Nitride formation heats

There is a reaction between beryllium and nitrogen that starts at about 750°C and is appreciable at 850°C, beryllium nitride being formed". The reaction with oxygen is less sluggish and at 900°C in oxygen oxidation proceeds at about twice the rate of nitride formation. Thus when beryllium is heated in air, beryllium nitride forms only a small proportion of the total scale —about 0-75% after 1 h at 1 000°C. 

Reactive sputter deposition is a useful technique not only for coating but also for obtaining metastable phases, especially nitrides. Nitrogen gas is activated in a plasma to enhance nitride formation and heating at high temperature is not required. It is possible to obtain metastable nitrides by sputter deposition in which species in the plasma are quenched on substrates. Compounds with different crystal structures normally do not form solid solutions, but by co-sputter deposition metastable solid solutions may form. 

Heated in vacuo or in nitrogen it begins to decompose at 500° C., and at 600° C. nitrogen is rapidly evolved. This reduction takes place even under a pressure of 18 atmospheres of nitrogen. For this reason there is no nitride formation when iron is heated at these temperatures in nitrogen.9... 

Grayish-white, lustrous, radioactive metal somewhat ductile and malleable, mp 1842 30" (Marden, Rentschler) 1690" (Cuthbert), d 11.3-11.7. T (KJTh) 1.4l X 1010 yrs. On heating bums in air with formation of the oxide. Attacked by coned acids. Reacts with the halogens at a red heat. Forms the sulfide when heated with sulfur, the nitride when heated with nitrogen. 

After the air is completely displaced from the apparatus by the NHg (air bubbles cease to emerge from the second Erlenmeyer flask), the Mg is heated at 800 to 850 C for four hours. The onset of nitride formation is recognized by incandescence of the Mg and the evolution of Hg. A high NHg flow must be maintained at the peak of the reaction to avoid sucking the absorption fluid into the reactor. Since the finished material always contains adsorbed NHg, heating in a Ng stream should be continued at the same temperature for 90 minutes. Because of the high moisture sensitivity of the material, bottling must be carried out with the usual precautions. 

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