The present invention includes a high-quality, large-area bulk GaN seed crystal for ammonothermal GaN growth and method for fabricating. The tie rod is formed from reinforcing fibres encapsulated within a matrix material, and at least a portion of the exterior surface of the shaft defines an engagement structure. The methods also include contacting the metal oxide ore and hydrogen in presence of the zero-valent metal nanoparticles to form zero-valent metal and metal nanoparticles. This procedure results in a highly effective one step de-oxygenation andor de-humidification of the container cavity.