Powder metallurgy crucible for aluminum nitride crystal growth

A crucible comprising at least one of hafnium or a carbide, and having an elongated wall structure extending in a longitudinal direction, the wall structure

• (i) comprising a plurality of grains and defining an interior crystal growth cavity;
• and
• (ii) having a thickness dimension (a) extending in a direction substantially perpendicular to said longitudinal direction and (b) being at least about 1.5 times the average grain size.

A method for fabricating a crucible, the method comprising fabricating a wall structure from a granular material comprising at least one of hafnium or a carbide, the wall structure defining an interior crystal growth cavity and comprising a plurality of grains forming at least first and second layers, the first layer including a portion of the plurality of grains forming an inside surface of the wall structure and the second layer being superimposed on the first layer.

A crucible comprising:

• at least one of hafnium or a carbide, and
• a wall structure defining an interior crystal growth cavity and comprising a plurality of grains defining a plurality of diffusion pathways within the wall structure, the plurality of grains swelling upon absorption of at least one of aluminum or nitrogen, thereby substantially obstructing at least some of the plurality of diffusion pathways.