Vitreous Borates

The uses in the glass and ceramics industries reflect the diagonal relation between boron and silicon and the similarity of vitreous borate and silicate networks (pp. 203, 206 and 347). In the UK and continental Europe (but not in the USA or Japan) sodium perborate (p. 206) is a major constituent of washing powders since it hydrolyses to H2O2 and acts as a bleaching agent in very hot water ( 90°C) in the USA domestic washing machines rarely operate above 70°, at which temperature perborates are ineffective as bleaches. 

Glass-forming systems other than siUca have been examined. The fraction of three- and four-coordinated boron in borate glasses can be determined by nmr (29). Both nmr and x-ray diffraction (30) results led to the suggestion that the boroxyl ring is the stmctural unit of vitreous The... 

Anhydrous metal borates may be prepared by heating the hydrated salts to 300—500°C, or by direct fusion of the metal oxide with boric acid or B2O2. Many binary and tertiary anhydrous systems containing B2O2 form vitreous phases over certain ranges of composition (145). 

The manufacture of glass and other vitreous products accounts for more than one half of all borate use worldwide. The history of borate use in glass manufacture has been reviewed [92]. 

In this paper we deal with complexes in which the donor atom is exclusively oxide(—II). Such complexes include aquo complexes, which are well documented, and oxyanion complexes such as phosphato, borato, etc. which are present in vitreous phosphates, borates, etc. and in anhydrous oxyacids. We therefore are dealing with complexes, of metal ions M , comprising a system which can be written schematically as... 

BORAX. This hydrated sodium borate mineral, NaiBtOy 101 1, O, is a product of evaporation from shallow lakes and plays. Borax crystallizes in the monoclinic system, usually in short prismatic crystals. Its color grades from colorless through gray, blue to greenish. Vitreous to resinous luster of translucent to opaque character. Hardness of 2-2.5, and specific gravity of 1.715. 

Suarez et al. [457] prepared and investigated the electrochemical window for the following ionic liquids l-n-butyl-3-methylimidazolium tetrafluoro-borate (BMI+)(BF4 ) and l-butyl-3-methylimidazolium hexafluorophosphate (BMF)(PF ) on tungsten and vitreous carbon. They found the following values for the electrochemical window 6.1 V and 5.45 V for (BMI+)(BF4 ) and 7.1 V and 6.35 V for (BMI+)(PF6 ), respectively. 

---