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1.
glass system, with 0 < x
50 mol%, was prepared and investigated by EPR method. For low content of V 2O 5 all the spectra present a hyperfine structure typical for isolated V 4+ ions. With the increasing of V 2O 5 content, the EPR absorption signal showing hyperfine structure is superposed by a broad line without hyperfine structure
characteristic for clustered ions. At high V 2O 5 content, the vanadium hyperfine structure disappears and only the broad line can be observed in the spectra.
Spin Hamiltonian parameters g
, g
, A
, A
, dipolar hyperfine coupling parameters, P, and Fermi contact interaction parameters, K, have been calculated.The composition dependence of line widths of the first two absorptions from the parallel band and of
the broad line characteristic to the cluster formations was also discussed. 相似文献
2.
A new Li 2O–Nb 2O 5–TiO 2 (LNT) ceramic with the Li 2O:Nb 2O 5:TiO 2 mole ratio of 3:1:3 has been investigated. The compound is composed of two phases, the Li 2TiO 3 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 0.83Li 2O–0.17V 2O 5 (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 ε r = 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
3.
Semiconducting glasses of the V 2O 5–NiO–TeO 2 system were prepared by the press-quenching method and their d.c. conductivities in the temperature range 300–450 K were measured. The d.c. conductivities at 395 K for the present glasses were determined to be 10 –7 to 10 –1 S m –1, indicating that the conductivity increased with increasing V 2O 5 concentration. A glass of composition 67.5V 2O 5–2.5NiO–30TeO 2 (mol %) having a conductivity of 2.47×10 –2 S m –1 at a temperature of 395 K was found to be the most conductive glass among the vanadium-tellurite glasses. From the conductivity–temperature relation, it was found that a small polaron hopping model was applicable at the temperature above D/2 ( D: the Debye temperature); the electrical conduction at T> D/2 was due to adiabatic small polaron hopping of electrons between vanadium ions. The polaron bandwidth ranged from 0.06 to 0.21 eV. The hopping carrier mobility varied from 1.1×10 –7 to 5.48×10 –5 cm 2 V –1 s –1 at 400 K. The carrier density is evaluated to be 1.85×10 19–5.50×10 19 cm –3. The conductivity of the present glasses was primarily determined by hopping carrier mobility. In the low-temperature (below D/2) regime, however, both Mott's variable-range hopping and Greaves intermediate range hopping models are found to be applicable. 相似文献
4.
Semiconductive oxide glasses in the system V2O5–MnO–TeO2 were prepared, and the mechanism of d.c. conduction was studied. The Seebeck coefficient measurements at temperatures from 375–475 K indicated the glasses to be n-type semiconducting. The d.c. conductivity ranged from 5×10–5 to 1.9×10–6 S cm–1 at 405 K for V2O5=60 mol% and MnO=0–20 mol%, and decreased with increasing MnO content. The conduction was confirmed to obey the adiabatic small polaron hopping model, and was due to mainly hopping between V-ions in the glasses. The polaron band width J was estimated to be J=0.10–0.20 eV. The electron–phonon interaction coefficient p was very large (21–26). The hopping mobility evaluated as 2.3×10–7–2.7×10–6 cm2 V–1 s–1 increased with increasing V2O5 content. The estimated carrier concentration was the order of 1019 cm–3. The principal factor determining conductivity was the polaron hopping mobility in these glasses. © 1998 Chapman & Hall 相似文献
5.
Phase relations in the Na 2O–Al 2O 3–Nb 2O 5and CaO–Al 2O 3–Nb 2O 5systems were studied. The Na 2O system was found to contain neither ternary compounds nor niobate–aluminate solid solutions. In the CaO system, a ternary compound of composition 4CaO · Al 2O 3·Nb 2O 5was identified (cubic structure, a= 7.628 Å, Z= 2, meas= x= 4.43 g/cm 3). 相似文献
6.
The phase relations in the Li–V 2O 5–Cu system at 600°C are studied by x-ray diffraction. The existence of the known vanadium bronzes M
x
V 2O 5 (M = Li, Cu) is confirmed, and the composition ranges of the related solid solutions are determined. -Li
x
V 2O 5 (0.22 x 0.49) and -Li
x
V 2O 5 (0.88 x 1.0) are shown to dissolve Cu, forming Li
x
Cu
y
V 2O 5 solid solutions with y = 0.72 – 1.48 x and y = 0.58 – 0.18 x, respectively. Cu
x
Li
y
V 2O 5 solid solutions ( y= 0.51 – 0.76 x) are only obtained from -Cu
x
V 2O 5 (0.24 x 0.67). -Li
x
V 2O 5 and -Cu
x
V 2O 5 form a continuous series of solid solutions. The cathodic properties of Li–V 2O 5–Cu materials in high-temperature pulsed lithium batteries are investigated. 相似文献
7.
The effect of sintering process on microstructure, electrical properties, and ageing behavior of ZnO–V 2O 5–MnO 2–Nb 2O 5 (ZVMN) varistor ceramics was investigated at 875–950 °C. The sintered density decreased from 5.52 to 5.44 g/cm 3 and the average grain size increased from 4.4 to 9.6 μm with the increase of sintering temperature. The breakdown field (E 1 mA) decreased from 6991 to 943 V/cm with the increase of sintering temperature. The ZVMN varistor ceramics sintered at 900 °C
led to surprisingly high nonlinear coefficient (α = 50). The donor concentration (N d) increased from 3.33 × 10 17 cm −3 to 7.64 × 10 17 cm −3 with the increase of sintering temperature and the barrier height (Φ b) exhibited the maximum value (1.07 eV) at 900 °C. Concerning stability, the varistors sintered at 925 °C exhibited the most
stable accelerated ageing characteristics, with %ΔE 1 mA = 1.5% and %Δα = 13.3% for DC accelerated ageing stress of 0.85 E 1 mA/85 °C/24 h. 相似文献
8.
Bioactivity and magnetic properties were investigated in glass and glass ceramics based on the SiO 2–Na 2O–Fe 2O 3–CaO–P 2O 5–B 2O 3 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 Na 3CaSi 3O 8 and Na 3-XFe XPO 4 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
9.
一维V2O5是一种非常重要的纳米尺度的材料,可广泛应用于催化剂、电致变色器件、电化学、场效应管、传感器、自旋电子器件以及纳米光刻模板等领域,综述了不同形态的一维V2O5纳米材料(包括纳米线、纳米棒、纳米管、纳米带)的制备方法及其电、磁、电化学和光学性质的最新研究进展。 相似文献
10.
采用溶胶-凝胶(sol-gel)法,用酸化方法生成的多钒加入到V2O5水溶液中,引发V-OH、V-OH2的无机聚合反应,制备V2O5干凝胶(VXG),且简便快速。IR及XRD分析表明,用这种方法制备的VXG的结构,介于无定型与结晶态之间,整体呈无定型状态,局部规整,维持了结晶态的层状结构。VXG的层间距为1.6nm,有序区域大小为5.25nm,约为多钒酸自聚合方法的VXG有序区域的一半。 相似文献
11.
Recently, demand increased for dielectric materials used in energy storage devices at high voltage applications. Appearance of polar clusters in glass matrix could promote its use in energy storage applications. Conventional quenched glass sample of composition 10PbTiO3–10Fe2O3–30V2O5–50B2O3 were successfully developed. The glassy nature was confirmed by XRD and DSC measurements. Boson peak observed at low frequency from the Raman spectra confirms polar cluster formation. Dielectric properties of prepared glass were investigated in a wide range of frequency and temperature. Broad and diffuse peak of dielectric permittivity shifted to the higher temperatures, denoting the typical relaxor ferroelectrics like behavior. Sample shows energy storage density of about 164.7 mJ/cm3 at room temperature. Quenched glass sample shows typical anti-ferromagnetic behavior. 相似文献
12.
A series of ceramics with a general formula Ca 1+xLa 4?xNb xTi 5?xO 17 (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, CaLa 4Ti 5O 17 and Ca 5Nb 4TiO 17, crystallized into single phases with orthorhombic and monoclinic crystal structure, respectively. For intermediate compounds with x = 1, 2, and 3, mixture phases CaLa 4Ti 5O 17 and Ca 5Nb 4TiO 17 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 CaLa 4Ti 5O 17 can be tuned to a near-zero value by addition of suitable amount of TiO 2. 相似文献
13.
Phase relations in the systems Al 2TiO 5–Fe 2O 3, Al 2TiO 5–Cr 2O 3, and Al 2O 3–TiO 2–Fe 2O 3 are investigated, and the composition ranges of pseudobrookite Al 2
– 2x
M 2x
TiO 5 (M = Fe, Cr) solid solutions are determined. 相似文献
14.
在常温下,用脉冲磁控溅射方法石英玻璃和硅片上制备了薄膜,经过450℃退火,得到V2O5薄膜.用XRD、XPS和AFM对薄膜微观结构进行了测试,用分光光度计测量从200~2500nm波段V2O5薄膜的透射和反射光谱.结果表明,V2O5薄膜纯度高、相结构单一、结晶度好.室温到320℃范围内电阻变化2个量级,薄膜的光学能隙为2.46eV,与V2O5体材料性能一致. 相似文献
15.
Effects of 1.0 wt.% V 2O 5–CuO mixture addition on the sintering behavior, phase composition and microwave dielectric properties of BiSbO 4 ceramics have been investigated. BiSbO 4 ceramics can be well densified below temperature about 930 °C with 1.0 wt.% V 2O 5–CuO mixtures addition with different ratios of CuO to V 2O 5. The formation of BiVO 4 phase and substitution of Cu 2+ can explain the decrease of sintering temperature. Dense BiSbO 4 ceramics sintered at 930 °C for 2 h exhibited good microwave dielectric properties with permittivity between 19 and 20.5, Qf values between 19,000 and 40,000 GHz and temperature coefficient of resonant frequency shifting between ?71.5 ppm °C ?1 and ?77.8 ppm °C ?1. BiSbO 4 ceramics could be a candidate for microwave application and low temperature co-fired ceramics technology. 相似文献
16.
在O2/Ar气氛中,用射频磁控溅射法在常温下溅射V2O5粉末靶得到氧化钒薄膜。在350℃热处理后,经XRD分析,薄膜的主要成分为V2O5。在不同温度下对V2O5薄膜作了对“空气和SO2”的混合气氛的敏感特性测试分析,发现在300~390℃范围内,薄膜对SO2气体灵敏随温度的升高而增大,在超过390℃后,灵敏度随温度升高而降低。在SO2气体去除后,薄膜的电阻值能恢复到初始状态,气敏过程可反复进行。文章对V2O3薄膜的气敏机理作了定性描述。 相似文献
17.
The evolution of elastic properties and structure upon the change of CaO/P 2O 5 ratio in SiO 2–CaO–Na 2O–P 2O 5 glasses (45S5-derived and 55S4-derived) at ambient conditions has been studied by using both Brillouin and Raman spectroscopy
coupled with X-ray diffraction. Under the same SiO 2/Na 2O ratio, it is found that a decrease in CaO/P 2O 5 molar ratio has caused a more-polymerized silicate network via a net consumption of Q 0, Q 1, and Q 2 species yet enriching in Q 3 and Q 4 species. Brillouin experiments revealed that all the bulk, shear and Young’s moduli of the glasses studied increases with
the increase of CaO/P 2O 5 molar ratio. The unexpected variation trend in shear modulus can be correlated to the contribution from cohesion, the less-polymerized
phosphate Q species, and density. Compared to the 45S5-derived, the more-polymerized 55S4-deived glass has a lower bulk but
slightly higher shear modulus at the given CaO/P 2O 5 ratio. 相似文献
18.
全固态薄膜锂离子电池由于具有能量密度高、循环性能和安全性能好等优点已成为目前研究的热点.其中,V2O5薄膜是锂离子电池中一种备受重视的阴极材料.对V2O5薄膜的离子扩散系数以及结构特点做了简单介绍,重点评述了V2O5薄膜电极制备和电化学性能研究方面的发展近况,并对今后的发展方向进行了展望. 相似文献
19.
V2O5薄膜具有优异的物理、化学性质,在化工催化、电子、电化学等许多领域有广泛的应用,由于V2O5薄膜对还原性气体和湿度具有良好的敏感特性,其在气体和湿度传感器上的研究也日渐广泛,因此本文综述了V2O5为基体的薄膜在气体传感器和湿度传感器上的研究进展及存在的问题和解决的思路. 相似文献
20.
综述了V2O2薄膜材料的结构、电学性质及其在电学中的应用。 相似文献
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