The crystal structure of lithium diborate, Li2O.2B2O3

Abstract

Single crystals of lithium diborate, Li20.2B~Oa, have been synthesized and the crystal structure determined. The crystals belong to the space group I41cd, with unit-cell dimensions:a=9.47 A, c=10.26 A.An approximate set of atomic parameters was determined by trial-and-error methods, and the parameters were refined by calculating electron-density projections. The result shows that the borate anion consists of two three-dimensional interlocking networks, extending throughout the crystal. The basic unit of the networks is a group consisting of two boron atoms tetrahedrally coordinated by oxygen and two boron atoms triangularly coordinated by oxygen. The atoms in the group are arranged as a twisted double ring. This group is similar to one found as an isolated ion in borax, Na20.2B~O a. 10H20. Half of the boron atoms in lithium diborate are four-fold coordinated. This is shown to be consistent with a relationship valid for most borate structures. Two exceptions to this relationship are discussed.

Infrared spectra of the crystalline inorganic borates

“…groups prOVIde an ?xygen bridge. Similar units are interconnected to form a 3 dimensional network [28].…”

Investigation of Cu-doped Li2B4O7single crystals by electron paramagnetic resonance and time-resolved optical spectroscopy

“…Its crystal structure is characterized by the space group I 4 1 cd belonging to the point group C 4v , and can be described as a =B-O-B≡ covalent network consisting of a frame of alternating oxygen-bonded BO 4 and BO 3 oxyanions and stabilized by Li + ions accommodated within this network [1]. The basic structural unit of the network is a cradle-like B 4 O 7 group (see figure 1).…”

The crystal structure of Na2[B4O6(OH)2]

“…On the other hand the 1:2:1 chains represent a degree of polymerization lower than that found in some anhydrous borates with a ratio metal oxide to boron oxide of 1 to 2. In fact, in the structure of Li20.2B20 (Krogh-Moe, 1962) as well as in CdO.2B20 3 (Ihara & Krogh-Moe, 1966) there is a three-dimensional B--O network, with repeat unit [B407] 2-, built up by the same polyanion found in 1:2:1. Of course there are no hydroxyl groups and each O atom is linked to two B atoms.…”