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The two known phases of germanium nitride (Ge3N4) have hexagonal and trigonal symmetries and consist of three-dimensional networks of corner-connected Ge–N tetrahedra. A new cubic spinel phase (space-group Fd3m, a0=8.3 A, Z=8, ρ=6.36 g/cm3) containing Ge–N octahedra and tetrahedra in a 2:1 ratio was synthesized from elemental germanium and molecular nitrogen starting materials in a laser-heated diamond-anvil cell above 14 GPa. This phase is isostructural to the recently discovered cubic spinel phase of Si3N4.

Nanoparticles composed of iron and carbon have been produced by chemical vapor synthesis. A detailed structural, electronic, and magnetic characterization has been performed by several methods. The atomic arrangement in the as-prepared particles is strongly affected and stabilized by excess carbon. Small clusters of different ferrous phases are the building blocks of the particles. Due to the in situ formation of a carbonaceous shell the particles are stable against oxidation at ambient conditions. The magnetic properties are influenced by the exceptionally small particle size. The particles exhibit superparamagnetic behavior with a blocking temperature of 30K and the temperature dependence of the magnetization is governed by the finite size of the system.