Europium(III) phosphate is one of the

phosphate 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 orthophosphoric acid . The phosphate or orthophosphate ion is derived from phospho ...

s of

europium Europium is a chemical element with the symbol Eu and atomic number 63. Europium is the most reactive lanthanide by far, having to be stored under an inert fluid to protect it from atmospheric oxygen or moisture. Europium is also the softest lanth ...

, 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(III) oxide (Eu2O3), is a chemical compound of europium and oxygen. It is widely used as a red or blue phosphor in television sets and fluorescent lamps, and as an activator for yttrium-based phosphors. It is also an agent for the manufact ...

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

nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...

, and then an excess of 10% phosphoric acid was added. The process also requires the addition of

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...

to adjust the pH to 4 and form a

gel A gel is a semi-solid that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state, although the liquid phase may still di ...

, which is then washed with

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

and heated to 1200 °C for a day.

Properties

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

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

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

is 159(2) GPa.

References

{{Phosphates Europium(III) compounds Phosphates