Structure and Phase Transition of GdBO₃

Abstract

The crystal structure and a phase transition of gadolinium orthoborate, GdBO 3 , were studied by electron diffraction and X-ray powder diffraction. GdBO 3 crystallizes in the vaterite structure (LT), in a rhombohedral space group R32 with the lattice constants of a ) 6.6357-(2) Å and c ) 26.706(1) Å. The structure of the LT phase was derived from the hexagonal YBO 3 structure and refined using X-ray powder diffraction data. The structure consists of tetrahedral polyborate group B 3 O 9 9and the gadolinium atoms, located respectively on the 3-fold screw axis and a general position. The material undergoes a first-order phase transition with a large thermal hysteresis. The high-temperature (HT) phase crystallizes in a calcite related structure with the lattice constants of a ) 4.1154(2) and c ) 8.592(1) Å, which consists of planer triangular borate group BO 3 3-. The observed large thermal hysteresis of the phase transition is mainly caused by a structural change of the borate group, from B 3 O 9 9in the LT phase to BO 3 3in the HT phase.

High-pressure Synthesis and Characterization of the Alkali Metal Borate HP-RbB3O5

“…6 and 7. For borates in general, bands in the region of 800 -1100 cm −1 usually apply to B-O stretching modes of boron atoms, which are tetrahedrally coordinated to oxygen atoms [45,46], while absorption bands at 1200 -1450 cm −1 are expected for borates containing BO 3 groups [46,47].…”

High‐Pressure Preparation, Crystal Structure, and Properties of α‐(RE)2B4O9 (RE=Eu, Gd, Tb, Dy): Oxoborates Displaying a New Type of Structure with Edge‐Sharing BO4 Tetrahedra

“…Boron, tetrahedrally coordinated to oxygen, displays stretching modes in the region n 1100 to 800 cm À1 as in p-YBO 3 , p-GdBO 3 , or TaBO 4 . [13,64,65] The most probable assignment is that the bands belonging to the antisymmetric stretching mode are centered at n Ä % 1050 cm…”

Single-crystal Structure Determination and Spectroscopic Characterization of KSr4(BO3)3

“…The single-crystal FTIR-ATR and the single-crystal Raman spectra of KSr 4 (BO 3 ) 3 For borates in general, bands in the region of 800 -1100 cm −1 usually apply to stretching modes of boron atoms which are tetrahedrally coordinated to oxygen atoms [25,26], while absorption bands at 1200 -1450 cm −1 are expected for borates containing BO 3 groups [26,27]. This fits well to the findings in the FTIR-ATR spectrum, where the bands above 1100 cm −1 can be assigned to the B-O stretching modes of planar BO 3 groups, while bands at 700 -800 cm −1 can be assigned to out of plane bending vibrations as suggested by Wu et al [1].…”