Lanthanum Oxide,La2O3,

           spec          typical
TREO:     97% min.        98.5%
La2O3/TREO: 99.9% min.    99.95%  
CeO2/ TREO: 0.025% max.    0.01%
Pr6O11/TREO: 0.025% max.   0.01%
Nd2O3/TREO: 0.015% max.    0.01% 
Sm2O3/TREO: 0.02% max.   0.003%
Y2O3/TREO: 0.01% max.    0.001%
Fe2O3:    0.02% max.      0.008%
CaO:      0.20% max.      0.07%
Cl:       0.10% max.      0.06%
SiO2:     0.03% max.      0.03%
L.O.I.:    3% max.        1.2%

Other cations
Scandium(III) oxide
Yttrium(III) oxide
Actinium(III) oxide
Related compounds Lanthanum aluminium oxide,
LaSrCoO4

La₂O₃ has largest of the rare earth oxides at 4.3 eV, while also having the lowest lattice energy, with very high , ε = 27. La₂O₃ is widely used in industry as well as in the research laboratory. Lanthanum oxide is an odorless, white solid that is insoluble in water, but soluble in dilute acid. Depending on the pH of the compound, different crystal structures can be obtained. Lanthanum oxide has p-type semi-conducting properties because its resistivity decreases with an increase in temperature, average room temperature resistivity is 10 kΩ·cm.

Synthesis
lanthanum oxide crystallizes as several polymorphs.

To produce hexagonal La2O3, a 0.1 M solution of LaCl3 is sprayed onto a preheated

substrate, usually made of metal chalcogenides.[3] The process can be viewed as occurring

in two steps - hydrolysis followed by dehydration:

2 LaCl3 + 3 H2O → La(OH)3 + 3 HCl
2 La(OH)3 → La2O3 + 3 H2O
An alternative route to hexagonal La2O3 involves precipitation of nominal La(OH)3 from

aqueous solution using a combination of 2.5% NH3 and the surfactant sodium dodecyl sulfate

followed by heating and stirring for 24 hours at 80 °C:

2 LaCl3+ 3 H2O + 3 NH3 → La(OH)3 + 3 NH4Cl
LaCl3·3H2O → La2O3
Other routes include:

2 La2S3 + 3 CO2 → 2 La2O3 + 3 CS2
2 La2(SO4)3 + heat → 2 La2O3 + 6 SO3