Abstract: A single phase, organic-inorganic sol-gel with controlled rheology that can be solidified readily and converted into a ceramic material is provided. The organic-inorganic sol-gel may be uranium-based or cerium-based. Highly spherical ceramic microspheres such as uranium or cerium gel microspheres are fabricated and are able to be converted to homogeneous ceramics after thermal decomposition at high temperatures. Pure phase UC2 can be obtained upon carbothermal reaction. Pure phase U2N3 can also be obtained after converting UC2 to U2N3.