A ceramic surface treatment method includes the following steps. An antibacterial ion and a sol-gel solution containing a silane compound are mixed to form a treatment solution. Next, a ceramic substrate is placed in the treatment solution to perform a treatment bonding reaction such that the antibacterial ion in the treatment solution can be grafted to the surface of the ceramic substrate via the silane compound. Next, a sintering condensation reaction is performed on the ceramic substrate after the treatment bonding reaction to form a protective film on the surface of the ceramic substrate. The protective film is attached to the surface of the ceramic substrate via a hydrophobic layer, and the antibacterial ion is spread on the hydrophobic layer.

A production method of an electroconductive mayenite compound having an electron density greater than or equal to 510.sup.20 cm.sup.3 includes preparing an object of processing containing a mayenite compound or a precursor of a mayenite compound, placing aluminum foil on at least part of a surface of the object of processing, and retaining the object of processing at temperatures falling within the range of 1080 C. to 1450 C. in a low oxygen partial pressure atmosphere.

A copper/ceramic bonded body includes: a copper member made of copper or a copper alloy; and a ceramic member made of an aluminum nitride, wherein, the copper member and the ceramic member are bonded to each other, and a Mg solid solution layer is provided between the copper member and the ceramic member and contains Mg in a state of a solid solution in a Cu primary phase.

A joining method includes placing a brazing element between an interface area of a first ceramic piece and an interface area of a second ceramic piece to create a joining pre-assembly and placing the components of said joining pre-assembly into a process chamber. Oxygen is removed from said process chamber and at least said brazing element of said joining pre-assembly is heated, thereby hermetically joining said first ceramic piece to said second ceramic piece. Said brazing element consists of Cobalt and Carbon.