Nonstoichiometric REEAl 2.07(B 4O 10)O 0.60 (REE = La, Pr) borates have been crystallized and analyzed by means of single crystal X-ray diffraction. The compounds resulted to be isostructural within hexagonal space group P62m (n. 189), with the following unit cell parameters: a = 4.6170(1) Å, c = 9.3640(3) Å and V = 172.87(1) Å 3 (La); a = 4.5990(1) Å; c = 9.3270(2) Å and V = 170.87(1) Å 3 (Pr). REE cations make up a trigonal prismatic coordination, by means of six REE-O bonds under 2.5 Å; aluminium cation is five-coordinated, displaying a square pyramidal coordination, while the boron atom forms BO 4 tetrahedral units. The present borates belong to the structural type of NdAl 2.07(B 4O 10)O 0.60 dimetaborate [1]: thus, the three-dimensional framework can be described as a structure packed down crystallographic axis c, with layers of six-membered rings of B tetrahedra alternated by inter-layers REE cations and layers of Al polyhedra. An intricate network of Al ? O and REE ? O interactions complete the array.
REEAl2.07(B4O10)O0.60 dimetaborates (REE=La, Pr); synthesis and X-ray structural characterization
G Chita;
2011
Abstract
Nonstoichiometric REEAl 2.07(B 4O 10)O 0.60 (REE = La, Pr) borates have been crystallized and analyzed by means of single crystal X-ray diffraction. The compounds resulted to be isostructural within hexagonal space group P62m (n. 189), with the following unit cell parameters: a = 4.6170(1) Å, c = 9.3640(3) Å and V = 172.87(1) Å 3 (La); a = 4.5990(1) Å; c = 9.3270(2) Å and V = 170.87(1) Å 3 (Pr). REE cations make up a trigonal prismatic coordination, by means of six REE-O bonds under 2.5 Å; aluminium cation is five-coordinated, displaying a square pyramidal coordination, while the boron atom forms BO 4 tetrahedral units. The present borates belong to the structural type of NdAl 2.07(B 4O 10)O 0.60 dimetaborate [1]: thus, the three-dimensional framework can be described as a structure packed down crystallographic axis c, with layers of six-membered rings of B tetrahedra alternated by inter-layers REE cations and layers of Al polyhedra. An intricate network of Al ? O and REE ? O interactions complete the array.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
