SYNTHESIS AND CHARACTERIZATION OF DIVALENT-EUROPIUM (EU2+) COMPOUNDS, EUB4O7, EUB2O4 AND EU2B2O5

Several new compounds, EuB4O7, EuB2O4 and Eu2B2O5 were synthesized. EuB4O7 and EuB2O4 crystallized in the orthorhombic, space group C2v7-Pnm21 with cell dimensions: a = 4.435(1), b = 10.731(1), c = 4.240(1) A ̊ and Z = 2, and space group D2h14-Pnca with cell dimensions: a = 6.593(1), b = 12.063(2), c = 4.343(1) A ̊and Z = 4, respectively. Eu2B2O5 is monoclinic, space group C2h5- P21 a with cell dimensions: a = 11.91(1), b = 5.36(1), c = 7.74(1) A ̊, β = 92.7(1)° and Z = 4. The IR patterns of EuB4O7, EuB2O4 and Eu2B2O5 were able to be ascribed to a three-dimensional network of BO4-tetrahedra, an endless chain of BO3 groups, (BO2)∞, and a B2O54- ion, respectively. The magnetic susceptibilities of these compounds were measured. EuB4O7 and Eu2B2O5 were paramagnetic in the ranges of measured temperature, and EuB2O4 was an antiferromagnet with the Néel temperature TN = 3 K. Their magnetic properties were understood by considering the relationship between their structures and the magnetic interactions. © 1979.