Phase equilibria and thermodynamic properties of solid solutions in the systems ZnOCoOTiO2 and ZnONiOTiO2 at 1050°C

Electrochemical determination of gibbs energy of formation of NiTiO3 (ilmenite)

“…[2,[8][9][10][11][12][13][14] It can be seen from Figure 6 that the present results are in reasonable agreement with those of Pejryd [12] and Lerch and Laqua [13] below 1450 K. The data obtained by Navrotsky and Muan [8] by the CO/CO 2 gas equilibration technique at 1323 K and Taylor and Schmalzried [10] between 1073 and 1373 K employing an emf technique are approximately 4.5 to 5 kJ mol Ϫ1 more negative than the results obtained in this study. The results of Challopadhyay and Kleykamp [11] are fairly close to the results obtained in this study but are almost independent of temperature.…”

“…Navrotsky and Muan [8] 1323 Ϫ11,000 ‫)0052ע(‬ CO/CO 2 2 Evans and Muan [9] 1673 Ϫ9,500 ‫)0052ע(‬ CO/CO 2 3 Muan [2] 1733 Ϫ10,278 ‫)0052ע(‬ tie-line data 4 Taylor and Schmalzried [10] 1073 to 1373 Ϫ15,786 ϩ 4.183T emf 5 Chattopadhyay and Kleykamp [11] 1000 to 1273 Ϫ8,500 ϩ 0.27T emf 6 Pejryd [12] 1120 to 1520 Ϫ11,440 ϩ 3.09T emf 7 Lerch and Laqua [13] 1050 to 1450 Ϫ11,600 ϩ 3.1T emf 8 Lerch and Laqua [13] 1573 to 1650 6,600 Ϫ 8.8T emf 9…”

“…In a simplest case, if the cation mixing is assumed to be ideal, then is the maximum entropy contribution due to the order-disorder transformation in NiTiO 3 (ilm). Based on the knowledge of the order-disorder transition temperature (1568 K) obtained in this study and ⌬S conf from Eq [8],. the Gibbs energy change for order-disorder transformation in NiTiO 3 (ilm) can be calculated as as the Gibbs energy of formation of disordered NiTiO 3 (ilm) from NiO (rs) and TiO 2 (rut).…”

“…The Gibbs energy of formation of NiTiO 3 from component oxides measured by either the gas equilibration technique [2,8,9] or the solid oxide electrochemical technique [10][11][12][13] operated in potentiometric mode and that estimated by Kubaschewski [14] are summarized in Table I. It can be seen from the equations given in Table I that there is a significant difference in the values of ''second-law' ' and for the formation of NiTiO 3 (ilmenite) from ⌬HЊ ⌬SЊ f f NiO (rock salt) and TiO 2 (rutile).…”

Thermodynamic evidence for order–disorder transition in NiTiO3

“…The enthalpy of formation and heat capacity of NiTiO 3 have not been measured by calorimetric techniques. The standard Gibbs free energy of formation from component oxides D f G ðoxÞ ðNiTiO 3 Þ has been measured by several groups of researchers [1][2][3][4][5][6][7]. These measurements fall into two categories with significant difference between their results.…”