Erbium phosphate
| Names | |
|---|---|
| Other names
Erbium orthophosphate | |
| Identifiers | |
CompTox Dashboard (EPA) |
|
| Properties | |
| ErPO4 | |
| Molar mass | 262.23 g/mol |
| Appearance | Solid |
| Melting point | 1,896 °C (3,445 °F; 2,169 K) (approximately) |
| Very slightly soluble in water | |
| Structure | |
| Tetragonal, xenotime type | |
| I41/amd, No. 141 | |
a = 0.68614 nm, c = 0.60082 nm | |
Formula units (Z) |
4 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Erbium phosphate is an inorganic compound of erbium and phosphate with the chemical formula ErPO4. Hydrated forms are also known.
Preparation
[edit]Hydrated erbium phosphate can be prepared by precipitation from aqueous solutions containing Er3+ and phosphate ions. A dihydrate has been obtained by reacting erbium(III) chloride with phosphoric acid.[1]
Heating hydrated erbium phosphate produces anhydrous ErPO4.
Anhydrous material can also be prepared by high-temperature solid-state or hydrothermal methods.[2]
Structure and properties
[edit]Anhydrous erbium phosphate crystallizes in the tetragonal crystal system with the xenotime structure, which is isostructural with zircon. It belongs to space group I41/amd (No. 141), with four formula units per unit cell.[3] Reported lattice parameters are a = 6.8614(5) Å and c = 6.0082(9) Å.[3]
The structure consists of isolated PO4 tetrahedra and eight-coordinate Er3+ ions. Like other heavy rare-earth orthophosphates, ErPO4 is chemically resistant and only very slightly soluble in water.[2]
Erbium phosphate has a high melting point, reported at approximately 1896 °C.[3] Thermodynamic measurements have been made over a wide temperature range; its heat capacity shows a Schottky anomaly associated with crystal-field splitting of the Er3+ electronic levels.[4]
High-pressure behaviour
[edit]At ambient pressure ErPO4 adopts the xenotime structure. Under compression it undergoes a reversible structural transformation to a denser monoclinic monazite-type phase, with the transition beginning at about 17.3 GPa.[5]
The monazite phase is less compressible than the xenotime phase because of its more efficient atomic packing.[5]
Reactions
[edit]Erbium phosphate reacts with sodium fluoride under suitable conditions to form the fluorophosphates NaErFPO4 and Na3Er2F3PO4.[6]
It also reacts with potassium metaphosphate, KPO3, to form potassium erbium diphosphate, KErP2O7.[7]
References
[edit]- ↑ Hikichi, Yasuo; Hukuo, Ken-iti; Shiokawa, Jiro (1978-12-01). "Syntheses of Rare Earth Orthophosphates". Bulletin of the Chemical Society of Japan. 51 (12): 3645–3646. doi:10.1246/bcsj.51.3645. ISSN 0009-2673.
- 1 2 Chong, Saehwa; Riley, Brian J.; Lu, Xiaonan; Du, Jincheng; Mahadevan, Thiruvillimalai; Hegde, Vinay (2024). "Synthesis and properties of anhydrous rare-earth phosphates, monazite and xenotime: a review". RSC Advances. 14: 18978–19000. doi:10.1039/D4RA01142B.
- 1 2 3 Piotrowska, D.; Znamierowska, T.; Szczygieł, I. (2013). "Phase equilibria in the ErPO4–K3PO4 system". Journal of Thermal Analysis and Calorimetry. 112: 929–934. doi:10.1007/s10973-012-2883-4.
- ↑ "Thermodynamic functions of erbium orthophosphate ErPO4 in the temperature range of 0–1600 K". Thermochimica Acta. 2012. doi:10.1016/j.tca.2012.01.023.
- 1 2 Lacomba-Perales, R.; Errandonea, D.; Meng, Y.; Bettinelli, M. (2010). "High-pressure stability and compressibility of APO4 (A = La, Nd, Eu, Gd, Er, and Y) orthophosphates: An x-ray diffraction study using synchrotron radiation". Physical Review B. 81 064113. doi:10.1103/PhysRevB.81.064113.
- ↑ Smirnova, I. N.; Gorkovenko, M. Yu.; Zimina, G. V.; Spiridonov, F. M.; Kaloev, N. I.; Komissarova, L. N. "Rare earth fluorophosphates". Izvestiya Vysshikh Uchebnykh Zavedenii, Tsvetnaya Metallurgiya. 1994. 1–2: 71–74.
- ↑ Piotrowska, D.; Znamierowska, T.; Szczygieł, I. (2016). "Phase equilibria in the ErPO4–KPO3 system". Journal of Thermal Analysis and Calorimetry. 123 (2): 1383–1389. doi:10.1007/s10973-015-5008-z.