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A systematic investigation of the influence of B content on the magnetoimpedance (MI) effect in melt-spun Fe91−xZr5BxNb4 (FZBN, 0 ? x ? 30) ribbons has been performed within a frequency range, f ∼ 310-1110 kHz and under a varying dc magnetic field (Hdc) up to 70 Oe. The MI effect is not observed in the sample with x ? 5 but within the range 8 ? x ? 30. A distinct MI effect has been observed with a maximum change of 180% at around 1.1 MHz in the sample with x = 20, coincident with a saturation magnetic field of 66 Oe and a field sensitivity of about 7%/Oe. Magnetic measurements reveal that the MI effect and B content dependence of the effect are closely related to coercivity of the FZBN alloy series, except for the sample with 20 at.%. The drastic MI ratio observed in the sample with x = 20 is ascribed to its special microstructure. The mechanism of the MI effect in FZBN alloys and of the significant MI value appearing at a B content of x = 20 is discussed in this paper. 相似文献
3.
Calorimetric, magnetic and X-ray diffraction measurements have been used to study the magnetic susceptibility and thermal stability of Co80ErxB20−x with (0 ? x ? 4) amorphous ribbons. The compounds are found to crystallize in Co2B and β-Co, after precipitation of the tetragonal Co3B phase. The addition of erbium shifts up the crystallization temperature leading to the increase in the stability of the amorphous state. Magnetic susceptibility measurements show that the addition of erbium increases the Curie temperature and induces noncollinear magnetic behavior. This latter fact is explained on the basis of random local magnetic anisotropy related to the rare earth atoms in amorphous materials. 相似文献
4.
Bulk metallic glasses (BMGs) of Zr46−xNbxCu37.6Ag8.4Al8 with x = 0, 0.5, 1, 2 and 4 at.% were prepared by copper mould casting. The corrosion resistance of the ZrCu-based BMGs with different Nb contents was carefully examined by weight loss measurements and potentiodynamic polarization tests in 3 mass% NaCl, 1 N HCl and 1 N H2SO4 solutions, respectively. Nb addition improves the newly developed BMGs’ corrosion resistance in chloride-containing solutions and the alloys all exhibit excellent corrosion resistance in 1 N H2SO4. The corrosion behavior of the alloy containing 0 and 4 at.% Nb in phosphate-buffered solution was examined by electrochemical polarization tests. The influence of Nb addition on glass forming ability (GFA), thermal stability and mechanical property was investigated by X-ray diffraction, differential scanning calorimetry and compression tests, respectively. It is found that the addition of Nb can deteriorate the GFA and thermal stability of the base system, but little effect is observed on the mechanical properties, e.g., yielding strength and plasticity, of the ZrCu-based BMG alloys. 相似文献
5.
Daniela Carta Dong Qiu Ifty Ahmed Ensanya A. Abou Neel Mark E. Smith 《Journal of Non》2008,354(31):3671-3677
Glasses in the system 40(P2O5)-x(B2O3)-(60 − x)(Na2O) (10 ? x ? 30 mol%) have been prepared by the melt-quenching technique. Thermal properties were studied using differential thermal analysis and the relationship between composition and thermal stability was obtained. Structural characterization was achieved by a combination of experimental data (infrared and Raman spectroscopy, 11B and 31P solid state NMR). In particular, variations in the phosphate network structure upon addition of B2O3 and Na2O were investigated. Analysis of the data indicates that with increasing B2O3 content and decreasing Na2O, the glass network shows increasing levels of cross-linking between phosphate and borate units. Evidence of direct B-O-P bonds was observed. In the compositional range investigated, borate groups contain boron almost exclusively in four-fold coordination. 相似文献
6.
S.B. Bhanu Prashanth 《Journal of Non》2009,355(3):164-1206
The thermal properties and electrical-switching behavior of semiconducting chalcogenide SbxSe55−xTe45 (2 ? x ? 9) glasses have been investigated by alternating differential scanning calorimetry and electrical-switching experiments, respectively. The addition of Sb is found to enhance the glass forming tendency and stability as revealed by the decrease in non-reversing enthalpy ΔHnr, and an increase in the glass-transition width ΔTg. Further, the glass-transition temperature of SbxSe55−xTe45 glasses, which is a measure of network connectivity, exhibits a subtle increase, suggesting a meager network growth with the addition of Sb. The crystallization temperature is also observed to increase with Sb content. The SbxSe55−xTe45 glasses (2 ? x ? 9) are found to exhibit memory type of electrical switching, which can be attributed to the polymeric nature of network and high devitrifying ability. The metallicity factor has been found to dominate over the network connectivity and rigidity in the compositional dependence of switching voltage, which shows a profound decrease with the addition of Sb. 相似文献
7.
Alternating differential scanning calorimetric (ADSC) studies and electrical switching experiments have been undertaken on Al15Te85−xSix (2 ? x ? 12) system of glasses. These glasses are found to exhibit two crystallization reactions (Tc1 and Tc2), for compositions with x < 8. Above x = 8, a single-stage crystallization is seen. Further, a trough is seen in the composition dependence of non-reversing enthalpy (ΔHNR), based on which it is proposed that there is a thermally reversing window in Al15Te85−xSix glasses, in the composition range 4 ? x ? 8. Electrical switching studies indicate that Al15Te85−xSix glasses exhibit a threshold type electrical switching at ON state currents less than 2 mA. Further, the switching voltages are found to increase with the increase in silicon content. It is interesting to note that the start (x = 4) and the end (x = 8) of the thermally reversing window are exemplified by a kink and a saturation in the composition dependence of switching voltages, respectively. 相似文献
8.
N. Manikandan 《Journal of Non》2009,355(1):58-60
The thermal diffusivity (α) of As20Te80−xGax glasses (7.5 ? x ? 18.5) has been measured using photo-thermal deflection (PTD) technique. It is found that the thermal diffusivity is comparatively lower for As20Te80−xGax glasses, which is consistent with the memory type of electrical switching exhibited by these samples. Further, the thermal diffusivity of As20Te80−xGax glasses is found to increase with the incorporation of gallium initially (for x ? 9), which is consistent with the metallicity of the additive. This increase in α results in a maximum at the composition x = 9; beyond x = 9, a decrease is seen in α leading to a minimum at the composition x = 15. The observed composition dependence of thermal diffusivity of As20Te80−xGax glasses has been found to be similar to that of Al20AsxTe100−x glasses, based on which it is proposed that As20Te80−xGax glasses exhibit an extended stiffness transition with compositions x = 9 and x = 15 being its onset and completion, respectively. Also, the composition x = 17.5 at which a second maximum is seen in the thermal diffusivity has been identified to be the chemical threshold (CT) of the As20Te80−xGax glassy system, as at CT, the glass is configurationally closest to the crystalline state and the scattering of the diffusing thermal waves is minimal for the chemically ordered phase. 相似文献
9.
No biocompatible Ti-based glassy alloys without a harmful element have been reported. We have examined the mechanical and chemical properties of Ti-Pd-Zr-Si glassy alloy in comparison with pure Ti metal and Ti-6Al-4V alloy which have been used so far for biomaterials. The present Ti-Pd base glassy alloys do not contain Al and Ni elements which are considered to be rather toxic. Melt-spun Ti45Zr50−xPdxSi5 glassy alloy ribbons (x = 35, 40, 45) exhibited good bend ductility and had higher Vickers’s hardness and lower Young’s modulus as compared to pure titanium and Ti-6Al-4V alloy. In addition, the Ti45Zr50−xPdxSi5 glassy alloys had higher corrosion resistance and were passivated over a wide range and at the lower passive current density of approximately 10−2 Am−2 than at of pure titanium and Ti-6Al-4V alloy in 1 mass% lactic acid and PBS(−) solutions at 310 K. 相似文献
10.
Two series (A and B series) of oxynitride glasses were prepared by melting batches at 1580 °C for 3 h under local CO reducing atmosphere in a Si-Mo-heated resistance furnace. Nominal compositions of A and B series glasses in equivalent percent (eq.%) are (28−x)Y:xMg:48Si:24Al:83O:17N and (28−x)Y:xMg:56Si:16Al:83O:17N (x = 0, 7, 14, 21), respectively. The influences of Mg/Y and Al/Si ratios on the properties such as glass transition temperature (Tg), crystallization temperature (TC), knoop hardness (H), three-point bending strength (σ) and chemical durability in 20%HF were investigated. At the same time, the relationship between these properties and the structures of the glasses were discussed. At constant ratio Si-Al-O-N, Tg decreases nonlinearly but glass leaching ratio increases linearly with increasing Mg/Y ratio. However, H and σ increase first and then decrease as the Mg/Y ratio increases. When the Y/Mg/O/N ratio is constant, Tg decreases slightly but H and σ increase slightly as the Al/Si ratio increases. 相似文献
11.
LixFePO4 glasses have been prepared by fast-quenching method in the whole range of composition 0 ? x ? 1. The amorphous state of glassy materials is confirmed by X-ray diffraction. Information concerning the local environment of Li and Fe cations and the configuration of (PO4)3− oxo-anions is obtained by Fourier transform infrared (FTIR) spectroscopy. While the LiFePO4 crystalline materials undergo a transition from the paramagnetic to the antiferromagnetic ordering at 52 K, no magnetic ordering is observed in the vitreous samples that realize random field systems, so that a spin glass-like freezing is observed at low temperature. The paramagnetic Curie temperature of LixFePO4 is independent of x and shifted to θ = −60 K in the glassy state, due to a significant distortion of the FeO6 octahedra that alters the superexchange path inside the atomic FeO4 layers of the crystallized structure. On another hand, the PO4 tetrahedra are not significantly distorted in the glassy phase. The results are compared with highly disordered, but nanocrystallized LiFePO4 recently obtained at the early stage of synthesis by solid state reaction at 300 °C. In this latter case, the lack of long-range antiferromagnetic ordering is due to substitutional disorder among the cationic sublattice. 相似文献
12.
N. Manikandan 《Journal of Non》2008,354(31):3732-3734
Time dependent photocurrent measurements have been undertaken on bulk Ge15Te85−xInx (1 ? x ? 11) series of glasses. It is found that samples with x < 3 do not exhibit any photo-degradation whereas a decrease in photo-conductivity under illumination is observed in samples with x ? 3. Further, the photosensitivity of Ge15Te85−xInx glasses is found to reveal specific signatures at compositions x = 3 and 7. The observed composition dependent photo-degradation behavior and photo-response of these glasses have been understood on the basis of an extended rigidity percolation and its influence on network related properties. 相似文献
13.
Hongxia Lu 《Journal of Non》2007,353(26):2528-2544
Tracer diffusion coefficients of the radioactive isotope Na-22 were measured in glasses of the type (CaO·Al2O3)x(2 SiO2)1−x to study the diffusion of sodium as a function of glass composition, x, temperature and initial water content. The diffusion of Na-22 in glasses diffusion-annealed in dry air can always be well described by a single tracer diffusion coefficient, but sometimes not in samples annealed in common air. It was found that the sodium tracer diffusion coefficient decreases by about six orders of magnitude when the glass composition x changes from 0 to 0.75 at 800 °C. The temperature dependence of the diffusion of sodium seems to decrease as the silica content increases. Variations of the initial water content in some of the glasses investigated did not very significantly influence the rate of the tracer diffusion of sodium. 相似文献
14.
Tungstate fluorophosphate glass compositions with high WO3 concentration were prepared in the ternary system (80−0.8x)NaPO3-(20−0.2x)BaF2-xWO3 with x = 40,50 and 60 mol%. Transparency decreases as WO3 concentration increases but can be improved by addition of oxidizing systems such as CeO2 or Sb2O3/NaNO3. Characterizations by thermal analysis (DSC) point out that an increase in the amount of WO3 results in a higher glass transition temperature. In addition, such compositions are very stable against devitrification since samples containing 40% and 50% of WO3 donot even exhibit the expected crystallization event. In these samples, the stability against crystallization decreases with the WO3 content and vitreous sample containing 60% of WO3 exhibits an endothermic event around 620 °C due to crystallization of monoclinic WO3 phase. In these glasses, it was shown that the nucleation stage can be induced by thermal-treatment when external nucleating agents such as Ti or Sb are used. Finally, gold-doped samples exhibit a higher crystallization tendency and monoclinic WO3 phase can be grown in such glasses. 相似文献
15.
Different thermodynamic parameters (quantities) of Se80 − xTe20Znx (x = 2, 4, 6, 8 and 10) glasses have been obtained from the phase transformation studies using Differential Scanning Calorimetry (DSC) under non-isothermal condition at five different heating rates (10-50 K/min). Specific heat measurements have been made to see the effect of Zn additive in Se-Te-Zn glasses which have further been utilized to evaluate various thermodynamic quantities such as entropy difference (ΔS), enthalpy difference (ΔH) and Gibbs free energy difference (ΔG) between the undercooled melt and the corresponding equilibrium solid phases as a function of temperature. The data obtained from different thermodynamic quantities have been used to determine the stability of these glasses. It has been found that the stability of the samples increases with the increase of Zinc (Zn) content in the investigated series of the glassy alloys. 相似文献
16.
Preparation and characterization of new fluorotellurite glasses for photonics application 总被引:1,自引:0,他引:1
Guihua Liao Jianjun Xing Hrvoje Gebavi Daniel Milanese Michael Fokine Monica Ferraris 《Journal of Non》2009,355(7):447-503
Glasses based on (85 − x)TeO2-xZnF2-12PbO-3Nb2O5 (x = 0-40) system have been studied for the first time for fabricating mid-infrared optical fiber lasers. The thermal and optical properties including UV-Vis, Raman as well as FTIR spectra are reported. It is demonstrated that increasing the ZnF2 concentration to 30 mol% significantly increased the thermal stability of the glass. Adding ZnF2 also reduced the hydroxyl (OH) content of the glass resulting in lower optical absorption in the mid-infrared region, which is crucial for infrared laser applications. The glass absorption cut-off edge near 400 nm blue-shifts with increasing ZnF2 addition. Raman spectra show a depolymerization of the glass network with increasing transformation of TeO3+1 to TeO3 structures. 相似文献
17.
Pulok Pattanayak 《Journal of Non》2008,354(32):3824-3827
The composition dependence of different thermal parameters such as glass transition temperature, non-reversing enthalpy, thermal diffusivity etc., of bulk As45Te55−xIx chalcohalide glasses (3 ? x ? 10), has been evaluated using the temperature modulated Alternating Differential Scanning Calorimetry (ADSC) and Photo Thermal Deflection (PTD) studies. It is found that there is not much variation in the glass transition temperature of As45Te55−xIx glasses, even though there is a wide variation in the average coordination number . This observation has been understood on the basis that the variation in glass transition temperature of network glasses is dictated by the variation in average bond energy rather than . Further, it is found that both the non-reversing enthalpy (ΔHnr) and the thermal diffusivity (α) exhibit a sharp minimum at a composition x = 6. A broad hump is also seen in glass transition and crystallization temperatures in the composition range 5 ? x ? 7. The results obtained clearly indicate a sharp thermally reversing window in As45Te55−xIx chalcohalide glasses around the composition x = 6. 相似文献
18.
Melt-spun ribbon and bulk samples in cylindrical rod form with diameter ranging from 2 mm to 4 mm of Ti40Cu40Zr10Ni10 alloy were prepared by melt-spinning technique and copper mould casting method, respectively. The microstructure, thermal stability and mechanical properties of the bulk samples were investigated. A completely glassy single phase is formed in the 2 mm rod sample. Increasing the diameter of the rod samples resulted in the formation of CuTi crystalline phase in the 3 mm and 4 mm rod samples. The 2 mm single glassy rod sample exhibited a large supercooled liquid region ΔTx = 58 K and γ = Tx/(Tg + Tl) is 0.390, which indicated that the alloy possessed a good glass-forming ability. The bulk samples also exhibited good mechanical properties. The 2 mm rod sample showed the highest yield strength of about 2086 MPa. The 3 mm rod sample not only showed high yield strength of about 2000 MPa, but also enhanced plastic strain of about 0.71%. 相似文献
19.
In this study, we have investigated the effect of substituting Mn for Fe on the crystallization kinetics of amorphous Fe73.5−xMnxCu1Nb3Si13.5B9 (x = 1, 3, 5, 7) alloys. The samples were annealed at 550 °C and 600 °C for 1 h under an argon atmosphere. The X-ray diffraction analyses showed only a crystalline peak belonging to the α-Fe(Si) phase, with the grain size ranging from 12.2 nm for x = 0 to 16.7 nm for x = 7. The activation energies of the alloys were calculated using Kissinger, Ozawa and Augis-Bennett models based on differential thermal analysis data. The Avrami exponent n was calculated from the Johnson-Mehl-Avrami equation. The activation energy increased up to x = 3, then decreased with increasing Mn content. The values of the Avrami exponent showed that the crystallization is typical diffusion-controlled three-dimensional growth at a constant nucleation rate. 相似文献
20.
The properties and structures of binary xSnO*(100 − x)P2O5 (50 ≤ x ≤ 70 mol%) glasses were evaluated. The glass transition temperatures (Tg), determined by differential thermal analysis (DTA), range from 246 to 264 °C, for glasses prepared under identical conditions. The refractive index (nD) increases from 1.701 to 1.833 as x increases from 50 to 70, and the Abbe number (νD) decreases from 29.1 to 20.4 over the same range. Infrared spectroscopy was used to estimate water contents in the glasses, which decreased with an increase in SnO content, from about 1570 ppm OH for x = 50 to about 50 ppm OH for x = 70, for glasses quenched from melts held at 1000 °C for 15 min. Residual water affects thermal properties, like Tg, and variations in water contents due to differences in melt processing explain the wide variety of glass properties reported in the literature. Raman spectroscopy indicates that progressively shorter phosphate chains are present in the structures of the binary Sn-phosphate glasses with increasing SnO contents. 相似文献