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1.
High temperature thermodynamic data for equilibria in the Ca-S-O, Mg-S-O, and La-S-0 systems were determined by a galvanic
cell technique using calcia stabilized zirconia (CSZ) solid electrolytes. The measured emf data were used to calculate the
standard free energy changes of the following reactions: [1] CaO(s) + 1/2S2(g) → CaS(s) + 1/2O2(g) 1000 to 1350 K ΔG° = 21906.9 − 0.8T(K)(±400 cal) = 91658 − 3.37 (±1700 J) [2] CaS(s) + 2O2(g) → CaSO4(s) 1050 to 1450 K ΔG° = -227530.7 + 80.632T(K) (±400 cal) = -951988.5 + 337.4T (±1700 J) [3] CaO(s) + 3/2O2(g) + 1/2S2(g) → CaSO4(s) 1050 to 1340 K ΔG° = -204892.7 + 79.83T(K)(±400 cal) = -857271.1 + 334.0T (±1700 J) [4] MgO(s) + 1/2S2(g) → MgS(s) + 5O2(g) 1000 to 1150 K ΔG° = 45708.6 − 2.897(K)(±500 cal) = 191244.8 − 12.1T (±2100 J) [5] La2O3(s) + 1/2S2(g) → La2O2S(s) + 1/2O2(g) 1080 to 1350 K ΔG° = 17507 − 2.32T(K)(±380 cal) = 73249.3 − 9.7T (±1600 J) [6] La2O3S(s) + S2(g) → La2S3(s) + O2(g) 950 to 1120 K ΔG° = 70940 + 2.25T(K)(±500 cal) = 296812.9 + 9.47 (±2100 J) The ΔG° values of reaction [5] were combined with the literature data for ΔG°f(La2O3) to obtain the standard free energy of formation of La2O2S at high temperatures. The values of ΔG°f thus calculated for La2O2S were combined with the ΔG° data for reaction [6] to obtain the standard free energy of formation of La2S3 at high temperatures. 相似文献
2.
Modified coulometric titrations on the galvanic cell:O in liquid Cu or Ag / ZrO2( + CaO) / Air, Pt, were performed to determine precisely the oxygen activities in liquid copper and silver in the range of
relatively low oxygen concentration. The present experimental results were remarkably reproducible in comparison with the
published data. The standard Gibbs energies of solution of oxygen in liquid copper and liquid silver for 1/2 O2(l atm) → O(l at. pct) were determined respectively to be ΔG° (in Cu) = −18040 −0.03 T(K) (± 120) cal · g-atom−1 = −75500
−0.12 T(K)(± 500) J · g-atom−1, ΔG°(inAg)= -3860+ 1.56 T(K) (±90) cal · g-atom−1 = −16140 + 6.52 T(K)(±380) J · g-atom−1 where
the reference state for dissolved oxygen was an infinitely dilute solution. The present value of the partial entropy of oxygen
dissolved in liquid copper differs significantly from that suggested by many investigators. Further, the present equation
for liquid copper has been found to be consistent with a correlation proposed previously by the present authors. The equation
for liquid silver is in good agreement with the published ones. 相似文献
3.
M. Morishita K. Koyama S. Shikata M. Kusumoto 《Metallurgical and Materials Transactions B》2004,35(5):891-895
The thermodynamic properties of Mg48Zn52 were investigated by calorimetry. The standard entropy of formation at 298 K, Δf
S
298
o
, was determined from measuring the heat capacity, C
p
, from near absolute zero (2 K) to 300 K by the relaxation method. The standard enthalpy of formation at 298 K, Δf
H
298
o
, was determined by solution calorimetry in hydrochloric acid solution. The standard Gibbs energy of formation at 298 K, Δf
G
298
o
, was determined from these data. The obtained results were as follows: Δf
H
298
o
(Mg48Zn52)=(−1214±(300) kJ · mol−1;ΔfS
298
o
(Mg48Zn52)=(−123±0.36) J · K−1 · mol−1; and Δf
G
298
o
(Mg48Zn52)=(−1177±(300) kJ · mol−1. The electronic contribution to the heat capacity of Mg48Zn52 was found to be approximately equal to pure magnesium, indicating that the density of states in the vicinity of the Fermi
level follows the free electron parabolic law. 相似文献
4.
High-temperature thermodynamic properties of Pt−Zr alloys containing 2 to 25 at. pct Zr and Pt−Hf alloys containing 20 to
25 at. pct Hf have been measured over the temperature range 1100 to 1400 K by a galvanic cell technique using a thoria-based
electrolyte. Activities of Zr and Hf show large negative deviations from Raoult's Law; at 1300 K and 23 at. pct Zr of Hf,
for instance,a
Zr=6.5×10−16 anda
Hf=7.9×10−17. Correlation of emf results with X-ray phase data enables calculation of standard free energies of formation of the intermetallic
compounds ZrPt5, ZrPt3, and HfPt3. At 1300 K ΔG
f
0
(ZrPt5) =−92,680 cal/mole; ΔG
f
0
(ZrPt3)=−91,740 cal/mole; and ΔG
f
0
(HfPt3)=−97,350 cal/mole. The high stabilities of phases in the Pt−Ti, Pt−Zr, and Pt−Hf systems verify the predictions of the Engel-Brewer
correlation. The large negative entropies of formation of TiPt3, ZrPt3 are discussed. Applications including side reactions in fuel cells and thermocouple systems are mentioned.
P. J. MESCHTER, formerly a Graduate Student at the University of Pennsylvania
This paper is based upon a dissertation submitted by P. J. Meschter in partial fulfillment of the requirements of the degree
of Doctor of Philosophy at the University of Pennsylvania. 相似文献
5.
Measurements have been made on the thermal capacity of γ-Gd2Se3 at 58.88–298.34 K. Values have been obtained for the thermal capacity, entropy, reduced Gibbs energy, and enthalpy under
standard conditions: C°p = 125.87 ± 0.5 J· mole−1 · K−1; S°(298.15 K) = 196.5 · 1.6 J · mole−1 · K−1; Φ°(298.15 K) = 103.6 ± 1.6 J · mole−1 · K−1; H°(298.15 K)-H°(0) = 27681 ± 138 J · mole−1. The enthalpy of Gd2Se3 has been measured and the major thermodynamic functions have been calculated for the solid and liquid states over the temperature
range 450–2300 K. The temperature dependence of the enthalpy in the ranges 300–1800 K and 2000–2300 K are represented: H°(T)-H°(298.15
K) = = 1.1949 · 10−2 · T2 + 122.38 · T + 347402 · T−1 − 38716 and H°(T)-H°(298.15 K) = 262.81 · T-− 196047, respectively. The calculated temperature, enthalpy, and entropy of
melting for Gd2Se3 are: Tm = 1925 ± 40 K, ΔmH° (Gd2Se3) = 68.5 kJ · mole-1, ΔmS°(Gd2Se3) = 35.6 J · mole−1 · K−1.
__________
Translated from Poroshkovaya Metallurgiya, Nos. 3–4(448), pp. 56–61, March–April, 2006. 相似文献
6.
O. Sjödén S. Seetharaman L. -I. Staffansson 《Metallurgical and Materials Transactions B》1986,17(1):179-184
Gibbs energy change for the reactionxFe(s) + 1/2O2(g) = Fe
x
O(s) has been redetermined using the galvanic cell (−) Fe(s), Fe
x
O(s)∥ZrO2 − CaO∥NiO(s), Ni(s)(+) in the temperature range 866 to 1340 K. The results are at variance with earlier works in that they reflect the transformations
occurring in the iron phase. The Gibbs energy function is represented by two nonlinear equations,viz., ΔG° (866 to 1184 K) = −251480 − 18.100T + 10.187T lnT ± 210 J/mol and ΔG° (1184 to 1340 K) = −286248 + 181.419T - 13.858T lnT ± 210 J/mol.
Formerly Research Assistant at the Department of Theoretical Metallurgy, The Royal Institute of Technology, Stockholm 相似文献
7.
The standard Gibbs energies of formation of Ca3As2, Ca3Sb2, and Ca3Bi2 were determined by a chemical equilibration technique yielding the following results: 3Ca(1)+2As(1)=Ca3As2 (s) ΔG°=−723,800+172.8T (±23,700)(J/mol) 1273 to 1573 K 3Ca(1)+2Sb(1)=Ca3Sb2(s) ΔG°=−726,300+159.3T(±24,600) (J/mol) 1273 to 1573K 3Ca(1)+2Bi(1)=Ca3Bi2(s) ΔG°=−696,400+195.6T(±23,200) (J/mol) 1148 to 1323 K
The thermodynamic data for removal of arsenic, antimony, and bismuth by other experimental investigations were discussed in
terms of the activity coefficients of these compounds in slags. The stabilities of these compounds were also discussed by
using the critical oxygen partial pressures calculated from the above equations.
D.J. MIN, formerly Graduate Student, Department of Metallurgy, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan 相似文献
8.
The standard enthalpies of formation of eight samarium alloys with late transition metals have been determined by direct synthesis
calorimetry at 1273±2 K. The following values of ΔH
f
0, in kJ·(mole atom)−, are reported: SmNi5, −27.4±0.5; Sm5Rh4, −66.5±1.0; SmRh2, −65.5±1.2; SmPd, −82.4±2.0; Sm3Pd4, −87.2±2.5; SmPd3, −82.9±2.5; SmPt, −108.7±3.5; and SmPt2, −100.2±2.6. The results are compared with predicted values from the Miedema model, with available literature data for SmNi5, SmPd, and SmPt, and with earlier values for similar compounds formed by other lanthanide metals reported by this laboratory.
The observed relationships between the enthalpies of formation and the number of f-electrons in the considered binary alloys RE
n
Me
m
(RE=lanthanide elements; and Me=Group VIII elements) are discussed. 相似文献
9.
The standard molar enthalpies of formation of RuAl, RhAl, and IrAl have been determined by the direct combination method using
a high-temperature calorimeter operated at (1473 ±2) K. The following values are reported: ΔH
f
o
(RuAl) = −(124.1 ± 3.3) kJ/mol; ΔH
f
o
(RhAl) =-(212.6 ± 3.2) kJ/mol; and ΔH
f
o
(IrAl) = -(185.5 ± 3.5) kJ/mol. For OsAl, an approximate value is −77 kJ/mol. The results are compared with available data
for related alloys and with predicted values. 相似文献
10.
K. T. Jacob K. P. Abraham S. Ramachandran 《Metallurgical and Materials Transactions B》1990,21(3):521-527
The standard Gibbs energies of formation of platinum-rich intermetallic compounds in the systems Pt-Mg, Pt-Ca, and Pt-Ba have
been measured in the temperature range of 950 to 1200 K using solid-state galvanic cells based on MgF2, CaF2, and BaF2 as
solid electrolytes. The results are summarized by the following equations: ΔG° (MgPt7) = −256,100 + 16.5T (±2000) J/mol ΔG° (MgPt3) = −217,400 + 10.7T (±2000) J/mol ΔG° (CaPt5) = −297,500 + 13.0T (±5000) J/mol ΔG° (Ca2Pt7) = −551,800 + 22.3T (±5000) J/mol ΔG° (CaPt2) = −245,400 + 9.3T (±5000) J/mol ΔG° (BaPt5) = −238,700 + 8.1T (±4000) J/mol ΔG° (BaPt2) = −197,300 + 4.0T (±4000) J/mol where solid platinum and liquid alkaline earth metals are selected as the standard states. The relatively large
error estimates reflect the uncertainties in the auxiliary thermodynamic data used in the calculation. Because of the strong
interaction between platinum and alkaline earth metals, it is possible to reduce oxides of Group ILA metals by hydrogen at
high temperature in the presence of platinum. The alkaline earth metals can be recovered from the resulting intermetallic
compounds by distillation, regenerating platinum for recycling. The platinum-slag-gas equilibration technique for the study
of the activities of FeO, MnO, or Cr2O3 in slags containing MgO, CaO, or BaO is feasible provided oxygen partial pressure in the gas is maintained above that corresponding
to the coexistence of Fe and “FeO.”
Formerly Professor and Chairman, Department of Metallurgy, Indian Institute of Science
Formerly Visiting Scientist, Department of Metallurgy, Indian Institute of Science 相似文献
11.
The standard enthalpies of formation of eight Pr alloys were determined by direct synthesis calorimetry at 1473 ± 2 K. The
following values of ΔHskƒ/°(kJ/g atom) are reported: PrNi5, −(25.6 ± 1.0); PrRu2, −(16.9 ± 1.5); PrRh2, −(60.4 ± 1.7); PrPd, −(78.8 ± 2.5); PrPd2, −(82.7 ± 3.1); PrIr2, −(70.7 ± 2.8); PrPt, −(103.4 ± 2.7); and PrPt2, − (93.5 ± 2.4). The results are compared with data from available literature for some of the Pr alloys and with predicted
values from the model of Miedemaet al. 相似文献
12.
The possibility of using quantitative differential thermal analysis to investigate phase transformations is examined. The
temperature, enthalpy, and entropy of polymorphic transformations in LaGe1.8 and SmSi2 are determined: Ttr = 724 K, ΔtrH = 1635 ± 79 J · mole−1, ΔtrS = 2.3 ± 0.1 J · mole−1 · K−1 (LaGe1.8); Ttr = 658 K, ΔtrH = 1384 ± 69 J · mole−1, ΔtrS = 2.1 ± 0.1 J · mole−1 · K−1 (SmSi2).
__________
Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 3–4 (454), pp. 72–78, 2007. 相似文献
13.
The Standard enthalpies of formation of 14 neodymium alloys have been determined by direct synthesis calorimetry at 1477 ±
2 K. The following values of ΔH
f
o
(kJ/g atom) are reported: NdNi5, −(26.2 ± 1.1); Nd5Ru2, −(17.2 ± 1.9); NdRu2, −(18.8 ± 1.2); Nd5Rh4, −(59.9 ± 2.5); NdRh, −(64.2 ± 2.0); NdRh2, −(59.9 ± 1.1); NdRh3, −(44.4 ± 1.6); NdPd, −(77.2 ± 2.7); NdPd3, −(73.3 ± 2.3); Nd5Ir3, −(59.7 ± 2.7); NdIr2, −(67.6 ± 1.5); NdPt, −(104.4 ± 2.6); NdPt2, −(97.9 ± 2.4); and NdP5, −(55.0 ± 3.1). The results are compared with available literature data for some of the neodymium alloys and with predicted
values from the Miedema model. 相似文献
14.
William G. O’Brien Harvey J. Jensen Robert N. Benedict Renato G. Bautista 《Metallurgical and Materials Transactions B》1976,7(4):671-677
The decomposition equilibria of platinum dichloride have been found to consist of two decomposition steps, with chlorine molecules
being the vapor species for both steps. An intermediate metastable PtCl solid is formed in the first step in addition to platinum
metal and chlorine molecules. The platinum dichloride decomposes incongruently, the stepwise decomposition being PtCl2 → PtCl → Pt. The PtCl2 decomposition reactions consist of PtCl2(s) = PtCl (metastables) + 1/2 Cl2
(g) and PtCl2(s) = Pt(s) + Cl2
(g). The sum of the third lawΔH
D, 298 K for the above two reactions is 214.637 ± 1.963 kJ/mole, in very good agreement with the second law ΔHD, 298 K = 215.107 ± 13.062 kJ/mole. The second decomposition step is given by the reaction 2PtCl (metastables) = 2Pt(s) + Cl2
(g) with a third law ΔHD, 298 K = 127.356 ± 0.791 kJ/mole, in excellent agreement with the second law ΔHD, 298 K = 127.509 ± 6.154 kJ/mole. The calculated heat of formation of PtCl2 is -139 ± 2 kJ/mole and that of PtCl is -63 ± 1 kJ/mole.
Formerly Graduate Assistant.
Formerly Undergraduate Research Helper, 相似文献
15.
V. S. Sudavtsova L. O. Romanova N. V. Kotova T. M. Zinevich 《Powder Metallurgy and Metal Ceramics》2007,46(3-4):169-174
Partial (for aluminum) and integral mixing enthalpies of ternary Si-Ni-Al liquid alloys are examined by high-temperature calorimetry
under isoperibolic conditions at 1770 ± 5 K. Alloys of five radial sections with a constant ratio of silicon-to-nickel mole
fractions (xSi/xNi = 0.85/0.15; 0.7/0.3; 0.5/0.5; 0.3/0.7, and 0.15/0.85) within the interval compositions to aluminum mole fraction xAl ∼ 0.6 are studied. The mixing enthalpies of Si-Ni-Al alloys are characterized by great exothermal values. Exothermal partial
enthalpies of aluminum mixing increase at infinite dilution
with increasing nickel concentration in starting binary alloys (
reaches −17.0 ± 3.3 kJ/mole for section with xSi/xNi = 0.85/0.15 and −119.0 ± 11.2 kJ/mole for xSi/xNi = 0.15/0.85). An analysis of alloy-formation energy parameters in the ternary Si-Ni-Al system indicates that the interaction
of the components in the bounded binary Si-Ni and Ni-Al systems greatly contributes to ΔmH, the effect of the former prevailing. The thermochemical properties of ternary alloys and of Ge-Ni-Al melts and simulated
mixing enthalpies of ternary Sn (C)-Ni-Al liquid alloys are compared.
__________
Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 3–4 (454), pp. 79–85, 2007. 相似文献
16.
L. L. Seigle C. L. Chang T. P. Sharma 《Metallurgical and Materials Transactions A》1979,10(9):1223-1228
The activity of C in the two-phase region Mo+Mo2C has been obtained from the C content of iron rods equilibrated with metal+carbide powder mixtures. From this activity data
the free energy of formation of α-Mo2C has been determined as ΔG
f
o
(α-Mo2C) (1270 to 1573 K)=−47,530−9.46T±920 J/mol. This is in good agreement with the expression obtained from gas-equilibration studies by Gleiser and Chipman,
ΔG
f
o
(α-Mo2C) (1200 to 1340 K)=−48,770−7.57 J/mol, but both our and Gleiser and Chipman's values are about 10 pct lower than those of
Pankratz, Weller and King calculated from ΔH
f,298
o
andC
p
vs T data. With the aid of available data for the solid solubility of C in Mo, the thermodynamic properties of C in the terminal
solid solution have been calculated as
J/mol,
J/mol and
, the excess entropy ofC in the solid solution assumingC is in the octahedral interstices =43.4±8.2 J/deg.-mol. 相似文献
17.
The standard Gibbs energies of formation of barium phosphide and barium orthophosphate were determined by a chemical equilibration
technique yielding the following results: 3Ba(1)+P2(g)=Ba3P2 (s) ΔG°=−732,000+156.1T(±12,800) (J/mol) 3BaO (s)+P2(g)+5/2O2(g)=Ba3(PO4)2(s) ΔG°=−2,523,000+580.0T(±16,600) (J/mol)
The stability and the thermodynamic behavior of barium compounds as reaction products of dephosphorization of steel were discussed
in terms of the oxygen partial pressure and the activity coefficient of Ba1.5P in molten Ba saturated with CaO.
D.J. MIN, formerly Graduate Student, Department of Metallurgy, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan 相似文献
18.
N. P. Gorbachuk S. N. Kirienko V. R. Sidorko I. M. Obushenko 《Powder Metallurgy and Metal Ceramics》2007,46(1-2):72-76
The thermodynamic properties of ErSi and ErSi1.67 are investigated for the first time within the temperature range of 52–300 K. Enthalpy (J · mole−1), heat capacity, entropy, and Gibbs free energy (J · mole−1 · K−1) at 298.15 K are calculated: Co
p(T) = 47.08 ± 0.19; Ho(T)-Ho(0 K) = 9701 ± 49; So(T) = 70.5 ± 0.6; Φo(T) = 38.0 ± 0.6 (ErSi); Co
p(T) = 60.65 ± 0.25; Ho(T)-Ho(0 K) = 12710 ± 64; So(T) = 93.5 ± 0.8; Φo(T) = 50.9 ± 0.8 (ErSi1.67).
__________
Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 1–2(453), pp. 87–93, 2007. 相似文献
19.
Activities of chromium in molten copper at dilute concentrations by solid-state electrochemical cell
In order to obtain the activities of chromium in molten copper at dilute concentrations (<0.008 chromium mole fractions),
liquid copper was brought to equilibrium with molten CaCl2 + Cr2O3 slag saturated with Cr2O3 (s), at temperatures between 1423 and 1573 K, and the equilibrium oxygen partial pressures were measured by means of solid-oxide
galvanic cells of the type Mo/Mo + MoO2/ZrO2(MgO)/(Cu + Cr))alloy + Cr2O3 + (CaCl2 + Cr2O3)slag/Mo. The free energy changes for the dissolution of solid chromium in molten copper at infinite dilution referred to 1 wt
pct were determined as Cr (s) = Cr(1 wt pct, in Cu) and ΔG° = + 97,000 + 73.3(T/K) ± 2,000 J mol−1. 相似文献
20.
The standard free energies of formation of calcium phosphide and calcium stannide were determined by a chemical equilibration
technique, yielding the following results: 3Ca(1) + P2(g) = Ca3P2(s) ΔG° = −653,460(±7110) + 144.01(±4.98)T (J/mol)1000 °C to 1300 °C2Ca(1) + Sn(1) = Ca2Sn(s) ΔG° = −353,970(±1670) + 79.28(±1.26)T (J/mol)1000 °C to 1300 °C 1120 °C The experimental data to express the thermodynamics for removal of phosphorus and tin from
molten iron by calcium based slags by other investigators were discussed in terms of the activity co-efficients of Ca3P2 and Ca2Sn in slag melts by using the present results described above. 相似文献