Sciencemadness Discussion Board

Making Boron oxynitride BNO

D4RR3N - 12-5-2008 at 02:49

I was wondering if anyone knew a simple methods of producing BNO preferably at lower temperatures. Maybe using boric acid as an ingredient? I want to produce perhaps 100g.......any ideas?

D4RR3N - 12-5-2008 at 11:29

Perhaps one method of making this would be to heat B2O3 (Melting point 480C) in a tube filled with Nitrogen gas, cant think of any method of producing this at lower temperatures.

not_important - 12-5-2008 at 11:45

Nitrogen is pretty inert until things get rather hot, or with reactive substances which B2O3 is not.

Five miutes on Google turn up a number of references. Many of the abstracts suggest that BNO is not stable in bulk, but exists as a surface layer phase between B2O3 and BN; this at least for ordinary pressures. A number of references have to do with BNO layers formed on BN through oxidation, or of by evaporation forming thin films where there's not enough material to support ready formation of multiple phases.
Quote:
Journal of Solid State Chemistry
Volume 109, Issue 2, April 1994, Pages 384-390
10.1006/jssc.1994.1117

A Coexistence of Boron Nitride and Boric Oxide

Milan HubáImage ek, Tadao Sato and Toshihiko Ishii

Abstract

Crystallization of turbostratic boron nitride, prepared from a mixture with varying ratios of boric acid and urea, was studied by heating from 220 to 1100°C. Formation of boron nitride layers was observed at temperatures as low as 220°C. Two ways to crystallization were revealed by further heating depending on the urea ratio in the starting mixture. Above 70%, the system remained monophasic and consisted of only one turbostratic phase. Below this ratio the system split into three phases at temperatures above 700°C. These were assigned as turbostratic boron nitride, boron oxynitride, and crystalline boric oxide. Boron oxynitride has been interpreted as an interfacial zone between turbostratic boron nitride crystallites and residual boric oxide resulting from an imperfect nitriding of starting oxidic precursors. Existence of this transition zone promotes the crystallization when heated at elevated temperatures.
Quote:

Journal of Alloys and Compounds
Volume 224, Issue 1, 15 June 1995, Pages 22-28
doi:10.1016/0925-8388(95)01532-9

Characterization of the nitridation process of boric acid

X. Gouina, Corresponding Author Contact Information, P. Grangea, L. Boisb, P. L'Haridonb and Y. Laurent

Abstract

Boric acid B(OH)3 has been thermally nitrided under flowing ammonia into a boron oxynitride. This reaction has been followed using various structural techniques: X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), X-ray diffraction and chemical analyses. Reaction of boric acid with ammonia began at 155 °C. The weight percent of nitrogen increases with the temperature of the pyrolysis process. Formation of B---N bonds is observed at 400 °C by infrared spectroscopy. Two boron species are observed by XPS and identified as boron linked mostly to oxygen atoms and as boron linked mostly to nitrogen atoms, denoted BOx and BNx, respectively. The intensity of the BNx signal increases with the pyrolysis temperature.

D4RR3N - 13-5-2008 at 02:38

I had read the first study quoted which I seem to remember stating that BNO was produced in thin surface layers using this particular method. I dont remember ever reading that BNO is unstable?

The second study quoted I find confusing, it starts out with stating that the experiment produces Boron oxynitride but ends with stating that BO Boron Oxide and BN Boron Nitride are the main products of the setup, what of the BNO?

Initially I thought that BNO would have been called Boron nitrate but could not find much info under that name. I have seen Boron oxynitride given variously as BNO & BON, which is more correct, would the nitrogen or oxygen atom be linked to the boron?

not_important - 13-5-2008 at 04:21

Nitrate means the oxygen and nitrogen are bonded into a unit, (O=)2N-O- for an inaccurate representation. With metals you'll have ionic compounds, the NO3 acting as a unit.

An oxynitride means the N and O are both bonded to the other element(s), so both B-N and B-O bonds. There may or may not be O-N, O-O, N-N bonding. More of a giant molecule than ionic in some cases, for other oxynitrides it's better to think of them as a solution of the oxide and nitride in each other - no actual compound.

I think it is the case with BNO that it only exists at the boundary between BO and BN. Attempting to produce massive nearly pure BNO results in it splitting into multiple phases of B2O3, BN, and BNO as a boundary between the other two phases.
Quote:
In turbostratic boron nitride, boron nitride and amorphous boric oxide phases are interconnected by coordinatively unsaturated dangling bonds at the periphery of the planar boron nitride molecules. Boron oxynitride exists between these two phases but is not an individual compound, rather it represents an interfacial zone present between t-BN and amorphous boric oxide networks. Also, the interfacial zone represents a natural transition from boron nitride to amorphous boric oxide.


[Edited on 13-5-2008 by not_important]

D4RR3N - 13-5-2008 at 11:36

As Oxygen is slightly more electronegative then Nitrogen would it be more strongly attracted to the Boron to produce B-O-N rather then B-N-O, just trying to workout the order in which the individual atoms are bonded together.

Nerro - 13-5-2008 at 11:49

Slightly off topic,

AlNO (Aluminium oxinitride) is under research as a bulletproof type off ceramic. Apparently it's at it's toughest when it's properly buffed. It's transparent and lighter than the currently used bulletproof ceramics.

How similar would BNO be to AlNO?

D4RR3N - 14-5-2008 at 07:02

BN boron nitride is soft like graphite, not sure how the addition of the oxygen would affect this, bulletproof?