X-ray crystal structure of synthetic REEAl2.07(B4O10)O0.60 (REE = (La, Ce); Ce; Nd) dimetaborates

Abstract

Aluminium dimetaborates / Rare earth elements (REE) / Peprossiite-(Ce) / Single crystal structure analysis / X-ray diffraction Abstract. NonstoichiometricREEAl 2.07 (B 4 O 10 )O 0.60 (REE ¼ (La, Ce); Ce; Nd) dimetaborates 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: (6) A; c ¼ 9.3170(10) A and V ¼ 170.44(4) A 3 (Ce); a ¼ 4.5830(7) A, c ¼ 9.2810(14) A and V ¼ 168.82(4) A 3 (Nd). The REE cations are surrounded by six oxygen atoms, making up a trigonal prismatic coordination; Al cation is surrounded by five oxygen atoms, resembling a square pyramidal coordination, while the BO 4 group displays tetrahedral arrangement. The three-dimensional framework can be described as a mica-like structure packed down crystallographic axis c, with layers of sixmembered rings of B tetrahedra alternated by inter-layers REE cations and layers of Al polyhedra. A complex network of REE . . . O and Al . . . O interactions concur to stabilize the framework.

Crystal growth, structure and optical properties of a new acentric crystal La2Al4.68B8O22 with a short UV absorption edge

“…Then Capitelli, F. reported a detailed crystal chemical study of this compound by means of single crystal X-ray diffractometry and revised its formula to be LaAl 2.07 (B 4 O 10 )O 0.60 with cell parameters a = 4.61700(10) Å, c = 9.3640(3) Å and V = 172.86 Å 3 . 12 We believe that LaAl 1. Differential scanning calorimetric (DSC) measurements were carried out with crystal powders.…”

“…S1 According to our knowledge, there are two flux systems that can grow LaAl 2.07 (B 4 O 10 )O 0.60 crystals, the K 2 Mo 3 O 10 flux system and the PbF 2 -PbO flux system. 12,13 Nevertheless, our earlier study of YAB revealed that the incorporation of Mo or Pb ions into the crystal lattice will cause an extrinsic absorption in the UV region. 8 In order to circumvent this problem, Mo or Pb ionfree flux systems are desired.…”

“…2,3 Usually the anhydrous rare earth aluminium borates can be divided into two large families: ReAl 3 (BO 3 ) 4 (Re = Nd-Lu) [4][5][6][7][8][9] with triangular BO 3 units and ReAl 1.67+0.67x (B 4 O 10 )O x (x r 1, Re = La, Ce, Nd, Pr) with BO 4 tetrahedral groups. [10][11][12][13][14] Among these rare earth ions, Y or La containing compounds have short absorption edges down to the UV or deep-UV region which are favourable as NLO crystals. For example, the cutoff wavelength of YAl 3 (BO 3 ) 4 is located at 170 nm if the extrinsic absorption is overcome.…”

Growth, Crystal Structures, and Characteristics of Li5ASrMB12O24 (A = Zn, Mg; M = Al, Ga) with [MB12O24] Frameworks

“…In the process of searching for new borates, cation modulating has been considered to be an effective strategy because the cation modulating can change the cation coordination environment and further influence the overall crystal structure. − Al and Ga atoms have similar outer electronic configurations with B atoms and exhibit flexible coordination environment, such as the tetrahedral [AlO 4 ] in K 2 Al 2 B 2 O 7 , pyramidal [AlO 5 ] in NdAl 2.07 (B 4 O 10 )­O 0.6 , and octahedral [GaO 6 ] in BiAlGa 2 (BO 3 ) 4 . Thus, it can be seen that the introduction of Al and Ga atoms can greatly enrich the structural chemistry of borates and further generate useful properties; − for example, K 3 Ba 3 Li 2 Al 4 B 6 O 20 F has sufficient SHG response for ultraviolet NLO applications which is composed of infinite [Li 2 Al 4 B 6 O 20 F] double layers.…”