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1.
Phase equilibria up to solidus line in CuO?CIn 2O 3 system have been investigated using XRD and DTA/TG methods. According to the results, only one compound of the formula Cu 2In 2O 5 formed in the system studied. Its thermal stability was determined in the air and argon proving that the compound did not melt but underwent decomposition. The decomposition of Cu 2In 2O 5 in the air atmosphere began at 1080?°C, while in argon at 835?°C. Additional studies were undertaken to determine the hitherto unknown colour properties of samples representing the CuO?CIn 2O 3 system in the equilibrium state. 相似文献
2.
Li 2O–MoO 3–B 2O 3 glasses mixed with different concentrations of CuO (ranging from 0 to 1.2 mol%) were prepared. The samples were characterized by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. Optical absorption, luminescence, ESR, IR and dielectric properties (viz., dielectric constant ?′, loss tan δ and a.c. conductivity σac, over a wide range of frequency and temperature) of these glass materials have been investigated. The results of differential scanning calorimetric studies suggest that the glass forming ability is higher for the glasses containing CuO beyond 0.6 mol%. The analysis of results of the dielectric properties has revealed that the glasses possess high insulating strength when the concentration of CuO is >0.6 mol%. The variation of a.c. conductivity with the concentration of CuO passes through a maximum at 0.6 mol%. In the high-temperature region, the a.c. conduction seems to be connected with the mixed conduction viz., electronic conduction and ionic conduction. The optical absorption spectra of these glasses exhibited bands due to Cu + ions in the UV region in addition to the conventional band due to Cu 2+ ions in the visible region. The ESR spectral studies have indicated that there is a gradual adoption of Cu 2+ ions from ionic environment to covalent environment as the concentration of CuO increases beyond 0.6 mol% in the glass matrix. The luminescence spectra excited at 271 nm have exhibited an intense yellow emission band centered at about 550 nm and a relatively broad blue emission band at about 450 nm; these bands have been attributed to the 3D 1 → 1S 0 transition of isolated Cu + ions and 3D 1 → 1S 0 transition of (Cu +) 2 pairs, respectively. The quantitative analysis of the results of all these studies has indicated that as the concentration of CuO is increased beyond 0.6 mol% in the glass matrix, a part of Cu 2+ ions have been reduced to Cu + ions that have influenced the physical properties of these glasses to a substantial extent. 相似文献
3.
Glasses with compositions 60Bi 2O 3–(40?x)B 2O 3–xGa 2O 3 ( x = 5, 10, 15, 20 mol%) are prepared by conventional melting method. The thermal properties are investigated by differential thermal analysis (DTA) and the structures of the glasses were probed by Infrared, Raman and X-ray photoelectron spectroscopy (XPS). The results show that density, refractive index and optical basicity increase with the increase of Ga 2O 3. The glass transition temperature ( Tg), the onset crystallization temperature ( Tx), Δ T ( Tx? Tg) decrease with the content of Ga 2O 3. The cut-off edges in ultraviolet and infrared shift to longer wavelength with the increase of Ga 2O 3. On the other hand, the addition of Ga 2O 3 causes a progressive coordination number change of the boron atom from 3 to 4. XPS result indicates both Bi 5+ and Bi 3+ exist in 5 mol% Ga 2O 3 content, while Bi 5+ amounts decrease with the increase of Ga 2O 3 contents. The glass is mainly composed of [BiO 6], [BO 3], [BO 4] and [GaO 4] polyhedra. Glasses are supposed to have layer structure. [BO 3] triangle and [BO 4] tetrahedra may be located between the [GaO 4] tetrahedral and [BiO 6] octahedra to prevent crystallization and to compensate electric charge. 相似文献
4.
Surface tension, density, and volatility of sodium disilicate, modified by additions of 1%, 5%, 10%, mole La 2O 3, have been evaluated at temperatures varying from 900 to 1500°C, under highly reducing conditions. These results and related data (such as activation energy of evaporation reaction; thermal expansivity; temperature coefficient of surface tension; nonideal behaviour; surface adsorption) have made possible interpretation of the role played by lanthanum in modifying the properties of the base glass. 相似文献
5.
Glasses with composition 50Bi 2O 3–(50 ? x) B 2O 3– xGeO 2 ( x = 0, 5, 10, 15 mol%) were prepared by conventional melting method. The thermal properties were investigated by differential thermal analysis (DTA) and the structures of the glasses were probed by Infrared, Raman and X-ray photoelectron spectroscopy (XPS). The results show that density, refractive index and optical basicity increase with the increase of GeO 2. The glass transition temperature ( Tg), onset crystallization temperature ( Tx) and Δ T ( Tx ? Tg) increase as well. The cut-off edges in ultraviolet and infrared shift to longer wavelength by the addition of GeO 2. Infrared, Raman and XPS results indicate that the glass network consists of [Bi–O 6] octahedron, [BO 3] triangle, [BO 4] tetrahedron and [GeO 4] tetrahedron and borate oxide mainly exists in [BO 3] units. XPS result indicates Ge 4+ ions form steady [GeO 4] tetrahedra units in the glass network and the number of non-bridging oxygens decreases with the addition of GeO 2. 相似文献
6.
Precursor glass of composition 25K 2O–25Nb 2O 5–50SiO 2 (mol%) doped with Er 2O 3 (0.5 wt% in excess) was isothermally crystallized at 800 °C for 0–100 h to obtain transparent KNbO 3 nanostructured glass–ceramics. XRD, FESEM, TEM, FTIRRS, dielectric constant, refractive index, absorption and fluorescence measurements were carried out to analyze the morphology, dielectric, structure and optical properties of the glass–ceramics. The crystallite size of KNbO 3 estimated from XRD and TEM is found to vary in the range 7–23 nm. A steep rise in the dielectric constant of glass–ceramics with heat-treatment time reveals the formation of ferroelectric nanocrystalline KNbO 3 phase. The measured visible photoluminescence spectra have exhibited green emission transitions of 2H 11/2, 4S 3/2 → 4I 15/2 upon excitation at 377 nm ( 4I 15/2 → 4G 11/2) absorption band of Er 3+ ions. The near infrared (NIR) emission transition 4I 13/2 → 4I 15/2 is detected around 1550 nm on excitation at 980 nm ( 4I 15/2 → 4I 11/2) of absorption bands of Er 3+ ions. It is observed that photoluminescent intensity at 526 nm ( 2H 11/2 → 4I 15/2), 550 nm ( 4S 3/2 → 4I 15/2) and 1550 nm ( 4I 13/2 → 4I 15/2) initially decrease and then gradually increase with increase in heat-treatment time. The measured lifetime ( τf) of the 4I 13/2 → 4I 15/2 transition also possesses a similar trend. The measured absorption and fluorescence spectra reveal that the Er 3+ ions gradually enter into the KNbO 3 nanocrystals. 相似文献
7.
The article presents a simple method that can be used to get the concentration of various species in mixed-modifier borate glasses. By using the fraction of four coordinated boron in xCaO (30 − x)Na 2O70B 2O 3 (0 ≤ x ≤ 27.5 mol%) and xCaO(40 − x)Na 2O60B 2O 3 glasses (10 ≤ x ≤ 40 mol%), the concentration of BO 4− and asymmetric BO 3 units related to each modifier oxide could be determined. CaO has a greater tendency to form asymmetric BO 3 units in the first glass series, while Na 2O has the ability to form BO 4 units to a greater extent. In xCaO(40 − x)Na 2O60B 2O 3 glasses, BO 4− and asymmetric BO 3 units are formed at the same rate from Na 2O and CaO. The fraction of four coordinated boron, can be predicted by treating the studied glasses as if they are mixtures of Na 2O–B 2O 3 and CaO–B 2O 3 matrices. The change in N4 is due to change in the relative concentration of these matrices. 相似文献
8.
The phase equilibria in the solid state in the system FeVO 4?CCu 3V 2O 8 and FeVO 4?CCuO have been determined. Based on the obtained DTA and XRD analysis results and some additional research, a phase diagram in the whole subsolidus area of the system CuO?CV 2O 5?CFe 2O 3 has been worked out. Eighteen subsidiary subsystems can be distinguished in this ternary system. Basic properties of the obtained phases with howardevansite- and lyonsite-type structure have been investigated by DTA, IR, and SEM methods. 相似文献
9.
Nd 3+-doped precursor glass in the K 2O–SiO 2–Y 2O 3–Al 2O 3 (KSYA) system was prepared by the melt-quench technique. The transparent Y 3Al 5O 12 (YAG) glass–ceramics were derived from this glass by a controlled crystallization process at 750 °C for 5–100 h. The formation of YAG crystal phase, size and morphology with progress of heat-treatment was examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Fourier transformed infrared reflectance spectroscopy (FT-IRRS). The crystallite sizes obtained from XRD are found to increase with heat-treatment time and vary in the range 25–40 nm. The measured photoluminescence spectra have exhibited emission transitions of 4F 3/2 → 4I J ( J = 9/2, 11/2 and 13/2) from Nd 3+ ions upon excitation at 829 nm. It is observed that the photoluminescence intensity and excited state lifetime of Nd 3+ ions decrease with increase in heat-treatment time. The present study indicates that the incorporation of Nd 3+ ions into YAG crystal lattice enhance the fluorescence performance of the glass–ceramic nanocomposites. 相似文献
10.
Phase equilibria in the DyBr 3–NaBr binary system were established from differential scanning calorimetry. This system exhibits incongruently melting compound Na 3DyBr 6 and one eutectic located at DyBr 3 molar fraction x = 0.409 ( T = 711 K). Na 3DyBr 6 undergoes a solid–solid phase transition at 740 K and melts incongruently at 762 K. The specific conductivity of DyBr 3–NaBr liquid mixtures was measured over the whole composition range. Results obtained are discussed in term of possible complex formation. 相似文献
11.
The solubility of the system Pr 2O 3-SeO 2-H 2O at 100°C was studied. The fields of crystallization of Pr 2(SeO 3) 3·H 2O, PrH(SeO 3) 2, Pr(HSeO 3) 3 were established. The compounds obtained were identified by means of chemical, X-ray and thermal analysis. The thermal decomposition of Pr 2(SeO 3) 3·H 2O, PrH(SeO 3) 2, and Pr(HSeO 3) 3 was determined.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
12.
The effect of the SrO addition on the microstructure and structure of the glazes from the SiO2–Al2O3–CaO–MgO–K2O system was investigated in this study. The results were obtained by testing the ability of the frits crystallization, the stability of the crystallizing phases during the single-step fast-firing cycle depending on their chemical composition and the effect of addition of strontium oxide. Differential scanning calorimetry (DSC) curves showed that all glazes crystallized, and diopside and anorthite were mainly identified as dominant phases in the obtained glazes, while the size and amount of each depended on the amount of SrO introduced. The thermal characteristic of the frits was carried out using DSC, and crystalline phases were determined by X-ray diffractometry. The glaze microstructure was investigated by scanning electron microscopy and transmission electron microscopy. Additional information on the microstructure of frits was derived from spectroscopic studies in the mid-infrared range. 相似文献
13.
The water activity and osmotic coefficients of the system { y NH 4NO 3+(1- y) KNO 3}(aq) has been measured at total molalities from 0.2 mol kg −1 to about saturation of one of the solutes for different ionic-strength fractions y of NH 4NO 3 with y=0.2, 0.5 and 0.8 at the temperature 298.15 K using the hygrometric method. The obtained data allow the deduction of the thermodynamic parameters. From these measurements, new Pitzer ionic mixing parameters are determined and used to predict the solute activity coefficients in the mixture. The results obtained are used to calculate the excess Gibbs energy at total molalities for different ionic-strength fractions of NH 4NO 3. 相似文献
14.
Kinetic analysis of the crystallization process in Bi 4(As 2S 3) 96 and Bi 6(As 2S 3) 94 glasses was performed based on DSC curves recorded under non-isothermal measurement conditions. Samples were thermally treated at different heating rates in the temperature range 300?C770?K. The activation energy of crystallization E and the pre-exponential factor K 0 are determined by the Kissinger method and the characteristic crystallization parameters m and n of investigated glasses by the Matusita method. For both crystallization processes the glass with 4 at.% of Bi is characterized by the mechanism of volume nucleation, which is manifested in the form of two-dimensional growth at the first crystallization process, and as three-dimensional at the second one. On the other hand, in the sample with 6 at.% Bi, the average value of the parameter m is close to one, which indicates one-dimensional crystal growth. Compatibility of the values of the parameters m and n suggests that this sample has a large number of crystallization centers, which do not increase significantly during the thermal treatment. 相似文献
15.
The partial system ErPO 4–NaPO 3–Er(PO 3) 3 of the Er 2O 3–Na 2O–P 2O 5 oxide system has been investigated by thermoanalytical methods and X-ray powder diffraction. On the basis of the obtained results the phase diagram of the partial system is proposed. The system is bounded by three subsystems: (i) ErPO 4–Er(PO 3) 3, (ii) Er(PO 3) 3–NaPO 3 and (iii) ErPO 4–NaPO 3. Their phase diagrams are proposed. In the Er(PO 3) 3–NaPO 3 subsystem an intermediate compound NaEr(PO 3) 4 occurs; it melts incongruently at 655 °C. It was found that ErPO 4 and NaEr(PO 3) 4 form a section which is a real system only in the subsolidus region (below 646 °C). Two ternary invariant points (one ternary peritectic and one ternary eutectic) occur in the investigated partial system ErPO 4–NaPO 3–Er(PO 3) 3. 相似文献
16.
Here, we report the preparation of nano silver (Ag) and nano Ag-erbium (Ag–Er) co-embedded potassium–zinc-silicate based monolithic glass nanocomposites by a controlled heat-treatment process of precursor glasses. The nanocomposites were characterized by differential scanning calorimeter, dilatometer, UV–Visible absorption spectrophotometer, X-ray diffractometer and transmission electron microscope and spectroflurimeter. A strong surface plasmon resonance (SPR) band is observed around 430 nm in all the heat-treated glass nanocomposite samples due to the formation of Ag 0 nanoparticles (NP). The Ag-glass nanocomposite samples display nearly 2-fold enhanced photoluminescence (PL) at 470 nm upon excitation at 290 nm until the size of the NP increases to the value equals to the mean free path of conduction electrons inside the particles. On contrary to this, the photoluminescence spectra of Er 3+ ions exhibit a gradual decrease of NIR emission at 1540 nm due to 4I 13/2 → 4I 15/2 transition under excitation at 523 nm in the heat-treated glass nanocomposites which happened due to excitation energy transfer of Er 3+ ions to the Ag NP, acting as ‘plasmonics diluents’ for Er 3+ ions. These nanocomposites have huge potential for various nanophotonic applications. 相似文献
17.
Within the Li–Pt–Sn system, we examine the electronic structures and Li-binding of LiPtSn 2, Li 2PtSn and Li 3Pt 2Sn 3 with fluorite-related crystal structures. The structures with totally de-intercalated lithium keep the characteristics of the pristine ternary compound with a reduction of the volume. In Li 3Pt 2Sn 3 the binding energies of lithium belonging to three crystallographically inequivalent Wyckoff sites are different and point to distinct activities of de-intercalation concomitant with site-selective bonding magnitudes. The derived potentials are within the range of non-oxide binary and ternary lithium based compounds and indicate the possibility of at least partial delithiation. 相似文献
18.
Phase equilibria involving LiMn 2O 4-, Li 2MnO 3-, LiMnO 2-, Mn 3O 4-, and MnO-base solid solutions were studied with varied temperature and partial oxygen pressure. The \({P_{{o_2}}}\)– T and x– y projections of the P– T– x– y phase diagram of the Li–Mn?O system were constructed, as well as the key x– y isotherms of the Li 2O–MnO–MnO 2 quasi-ternary system. In some experiments, the authors’ hydride lithiation method was employed to prepare lithium-rich homogeneous three-component nonstoichiometric phases. 相似文献
19.
Multicomponent glasses from the SiO 2–P 2O 5–K 2O–MgO–CaO–CuO system acting as slow release fertilizers were synthesized by the melt-quenching technique. The influence of CuO and P 2O 5 addition on the structure of glasses was evaluated by FTIR, Raman, 31P, and 29Si MAS NMR spectroscopies. The studies showed that the Cu 2+ ions displacing Ca 2+ ions and Mg 2+ ions in the structure of glass prefer to associate with the phosphorus Q 1 species, forming the Q 0 species with chemically stable POCu bonds. This is accompanied by the reduction of the degree of polymerization of the phospho-oxygen sub-network, with a simultaneous increased degree of polymerization of the silico-oxygen sub-network of the silicate–phosphate glasses. 相似文献
20.
By means of the conventional quenching route, the glass series 33Na 2O– xSrO– xTiO 2–(50 ? 2 x)B 2O 3–17P 2O 5 ( x = 0–12.5 mol%) were prepared. The amorphous state of samples was verified by X-ray diffraction (XRD). Density, molar volume, micro-hardness, glass transition temperature ( T g), and crystallization temperature ( T c) parameters are determined for each glass. The results show that they depend strongly on the chemical compositions. The structure approach of the glasses is determined by Infrared spectroscopy (IR). This investigation highlights that the glassy-matrix contains various phosphate and borate structural units. The crystallization of the high-TiO 2 glasses by heat-treatments favors the formation of titanate phosphate Na 4TiO(PO 4) 2 or Sr 0.5Ti 2(PO 4) 3 along with Sr 3(PO 4) 2 inside the glass-matrix. 相似文献
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