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1.
The Na2O-B2O3 system is thermodynamically optimized by means of the CALPHAD method. A two-sublattice ionic solution model, (Na+1)P(O−2,BO3
−3,B4O7
−2,B3O4.5)Q, has been used to describe the liquid phase. All the solid phases were treated as stoichiometric compounds. A set of thermodynamic
parameters, which can reproduce most experimental data of both phase diagram and thermodynamic properties, was obtained. Comparisons
between the calculated results and experimental data are presented. 相似文献
2.
The BaO-B2O3 pseudobinary system is assessed. A two-sublattice ionic solution model, (Ba2+)
P
(O2−, BO
3
3−
, B4O
7
2−
, B3O4.5)
Q
, is adopted to describe the liquid phase. All the solid phases are treated as stoichiometric compounds. A set of parameters
consistent with most of the available experimental data on both phase diagram and thermodynamic properties is obtained by
using CALPHAD technique. A comparison between the calculated results and experimental data as well as a previous assessment
is presented. 相似文献
3.
The BaO-B2O3 pseudobinary system is assessed. A two-sublattice ionic solution model, (Ba2+) P (O2−, BO33−, B4O72−, B3O4.5) Q , is adopted to describe the liquid phase. All the solid phases are treated as stoichiometric compounds. A set of parameters consistent with most of the available experimental data on both phase diagram and thermodynamic properties is obtained by using CALPHAD technique. A comparison between the calculated results and experimental data as well as a previous assessment is presented. 相似文献
4.
Available thermodynamic and phase diagram data have been critically assessed for all phases in the CrO-Cr2O3, CrO-Cr2O2-Al2O3, and CrO-Cr2O2-CaO systems from 298 K to above the liquidus temperatures and for oxygen partial pressures ranging from equilibrium with
metallic Cr to equilibrium with air in the case of the first two systems and toP
O
2 = 10−3 atm for the CrO-Cr2O3-CaO system. All reliable data have been simultaneously optimized to obtain one set of model equations for the Gibbs energy
of the liquid slag and all solid phases as functions of composition and temperature. The modified quasichemical model was
used for the slag. The models permit phase equilibria to be calculated for regions of composition, temperature, and oxygen
potential where data are not available. 相似文献
5.
M. Hoch 《Journal of Phase Equilibria and Diffusion》1996,17(4):302-310
We evaluated the six binary phase diagrams, B2O3-PbO, B2O3-SiO2, B2O3-ZnO, PbO-SiO2, PbO-ZnO, and SiO2-ZnO, to obtain a consistent picture for the quaternary system B2O3-PbO-SiO2-ZnO. We used all the available thermodynamic data: enthalpies of mixing, activity data, complete phase diagrams, and miscibility
gaps. The agreement between the various sets of data is good. We also calculated the enthalpy of formation of the ternary
compound 5PbO-B2O3-SiO2. ΔfH/R of 1/8 [5PbO-B2O3-SiO2] =-(2.104 ± 0.057) kK. 相似文献
6.
Xinyu Ye Weidong Zhuang Jingfang Wang Wenxia Yuan Zhiyu Qiao 《Journal of Phase Equilibria and Diffusion》2007,28(4):362-368
The Al2O3-SrO binary system has been studied using the CALPHAD technique in this paper. The modeling of Al2O3 in the liquid phase is modified from the traditional formula with the liquid phase represented by the ionic two-sublattice
model as (Al3+, Sr2+)
P
(, O2−)
Q
. Based on the measured phase equilibrium data and experimental thermodynamic properties, a set of thermodynamic functions
has been optimized using an interactive computer-assisted analysis. The calculated results are compared with experimental
data. A comparison between this system and similar systems is also given. 相似文献
7.
8.
In-Ho Jung Sergei A. Decterov Arthur D. Pelton 《Journal of Phase Equilibria and Diffusion》2004,25(4):329-345
A complete literature review, critical evaluation, and thermodynamic modeling of the phase diagrams and thermodynamic properties
of all oxide phases in the MgO-Al2O3, CaO-MgO-Al2O3, and MgO-Al2O3-SiO2 systems at 1 bar total pressure are presented. Optimized model equations for the thermodynamic properties of all phases are
obtained that reproduce all available thermodynamic and phase equilibrium data within experimental error limits from 25 °C
to above the liquidus temperatures at all compositions. The database of the model parameters can be used along with software
for Gibbs energy minimization to calculate all thermodynamic properties and any type of phase diagram section. The modified
quasichemical model was used for the liquid slag phase and sublattice models, based upon the compound energy formalism, were
used for the spinel, pyroxene, and monoxide solid solutions. The use of physically reasonable models means that the models
can be used to predict thermodynamic properties and phase equilibria in composition and temperature regions where data are
not available. 相似文献
9.
A. Nicholas Grundy Ludwig J. Gauckler Bengt Hallstedt 《Journal of Phase Equilibria and Diffusion》2004,25(4):311-319
A thermodynamic assessment of the Sr-Mn-O system is presented. The main practical relevance of this system is that it contains
the perovskite phase SrMnO3, which is the Sr-rich end member of the phase (La,Sr) MnO3, that finds widespread use as a cathode material for solid oxide fuel cells (SOFCs) and has recently attracted a lot of attention
due to its interesting giant magnetoresistive properties. The thermodynamic parameters are optimized by applying the CALPHAD
method. The SrMnO3−z
phase exists in two modifications, a layered hexagonal modification at low temperatures and a perovskite modification at
high temperatures. Both modifications show considerable oxygen deficiencies, which are modeled using the compound energy model.
The sublattice occupation of the phases is (Sr2+) (Mn3+, Mn4+)(O2−, Va)3. On reducing Mn4+ to Mn3+, oxygen vacanices are formed. The phase SrMn3O6−z
also shows an oxygen deficiency, which is modeled in an identical way. The Ruddlesden-Popper phases Sr2MnO4 and Sr3Mn2O7, and the phases Sr7Mn4O15 and Sr4Mn3O10 are modeled as stoichiometric phases. The ionic liquid is modeled using the two-sublattice model for ionic liquids. The stability
and thermodynamic data on many of the phases in this system are poorly known. For this reason, some aspects of this assessment
must be regarded as tentative. 相似文献
10.
Fenghua Liu Gaojie XuLei Duan Yali LiYong Li Ping Cui 《Journal of Alloys and Compounds》2011,509(5):L56
B2O3-doped ZnO-Bi2O3-Sb2O3-based varistors were fabricated by conventional ceramic technique. The microstructure and electrical properties were investigated by SEM, XRD and electrical measurements. With the addition of B2O3, the liquid-assisted sintering based on Bi2O3 was improved, and the Bi2O3-B2O3 glass and Zn3(BO3)2 phase were formed on the grain boundaries. The doping of B2O3 markedly improved the varistor performance of the ZnO-Bi2O3-Sb2O3-based varistors. The nonlinear coefficient of the sample with 3.5 mol% B2O3 sintered at 1100 °C reached 56 and the leakage current was only 0.3 μA. 相似文献
11.
M. Hoch 《Journal of Phase Equilibria and Diffusion》1996,17(4):290-301
We applied our model to the enthalpy of mixing data of the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3. The most stable composition in the liquid, that is where the enthalpy of mixing is most negative, is with a metal-oxygen
ratio of 4 to 3, for monovalent metals (Na and Li) and 3 to 4 for divalent metals (Ba and Ca) in liquid silicates or borates.
The same applies to the CaO-SiO2, CaO-Al2O3, PbO-B2O3, PbO-SiO2, ZnO-B2O3, and ZnO-SiO2 systems. The oxygen to metal ratio, its constant value in various types of systems, reflects and describes the structure
of the liquid.
Using the analyzed enthalpies of mixing data and the available phase diagrams, we calculated the enthalpies of formation of
the various binary compounds. The results are in excellent agreement with data in the literature that were obtained from direct
solid-solid calorimetry. 相似文献
12.
M.A. Khaghani-DehaghaniR. Ebrahimi-Kahrizsangi N. SetoudehB. Nasiri-Tabrizi 《International Journal of Refractory Metals and Hard Materials》2011,29(2):244-249
Alumina-titanium diboride nanocomposite (Al2O3-TiB2) was produced using mixtures of titanium dioxide, acid boric and pure aluminum as raw materials via mechanochemical process. The phase transformation and structural characterization during mechanochemical process were utilized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analyses (TG-DTA) techniques. A thermodynamic appraisal showed that the reaction between TiO2, B2O3 and Al is highly exothermic and should be self-sustaining. XRD analyses exhibited that the Al2O3-TiB2 nanocomposite was formed after 1.5 h milling time. The results indicate that increasing milling time up to 40 h had no significant effect other than refining the crystallite size. 相似文献
13.
J. Leitner M. Nev?ivaD. Sedmidubský P. Voňka 《Journal of Alloys and Compounds》2011,509(15):4940-4943
The heats of drop-solution in 3Na2O + 4MoO3 melt at 973 K and 1073 K for calcium and strontium carbonates, Bi2O3, Nb2O5 and several stoichiometric mixed oxides in CaO-Nb2O5, SrO-Nb2O5 and Bi2O3-Nb2O5 systems were measured using a Setaram Multi HTC-96 calorimeter. The values of enthalpy of formation from constituent binary oxides at 298 K, ΔoxH, were derived for the mixed oxides under investigation: ΔoxH(CaNb2O6) = −132.0 ± 23.8 kJ mol−1, ΔoxH(Ca2Nb2O7) = −208.0 ± 31.9 kJ mol−1, ΔoxH(SrNb2O6) = −167.9 ± 19.1 kJ mol−1, ΔoxH(Sr2Nb2O7) = −289.2 ± 37.5 kJ mol−1 and ΔoxH(BiNbO4) = −41.9 ± 11.1 kJ mol−1. Additionally, the values ΔoxH for other mixed oxides with different stoichiometries were estimated on the basis of these experimental results. 相似文献
14.
Synthesis and luminescent properties of Ln3+ (Ln3+ = Eu3+, Dy3+) -doped Bi2ZnB2O7 phosphors 总被引:1,自引:0,他引:1
The new phosphors Bi2ZnB2O7:Ln3+ (Ln3+ =Eu3+,Dy3+) were synthesized by solid-state reaction technique.The obtained phosphors were investigated by means of X-ray powder diffraction (XRD),photoluminescence excitation and emission spectra with the aim of enhancing the fundamental knowledge about the luminescent properties of Eu3+ and Dy3+ ions in the Bi2ZnB2O7 host lattice.XRD analysis shows that all these compounds are of a single phase of Bi2ZnB2O7.The excitation and emission spectra of Bi2ZnB2O7:Ln3+ (Ln3+ =Eu3+,Dy3+) at room temperature show the typical 4f-4f transitions of Eu3+ and Dy3+,respectively.The hypersensitive transitions of 5D0→7F2 (Eu3+) and 4F9/2→ 6H13/2 (Dy3+) are relatively higher than those of the insensitive transitions in Bi2ZnB2O7.It is conceivable that the Bi2ZnB2O7 structure provides asymmetry sites for activators (Eu3+,Dy3+).The optimum concentrations of Eu3+ and Dy3+ ions in Bi2ZnB2O7 phosphors are both x =0.05. 相似文献
15.
The isothermal section of the phase diagram for the system NiO-MgO-SiO2 at 1373 is established. The tie lines between (NixMg1-x
)O solid solution with rock salt structure and orthosilicate solid solution (NiyMg1-y)Si0.5O2 and between orthosilicate and metasilicate (NizMg1-z)SiO3 crystalline solutions are determined using electron probe microanalysis (EPMA) and lattice parameter measurement on equilibrated
samples. Although the monoxides and orthosilicates of Ni and Mg form a continuous range of solid solutions, the metasilicate
phase exists only for 0 < Z < 0.096. The activity of NiO in the rock salt solid solution is determined as a function of composition
and temperature in the range of 1023 to 1377 using a solid state galvanic cell. The Gibbs energy of mixing of the monoxide
solid solution can be expressed by a pseudo-subregular solution model: ΔGex = X(l - X)[(-2430 + 0.925T)X + (-5390 + 1.758T)(1 - X)] J/mol. The thermodynamic data for the rock salt phase are combined
with information on interphase partitioning of Ni and Mg to generate the mixing properties for the orthosilicate and the metasilicate
solid solutions. The regular solution model describes the orthosilicate and the metasilicate solid solutions at 1373 K within
experimental uncertainties. The regular solution parameter ΔGex/Y(1-Y) is -820 (±70) J/mol for the orthosilicate solid solution. The corresponding value for the metasilicate solid solution is
-220 (±150) J/mol. The derived activities for the orthosilicate solid solution are discussed in relation to the intracrystalline
ion exchange equilibrium between Ml and M2 sites. The tie line information, in conjunction with the activity data for orthosilicate
and metasilicate solid solutions, is used to calculate the Gibbs energy changes for the intercrystalline ion exchange reactions.
Combining this with the known data for NiSi0.5O2, Gibbs energies of formation of MgSi0.5O2, MgSiO3, and metastable NiSiO3 are calculated. The Gibbs energy of formation of NiSiO3, from its component oxides, is equal to 7.67 (±0.6)kJ/mol at 1373K. 相似文献
16.
Harumi Yokokawa Natsuko Sakai Teruhisa Horita Katsuhiko Yamaji Yueping Xiong Takanori Otake Hiroo Yugami Tatsuya Kawada Junichiro Mizusaki 《Journal of Phase Equilibria and Diffusion》2001,22(3):331-338
Phase diagram calculations that were made previously for the ZrO2-MO
m/2 (m = 2, 3, 4) systems and for the ZrO2-YO1.5-MO
m/2 (M = transition metals) systems have been extended to the ZrO2-YO1.5-CeO2(-CeO1.5) system to make an attempt to explain (1) thermogravimetric (TG) results as a function of oxygen potential, (2) electronic
conductivity as a function of oxygen potential, and (3) a miscibility gap observed in air. The interaction parameters for
the CeO2-CeO1.5-YO1.5 system were obtained from the reported oxygen nonstoichiometry in CeO2−x
and rate earth doped ceria, (Ce,RE)O2−δ
. The interaction parameters for the ZrO2-CeO2 subsystem were obtained so as to reproduce the observed miscibility gap at 1273 K. Those thermodynamic properties can reproduce
consistently the experimental behaviors of the electronic conductivity and the TG results in the (Zr1−x
Ce
x
)0.8Y0.2O1.9 solid solutions; these indicate the enhancement of reduction of CeO2. 相似文献
17.
W. Gasior J. Pstru Z. Moser A. Krzyak K. Fitzner 《Journal of Phase Equilibria and Diffusion》2003,24(1):40-49
With the maximum bubble pressure method, the density and surface tension were measured for five Ag-Bi liquid alloys (X
Bi=0.05, 0.15, 0.25, 0.5, and 0.75), as well as for pure silver. The experiments were performed in the temperature range 544–1443
K. Linear dependences of both density and surface tension versus temperature were observed, and therefore the experimental
data were described by linear equations. The density dependence on concentration and temperature was derived using the polynomial
method. A similar dependence of surface tension on temperature and concentration is presented. Next, the Gibbs energy of formation
of solid Bi2O3, as well as activities of Bi in liquid Ag-Bi alloys, were determined by a solid-state electromotive force (emf) technique
using the following galvanic cells: Ni, NiO, Pt/O
−2/W, Ag
X
Bi
(1−X), Bi
2
O
3(s). The Gibbs energy of formation of solid Bi2O3 from pure elements was derived:
=−598 148 + 309.27T [J · mol−1] and
=−548 008 + 258.94T [J · mol−1]; the temperature and the heat of the α → δ transformation for this solid oxide were calculated as 996 K and 50.14 J · mol−1. Activities of Bi in the liquid alloys were determined in the temperature range from 860–1075 K, for five Ag-Bi alloys (X
Ag=0.2, 0.35, 0.5, 0.65, 0.8), and a Redlich-Kister polynomial expansion was used to describe the thermodynamic properties of
the liquid phase. Using Thermo-Calc software, the Ag-Bi phase diagram was calculated. Finally, thermodynamic data were used
to predict surface tension behavior in the Ag-Bi binary system. 相似文献
18.
With the maximum bubble pressure method, the density and surface tension were measured for five Ag-Bi liquid alloys (X
Bi=0.05, 0.15, 0.25, 0.5, and 0.75), as well as for pure silver. The experiments were performed in the temperature range 544–1443
K. Linear dependences of both density and surface tension versus temperature were observed, and therefore the experimental
data were described by linear equations. The density dependence on concentration and temperature was derived using the polynomial
method. A similar dependence of surface tension on temperature and concentration is presented. Next, the Gibbs energy of formation
of solid Bi2O3, as well as activities of Bi in liquid Ag-Bi alloys, were determined by a solid-state electromotive force (emf) technique
using the following galvanic cells: Ni, NiO, Pt/O
−2/W, Ag
X
Bi
(1−X), Bi
2
O
3(s). The Gibbs energy of formation of solid Bi2O3 from pure elements was derived: =−598 148 + 309.27T [J · mol−1] and =−548 008 + 258.94T [J · mol−1]; the temperature and the heat of the α → δ transformation for this solid oxide were calculated as 996 K and 50.14 J · mol−1. Activities of Bi in the liquid alloys were determined in the temperature range from 860–1075 K, for five Ag-Bi alloys (X
Ag=0.2, 0.35, 0.5, 0.65, 0.8), and a Redlich-Kister polynomial expansion was used to describe the thermodynamic properties of
the liquid phase. Using Thermo-Calc software, the Ag-Bi phase diagram was calculated. Finally, thermodynamic data were used
to predict surface tension behavior in the Ag-Bi binary system. 相似文献
19.
Min YangKuo Li Jie SuQ. Huang Wei BaoLiping You Zhaofei LiYingxia Wang Yu JiangFuhui Liao Jianhua Lin 《Journal of Alloys and Compounds》2011,509(14):4707-4713
Yb26B12O57, a rare earth oxyborate previously assigned as Yb3BO6, has been studied by various techniques including neutron and X-ray diffraction, 11B NMR spectroscopy, electron diffraction and high angle angular dark field-scanning transmission electron microscopy (HADDF-STEM). It crystallizes in the space group C2/m with cell parameters of a = 24.5780(4) Å, b = 3.58372(5) Å, c = 14.3128(3) Å and β = 115.079(1)°. The structure consists of slabs of rare earth sesquioxide and borate groups. The sesquioxide part is identified from the structural refinement, and is observed from HADDF-STEM image, while elucidation of borate groups is not straightforward. An additional oxygen atom (O31), which links two B2O5 groups into a B4O11 polyanion, is identified from the analysis of neutron diffraction data. The occupancy of this oxygen site is only quarter, which results in a random distribution of B4O11 and B2O5 groups along the b-direction. The chemical formula of ytterbium oxyborate is Yb26(BO3)4(B2O5)2(B4O11)O24, instead of the simple stoichiometric formula Yb3BO6. This compound is paramagnetic but its susceptibility deviated from the Curie-Weiss law at low temperature. 相似文献
20.
Yeon Hwa Jo Deuk Ho Yeon Bhaskar C. Mohanty Yong Soo Cho 《Metals and Materials International》2008,14(4):493-496
New microwave materials based on a gadolinium zinc borate (20ZnO−20Gd2O3−60B2O3) glass with typical Al2O3 filler have been investigated as a dielectric candidate for low temperature co-fired ceramic (LTCC) applications. The experimental
parameters, such as filler contents and firing temperature, were found to affect seriously densification, crystallization
and microwave dielectric properties. The presence of ZnAl2O4 and GdBO3 phases with an unexpected GdAl3(BO3)4 phase were assumed to influence the final performance of the materials. In particular, the GdAl3(BO3)4 phase is the consequence of chemical reactions between the glass and Al2O3 filler during firing. As a promising dielectric composition, the sample consisting of 20ZnO−20Gd2O3−60B2O3 and 40 wt.% Al2O3 filler exhibited k (dielectric constant) ∼8.1 and Q (quality factor) ∼312 at 18.6 GHz when fired at 850°C. 相似文献