共查询到20条相似文献,搜索用时 15 毫秒
1.
Ming He Huaiwu Zhang Shuren Zhang Jing Wan 《Journal of Materials Science: Materials in Electronics》2012,23(9):1734-1738
The microstructure, sintering and dielectric properties of ZrO2-, TiO2-doped Ca–Si–B based ceramics prepared by solid-phase process were investigated, and the effects of ZrO2, TiO2 content on these performances were analyzed. The Ca–Si–B based ceramics without additive (ZrO2 or TiO2) showed a high sintering temperature (1,100?°C) and had the dielectric properties: dielectric constant (εr) of 8.38, dielectric loss (tanδ) of 1.51?×?10?3 at 1?MHz, and volume density of 2.47?g/cm3. The addition of ZrO2, TiO2 was revealed to lower the sintering temperature of Ca–Si–B based ceramics to 1,000?°C and enhance the sintering and dielectric properties: ρ?=?2.61?g/cm3, εr?=?5.85, tanδ?=?1.59?×?10?4 (1?MHz) with ZrO2 addition, and ρ?=?2.65?g/cm3, εr?=?6.12, tanδ?=?6.4?×?10?4 (1?MHz) with TiO2 addition, which are superior to the pure Ca–Si–B. The results show that ZrO2, TiO2 as nucleating agents, are conducive to the precipitation of crystals, thus decrease the sintering temperature and improve the dielectric properties of Ca–Si–B based ceramics. 相似文献
2.
Bioactivity and magnetic properties were investigated in glass and glass ceramics based on the SiO2–Na2O–Fe2O3–CaO–P2O5–B2O3 system to find their suitability as thermoseed for hyperthermia treatment of cancer. The effect of change in compositions on bioactivity was examined in simulated body fluids. The glass ceramic samples exhibit Na3CaSi3O8 and Na3-XFeXPO4 phases. After dipping the glass ceramic samples in simulated body fluids silica hydrogel first forms, followed by an amorphous calcium phosphate layer. Magnetic and microwave resonance experiments further demonstrate the potential of these glass ceramics for possible use in hyperthermia. 相似文献
3.
A. W. Wren T. Keenan A. Coughlan F. R. Laffir D. Boyd M. R. Towler M. M. Hall 《Journal of Materials Science》2013,48(11):3999-4007
The structural role of Gallium (Ga) is investigated when substituted for Zinc (Zn) in a 0.42SiO2–0.40–xZnO–0.10Na2O–0.08CaO glass series, (where x = 0.08). Each starting material was amorphous, and the network connectivity (NC) was calculated assuming Ga acts as both a network modifier (1.23), and also as a network former. Assuming a network forming role for Ga the NC increased with increasing Ga concentration throughout the glass series (Control 1.23, TGa-1 2.32 and TGa-2 3.00). X-ray photoelectron spectroscopy confirmed both composition and correlated NC predictions. Raman spectroscopy was employed to investigate Q-structure and found that a shift in wavenumbers occurred as the Ga concentration increased through the glass series, from 933, 951 to 960 cm?1. Magic angle spinning nuclear magnetic resonance determined a chemical shift from ?73, ?75 to ?77 ppm as the Ga concentration increased, supporting Raman data. These results suggest that Ga acts predominantly as a network former in this particular Zn-silicate system. 相似文献
4.
T. N. Kol'tsova 《Inorganic Materials》2004,40(6):656-660
The phase region of cubic perovskite-like solid solutions (a = 8.28–8.40 Å) in the Y2O3–BaO–WO3–CuO system is outlined, and the phase compatibility diagram of the BaWO4–BaCuO2–Y2Cu2O5–1010 (1010 = Y2WO6 + Y2W3O12) is constructed. 相似文献
5.
The phase diagram of the TlInSe2–TlSmSe2 system was mapped out using differential thermal analysis, microstructural examination, and x-ray diffraction data. The system was found to contain a partial solid-solution series (0–9 mol % TlSmSe2 at room temperature) and a quaternary compound of composition Tl2InSmSe4, which melts congruently at 1250 K. The electrical conductivity and Hall coefficient of TlInSe2–TlSmSe2 alloys were measured as a function of temperature. With increasing Sm content, the lattice parameters of the solid solution increase linearly, while its band gap decreases. 相似文献
6.
The magnetic, electrical, catalytic, and photocatalytic properties of ZrO2–TiO2materials were studied. The ZrO2–TiO2system was shown to contain ZrO2-, TiO2, and ZrTiO4-based solid solutions. Procedures for the preparation of high-activity ZrO2–TiO2photocatalysts and photostable pigments were developed. 相似文献
7.
I. V. Bodnar' 《Inorganic Materials》2003,39(1):10-14
It was shown by x-ray diffraction and differential thermal analysis that CuGaTe2 and CuAlTe2 form a continuous series of solid solutions. CuGaTe2, CuAlTe2, and CuAl
x
Ga1 – x
Te2 crystals consisting of large blocks were grown by the horizontal Bridgman process, and their thermal expansion and near-edge transmission and reflection spectra were measured. The thermal expansion coefficient was shown to vary linearly across the solid-solution series, while the band gap is a nonlinear function of composition. 相似文献
8.
《材料与设计》2015
Laser additive manufacturing (LAM) is a novel manufacturing technique in which metal components can be fabricated layer by layer. In this study, a recently developed damage tolerance titanium alloy TC21 (Ti–6Al–2Zr–2Sn–3Mo–1.5Cr–2Nb) was deposited by LAM process. Texture and microstructure characterization have been investigated by XRD, SEM and EBSD. Prior β grains texture analysis indicates that the (100) poles concentrate in build direction with a texture intensity about 18.7. During cooling down from β phase field, the β to α phase transformation follows the Burger orientation relationship and a pronounced variant selection occurred. Besides, morphology and scale of α phase are quite different along the build direction due to different thermal history. Very fine rib-like α phase with the length less than 2 μm and acicular martensite α' can be obtained at the bottom and the top of the sample, respectively. In the middle position, distribution and morphology of α phase is quite uneven and the precipitation sequence of α phase is αGB → αWGB → αWM → αS. The reasons by which they formed are discussed. 相似文献
9.
10.
Room temperature tensile properties of polycrystal Ti–47Al–2Mn–2Nb alloy with near lamellar (NL) microstructures were investigated at the strain rates between 10–5 and 1000 s–1 using a self-designed Split-Hopkinson tensile bar setup with a rotating disk and conventional testing machine. It was found that tensile ductility varies within a narrow range with the strain rate, while dynamic strengths (d) of the alloy are obviously higher than static strengths (s). There exists linear relationship between s and the logarithm of the strain rate (ln ), and between d and the strain rate itself (). Fractography analysis indicates that the alloy fractures in a mixed mode of predominant transgranular cleavage and minor intergranular cracking under static and dynamic strain rates. Environmental effect is excluded from the main cause for the room temperature brittleness of the investigated alloy. 相似文献
11.
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
12.
Yonggang Zhang Shunhua Wu Baolin Zhang Xiaogang Wu 《Journal of Materials Science: Materials in Electronics》2014,25(7):3085-3089
The effect of Li2O3–B2O3–SiO2 (LBS) liquid-phase additives on the sintering, microstructures, and dielectric properties of MgO–TiO2–ZnO–CaO (MTZC) ceramics was investigated. It was found that the sintering temperature could be lowered easily, and the dielectric properties of MTZC ceramics could be greatly improved by adding a small amount of LBS solution additives. With the addition of 10 wt% LBS, the ceramics sintered at 900 °C showed favorable dielectric properties with εr = 21.7, Qf = 5.0 × 104 GHz, and TCF = ?21.6 ppm/ °C. The distructive physical analysis showed an excellent co-firing interfacial behavior between the MTZC ceramic and the Ag electrode. It indicated that MTZC ceramics with LBS solution additives have a number of potential applications on passive integrated devices based on the low-temperature co-fired ceramics technology. 相似文献
13.
E. M. Godzhaev A. M. Nazarov S. I. Mamedova A. Yu. Dzhangirov 《Inorganic Materials》2001,37(6):544-547
TlInS2–TlCeS2solid solutions were characterized by x-ray diffraction and electrical measurements. The solubility limit of TlCeS2in TlInS2was found to be 8 mol %. The electrical conductivity and Hall coefficient of TlIn1 – x
Ce
x
S2(0 x 0.08) were measured from 300 to 1100 K. It was found that, as the Ce content of the solid solution increases, the band gap decreases, and the lattice parameters increase. 相似文献
14.
《International Journal of Inorganic Materials》2000,2(4):319-323
In this paper, colloid-based highly reflective coatings consisting of alternating layers of quarterwave thick high- and low-refractive index components were deposited on glass substrates by a sol–gel spin-coating method. SiO2 was used as the low-refractive index component, and ZrO2 as the high-refractive index material. The colloidal suspension of ZrO2, prepared by hydrothermal hydrolysis of ZrOCl2, contained monoclinic nanocrystalline ZrO2, with an average particle size of 15 nm. A minimum transmittance of 1% near 1064 nm was obtained from a 20-layer SiO2–ZrO2/PVP multilayer film. The ZrO2 particles were deposited in an ethanolic suspension containing polyvinylpyroldione (PVP) as a binder. The maximum transmittance in the visible range was about 85%. A 1-on-1 laser-induced damage threshold of 16 J/cm2 for the 20-layer SiO2–ZrO2/PVP film was observed using a Q-switched Nd:YAG high power laser at a wavelength of 1.06 μm and with a pulse width of 2.5 ns. 相似文献
15.
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
16.
《Materials Science & Technology》2013,29(12):1203-1212
AbstractIn arc melted and aluminothermically prepared alloys with composition in the triangle Al–AlB2–TiB2 four solid phases are observed: α-Al, ρ-AlB12, AlB2, and TiB2. The univariant reaction between L, ρ-AlB12, and TiB2 is the eutectic one L? α-AlB12 + TiB2. During the reaction TiB2 platelets are sequentially formed on facets of α-AlB12, but their formation may be completely suppressed by the presence of primary TiB2. Decomposition of α-AlB12 does not occur on cooling, but only during isothermal annealing under 900°C probably according to the transition reaction L + α-AlB12 → TiB2 + AlB2. Dissolution of α-AlB12 and growth of AlB2 take place in afaceted manner owing to their high entropies of solution. The low temperature AlB2 phase is not formed at all on cooling of concentrated alloys with an overall composition lying on the AlB2-TiB2 tieline, whereas in less concentrated alloys it is usually formed on the primary TiB2 particles in the regions distant from α-AlB12 相似文献
17.
Materials Science - For alloys of the Mo–Ni–B system annealed at subsolidus temperatures (and some as-cast alloys) in the Ni–MoNi–Mo2NiB2–Ni2B region, we study the... 相似文献
18.
Ac conductivity measurements and its analysis has been performed on xBi2O3–(65?x)Li2O–20ZnO–15B2O3 (0 ≤ x ≤ 20) glasses in the temperature range 30–300 °C and a frequency range of 100 Hz to 1 MHz. The dc conductivity increased and the activation energy decreased with lithium content. The frequency dependent conductivity has been analyzed employing conductivity and modulus formalisms. The onset of conductivity relaxation shifts towards higher frequencies with temperature. The Almond–West conductivity formalism is used to explain the scaling behavior, and the relaxation mechanism is independent of temperature. 相似文献
19.
《Materials Letters》2004,58(7-8):1383-1386
Hot-pressure sintered β-Si3N4 ceramic was bonded to itself using Y2O3–Al2O3–SiO2–TiO2 mixtures. Reactive behavior at interface between Si3N4 and Y2O3–Al2O3–SiO2–TiO2 mixtures during silicon nitride ceramic joining was studied by means of scanning electron microscopy (SEM), electron probe microanalyses (EPMA), X-ray diffraction (XRD) and auger electron spectroscopy (AES). The joint strength under different bonding conditions was measured by four-point bending tests. The results of EPMA, AES and XRD analyses show that the liquid glass solder reacts with silicon nitride at interface, forming the Si3N4/Y–Si–Al–Ti–O–N glass/TiN/Y–Si–Al–O glass gradient interface. From the results of four-point bending tests, it is known that with increase of bonding temperature and holding time, the joint strength increased reaching a peak, and then decreased. The maximum joint strength of 200 MPa measured by the four-point bending tests is obtained for silicon nitride bonded at 1823 K for 30 min. 相似文献
20.
Inorganic Materials - We have studied the self-propagating high-temperature synthesis (SHS) process due to the combustion of a WO3 + ZrO2 + TiO2 + Mg multicomponent mixture. The ratio of the oxide... 相似文献