A single fuel cell according to the present disclosure includes a power generation section, a power non-generation section which does not include the power generation section, and an oxygen-ion-insulating gas seal film arranged so as to cover the surface of the power non-generation section, and the gas seal film is configured by a structure formed by firing a material containing MTiO.sub.3 (M: alkaline earth metal element) and metal oxide. The structure may include a first structure and a second structure which are different in composition, the first structure may include components derived from MTiO.sub.3 in larger amounts than the second structure, the second structure may include a metal element contained in the metal oxide in a larger amount than the first structure, and the area ratio of the second structure in the structure may be not less than 1% and not more than 50%.

An electrochemical reaction unit includes a unit cell including an electrolyte layer, and a cathode and an anode which face each other in a first direction with the electrolyte layer intervening therebetween, and one or a plurality of structural members. The electrochemical reaction unit further includes a glass seal member which contains glass and is in contact with two members facing each other in the first direction, the two members being selected from the unit cell and the one or the plurality of structural members. The glass seal member contains a plurality of crystal grains each having a ratio of a vertical dimension in the first direction to a horizontal dimension in a second direction orthogonal to the first direction of 1.5 or more.

An electrochemical reaction unit includes a unit cell including an electrolyte layer, and a cathode and an anode which face each other in a first direction with the electrolyte layer intervening therebetween, and one or a plurality of structural members. The electrochemical reaction unit further includes a glass seal member which contains glass and is in contact with two members facing each other in the first direction, the two members being selected from the unit cell and the one or the plurality of structural members. The glass seal member contains a plurality of crystal grains each having a ratio of a vertical dimension in the first direction to a horizontal dimension in a second direction orthogonal to the first direction of 1.5 or more.

A cell stack device may include a cell stack comprising a plurality of cells, a manifold configured to supply a reaction gas to the plurality of cells, and a reaction gas supply pipe connected to the manifold. The manifold may include an insertion portion configured to connect the reaction gas supply pipe to the manifold and a first joining portion configured to join the insertion portion and the reaction gas supply pipe. A module may include the cell stack device contained in a housing container. A module housing device may include the module, an auxiliary device configured to operate the module, and an external casing configured to contain the module and the auxiliary device therein.

A join is provided that includes a first joining partner, a second joining partner having a surface, an electrically insulating component connecting the first joining partner in the second joining partner so that the first joining partner is electrically insulated from the second joining partner and so that the first joining partner extends from the surface. The electrically insulating component has a structure between the first and second joining partners that elongates from the surface along the first joining partner. The electrically insulating component and/or the structure is an at least partially crystallized glass.

An electrochemical reaction unit including a unit cell including an electrolyte layer, and a cathode and an anode that face each other in a first direction with the electrolyte layer intervening therebetween; and a felt member containing a ceramic material or a metal and a silica component. The felt member includes both a first crystal structure and a second crystal structure, which is an SiO.sub.2 crystal structure. Also disclosed is an electrochemical reaction cell stack including a plurality of electrochemical reaction units disposed in the first direction, at least one of the electrochemical reaction units being the above-described unit. Yet further disclosed is a method for producing the electrochemical reaction unit.

An electrochemical reaction unit including a unit cell including an electrolyte layer, and a cathode and an anode that face each other in a first direction with the electrolyte layer intervening therebetween; and a felt member containing a ceramic material or a metal and a silica component. The felt member includes both a first crystal structure and a second crystal structure, which is an SiO.sub.2 crystal structure. Also disclosed is an electrochemical reaction cell stack including a plurality of electrochemical reaction units disposed in the first direction, at least one of the electrochemical reaction units being the above-described unit. Yet further disclosed is a method for producing the electrochemical reaction unit.

An inorganic felt material includes zirconia stabilized by at least one Group IIA material, such that the Group IIA material includes at least one of calcium (Ca), magnesium (Mg), or a combination thereof. The felt material may also include at least one Group III material.

An inorganic felt material includes zirconia stabilized by at least one Group IIA material, such that the Group IIA material includes at least one of calcium (Ca), magnesium (Mg), or a combination thereof. The felt material may also include at least one Group III material.

An electrochemical reaction unit including a unit cell including an electrolyte layer, and a cathode and an anode that face each other in a first direction with the electrolyte layer intervening therebetween; and a felt member containing a ceramic material or a metal and a silica component. The felt member has an Si content of 0.9 mass % to 13.2 mass %. Also disclosed is an electrochemical reaction cell stack including a plurality of electrochemical reaction units, at least one of the units being the above-described electrochemical reaction unit.