Abstract: An object of the invention is to provide an electron microscope capable of obtaining a sufficient energy resolution without forming a long drift space and capable of attaining high energy discrimination detection performance with approximately the same device size as in the related art. The electron microscope according to the invention includes a pulsed electron emission mechanism configured to emit an electron beam in a pulsed manner, and discriminates energy of signal electrons by discriminating the signal electrons, which are emitted from a sample by irradiating the sample with the electron beam, according to a time of flight (see FIG. 2).

Abstract: An electron beam emitted from a photoexcited electron gun is increased in luminance. An electron gun 15 includes: a photocathode 1 including a substrate 11 and a photoelectric film 10; a light source 7 that emits pulsed excitation light; a condenser lens 2 that focuses the pulsed excitation light toward the photocathode; and an extractor electrode 3 that faces the photocathode and that accelerates an electron beam generated from the photoelectric film by focusing the pulsed excitation light by the condenser lens, transmitting the pulsed excitation light through the substrate of the photocathode, and causing the pulsed excitation light to be incident on the photocathode. The pulsed excitation light is condensed at different timings at different positions on the photoelectric film of the photocathode.

Abstract: There is disclosed an Al.sub.2 O.sub.3 based ceramic which includes 5% to 50% by weight of a hard dispersed phase of at least one compound selected from metal carbide, metal nitride, metal carbonitride, metal oxy-carbide, metal oxy-nitride and metal carbo-oxy-nitride. The compound is represented by M(CNO), wherein M is at least one metal selected from the group consisting of Ti, Zr and Hf. The ceramic optionally contains 1% to 25% by weight of ZrO.sub.2, and balance Al.sub.2 O.sub.3 matrix, which contains an additive dissolved in the Al.sub.2 O.sub.3 grains so as to form solid solution therewith. The additive is contained in an amount of 0.01% to 12% by weight with respect to the Al.sub.2 O.sub.3 matrix and is at least one oxide of an element selected from the group consisting of Y, Mg, Cr, Ni, Co, and rare earth elements. The Al.sub.2 O.sub.3 grains have an average grain size no larger than 1.0 .mu. m while the hard phase constituent has an average grain size no larger than 0.6 .mu. m.

Abstract: There is disclosed an Al.sub.2 O.sub.3 based ceramic which includes 5% to 50% by weight of a hard dispersed phase of at least one compound selected from metal carbide, metal nitride, metal carbonitride, metal oxy-carbide, metal oxy-nitride and metal carbo-oxy-nitride. The compound is represented by M(CNO), wherein M is at least one metal selected from the group consisting of Ti, Zr and Hf. The ceramic contains no greater than 25% by weight of ZrO.sub.2, and balance Al.sub.2 O.sub.3 matrix. which contains an additive dissolved in the Al.sub.2 O.sub.3 grains so as to form solid solution therewith. The additive is contained in an amount of 0.01% to 12% by weight with respect to the Al.sub.2 O.sub.3 matrix and is at least one oxide of an element selected from the group consisting of Y, Mg, Cr, Ni, Co, and rare earth elements. The Al.sub.2 O.sub.3 grains have an average grain size no larger than 1.0 .mu.m while the hard phase constituent has an average grain size no larger than 0.6 .mu.m.

Abstract: There is disclosed a silicon nitride based sintered material which contains 0.1% to 20% by volume of zirconium oxide, 0.1% to 14% by volume of zirconium nitride, 3% to 15% by volume of a binder phase of an Mg-Si-O-N or Mg-Si-Zr-O-N system, and balance .beta.-silicon nitride. The sintered material may include an oxide layer of an average thickness of 10 to 1,000 .mu.m in a surface thereof and having a zirconium oxide concentration increasing toward the surface thereof. A process specifically adapted to manufacture the above sintered material is also disclosed.