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1.
E. V. Dudnik V. V. Tsukrenko A. V. Shevchenko A. K. Ruban L. M. Lopato 《Inorganic Materials》2011,47(10):1107-1110
We have studied the properties of nanocrystalline ZrO2-Y2O3-CeO2-CoO-Al2O3 powders prepared via hydrothermal treatment of a mixture of coprecipitated hydroxides at 210°C. A number of general trends
are identified in the variation of the properties of the synthesized powders during heat treatment at temperatures from 500
to 1200°C. Our results demonstrate that the addition of 0.3 mol % CoO to nanocrystalline ZrO2-based powders containing 1 to 5 mol % Al2O3 allows one to obtain composites with good sinterability at a reduced temperature (1200°C). 相似文献
2.
The formation mechanisms of Li x Na1 ?x Ta y Nb1 ? y O3 perovskite solid solutions in the Li2CO3-Na2CO3-Nb2O5-Ta2O5 system have been studied by x-ray diffraction, differential thermal analysis, thermogravimetry, IR spectroscopy, and mass spectrometry at temperatures from 300 to 1100°C. The results indicate that the synthesis of Li x Na1 ? x Ta y Nb1 ? y O3 solid solutions involves a complex sequence of consecutive and parallel solid-state reactions. An optimized synthesis procedure for Li x Na1 ? x Ta y Nb1 ? y O3 solid solutions is proposed. 相似文献
3.
S. A. Lokare R. S. Devan D. R. Patil Y. D. Kolekar K. K. Patankar B. K. Chougule 《Journal of Materials Science》2007,42(24):10250-10253
Polycrystalline samples of mixed composites of Ni0.93Co0.02Mn0.05Fe2O4 + BaTiO3 were prepared by conventional double sintering ceramic method. The phase analysis was carried out by using X-ray diffraction
technique. Variation of dc resistivity and thermo emf was studied as a function of temperature. AC conductivity (σac) was investigated in the frequency range 100 Hz–1 MHz. The loss tangent (tan δ) measurements conclude that the conduction
mechanism in these samples is due to small polaron hopping. The magnetoelectric conversion factor, i.e. dc(ME)
H
was studied as a function of intensity of magnetic field and the maximum value 407 μV/cm/Oe was observed at a field of 0.8 kOe
in a composite with 85% BaTiO3 and 15% Ni0.93Co0.02Mn0.05Fe2O4 phase. 相似文献
4.
Lead-free ferroelectric ceramics of (1−x) [0.88Na0.5Bi0.5TiO3-0.12K0.5Bi0.5TiO3]-x KNbO3(x = 0, 0.02, 0.04, and 0.06) were prepared by the conventional ceramic fabrication technique. The crystal structure, dielectric properties and P-E hysteresis loops were investigated. XRD data showed that all compositions could form pure perovskite structure. Temperature dependence of dielectric constant ε r and dissipation factor tanδ measurement between room temperature and 500∘C revealed that the compounds experience phase transitions that from ferroelectric to anti-ferroelectric and anti-ferroelectric to paraelectric in the range of x = 0–0.04. The frequency dependent dielectric constant showed these compounds were relaxor ferroelectric. At low frequency and high temperature, dielectric constant and dissipation factor increased sharply attributed to the superparaelectric clusters after the KNbO3 doped. 相似文献
5.
Semiconducting glasses of the Fe2O3-Bi2O3-K2B4O7 system were prepared by the press-quenching method and their dc conductivity in the temperature range 223–393 K was measured. The glass transition temperature values (Tg) of the present glasses were larger than those of tellurite glasses. This indicates a higher thermal stability of the glass in the present system. The density for these glasses was consistent with the ionic size, atomic weight and amount of different elements in the glasses. Mössbauer results revealed that the relative fraction of Fe increases with increasing Fe2O3 content. Electrical conductivity showed a similar composition dependency as the fraction of Fe. The glasses had conductivities ranging from 10 to 10 Scm at temperatures from 223 to 393 K. Electrical conduction of the glasses was confirmed to be due to non-adiabatic small polaron hopping and the conduction was primarily determined by hopping carrier mobility. 相似文献
6.
A. S. Antsyshkina G. G. Sadikov T. I. Koneshova V. S. Sergienko 《Inorganic Materials》2004,40(12):1259-1263
The structure of three compounds in the Cu2Se-In2Se3-Cr2Se3 system near CuInCr2Se5 is determined by single-crystal x-ray diffraction: CuInCr4Se8 (I), Cu2In2Se4 (II), and Cu0.5In0.5Se (III). I has a cubic (spinel type) structure: a = 10.606(4) Å, Z = 4, sp. gr. F43m. II has a pseudotetragonal (sphalerite type) structure: a = 5.774(2) Å, c = 11.617(6) Å. The structure of II was solved in a reduced unit cell with a = 5.774(2) Å, b = 5.774(2) Å, c = 7.095(6) Å, = 113.95(5)°, = 113.95(5)°, = 90.00(4)°, Z = 1, sp. gr. P1. III has a triclinic cell (disordered structure of II): a = 4.088(1) Å, b = 4.091(2) Å, c = 4.101(1) Å, = 60.05(1)°, = 60.08(1)°, = 89.98(4)°, Z = 1, sp. gr. P1. The Cu and In atoms in I sit in inequivalent tetrahedral sites, and the Cr atoms reside in octahedral interstices of the close packing of Se atoms. The bond lengths are In–Se = 2.538(6), Cr(1)–Se(1) = 2.514(7), Cr(1)–Se(2) = 2.576(8), and Cu–Se = 2.437(5) Å. In II, all of the atoms sit in tetrahedral sites; the mean bond lengths are In–Se = 2.578(6) and Cu–Se = 2.44(1) Å. In III, the Cu and In atoms are fully disordered in the same tetrahedral site; the mean Cu(In)–Se bond length is 2.508(6) Å.Translated from Neorganicheskie Materialy, Vol. 40, No. 12, 2004, pp. 1435–1439.Original Russian Text Copyright © 2004 by Antsyshkina, Sadikov, Koneshova, Sergienko. 相似文献
7.
The compounds Gd14Cu48Ga3 and Tb14Cu48Ga3 have been synthesized, and their structures have been determined by powder x-ray diffraction (Gd14Ag51 type). 相似文献
8.
New solid solutions, Bi2?x?y Tm x Nb y O3+δ, with tetragonal and cubic structures have been synthesized in the Bi2O3-Tm2O3-Nb2O5 system, and their electrical conductivity has been measured at temperatures from 670 to 1020 K. The 1020-K conductivity of the tetragonal solid solution Bi1.8Tm0.15Nb0.05O3+δ is comparable to that of Bi1.75Tm0.25O3, the best conductor in the Bi2O3-Tm2O3 system. 相似文献
9.
We have measured the thermal conductivity of Bi2Te3-Sb2Te3-Gd2Te3 solid solutions at temperatures from ~80 to 300 K and have determined the electronic and lattice components of their total thermal conductivity and the contributions of Sb2Te3 and Gd2Te3 to their thermal resistance. The results indicate that heat in these materials is transported largely by phonons and that three-phonon processes play a key role in determining the lattice thermal conductivity of the solid solutions. 相似文献
10.
V. M. Chumarev V. P. Mar’evich A. V. Larionov A. Ya. Dubrovskii 《Inorganic Materials》2011,47(3):267-272
Reactions of vanadium, niobium, and tantalum pentoxides with aluminum nitride have been studied using X-ray diffraction. At
temperatures from 1000 to 1600°C, we have identified various V, Nb, and Ta nitrides. The composition of the niobium and tantalum
nitrides depends on the reaction temperature. The tendency toward nitride formation becomes stronger in the order V2O5 < Ta2O5 < Nb2O5. 相似文献
11.
The oxygen-ion conductivity of porous materials, the coarse-grained pyrochlore-like Sm2Ti2O7 and fine-grained Sm2TiO5 compounds, produced by mechanical activation of initial oxides is studied at 400–1000 °C. The Sm2TiO5 samples contain ~15 wt % of the nanosized pyrochlore-like Sm2TiO5 phase in addition to the rhombic phase. As determined by impedance spectroscopy, the ionic conductivities of Sm2TiO5 and Sm2Ti2O7 at 1000°C are 1.3 × 10?3 and 1.8 × 10?4 S cm?1, and the activation energies of the bulk and grainboundary conductivities of the materials are 1.04 and 1.24 eV for Sm2TiO5 and 1.69 and 1.80 eV for Sm2Ti2O7. 相似文献
12.
Y2O3 + Nd2O3 co-stabilized ZrO2-based composites with 40 vol% WC were fully densified by pulsed electric current sintering (PECS) at 1350 °C and 1450 °C.
The influence of the PECS temperature and Nd2O3 co-stabilizer content on the densification, hardness, fracture toughness and bending strength of the composites was investigated.
The best combination of properties was obtained for a 1 mol% Y2O3 and 0.75 mol% Nd2O3 co-stabilized composite densified for 2 min at 1450 °C under a pressure of 62 MPa, resulting in a hardness of 15.5 ± 0.2
GPa, an excellent toughness of 9.6 ± 0.4 MPa.m0.5 and an impressive 3-point bending strength of 2.04 ± 0.08 GPa. The hydrothermal stability of the 1 mol% Y2O3 + 1 mol% Nd2O3 co-stabilized ZrO2-WC (60/40) composites was compared with that of the equivalent 2 mol% Y2O3 stabilized ceramic. The double stabilized composite did not degrade in 1.5 MPa steam at 200 °C after 4000 min, whereas the
yttria stabilized composite degraded after less than 2000 min. Moreover, the (1Y,1Nd) ZrO2-WC composites have a substantially higher toughness (~9 MPa.m0.5) than their 2Y stabilized equivalents (~7 MPa.m0.5). 相似文献
13.
Mohamed Baazaoui Sobhi Hcini Michel Boudard Sadok Zemni Mohamed Oumezzine 《Journal of Superconductivity and Novel Magnetism》2015,28(7):1887-1893
The critical behavior of perovskite manganite La0.67Ba0.33Mn0.95Fe0.05O3 at the ferromagnetic–paramagnetic has been analyzed. The results show that the sample exhibited the second-order magnetic phase transition. The estimated critical exponents derived from the magnetic data using various such as modified d’Arrott plot Kouvel–Fisher method and critical magnetization M(T C, H). The critical exponents values for the La0.67Ba0.33Mn0.95Fe0.05O3 are close to those expected from the mean field model β = 0.504 ± 0.01 with T C = 275661 ± 0.447 (from the temperature dependence of the spontaneous magnetization below T C ), γ = 1.013 ± 0.017 with T C = 276132 ± 0.452 (from the temperature dependence of the inverse initial susceptibility above T C ), and δ = 3.0403 ± 0.0003. Moreover, the critical exponents also obey the single scaling equation of M(H, ε) = |ε| β f ±(H/|ε| β+γ ). 相似文献
14.
C. A. Veliev 《Inorganic Materials》2010,46(5):452-455
The Ho2S3-Ga2S3 system has been studied using differential thermal analysis, X-ray diffraction, microstructural analysis, microhardness tests, and density measurements, and its phase diagram has been constructed. The system contains three ternary compounds: Ho3GaS6, HoGaS3, and Ho6Ga10/3S14. Their melting behavior has been studied for the first time. The compound Ho6Ga10/3S14 melts congruently at 1435 K; Ho3GaS6 and HoGaS3 melt incongruently at 1370 and 1250 K, respectively. The Ho2S3-Ga2S3 system is a pseudobinary join of the ternary system Ho-Ga-S. At room temperature, the β-Ga2S3-based solid solution extends to 1.5 mol % Ho2S3; the Ho2S3 solubility in γ-Ga2S3 is 10 mol %. The compounds HoGaS3 and Ho3GaS6 crystallize in orthorhombic symmetry (Ho3GaS6: a = 10.40 Å, b = 13.20 Å, c = 6.44 Å, Z = 4; HoGaS3: a = 6.8 Å, b = 9.92 Å, a = 3.08 Å, Z = 4). Ho6Ga10/3S14 has a hexagonal structure (a = 9.62 Å, c = 6.04 Å). 相似文献
15.
T. N. Kol’tsova 《Inorganic Materials》2010,46(8):870-877
The structures of gismondine and amicite are analyzed in comparison with one another and with those of the zeolites whose
compositions lie in the hypothetical plane “CaAl2Si3O10”-Na2Al2Si3O10-H2O. It is shown that the structures are similar to each other and may undergo mutual transformations. 相似文献
16.
The crystal structure of a previously unknown compound [CH3NH3][(UO2)(H2AsO4)3] was solved by direct methods and refined to R 1 = 0.038 for 3041 reflections with |F hkl | >-4σ |F hkl |. The compound crystallizes in the monoclinic system, space group P21/c, a = 8.980(1), b = 21.767(2), c = 7.867(1) Å, β = 115.919(5)°, V = 1383.1(3) Å3, Z = 4. In the structure of the compound, pentagonal bipyramids of uranyl ions, sharing bridging atoms with tetrahedral [H2AsO4]? anions, form strongly corrugated layered complexes [(UO2)(H2AsO4)3]? arranged parallel to the (100) plane. The protonated methylamine molecules [CH3NH3]+ form unidimensional tapelike packings parallel to the c axis and linked by hydrophilic-hydro-phobic interactions. The topology of the layered uranyl arsenate complex [(UO2)(H2AsO4)3]? is unusual for uranyl compounds and was not observed previously. A specific feature of this topology is the presence of monodentate arsenate “branches” arranged within the layer. 相似文献
17.
N. A. Gorodylova V. N. Baumer I. V. Zatovsky A. A. Babarik N. S. Slobodyanik O. V. Shishkin 《Inorganic Materials》2011,47(2):156-162
We have studied general trends of crystallization from high-temperature solutions in the K2O-P2O5-V2O5-Bi2O3 system at P/V = 0.5?2.0, K/(P + V) = 0.7?1.4, and Bi2O3 contents from 25 to 50 wt % and identified the stability regions of BiPO4, K3Bi5(PO4)6, K2Bi3O(PO4)3, and K3Bi2(PO4)3 ? x (VO4) x (x = 0?3) solid solutions. The synthesized compounds have been characterized by X-ray powder diffraction and IR spectroscopy, and the structure of two solid solutions has been determined by single-crystal X-ray diffraction (sp. gr. C 2/c): K3Bi2(PO4)2(VO4), a = 13.8857(8), b = 13.5432(5), c = 6.8679(4) Å, β = 114.031(7)°; K3Bi2(PO4)1.25(VO4)1.75, a = 13.907(4), b = 13.615(2), c = 6.956(2) Å, β = 113.52(4)°. 相似文献
18.
We have studied the electric-field effect on crystallization processes in the Li3PO4-Li4GeO4-Li2MoO4-LiF system. In zero field, Li3+x P1?x Ge x O4 (x = 0.31) crystals were grown on the cathode under the conditions of this study. At low applied voltages (≤ 0.5 V), we obtained Li2MoO4, Li2GeO3, and Li1.3Mo3O8. In the range V = 0.5–1 V, crystals of Li3+x P1?x Ge x O4 solid solutions with x = 0.17, 0.25, 0.28, 0.29, and 0.36 were obtained. An applied electric field was shown to reduce the melting temperature of the starting mixtures and the crystallization onset temperature. 相似文献
19.
A. B. Bodade Minaz Alvi A. V. Kadu G. N. Chaudhari 《Journal of Materials Science》2010,45(19):5264-5270
Nanocrystalline La1−x
Co
x
Mn1−y
Ni
y
O3 (x = 0.2 and 0.4; y = 0.1, 0.3, and 0.5) thick films sensors prepared by sol–gel method were studied for their H2S gas sensitivity. The structural and morphological properties have been carried out by X-ray diffraction (XRD) and transmission
electron microscopy (TEM). Average particle size estimated from XRD and TEM analyses was observed to be 30–35 nm. The gas
response characteristics were found to depend on the dopants concentration and operating temperature. The maximum H2S gas response of pure LaMnO3 was found to be at 300 °C. In order to improve the gas response, material doped with transition metals Co and Ni on A- and
B-site, respectively. The La0.6Co0.4Mn0.5Ni0.5O3 shows high response towards H2S gas at an operating temperature 250 °C. The Pd-doped La0.6Co0.4Mn0.5Ni0.5O3 sensor was found to be highly sensitive to H2S at an operating temperature 200 °C. The gas response, selectivity, response time and recovery time were studied and discussed. 相似文献
20.
M. Sh. Gasanova 《Inorganic Materials》2009,45(8):851-853
A diagram of the CuInSe2-In2Te3 system state is constructed using the methods of physicochemical analysis. The system is quasi-binary with limited areas of solid solutions based on both source components. The investigations of thermal conductivity of the (CuInSe2)0.99(In2Te3)0.01 solid solution demonstrate a complex nature of the heat transfer attributed to both a multicomponent structure of the composition and a defect crystalline structure. 相似文献