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1.
(1 − x)(0.75GeSe2-0.25In2Se3) − x(1/3In2Se3-2/3KBr) (x = 0, 0.15, 0.3, 0.45, 0.525) chalcohalide glasses were prepared by traditional melt-quenching method and its glass-forming region was determined. The physical, thermal and optical properties of the GeSe2-In2Se3-KBr ternary glass system are reported. The results show that the GeSe2-In2Se3-KBr glass system has relatively high glass transition temperature (Tg = 286-335 °C) and good thermal stability. With increasing KBr content from 0 to 35 mol%, a blue-shift from 750 to 620 nm at the visible absorbing cutting-off edge is observed. The red-shifting of the transmission cutting-off edge at the long-wave IR band occurs linearly with increasing KBr. The allowed direct transition and indirect transition of samples were calculated according to the classical Tauc equation. The direct optical band gaps and indirect optical band gaps were in the range from 1.649 to 1.931 eV and 1.513 to 1.863 eV, respectively. 相似文献
2.
Differential scanning calorimetry (DSC), infrared (IR) and direct current (DC) conductivity studies have been carried out on (100 − 2x)TeO2-xAg2O-xWO3 (7.5 ≤ x ≤ 30) glass system. The IR studies show that the structure of glass network consists of [TeO4], [TeO3]/[TeO3+1], [WO4] units. Thermal properties such as the glass transition (Tg), onset crystallization (To), thermal stability (ΔT), glass transition width (ΔTg), heat capacities in the glassy and liquid state (Cpg and Cpl), heat capacity change (ΔCp) and ratios Cpl/Cpg of the glass systems were calculated. The highest thermal stability (237 °C) obtained in 55TeO2-22.5Ag2O-22.5WO3 glass suggests that this new glass may be a potentially useful candidate material host for rare earth doped optical fibers. The DC conductivity of glasses was measured in temperature region 27-260 °C, the activation energy (Eact) values varied from 1.393 to 0.272 eV and for the temperature interval 170-260 °C, the values of conductivity (σ) of glasses varied from 8.79 × 10−9 to 1.47 × 10−6 S cm−1. 相似文献
3.
New tellurite glasses with a large glass forming domain were elaborated within the TeO2-Tl2O-ZnO ternary system. The evolution of the glass transition (Tg) and onset crystallization (T0) temperatures for such tellurite glasses was studied, in particular, as a function of the Tl2O addition. A decrease of both Tg and T0 temperatures was observed; the former being more affected. Structural modifications induced by the addition of the modifiers were studied by Raman spectroscopy. For a fixed ZnO concentration, the increase in the Tl2O content leads to a destruction of the glass framework, characterized by the transformation of TeO4 disphenoids into isolated TeO32− trigonal pyramid-like ortho-groups. For a fixed Tl2O concentration, the ZnO addition induces similar effects on the glass structure. The optical transmission of the ((80 − x)TeO2-xTl2O-20ZnO) (x = 10, 20 and 30 mol%) glasses was measured in the 300-2000 nm range. Their good transparency was evidenced and a clear reduction of the optical band-gap was noticed with the increase in the Tl2O content. Finally, Second Harmonic Generation was unambiguously detected for each glass composition. The second order non-linearity amplitude is found to be increasing as a function of the Tl2O concentration, in the tested range. 相似文献
4.
Mass density, glass transition temperature and ionic conductivity are measured in xLi2O-(40 − x)Na2O-50B2O3-10Bi2O3 and xK2O-(40 − x)Na2O-50B2O3-10Bi2O3 glass systems with 0 ≤ x ≤ 40 mol%. The strength of the mixed alkali effect in Tg, dc electrical conductivity and activation energy has been determined in each glass system. The magnitudes of the mixed alkali effect in Tg for the mixed Li/Na glass system are much smaller than those in the mixed K/Na glasses. The impact of mixed alkali effect on dc electrical conductivity in mixed Li/Na glass system is more pronounced than in the K/Na glass system. The results are explained based on dynamic structure model. 相似文献
5.
Toru Okada 《Materials Research Bulletin》2010,45(10):1443-9624
Glasses with the compositions of xLi2O-(70 − x)Nb2O5-30P2O5, x = 30-60, and their glass-ceramics are synthesized using a conventional melt-quenching method and heat treatments in an electric furnace, and Li+ ion conductivities of glasses and glass-ceramics are examined to clarify whether the glasses and glass-ceramics prepared have a potential as Li+ conductive electrolytes or not. The electrical conductivity (σ) of the glasses increases monotonously with increasing Li2O content, and the glass of 60Li2O-10Nb2O5-30P2O5 shows the value of σ = 2.35 × 10−6 S/cm at room temperature and the activation energy (Ea) of 0.48 eV for Li+ ion mobility in the temperature range of 25-200 °C. It is found that two kinds of the crystalline phases of Li3PO4 and NbPO5 are formed in the crystallization of the glasses and the crystallization results in the decrease in Li+ ion conductivity in all samples, indicating that any high Li+ ion conducting crystalline phases have not been formed in the present glasses. 60Li2O-10Nb2O5-30P2O5 glass shows a bulk nanocrystallization (Li3PO4 nanocrystals with a diameter of ∼70 nm) and the glass-ceramic obtained by a heat treatment at 544 °C for 3 h in air exhibits the values of σ = 1.23 × 10−7 S/cm at room temperature and Ea = 0.49 eV. 相似文献
6.
M. Kassem D. Le Coq M. Fourmentin F. Hindle M. Bokova A. Cuisset P. Masselin E. Bychkov 《Materials Research Bulletin》2011,46(2):210-215
The glass-forming region in the pseudo-ternary CdSe-AgI-As2Se3 system was determined. Measurements including differential scanning calorimetry (DSC), density, and X-ray diffraction were performed. The effect resulting from the addition of CdSe or AgI has been highlighted by examining three series of different base glasses. The characteristic temperatures of the glass samples, including glass transition (Tg), crystallisation (Tx), and melting (Tm) temperatures are reported and used to calculate their ΔT = Tx − Tg and their Hruby, Hr = (Tx − Tg)/(Tm − Tx), criteria. Evolution of the total electrical conductivity σ and the room temperature conductivity σ298 was also studied. The terahertz transparency domain in the 50-600 cm−1 region was pointed for different chalcogenide glasses (ChGs) and the potential of the THz spectroscopy was suggested to obtain structural information on ChGs. 相似文献
7.
D. Linda M. Dutreilh-Colas D. Hamani A. Mirgorodsky O. Masson A. Kabadou 《Materials Research Bulletin》2010,45(12):1816-1824
Within the Tl2O-Ag2O-TeO2 system, a large glass-forming domain was evidenced and is presented for the fist time. Densities, glass transition (Tg) and crystallization (Tc) temperatures of the relevant glasses were measured. A structural approach of these glasses as functions of the composition was performed using Raman scattering. The Raman spectra were analysed in terms of the structural modifications induced by the Tl2O and Ag2O modifiers. It has clearly evidenced a phase separation inherent in tellurite glasses with low valence cations (as Tl+ and Ag+). The glasses would be constituted of two phases only: one of pure TeO2 and one of pure ortho-tellurite M2TeO3 (M = Ag, Tl) with the statistically mixed Ag-Tl cationic composition. 相似文献
8.
Chalcogenide glasses in the GeS2-Ga2S3-Ag2S pseudo-ternary system were prepared by melt-quenching technique. The structural evolvement of the glasses was studied by Raman spectroscopy. The Raman results show that the addition of Ag2S involves the breaking of [S3Ge-GeS3] ethane-like units and the formation of Ag-S ionic bonds. The results of differential scanning calorimetry (DSC) show that the glasses have relatively high-glass transition temperatures and good thermal stabilities. These GeS2-Ga2S3-Ag2S glasses have a wide range of transmission approximately from 0.50 to 12.5 μm. In addition, with the method of Maker fringe, SHG was observed in the 0.9GeS2-0.05Ga2S3-0.05Ag2S glass irradiated by an electron beam. The value of second-order nonlinear optical susceptibility d is as large as 6.6 pm/V, and the poling mechanism of electron beam irradiation was also discussed in this work. 相似文献
9.
A ChahineM Et-tabirou 《Materials Research Bulletin》2002,37(12):1973-1979
(50−x)Na2O-xCuO-10Bi2O3-40P2O5 glasses (0≤x≤25) were prepared by melting at 900-1100°C mixtures of Na2CO3, Bi2O3, CuO and (NH4)2HPO4. DSC measurements give the variation of glass transition temperature Tg from 318 (x=0) to 378°C (x=25). FTIR spectroscopy shows the evolution of the phosphate skeleton: (PO3)∞ chains for 60Na2O-40P2O5 to P2O7 groups in the glass containing Bi2O3 or both Bi2O3 and CuO. When bismuth and copper oxides replace Na2O, phosphate chains are depolymerized by the incorporation of Bi2O3 and CuO through POBi and POCu bonds. P2O7 groups are predominant structural units in the richest CuO glass. The variation of Tg also supports these results. 相似文献
10.
0.60Na2O-0.40P2O5 and (0.55−z)Na2O-0.05Bi2O3-zTiO2-0.40P2O5 glasses (0≤z≤0.15) were prepared by melting at 1000°C mixtures of Na2CO3, Bi2O3, TiO2 and (NH4)2HPO4. Differential Scanning Calorimetry (DSC) measurements give the variation of glass transition temperature (Tg) from 269°C (for 0.60Na2O-0.40P2O5) to 440°C (for z=0.15). The density measurements increases from 2.25 to 3.01 g/cm3. FTIR spectroscopy shows the evolution of the phosphate skeleton: (PO3)∞ chains for 0.60Na2O-0.40P2O5 to P2O74− groups in the glasses containing Bi2O3 or both Bi2O3 and TiO2. When bismuth oxide and titania are added to sodium phosphate glass, phosphate chains are depolymerized by the incorporation of distorted Bi(6) and Ti(6) units through POBi and POTi bonds. Bi2O3 and TiO2 are assumed to be present as six co-ordinated octahedral [BiO6/2]3−and [TiO6/2]2− units again with shared corners. This is accompanied by the simultaneous conversion of [POO3/2] into [PO4/2]+ units which achieves charge neutrality in the glasses. 相似文献
11.
A.V. Shlyakhtina A.V. Levchenko V.Yu. Bychkov V.A. Rassulov O.K. Karyagina 《Materials Research Bulletin》2007,42(4):742-752
The Er2+xTi2−xO7−δ (x = 0.096; 35.5 mol% Er2O3) solid solution and the stoichiometric pyrochlore-structured compound Er2Ti2O7 (x = 0; 33.3 mol% Er2O3) are characterized by X-ray diffraction (phase analysis and Rietveld method), thermal analysis and optical spectroscopy. Both oxides were synthesized by thermal sintering of co-precipitated powders. The synthesis study was performed in the temperature range 650-1690 °C. The amorphous phase exists below 700 °C. The crystallization of the ordered pyrochlore phase (P) in the range 800-1000 °C is accompanied by oxygen release. The ordered pyrochlore phase (P) exists in the range 1000−1200 °C. Heat-treatment at T ≥ 1600 °C leads to the formation of an oxide ion-conducting phase with a distorted pyrochlore structure (P2) and an ionic conductivity of about 10−3 S/cm at 740 °C. Complex impedance spectra are used to separately assess the bulk and grain-boundary conductivity of the samples. At 700 °C and oxygen pressures above 10−10 Pa, the Er2+xTi2−xO7−δ (x = 0, 0.096) samples are purely ionic conductors. 相似文献
12.
Zhiyong Yang 《Materials Research Bulletin》2008,43(12):3596-3600
The glass forming, optical, thermal, and mechanical properties of GeSe2-Ga2Se3-MX (MX is alkali halide) chalcohalide glasses are reported. A unique property of the glasses is that they have excellent transparency in red-light region in addition to the 8-14 μm atmospheric window. This property is interesting and important for improving the quality control of infrared systems. These glasses also present good thermal stability. They could be promising materials for infrared transmitting applications, although their thermo-mechanical properties are relatively weak. 相似文献
13.
C. Ruvalcaba-CornejoMa. E. Zayas S.J. CastilloR. Lozada-Morales M. Pérez-TelloC.G. Díaz J. Ma. Rincón 《Optical Materials》2011,33(6):823-826
It is presented the Nd doping of the glassy ZnO-CdO-TeO2 ternary system. The Nd-doped oxide glasses were prepared by conventional melt-quenching method using three different compositions from this system. X-rays diffraction (XRD) diagrams in these materials reveal that they are basically vitreous structure. Infrared (IR) spectra of the glasses showed the characteristic bands at 665, 670, and 675 cm−1, which correspond to the trigonal structure of TeO3. The presence of Nd3+ was detected in the visible and infrared region of the spectra by optical absorption (OA) measurements of the band gap and by photoluminescence (PL) experiments. Glasses showed light emission due to the transition: 4F3/2 → 4I9/2. Differential thermal analysis (DTA) of these glasses have shown that Tg temperatures are in the 465-485 °C and Tc in the 800-1000 °C ranges. 相似文献
14.
The effect of CaO-SiO2-B2O3 (CSB) glass addition on the sintering temperature and dielectric properties of BaxSmyTi7O20 ceramics has been investigated using X-ray diffraction, scanning electron microscopy and differential thermal analysis. The CSB glass starts to melt at about 970 °C, and a small amount of CSB glass addition to BaxSmyTi7O20 ceramics can greatly decrease the sintering temperature from about 1350 to about 1260 °C, which is attributed to the formation of liquid phase. It is found that the dielectric properties of BaxSmyTi7O20 ceramics are dependent on the amount of CSB glass and the microstructures of sintered samples. The product with 5 wt% CSB glass sintered at 1260 °C is optimal in these samples based on the microstructure and the properties of sintering product, when the major phases of this material are BaSm2Ti4O12 and BaTi4O9. The material possesses excellent dielectric properties: ?r = 61, tan δ = 1.5 × 10−4 at 10 GHz, temperature coefficient of dielectric constant is −75 × 10−6 °C−1. 相似文献
15.
Sherin Thomas 《Materials Research Bulletin》2008,43(4):843-851
The 0.83ZnAl2O4-0.17TiO2 (ZAT) ceramics were synthesized by solid state ceramic route. The effect of 27B2O3-35Bi2O3-6SiO2-32ZnO (BBSZ) glass on the microwave dielectric properties of ZAT was investigated. The crystal structure and the microstructure of the ceramic-glass composites were studied by X-ray diffraction and scanning electron microscopic techniques. The low frequency dielectric loss was measured at 1 MHz. The dielectric properties of the sintered samples were measured in the microwave frequency range by the resonance method. Addition of 0.2 wt% of BBSZ improved the dielectric properties with quality factor (Qu × f) > 120,000 GHz, temperature coefficient of resonant frequency (τf) = −7.3 ppm/°C and dielectric constant (?r) = 11.7. Addition of 10 wt% of BBSZ lowered the sintering temperature to about 950 °C with Qu × f > 10,000 GHz, ?r = 10 and τf = −23 ppm/°C. The reactivity of 10 wt% BBSZ added ZAT with silver was also studied. The results show that ZAT doped with suitable amount of BBSZ glass is a possible material for low-temperature co-fired ceramic (LTCC) application. 相似文献
16.
Low temperature co-fired ceramic (LTCC) is prepared by sintering a glass selected from CaO-SiO2-B2O3 system, and its sintered bodies are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It is found that the optimal sintering temperature for this glass-ceramic is 820 °C for 15 min, and the major phases of this material are CaSiO3, CaB2O4 and SiO2. The glass-ceramic possesses excellent dielectric properties: ?r = 6.5, tan δ < 2 × 10−3 at 10 MHz, temperature coefficient of dielectric constant about −51 × 10−6 °C−1 and coefficient of thermal expansion about 8 × 10−6 °C−1 at 20-400 °C. Thus, this material is supposed to be suitable for the tape casting process and be compatible with Ag electrode, which could be used as the LTCC materials for the application in wireless communications. 相似文献
17.
Thin films of nanocrystalline SnS2 on glass substrates were prepared from solution by dip coating and then sulfurized in H2S (H2S:Ar = 1:10) atmosphere. The films had an average thickness of 60 nm and were characterized by X-ray diffraction studies, scanning electron microscopy, EDAX, transmission electron microscopy, UV-vis spectroscopy, and Raman spectroscopy. The influence of annealing temperature (150-300 °C) on the crystallinity and particle size was studied. The effect of CTAB as a capping agent has been tested. X-ray diffraction analysis revealed the polycrystalline nature of the films with a preferential orientation along the c-axis. Optical transmission spectra indicated a marked blue shift of the absorption edge due to quantum confinement and optical band gap was found to vary from 3.5 to 3.0 eV with annealing temperature. Raman studies indicated a prominent broad peak at ∼314 cm−1, which confirmed the presence of nanocrystalline SnS2 phase. 相似文献
18.
An oxyfluoride glass with the composition of 25CaF2-5CaO-20Al2O3-50SiO2 (mol%) and crystallized glasses containing CaF2 nanocrystals (10-70 nm) are fabricated. The size and morphology of CaF2 nanocrystals is examined using transmission electron microscopy and atomic force microscopy (AFM), and elastic properties of crystallized glasses are evaluated using a cube resonance method. The large increase in the glass transition temperature in crystallized glasses suggests that the Al2O3-SiO2 based glass network having a high thermal stability is created due to the formation of CaF2 nanocrystals. It is suggested from AFM observations that the chemical bonding between CaF2 nanocrystals and oxide glass matrix is weak. Young’s modulus (E) increases with increasing heat treatment temperature, i.e., E = 88.4 GPa for the glass and E = 93.3 GPa for the sample heat-treated at 700 °C for 1 h. The present study demonstrates that oxyfluoride crystallized glasses containing CaF2 nanocrystals have good elastic (mechanical) properties, being available in practical device applications even from the mechanical point of view. 相似文献
19.
The aim of this article was to study the influence of GeO2 on the thermal stability and optical properties of Er3+/Yb3+ codoped (70 − x)TeO2–xGeO2–PbF2–BaF2 (TGEYx) glasses prepared by using a melting method. The properties of Er3+/Yb3+ codoped glasses were investigated by using differential scanning calorimetry, upconversion luminescence, Raman and optical absorption spectra. The results indicated that TGEY35 glass with the germanate–tellurite mixed network showed the best thermal stability and poor crystallization tendency. With increasing the GeO2 content, the maximum phonon energy of oxyfluoride tellurite glass network increased, while the phonon density decreased. The upconversion emission intensities enhanced obviously based on the decreasing phonon density of glass hosts, while the increasing red emission (657 nm) with the increase of GeO2 concentration was attributed to the relative larger maximum phonon energy which matching the energy gap between the pertinent 4S3/2 and 4F9/2 levels. 相似文献
20.
The high-temperature (HT) properties of RbH2PO4 have been investigated here by several methods. Two anomalies at Tp (∼109 °C) and T′p (∼276 °C) in differential scanning calorimetry (DSC) measurement are due to structural transition from tetragonal (phase III) to monoclinic (phase II) and monoclinic to an unidentified phase I, respectively. The initial dehydration event in RbH2PO4 occurs at ∼250 °C, leading to the formation of dimer crust (Rb2H2P2O7) on the external surface of crystal particles which decelerates the further dehydration process. The conductivity measurement was performed under a highly humidified N2 condition PH2O≈0.56 atm to suppress its dehydration. It revealed two reversible superprotonic phase transition at Tp and T′p. For the one at T′p, the conductivity increases sharply by ∼2 orders of magnitude and the high-conductivity phase I was stable till melting. However, the other one at Tp shows a relatively small jump in conductivity. 相似文献