permittivity (∼51), high Q × f value up to 8700, and small temperature coefficient (∼37 ppm/°C). The low-amount doping of 0.83Li2O–0.17V2O5 (LV) can effectively lower the sintering temperature from 1100 to 900 °C and induce no obvious degradation of the microwave
dielectric properties. Typically, the 1 wt.% LV-doped ceramic sintered at 900 °C has better microwave dielectric properties
of εr = 51.3, Q × f = 7235 GHz, τ
f
= 22 ppm/°C, which suggests that the ceramics can be applied in microwave LTCC devices. 相似文献
17.
M. I. Pantyukhina O. L. Andreev Z. S. Martem'yanova N. N. Batalov 《Inorganic Materials》2004,40(4):404-406
The Li8ZrO6–LiYO2 system is shown to contain two partial solid-solution series, which extend to 1 mol % LiYO2 in Li8ZrO6 and 10 mol % Li8ZrO6 in LiYO2. The electrical properties (temperature and composition dependences of conductivity, activation energy, and electronic conductivity) of LiYO2 and Li8ZrO6–LiYO2 solid solutions are studied. 相似文献
18.
Ferroelectric films of Ba0.7–0.8Sr0.2–0.3TiO3 solid solutions 2–3 m in thickness were deposited onto platinum substrates from carboxylate solutions and characterized by dielectric measurements at 1000 Hz: t
C = 15–16°C, 20 > 1000, tan = 0.04–0.06 in the range 10–100°C. The controllability coefficient of the films in a dc electric field between 36 and 42°C is 1.6. 相似文献
19.
Phase relations in the Na2O–Al2O3–Nb2O5and CaO–Al2O3–Nb2O5systems were studied. The Na2O system was found to contain neither ternary compounds nor niobate–aluminate solid solutions. In the CaO system, a ternary compound of composition 4CaO · Al2O3·Nb2O5was identified (cubic structure, a= 7.628 Å, Z= 2, meas= x= 4.43 g/cm3). 相似文献
20.
Cd4GeS6, Hg4GeS6, and Cd4 – x
Hg
x
GeS6 crystals are grown from presynthesized charges. The electrochemical and photoelectrochemical properties of a Cd1.2Hg2.8GeS6 electrode are studied. The energy positions of the conduction-band and valence-band edges are compared for two samples having identical cation compositions but differing in anion composition. 相似文献