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1.
Series of glass based on the (80 − x)TeO2–20ZnO–(x)Er2O3 system (0.5 mol% ≤ x ≤ 2.5 mol%) has successfully been made by melt quenching technique. The optical properties of glass have been investigated
by means of IR and Raman spectroscopy. It is observed that as the Er2O3 content is being increased, the sharp IR absorption peaks are consistently shifted from 650 to 672 cm−1 while the Raman shift intensity around 640–670 cm−1 is decreases but increases around 720–740 cm−1. It is found out that both phenomenons are related to the structural changes between the stretching vibration mode of TeO4 tbp and TeO3 tp, and bending vibration mode of Te–O bonds in the glass linkages. 相似文献
2.
Josef Jirák Ladislav Koudelka Jaroslav Pospíšil Petr Mošner Lionel Montagne Laurent Delevoye 《Journal of Materials Science》2007,42(20):8592-8598
Glasses of the ternary system ZnO–Bi2O3–P2O5 were prepared and studied in two compositional series 50ZnO–xBi2O3–(50 − x)P2O5 and (50 − y)ZnO–yBi2O3–50P2O5. Two distinct glass-forming regions were found in the 50ZnO–xBi2O3–(50 − x)P2O5 glass series with x = 0–10 and 20–35 mol.% Bi2O3. All prepared Bi2O3-containing glasses reveal a high chemical durability. Small additions of Bi2O3 (∼5 mol.%) improve thermal stability of glasses. All glasses crystallize on heating within the temperature range of 505–583 °C.
Structural studies by Raman and 31P MAS NMR spectroscopies showed the rapid depolymerisation of phosphate chains within the first region with x = 0–15 and the presence of isolated Q0 phosphate units within the second region with x = 20–35. Raman studies showed that bismuth is incorporated in the glass structure in BiO6 units and their vibrational bands were observed within the spectral region of 350–700 cm−1. The evolution of properties and the spectroscopic data are both in accordance with a network former effect of Bi2O3. 相似文献
3.
We have studied the optical absorption and luminescence spectra of 45Na2O · xNb2O5 · (55 − x)P2O5 glasses containing 5, 10, 20, 25, 30, and 35 mol % Nb2O5. The results indicate that the absorption band around 26000 cm−1, responsible for the yellow color of the glasses, is due to the [Nb(5+)--O−] center and disappears upon secondary heat treatment. Heat treatment of europium-doped glasses increases the concentration
of Eu3+ centers in an asymmetric environment, which is accompanied by an increase in luminescence efficiency. The reason for this
is that the Eu3+ ions are located outside the niobate subsystem of the glass matrix. The europium in the glasses studied acts as a protector
ion. 相似文献
4.
The study of electrical conductivity of 30Li2O: (70 − x) B2O3: xV2O5 glass samples has been carried out. The results have been explained by dividing the temperature range into two regions. In
region I, conductivity shows Arrhenius behaviour for all the samples. The conductivity increases with addition of V2O5. The results have been explained in the light of Anderson and Stuart Model. In region II, an anomalous enhancement in the
conductivity is observed for all the samples up to certain temperature beyond which the conductivity decreases. The enhancement
in the conductivity in the annealed glass sample has been attributed to nanocrystallization. 相似文献
5.
The thermoelectric power and d.c electrical conductivity of x V2O5⋅40CaO⋅(60−x)P2O5 (10 ≤ x ≤ 30) glasses were measured. The Seebeck coefficient (Q) varied from +88 μ V K−1 to −93 μV K−1 as a function of V2O5 mol%. Glasses with 10 and 15 mol% V2O5 exhibited p-type conduction and glasses with 25 and 30 mol% V2O5 exhibited n-type conduction. The majority charge carrier reversal occurred at x = 20 mol% V2O5. The variation of Q was interpreted in terms of the variation in vanadium ion ratio (V5 +/V4 +). d.c electrical conduction in x V2O5⋅40CaO⋅(60−x)P2O5 (10 ≤ x ≤ 30) glasses was studied in the temperature range of 150 to 480 K. All the glass compositions exhibited a cross over from
small polaron hopping (SPH) to variable range hopping (VRH) conduction mechanism. Mott parameter analysis of the low temperature
data gave values for the density of states at Fermi level N (EF) between 1.7 × 1026 and 3.9 × 1026 m−3 eV−1 at 230 K and hopping distance for VRH (RVRH) between 3.8 × 10−9m to 3.4 × 10−9 m. The disorder energy was found to vary between 0.02 and 0.03 eV. N (EF) and RVRH exhibit an interesting composition dependence. 相似文献
6.
S. M. Levshov I. V. Berezovskaya N. P. Efryushina B. I. Zadneprovskii V. P. Dotsenko 《Inorganic Materials》2011,47(3):285-289
We have studied the luminescence spectra of Li2Sr1 − x
Eu
x
SiO4 (x = 0.0001–0.01) solid solutions prepared by solid-state reactions and a sol-gel process in a reducing atmosphere. The spectra
show a broad band in the range 500–700 nm, centered at 578 nm, which is due to the 4f
65d → 4f
7 transition. The luminescence excitation spectrum shows, in addition to bands due to Eu2+ 4f
7 → 4f
65d transitions, a strong band centered at 174 nm, attributable to absorption in the SiO44− group. 相似文献
7.
I. Ardelean R. Lungu P. Păşcuţă 《Journal of Materials Science: Materials in Electronics》2007,18(8):837-841
Glasses of the xFe2O3·(100−x)[B2O3·SrO] system, with 0 ≤ x ≤ 30 mol% were studied by X-ray diffraction, density, optical microscopy and FT-IR spectroscopy measurements. The X-ray patterns
for the prepared system show that vitreous phase is present only in the sample with x < 40 mol%. For x ≥ 40 mol% in the studied samples is evidenced crystalline phase of Fe2O3. SEM measurements for the sample with x = 40 mol% shows that there are formed Fe2O3 microcrystallites with 10–20 μm dimension. FT-IR spectroscopy measurements shown that BO3 and BO4 are the main structural units of the glass system and the iron ions are located in the glass network. 相似文献
8.
We have performed partial HSO4− substitution in CsH2PO4 and studied the associated structural changes and the proton conductivity of the resultant (CsH2PO4)1 − x
(CsHSO4)
x
solid solutions in the range x = 0.01–0.3. The results indicate that, at room temperature, the solid solutions are disordered. In the range x = 0.01–0.1, they are isostructural with the low-temperature phase of CsH2PO4 (sp. gr. P21/m), and their unit-cell parameters increase with x, whereas in the range x = 0.15–0.3 the solid solutions are isostructural with the high-temperature, cubic phase of CsH2PO4 (Pm3m), and their unit-cell parameter decreases. The conductivity of the (CsH2PO4)1 − x
(CsHSO4)
x
solid solutions with x ≤ 0.3 depends significantly on their composition and increases at low temperatures by up to four orders of magnitude, approaching
that of the superionic phase of CsH2PO4 in the range x = 0.15–0.3 because of the hydrogen bond weakening and increased proton mobility. The conductivity of the superionic phase
decreases with increasing x by no more than a factor of 1.5–2, and the superionic phase transition, which occurs at 231°C in CsH2PO4, shifts to lower temperatures and disappears for x ≥ 0.15. The activation energy for low-temperature conduction decreases with increasing x: from 0.9 eV in CsH2PO4 to 0.48 eV at x = 0.1. 相似文献
9.
Caixuan Xu Anming Hu Naomichi Sakai Izumi Hirabayashi Mitsuru Izumi 《Journal of Superconductivity and Novel Magnetism》2007,20(4):309-314
Single domain GdBa2Cu7-δ (Gd123) bulk superconductors were fabricated in air by top-seeding melt-texture growth. Performance of the air-processed
Gd123 was successfully enhanced by addition of both BaCO3 and BaCuO2−x
, which suppress the formation of Gd1+x
Ba2−x
Cu3O7-δ solid solutions. The optimum doping amount ranges from 0.05 to 0.15, M BaCO3 and 0.05 to 0.1, M BaCuO2−x
per molar Gd123. The distribution of the second phase particles was observed by scanning electron microscopy. A narrow band
formed by Gd2BaCuO5 particle concentration appeared around the seeding zone in both a–b plane and c-growth sector in Gd123 single grain. Trapped magnetic field density reached 0.67, T for sample with 24 mm in diameter and
8, mm in thickness and a high critical current density J
c up to 91,200, A/cm2 was achieved at 77, K under self-field. 相似文献
10.
S. M. Rao J. K. Srivastava M. K. Wu B. H. Mok C. L. Chen M. C. Ling H.-L. Liu Y. Y. Chen J. C. Ho 《Journal of Superconductivity and Novel Magnetism》2011,24(4):1249-1262
We report here SQUID (magnetization) measurements, along with supporting specific heat, Raman, SEM (scanning electron microscope),
EDX (energy dispersive X-ray) and XRD (X-ray diffraction) measurements, on Cu-doped and undoped double perovskite Sr22+Y3+Ru5+O62-\mathrm{Sr}_{2}^{2+}\mathrm{Y}^{3+}\mathrm{Ru}^{5+}\mathrm{O}_{6}^{2-} (abbreviated as SrY2116) system grown as single crystal using high-temperature solution growth technique. These measurements
show the undoped system to be a nonmetallic (insulating) spin glass (SG) and the ∼5–30% Cu-doped (i.e. Cu-concentration/(Cu + Ru-concentration)
∼5–30%) system to be a spin glass superconductor (SGSC) with T
c (critical temperature) ∼28–31 K and superconducting volume fraction, f
sc∼2.2–9%. To mention, similar measurements done on undoped and Cu-doped BaY2116 and BaPr2116 systems show for them the same
(SG, SGSC) behaviors. However they show a decrease in T
c and f
sc when diamagnetic Y3+ ions are replaced by Pr3+ spins, presumably due to enhanced internal pair breaking, and also decreased Cu–O–Cu overlap, owing to Pr3+ presence; these phenomena are known to exist in the Pr123 compound, PrBa2Cu3O7−δ
(δ∼0), due to ∼10% of Pr3+ ions having tendency to occupy Ba2+ sites. Measurements done on undoped and Cu-doped SrHo2116 show similar SG and SGSC properties. Further, the undoped and Cu-doped
SrY2116 crystals grown by hydrothermal growth technique (i.e., grown using lower temperature and high pressure) show same
behaviors. From these investigations it can be said that the undoped Ru-double perovskites (A2BB′O6, B′=Ru) are SG systems and that Cu-doped Ru-double perovskites (A2BB′O
δ
, δ∼6, B′=Ru1−x
Cu
x
, 0<x≲0.3) are SG superconductors (SGSCs). Results are discussed. 相似文献
11.
Polycrystalline soft ferrites, Zninx Cu1−x
Fe2O4 (x = 0.30, 0.50, 0.70, 0.80 and 0- 90), doped with controlled amount of calcium chloride (CaCl2) were prepared by standard ceramic route and studied for a.c. susceptibility. X- ray diffraction studies of the compositions
reveal formation of single- phase cubic spinel. The values of lattice constant increase as doping percentage of CaCl2 increased from 001% to 005% and afterwards decrease slightly. The presence of chlorine ions is confirmed by absorption peak
in far IR spectra near 650 cm− 1 for all the samples. The variation of a.c. susceptibility with temperature shows the existence of single domain structure
forx = 0.3 and exhibits transition from single domain to multidomain structure with increased Ca2+ contents from 0.01 to 0.1%. The composition,x = 0.5, shows multidomain structure independent of Ca2+ content. The samples forx = 0.70, 0.80 and 0.90 show paramagnetic behaviour at and above room temperature. 相似文献
12.
Ismail Hakki Karahan 《Journal of Materials Science》2007,42(24):10160-10163
Zn1−x
Fe
x
alloys were electrochemically deposited on AISI 4140 steel substrates from sulfate bath. The bath was consisted of 40 g dm−3 ZnSO4·7H2O, 20–40 g dm−3 FeSO4·7H2O, 25 g dm−3 Na3C6H5O7, and 16 g dm−3 H3BO3. The effect of bath composition on the electrical resistivity, the phase structure, and the corrosion behavior were investigated
by the current–voltage measurements versus temperature, the X-ray diffraction (XRD) analysis, the atomic absorption spectrometry
analysis, and the polarization measurements, respectively. Iron content was shown to strongly affect the structure, the electrical
resistivity and the corrosion stability of Zn–Fe alloys. 相似文献
13.
A new glass system SnO–MgO–P2O5 with low viscosity has been developed by a melt-quenching method. Formation, thermal properties, and chemical durability
of these glasses have been investigated. For a constant P2O5 concentration, the glass formation ability is enhanced with the increasing Sn/(Sn + Mg) ratio. The glasses exhibit low glass
transition temperature (T
g = 270–400 °C), low dilatometric softening temperature (T
DS = 290–420 °C), and high thermal expansion coefficient (CTE = 110–160 × 10−7 K−1). With the increasing Sn/(Sn + Mg) ratio, T
g and T
DS decrease, and CTE increases. When Sn/(Sn + Mg) ratio is varied, the relationship between chemical durability and thermal properties of the
present glasses is not consistent with what expected in general cases. It is noted that the glasses with 32–32.5 mol% P2O5 exhibit excellent chemical durability and tunable T
g, T
DS, and CTE (by varying Sn/(Sn + Mg) ratio). 相似文献
14.
Daocong Li Zhenghe Peng Wenyong Guo Chaoqun Yuan Yangmei Liu Yunhong Zhou 《Journal of Materials Science》2007,42(22):9221-9226
LiNi0.9Co0.1O2 cathode material is prepared from LiOH·H2O and Ni0.9Co0.1(OH)2 by co-precipitation and subsequent two-stage heat treatment in flowing oxygen based on the results of thermogravimetric.
The structural and electrochemical properties of the samples are characterized by means of inductively coupled plasma-atomic
emission spectrometer (ICP-AES), X-ray diffraction (XRD), scanning electron microscope (SEM), cyclic voltammogram (CV) and
charge–discharge studies. All the samples sintered at different temperatures have a typical layered structure with space group
R3-m and good electrochemical performances. The sintering temperature has a remarkable effect on the electrochemical performance
of the samples. The sample sintered at 730 °C shows the largest initial discharge capacity 191.1 mAh g−1 (50 mA g−1, 3.0–4.3 V) and the best cycling performance. The initial discharge capacity rises to above 200 mAh g−1 with the voltage range 3.0–4.5 V. 相似文献
15.
In this paper, mixed Ca–Ba oxide Ca1 − x
Ba
x
Bi4Ti4O15 (CBBT) ceramics, fabricated by the improved traditional ceramics process were investigated by doping concentrations of Ba
ion up to x =\emph{x} {=} 0·9 (in steps of 0·1). At room temperature, an orthorhombic crystal system was confirmed using XRD, and their parameter was
obtained using the Rietveld method. Dielectric properties and phase transitions were studied and are explained in terms of
lattice response of these ceramics. A shift in ferroelectric–paraelectric phase transition (TC\emph{T}_{C}) to lower temperatures and a corresponding decrease in permittivity peak with increasing concentration of Ba2 + are also observed. The ferroelectric–paraelectric phase transition of CBBT compounds is of normal type in nature, differing
from the relaxor characteristic of BBT. The decrease of orthorhombicity in the lattice structure by the larger Ba2 + ion incorporation, indicating an approach of a and b, results in lower Curie temperature. Appearance of anomalous loss peaks of Ba-rich compounds at 530°C reveals a phase transition
development trend from ferroelectric orthorhombic structure to the paraelectric orthorhombic structure. Relationship of polarization
with lattice response is discussed. 相似文献
16.
Solid solution of (1−x)LaCrO3–xBiCrO3 (x = 0, 0.10, 0.15, 0.20 and 0.25) was prepared via the citrate–nitrate combustion synthesis. Pure perovskite phase was obtained
at 800 °C, a much lower synthesis temperature than that needed in the solid-state reactions. The thermodynamics of phase formation
and the ceramic sintering mechanism were investigated. The substitution of Bi3+ for La3+ was found to give a separate exothermic decomposition event in the gels and the precursor did not produce a transient liquid
phase while heating to 1200 °C, as was found in ceramics prepared by solid state reaction. This finding shows that the role
of Bi2O3 in the sintering of the La1−x
Bi
x
CrO3 ceramics depends on the processing method. 相似文献
17.
New potassium ion conducting solid electrolytes based on potassium monoferrite have been prepared through partial substitution
of the divalent cation Cd2+ on the potassium site, and their properties have been investigated. The introduction of cadmium cations sharply increases
the electrical conductivity of KFeO2 over the entire temperature range studied. In addition to the maximum in conductivity at the boundary of the K1 − 2x
Cd
x
FeO2 solid solution, there is a maximum at a higher cadmium content (x = 0.30–0.35). The possible origins of this maximum are discussed. 相似文献
18.
Sushil Kumar M. A. Majeed Khan M. Zulfequar M. Husain 《Journal of Materials Science》2007,42(1):363-367
The fabrication of devices with lead salts and their alloys with detecting and lasing capabilities has been an important technological
development. The high quality polycrystalline thin films of PbTe1−x
S
x
with variable composition (0 ≤ x ≤ 1) have been deposited onto ultra clean glass substrates by vacuum evaporation technique. Optical, structural and electrical
properties of PbTe1−x
S
x
thin films have been examined. Absorption coefficient and band gap of the films were determined by absorbance measurements
in wavelength range 2,500–5,000 nm using FTIR spectrophotometer. Sample nature, crystal structure and lattice parameter of
the films were determined from X-ray diffraction patterns. DC conductivity and activation energy of the films were measured
in temperature range 300–380 K through I–V measurements. 相似文献
19.
Biao Dong Hua Yang Lianxiang Yu Yuming Cui Weiqun Jin Shouhua Feng 《Journal of Materials Science》2007,42(13):5003-5006
Sm
x
BiY2–x
Fe5O12 (x = 0, 0.1, 0.2, 0.4, 0.6, 0.8) nanocrystals were fabricated by sol–gel method. Samples were characterized by powder X-ray
diffraction (XRD), thermal gravity analysis (TGA) and differential thermal analysis (DTA), transmission electron microscopy
(TEM), vibrating sample magnetometer(VSM). The samples were calcined at 850 °C and 1000 °C and the average size of the particles
were determined by Scherrer’s formula . In this paper, we discussed the effect of Sm3+ substitution for Y3+ on magnetic properties of BiY2Fe5O12. The magnetic properties of Sm
x
BiY2−x Fe5O12 are decreased with increasing content of Sm ion. 相似文献
20.
Z. Nagamedianova E. Sánchez 《Journal of Materials Science: Materials in Electronics》2007,18(5):547-552
There is great interest in sulfide glasses because of their high lithium ion conductivity. New sulfide glasses based on Li2S-P2S5-Sb2S3 system have been synthesized by a classical quenching technique. A summary of thermal and structural characterization is
presented. Electrical conductivities of the samples have been determined by Impedance Spectroscopy. The compositions of low
lithium content (below 20% mol) have presented low electronic conductivities close to 10−8 S/cm at room temperature. The compositions of medium lithium content (30–50% mol) have presented mixed ionic-electronic behavior
with predominant on ionic conductivity with a maximum values around 10−6 S/cm for samples up to 50% Li2S at room temperature. Arrhenius behavior is verified between 25°C and Tg for all glasses with activation energies about 0.55–0.64 eV. A comparative study of conductivities with glasses belonging
to the other chalcogenide systems has been undertaken. 相似文献