Europium(III) phosphate is one of the

phosphate Phosphates are the naturally occurring form of the element phosphorus. In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthop ...

s of

europium Europium is a chemical element; it has symbol Eu and atomic number 63. It is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. Europium is the most chemically reactive, least dense, and soft ...

, with the chemical formula of EuPO₄. Other phosphates include europium(II) phosphate (Eu₃(PO₄)₂) and europium(II,III) phosphate (Eu₃Eu(PO₄)₃).

Preparation

Europium phosphate can be produced by the sol-gel method of

europium(III) oxide Europium is a chemical element; it has symbol Eu and atomic number 63. It is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. Europium is the most chemically reactive, least dense, and sof ...

. First, europium(III) oxide was dissolved in an equimolar amount of

nitric acid Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...

, and then an excess of 10%

phosphoric acid Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, ...

was added. The process also requires the addition of

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

to adjust the pH to 4 and form a gel, which is then washed with

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

and heated to 1200 °C for a day.

Properties

Europium(III) phosphate is isotypic to CePO₄ and crystallizes in the

monazite Monazite is a primarily reddish-brown phosphate mineral that contains rare-earth elements. Due to variability in composition, monazite is considered a group of minerals. The most common species of the group is monazite-(Ce), that is, the cerium ...

structure type, in the space group ''P''2₁/n (no. 14, position 2) with the lattice parameters ''a'' = 668.13(10), ''b'' = 686.18(9), ''c'' = 634.91(8) pm and β = 103.96(1)° with four formula units per unit cell. Its

heat capacity Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K). Heat capacity is a ...

is 111.5 J·K⁻¹·mol⁻¹ at 298.15 K, and its

bulk modulus The bulk modulus (K or B or k) of a substance is a measure of the resistance of a substance to bulk compression. It is defined as the ratio of the infinitesimal pressure increase to the resulting ''relative'' decrease of the volume. Other mo ...

is 159(2) GPa.

References

{{Phosphates Europium(III) compounds Phosphates