Chemistry:Erbium phosphate
| Names | |
|---|---|
| Other names
Erbium orthophosphate
| |
| Identifiers | |
| 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). | |
| Infobox references | |
Erbium phosphate is an inorganic compound of erbium and phosphate with the chemical formula ErPO4. Hydrated forms are also known.
Preparation
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
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
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
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
- ↑ 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. https://doi.org/10.1246/bcsj.51.3645.
- ↑ 2.0 2.1 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.
- ↑ 3.0 3.1 3.2 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.
- ↑ 5.0 5.1 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. 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.
 |  |
