共查询到20条相似文献,搜索用时 15 毫秒
1.
BaFe12O19 hexaferrite films have been produced on thermally oxidized single-crystal silicon (SiO2/Si) substrates by sequential ion-beam sputtering of BaFe2O4 and α-Fe2O3 targets in an argon-oxygen atmosphere. Their crystal structure has been studied, and the origin of the impurity phases forming during heat treatment has been identified. The results show that heat treatment may lead to the formation of eutectic melts. As a result, the hexaferrite films may contain spherulites. 相似文献
2.
The dc conductivity of the glasses in the Fe2O3-Bi2O3-K2B4O7 system was studied at temperatures between 223 and 393 K. At temperatures from 300 to 223 K, T–1/4 (T is temperature) dependence of the conductivity was found, however, both Mott variable-range hopping and Greaves intermediate range hopping models are found to be applicable. Mott and Greaves parameters analysis gave the density of states at Fermi level N (EF) = 3.13 × 1020–21.01 × 1020 and 1.93 × 1021–16.39 × 1021 cm–3eV–1 at 240 K, respectively. The variable-range hopping conduction occurred in the temperature range T = 300–223 K, since WD was found to be large (WD = 0.08–0.14 eV for these glasses) and dominated the conduction at T < 300 K. 相似文献
3.
Xiangyu Meng Xiansong Liu Chaocheng Liu Cong Zhang Haohao Li Khalid Mehmood Ur Rehman 《Journal of Materials Science: Materials in Electronics》2018,29(2):881-886
In the case of Ti4+ remain unchanged, the Ca2+ substituted Ba0.75?xCaxLa0.25Fe11.6Co0.25Ti0.15O19 (0?≤?x?≤?0.05) were prepared by conventional solid-state reaction method at temperature of 1280 °C. A ball-to-power weight ratio of 10:1. Their crystal structure and magnetic properties were mainly investigated. The results show that the single magnetoplumbite phase structure transformed into the multiphase structure. Meanwhile, the small amount of α-Fe2O3 phase existed in M-type phase. The micrographs were observed by a field emission scanning electron microscopy (SEM). Vibrating sample magnetometer (VSM) was used to analyze the magnetic properties. The saturation magnetization (M s ) first increases then decreases when x from 0 to 0.03. But, when x from 0.03 to 0.05, the saturation magnetization (M s ) first increases then decreases too. The maximum value is at x?=?0.04 (M s ?=?70.73 emu/g). The value of coercivity (H c ) first increases then decreases when x from 0 to 0.04. But, the value increased when x from 0.04 to 0.05. The maximum value is at x?=?0.02 (H c ?=?1691 Oe). 相似文献
4.
T. N. Kol’tsova 《Inorganic Materials》2010,46(3):242-250
The phase equilibria in the “CaAl2Si3O10”-Na2Al2Si3O10-H2O system are analyzed using structural and thermal analysis data, and the ideal gonnardite structure is modeled. The results
suggest that, to ensure a better correlation with the structures of the zeolites in this series, a new structural model of
the gonnardite-based solid solution must be selected, with the structure rotated through 45° about the c axis in the ab plane. 相似文献
5.
S. Z. Imamaliyeva T. M. Gasanly V. P. Zlomanov M. B. Babanly 《Inorganic Materials》2017,53(7):685-689
Phase equilibria in the Tl5Te3–Tl9BiTe6–Tl9TbTe6 system have been studied using differential thermal analysis, X-ray diffraction, and microhardness measurements. We have mapped out a number of vertical sections, the 760-K isothermal section of its phase diagram, and projections of its liquidus and solidus surfaces. The composition dependences of lattice parameters and microhardness have been obtained. The system has been shown to contain a continuous series of solid solutions, which crystallize in a tetragonal structure (Tl5Te3 type, sp. gr. I4/mcm). 相似文献
6.
The (1−x) Ba0.40Sr0.60TiO3 (BST)−xZr0.80Sn0.20TiO4 (ZST) composite ceramics with x = 10, 20, 30, and 40 wt% were fabricated by conventional solid-state reaction method. With increasing of ZST content, the
dielectric constant of composite ceramics was decreased and dielectric loss increases. The effect of ZnO addition to 70 wt%
BST–30 wt% ZST composition on the microstructure and dielectric properties was investigated. The improvements in dielectric
constant, dielectric loss, and microwave dielectric properties of composite ceramics can be achieved by ZnO addition. The
sample with 98 wt% (70 wt% BST–30 wt% ZST)–2 wt%ZnO composition exhibits promising dielectric properties, with dielectric
constant, loss tangent and tunability at 4 kV/mm, of 125, 0.0016 and 12%, at 10 kHz and room temperature. At ~2 GHz, it possesses
a dielectric constant of 101 and a Q factor of 187, which makes it a good candidate for tunable microwave device applications. 相似文献
7.
Semih Seyyidoğlu Macit Özenbaş Necmeddin Yazıcı Ayşen Yılmaz 《Journal of Materials Science》2007,42(15):6453-6463
In this study, ZrP2O7 was synthesized by the solid state reaction of ZrO2 and NH4H2PO4 at 900 °C. Then, in set 1; 10, 5, 1, 0.5, 0.1, 0.05, 0.03% previously prepared Sr2P2O7 were doped into ZrP2O7, and Sr2P2O7 slightly affect the unit cell parameter of cubic ZrP2O7 (a = 8.248(6)–8.233(8) Å). The reverse of this process was also applied to Sr2P2O7 system (set 2). ZrP2O7 changes the unit cell parameters of orthorhombic Sr2P2O7 in between a = 8.909(5)–8.877(5) Å, b = 13.163(3)–13.12(1) Å, and c = 5.403(2)–5.386(4) Å. Analysis of the vibrations of the P2O 7 4? ion and approximate band assignments for IR and Raman spectra are also reported in this work. Some coincidences in infrared and Raman spectra both sets were found and strong P–O–P bands were observed. Surface morphology, EDX analysis, and thermoluminescence properties of both sets were given the first time in this paper. 相似文献
8.
Differential thermal analysis and x-ray diffraction data indicate that the ZnO B2O3-CuO B2O3 join of the ternary system CuO-B2O3-ZnO is pseudobinary, with eutectic phase relations and a liquid-liquid miscibility gap in the composition range 25–35 mol % CuO.Translated from Neorganicheskie Materialy, Vol. 41, No. 3, 2005, pp. 339–340.Original Russian Text Copyright © 2005 by Kasumova, Bananyarly.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date. 相似文献
9.
The Tl2Te–Tl5Te3–Tl9TbTe6 system has been studied using differential thermal analysis, X-ray diffraction, and microhardness measurements. We have mapped out a number of vertical sections, the 680 K isothermal section of its phase diagram, and projections of its polythermal projections of its liquidus and solidus surfaces. The field of solid solutions with the Tl5Te3 structure (δ-phase) has been shown to account for more than 90% of the area of the composition triangle. Tl2Te-based solid solutions (α-phase) exist in a narrow composition region. 相似文献
10.
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
11.
Jun Wang Changrong Zhou Qingning Li Weidong Zeng Jiwen Xu Guohua Chen Changlai Yuan Guanghui Rao 《Journal of Materials Science》2018,53(12):8844-8854
Lead-free ceramics (1???x)Bi0.5Na0.5TiO3–xSr0.85Bi0.1TiO3 (BNT–xSBT, x?=?0.4, 0.5, 0.6 and 0.7) were prepared by a solid-state reaction process. Coexistence of ferroelectric relaxation at low temperature and Maxwell–Wagner dielectric relaxation at high temperature was revealed for the first time in this system. Meanwhile, hysteresis-free P–E loops combined with a very high piezoelectric strain coefficient (d33) of 1658 pC/N concurrently with large electrostrictive coefficient Q?=?0.287 m4C?2 were achieved. The ferroelectric relaxor behavior and large electrostrictive strain might be linked to easy reorientation and reversal of ergodic PNRs and the combined effect of Bi off-center position and lone pair electrons. 相似文献
12.
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
13.
Hui-Juan Wang Tilman Zscheckel Bo-Tao Li Hui-Xing Lin Christian Bocker Christian Rüssel Lan Luo 《Journal of Materials Science》2017,52(3):1330-1347
Crystallization and microstructure of glasses with the molar compositions 1MgO·1.2Al2O3·2.8SiO2·1.2TiO2·xLa2O3 (x = 0.1 and 0.4) were thermally treated at different temperatures in the range from 950 to 1250 °C and then analyzed by X-ray diffraction and scanning electron microscopy, in combination with energy-dispersive X-ray spectroscopy and electron backscatter diffraction. It was found that the microstructure is first homogeneous with the precipitation of randomly distributed crystals and then indialite domains with embedded perrierite and rutile crystals are formed. For higher temperatures or prolonged times, more domains appear and expand into the bulk of the sample. Finally, the entire sample consists of the indialite domains and the boundaries that are enriched in rutile, perrierite, and magnesium aluminotitanate. Nevertheless, very distinct differences are observed between the samples with different La2O3 concentrations. For the sample with x = 0.4, the domains were detected at lower temperatures, while the quantity and size of the domains increase faster due to the promoted precipitation of indialite. For the sample with x = 0.1, in addition to the domain boundaries, secondary boundaries between the “regions” (assemblages of the domains) are observed in a larger length scale. The average size of the crystalline phases found between the “regions” is larger than that typically observed at the domain boundaries. The sizes of the crystals at the boundaries decrease with higher concentrations of La2O3, and the crystals (especially perrierite) within the domains become larger, resulting in a more homogeneous microstructure. This results in better dielectric properties, i.e., much higher quality factor for the sample with x = 0.4 in comparison to that with x = 0.1 after heat-treatment at 1150 or 1250 °C. 相似文献
14.
Rajendra Kumar Singh A. Srinivasan G. P. Kothiyal 《Journal of materials science. Materials in medicine》2009,20(1):147
Magnetic bioglass ceramics (MBC) are being considered for use as thermoseeds in hyperthermia treatment of cancer. While the bioactivity in MBCs is attributed to the formation of the bone minerals such as crystalline apatite, wollastonite, etc. in a physiological environment, the magnetic property arises from the magnetite [Fe3O4] present in these implant materials. A new set of bioglasses with compositions 41CaO · (52 ? x)SiO2 · 4P2O5 · xFe2O3 · 3Na2O (2 ≤ x ≤ 10 mol% Fe2O3) have been prepared by melt quenching method. The as-quenched glasses were then heat treated at 1050°C for 3 h to obtain the glass-ceramics. The structure and microstructure of the samples were characterized using X-ray diffraction and microscopy techniques. X-ray diffraction data revealed the presence of magnetite in the heat treated samples with x ≥ 2 mol% Fe2O3. Room temperature magnetic property of the heat treated samples was investigated using a Vibrating Sample Magnetometer. Field scans up to 20 kOe revealed that the glass ceramic samples had a high saturation magnetization and low coercivity. Room temperature hysteresis cycles were also recorded at 500 Oe to ascertain the magnetic properties at clinically amenable field strengths. The area under the magnetic hysteresis loop is a measure of the heat generated by the MBC. The coercivity of the samples is another important factor for hyperthermia applications. The area under the loop increases with an increase in Fe2O3 molar concentration and the. coercivity decreases with an increase in Fe2O3 molar concentration The evolution of magnetic properties in these MBCs as a function of Fe2O3 molar concentration is discussed and correlated with the amount of magnetite present in them. 相似文献
15.
T. Jardiel A. C. Caballero L. Fuentes M. Villegas 《Journal of Materials Science》2009,44(21):5824-5828
In a recent report, the evaluation of the phase relations in the Bi2O3–TiO2–WO3 ternary system has shown the existence of a new phase with nominal composition close to Bi6Ti5WO22. In the present contribution we attempt to prepare this single phase by using a solid state route. Although XRD analyses
also show traces of two minority Aurivillius-type phases in the synthesized materials, the crystal structure of the Bi6Ti5WO22 phase has been determined by Rietveld analyses revealing a complex structure similar to that of Bi3(AlSb2)O11 and PbHoAl3O8 related compounds. The electrical response of this new phase was characterized as well. Three peaks are observed in its dielectric
response: two of them positioned around 0 °C and can be assigned to this Bi6Ti5WO22 structure. The third one rises up to 665 °C and confirms the presence of the Aurivillius-type phases. 相似文献
16.
F. M. Sadygov T. M. Il’yasly G. T. Ganbarova V. P. Zlomanov I. I. Aliev 《Inorganic Materials》2017,53(7):665-669
We have studied phase relations in the Sb2Se3–Nd2Se3 system and mapped out its T–x phase diagram using differential thermal analysis, X-ray diffraction, microstructural analysis, microhardness tests, and density measurements. The system contains one compound, with the composition NdSbSe3, which melts incongruently at 865 K and crystallizes in orthorhombic symmetry with the following lattice parameters: а = 12.77(1) Å, b = 14.08(1) Å, and c = 5.82(5) Å (Z = 8, ρmeas = 6.20 g/cm3, ρx = 6.38 g/cm3). At room temperature, the Nd2Se3 solubility in Sb2Se3 is 5 mol % and the Sb2Se3 solubility in Nd2Se3 is 2.5 mol %. The Sb2Se3–Nd2Se3 system has a eutectic located at 15 mol % Nd2Se3, with a melting point at 755 K. The electrical conductivity and thermoelectric power of the (Sb2Se3)1–x (Nd2Se3) x solid solutions have been measured as functions of temperature. 相似文献
17.
Ekkehard Krüger 《Journal of Superconductivity and Novel Magnetism》2010,23(2):213-223
It is shown that the ceramic superconductor YBa2Cu3O7 as well as the superconducting intermetallic compound MgB2 possesses a narrow, partly filled “superconducting band” with Wannier functions of special symmetry in their band structures.
This result corroborates previous observations about the band structures of numerous superconductors and non-superconductors
showing that evidently superconductivity is always connected with such superconducting bands. These findings are interpreted
in the framework of a nonadiabatic extension of the Heisenberg model. Within this new group-theoretical model of correlated
systems, Cooper pairs are stabilized by a nonadiabatic mechanism of constraining forces effective in narrow superconducting
bands. The formation of Cooper pairs in a superconducting band is mediated by the energetically lowest boson excitations in
the considered material that carry the crystal-spin angular momentum 1⋅ℏ. These crystal-spin-1 bosons are proposed to determine whether the material is a conventional low-T
c or a high-T
c superconductor. This interpretation provides the electron–phonon mechanism that enters the BCS theory in conventional superconductors. 相似文献
18.
R. Rejini G. Subodh M. T. Sebastian 《Journal of Materials Science: Materials in Electronics》2008,19(12):1153-1155
A novel low loss dielectric material Ca4La2Ti5O17 was prepared by solid state ceramic route. The structure and microstructure of the Ca4La2Ti5O17 ceramics was investigated using XRD, SEM and EDX techniques. XRD result showed cubic perovskite like structure for Ca4La2Ti5O17 ceramics. The ceramics were sintered in the temperature range of 1,450–1575 °C. The microwave dielectric properties of the
material were investigated using a network analyzer in the frequency range of 3–6 GHz. The variation in microwave dielectric
properties of the Ca4La2Ti5O17 ceramics with sintering temperature was correlated with bulk density of the material. Ca4La2Ti5O17 has εr of 73, Quxf of 16,000 at 3.3 GHz, and τf of 127 ppm/°C at the optimized sintering temperature of 1,550 °C/4h. 相似文献
19.
Hao Zhang De-yi Zheng Shun-min Hu Cheng Cheng Gui-gui Peng Jing Zhang Liang-liang Li 《Journal of Materials Science: Materials in Electronics》2017,28(1):67-74
The structure, microstructure, field-induced strain, ferroelectric, piezoelectric and dielectric properties of (1 ? x) (Bi0.5Na0.5)0.935Ba0.065TiO3–xSr3CuNb2O9 (BNT-BT6.5–xSCN, with x = 0, 0.003, 0.006, 0.009) ceramics were investigated. X-ray diffraction patterns show that all samples are pure perovskite structure and Sr3CuNb2O9 (SCN) effectively diffused into the 0.935Bi0.5Na0.5TiO3–0.065BaTiO3 (BNT–BT6.5) solid solution which also reflected in the Raman spectra and the energy disperse spectroscopy (EDS) analysis. With the increases of SCN content, the coercive field (E c = 18.41 kV/cm) decreases greatly, whereas the remnant polarization (P r = 29.11 μC/cm2) increases a little at x = 0.003 which is showed in the polarization hysteresis (P–E) loops, the result indicate that the ferroelectric order would be disrupted. Around critical composition (x = 0.003) at a driving field of 60 kV/cm, a large unipolar strain of 0.29 % with a normalized strain (d 33 * = 483 pm/V) is obtained at room temperature. The results indicate that BNT-BT6.5-xSCN ceramics with excellent properties are promising to replace lead-based piezoelectric ceramics and can be used in practical applications. 相似文献
20.
D. S. Lipatov A. N. Guryanov M. V. Yashkov M. M. Bubnov M. E. Likhachev 《Inorganic Materials》2018,54(3):276-282
An all-vapor phase MCVD process has been proposed for the fabrication of fiber preforms with a Yb2O3–Al2O3–P2O5–SiO2 multicomponent glass core. We have investigated the tubular preform collapse into a rod and demonstrated approaches capable of preventing P2O5 losses in the central part of the core during the collapse process. Preforms with a flat, perfect step-index profile have been fabricated. 相似文献