Ultra-lightweight aerogels and methods for fabricating such aerogels from ammonia borane and a support structure, where the support structure is either two-dimensional nanostructures, or hydrocarbon polymer colloids. The components are mixed, then annealed. The properties of the disclosed aerogels can be tuned by controlling the ratio between the support structure and the ammonia borane, or by infiltrating the aerogels with additives.

Ultra-lightweight aerogels and methods for fabricating such aerogels from ammonia borane and a support structure, where the support structure is either two-dimensional nanostructures, or hydrocarbon polymer colloids. The components are mixed, then annealed. The properties of the disclosed aerogels can be tuned by controlling the ratio between the support structure and the ammonia borane, or by infiltrating the aerogels with additives.

A silicon nitride sintered body includes a silicon nitride crystal grains and grain boundary phases. Further, when D stands for width of the silicon nitride sintered body before being subjected to surface processing, relations between an average grain diameter dA and an average aspect ratio rA of the silicon nitride crystal grain in a first region from an outermost surface to a depth of 0 to 0.01D and an average grain diameter dB and an average aspect ratio rB of the silicon nitride crystal grain in a second region inside the first region satisfy the inequalities:

0.8≤ dA/dB≤ 1.2; and

0.8≤ rA/rB≤ 1.2.

A silicon nitride sintered body includes a silicon nitride crystal grains and grain boundary phases. Further, when D stands for width of the silicon nitride sintered body before being subjected to surface processing, relations between an average grain diameter dA and an average aspect ratio rA of the silicon nitride crystal grain in a first region from an outermost surface to a depth of 0 to 0.01D and an average grain diameter dB and an average aspect ratio rB of the silicon nitride crystal grain in a second region inside the first region satisfy the inequalities:

0.8≤ dA/dB≤ 1.2; and

0.8≤ rA/rB≤ 1.2.

A ceramic composition contains Fe, Cu, Ni, Zn, Co, and Cr. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by mole, the ceramic composition contains from 48.20 to 49.85 parts by mole Fe in terms of Fe.sub.2O.sub.3, from 2.00 parts to 8.00 parts by mole Cu in terms of CuO, from 11.90 to 18.70 parts by mole Ni in terms of NiO, and from 27.00 to 33.50 parts by mole Zn in terms of ZnO. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by weight, the ceramic composition contains from 5 to 100 ppm Co in terms of CoO and from 10 to 400 ppm in terms of Cr.sub.2O.sub.3.

An article includes a body having a first phase comprising alpha silicon carbide and pores contained in the body; the pores having a mean spacing distance of at least 205 microns and not greater than 300. The body can have a ballistic.

A multilayer capacitor includes a body including a dielectric layer and first and second internal electrodes stacked on each other and having the dielectric layer interposed therebetween; a pair of first external electrodes respectively disposed on first and second corners of the body, which are not adjacent to each other, and connected to the first internal electrode; a pair of second external electrodes respectively disposed on third and fourth corners of the body, which are not adjacent to each other, and connected to the second internal electrode; and a reinforcing portion disposed on a surface of the body, not covered by at least one of the first and second external electrodes, and including a sintered ceramic body.

A multilayer capacitor includes a body including a dielectric layer and first and second internal electrodes stacked on each other and having the dielectric layer interposed therebetween; a pair of first external electrodes respectively disposed on first and second corners of the body, which are not adjacent to each other, and connected to the first internal electrode; a pair of second external electrodes respectively disposed on third and fourth corners of the body, which are not adjacent to each other, and connected to the second internal electrode; and a reinforcing portion disposed on a surface of the body, not covered by at least one of the first and second external electrodes, and including a sintered ceramic body.

A ceramic electronic component includes a body including a dielectric layer and an internal electrode; and an external electrode disposed on the body and connected to the internal electrode. The dielectric layer has a perovskite structure represented by a general formula ABO.sub.3 as a main phase, and includes a region in which Dy is dissolved. In the region in which Dy is dissolved, an atomic ratio of a content of Dy dissolved in an A-site of the perovskite structure to a content of Dy dissolved in a B-site is 1.6 or more and 2.0 or less.

A ceramic electronic component includes a body including a dielectric layer and an internal electrode; and an external electrode disposed on the body and connected to the internal electrode. The dielectric layer has a perovskite structure represented by a general formula ABO.sub.3 as a main phase, and includes a region in which Dy is dissolved. In the region in which Dy is dissolved, an atomic ratio of a content of Dy dissolved in an A-site of the perovskite structure to a content of Dy dissolved in a B-site is 1.6 or more and 2.0 or less.