Thermal Expansion of MgTiO3 Made by Sol-Gel Technique at Temperature Range 25–890 °C
Abstract
:1. Introduction
- (a)
- Geikielite, MgTiO3, is rhombohedral of ilmenite type, space group R-3 (148), Pearson Symbol hR10.0; formed at temperatures above 600 °C, is stable from room temperature to its melting point;
- (b)
- Qandilite, Mg2TiO4, cubic of inverse spinel type, space group Fd-3m (227), Pearson Symbol cF56.0, formed at above 1150 °C;
- (c)
- Karrooite, MgTi2O5, orthorhombic of pseudo-brookite type, space group Cmcm (63), Pearson Symbol oC32.0 formed above 500 °C.
2. Materials and Methods
2.1. Synthesis
2.2. RT XRD Measurements
2.3. HT XRD Measurements
2.4. Thermal Expansion Methodology
3. Results
3.1. As-Received Sample
3.2. High-Temperature XRD (HT-XRD)
3.3. Thermal Expansion Coefficients for the Reference Material (Mg2TiO4)
γ = 2.5 × 10−5 + 9.3 × 10−9 (T − 25) [1/°C]
γ = 2.7 × 10−5 + 6.2 × 10−9 (T − 25) [1/°C]
3.4. Thermal Expansion Coefficients for MgTiO3
3.5. Atomic Positions
4. Discussion
5. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Lattice Parameters | Lattice Volume | ICDD # | Comment | |
---|---|---|---|---|
a [Å] | c [Å] | V [Å3] | Quality | |
5.057 | 13.903 | 307.9 | 01-073-7748 | Star |
5.057 | 13.903 | 307.9 | 01-075-8341 | Star |
5.054 | 13.899 | 307.5 | 01-79-0831 | Star |
5.056 (2) | 13.902 (2) | 307.8 (3) | ICDD | Average |
5.054 (1) | 13.904 (2) | 307.6 (3) | GQ AR | Reitveld, FullProf |
5.054 (1) | 13.902 (2) | 307.5 (3) | GQ AR | Reitveld, Topas * |
Lattice Parameter | ICDD # | Comment |
---|---|---|
a [Å] | Quality | |
8.442 | 01-072-6966 | Star |
8.447 | 01-072-6977 | Star |
8.447 | 01-72-6967 | Star |
8.441 | 00-025-1157 | Star |
8.444 (3) | ICDD | Average |
8.442 (1) | GQ AR | Ambient |
8.441 (1) | GQ AR | Hot stage * |
MgTiO3 | |||
---|---|---|---|
ion/position | GQ- * | GQ- ** | Reference [3] |
z(Mg2+) | 0.3561 | 0.3556 | 0.3556 |
z(Ti4+) | 0.1445 | 0.1446 | 0.1451 |
x(O2−) | 0.3108 | 0.3173 | 0.3159 |
y(O2−) | 0.0140 | 0.0215 | 0.0215 |
z(O2−) | 0.2491 | 0.2465 | 0.2470 |
Mg2TiO4 | ||
---|---|---|
Ion/position | GQ | Reference [3] |
z(O2−) | 0.2588 | 0.2605 |
MgTiO3 | Mg2TiO4 | ||
---|---|---|---|
T °C | a * [Å] | c # [Å] | a # [Å] |
25 | 5.054 | 13.902 | 8.441 |
50 | 5.055 | 13.905 | 8.443 |
100 | 5.056 | 13.913 | 8.445 |
200 | 5.061 | 13.929 | 8.453 |
400 | 5.071 | 13.963 | 8.471 |
500 | 5.076 | 13.980 | 8.480 |
550 | 5.079 | 13.989 | 8.484 |
600 | 5.081 | 13.998 | 8.489 |
650 | 5.084 | 14.007 | 8.494 |
700 | 5.087 | 14.016 | 8.499 |
800 | 5.092 | 14.035 | 8.510 |
890 | 5.098 | 14.054 | 8.520 |
Geikielite | ||
---|---|---|
T °C | a [Å] | c [Å] |
700 | 5.087 | 14.014 |
800 | 5.092 | 14.035 |
900 | 5.098 | 14.050 |
1000 | 5.104 | 14.072 |
1100 | 5.111 | 14.093 |
1200 | 5.117 | 14.115 |
1300 | 5.123 | 14.136 |
Sample | GQ (AR) | GQ25 | GQ200 | GQ400 | GQ600 | GQ800 | GQ900 | GQPOST | |
---|---|---|---|---|---|---|---|---|---|
Position | T [°C] | 25 | 25 | 200 | 400 | 600 | 800 | 890 | 25 |
c | z(Mg) | 0.3556 | 0.3562 | 0.3563 | 0.3563 | 0.3571 | 0.3569 | 0.3574 | 0.3565 |
c | z(Ti) | 0.1446 | 0.1444 | 0.1445 | 0.1445 | 0.1447 | 0.1450 | 0.1451 | 0.1453 |
f | x(O) | 0.3173 | 0.3198 | 0.3203 | 0. 3199 | 0. 3193 | 0. 3142 | 0. 3169 | 0.3166 |
f | y(O) | 0.0215 | 0.0214 | 0.0218 | 0. 0211 | 0. 0206 | 0. 0183 | 0.0190 | 0.0252 |
f | z(O) | 0.2465 | 0.2433 | 0.2433 | 0. 2433 | 0. 2433 | 0. 2457 | 0. 2426 | 0.2465 |
Rp | 14.3 | 9.89 | 9.66 | 8.32 | 8.12 | 8.01 | 7.97 | 4.93 | |
Rwp | 19.8 | 11.88 | 11.52 | 9.74 | 9.35 | 9.26 | 9.05 | 2.1 | |
χ2 | 1.26 | 1.34 | 1.31 | 1.29 | 1.37 | 1.26 | 1.26 | 7.1 |
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Tuval, T.; Rosen, B.A.; Zabicky, J.; Kimmel, G.; Dilman, H.; Shneck, R.Z. Thermal Expansion of MgTiO3 Made by Sol-Gel Technique at Temperature Range 25–890 °C. Crystals 2020, 10, 887. https://doi.org/10.3390/cryst10100887
Tuval T, Rosen BA, Zabicky J, Kimmel G, Dilman H, Shneck RZ. Thermal Expansion of MgTiO3 Made by Sol-Gel Technique at Temperature Range 25–890 °C. Crystals. 2020; 10(10):887. https://doi.org/10.3390/cryst10100887
Chicago/Turabian StyleTuval, Tamir, Brian A. Rosen, Jacob Zabicky, Giora Kimmel, Helena Dilman, and Roni Z. Shneck. 2020. "Thermal Expansion of MgTiO3 Made by Sol-Gel Technique at Temperature Range 25–890 °C" Crystals 10, no. 10: 887. https://doi.org/10.3390/cryst10100887
APA StyleTuval, T., Rosen, B. A., Zabicky, J., Kimmel, G., Dilman, H., & Shneck, R. Z. (2020). Thermal Expansion of MgTiO3 Made by Sol-Gel Technique at Temperature Range 25–890 °C. Crystals, 10(10), 887. https://doi.org/10.3390/cryst10100887