A semiconductor crystal containing a clathrate compound represented by the following formula (I), the semiconductor crystal having one end portion and the other end portion, wherein the one and the other end portions differ in concentration of at least one element in the formula (I):
A.sub.xD.sub.yE.sub.46-y(I)
wherein A represents at least one element selected from the group consisting of Ba, Na, Sr, and K, D represents at least one element selected from the group consisting of B, Ga, and In, E represents at least one element selected from the group consisting of Si, Ge, and Sn, x is 7 or more and 8 or less, and y is 14 or more and 20 or less.

A magnesium-based thermoelectric conversion material includes a first layer formed of Mg.sub.2Si and a second layer formed of Mg.sub.2Si.sub.xSn.sub.1-x (here, x is equal to or greater than 0 and less than 1), in which the first layer and the second layer are directly joined to each other, and within a junction surface with the first layer and in the vicinity of the junction surface, the second layer has a tin concentration transition region in which a tin concentration increases as a distance from the junction surface increases. The junction layer is regarded as a site in which a tin concentration is found to be equal to or lower than a detection limit by the measurement performed using EDX.

An apparatus and method perform supersonic cold-spraying to deposit N and P-type thermoelectric semiconductor, and other polycrystalline materials on other materials of varying complex shapes. The process developed has been demonstrated for bismuth and antimony telluride formulations as well as Tetrahedrite type copper sulfosalt materials. Both thick and thin layer thermoelectric semiconductor material is deposited over small or large areas to flat and highly complex shaped surfaces and will therefore help create a far greater application set for thermoelectric generator (TEG) systems. This process when combined with other manufacturing processes allows the total additive manufacturing of complete thermoelectric generator based waste heat recovery systems. The processes also directly apply to both thermoelectric cooler (TEC) systems, thermopile devices, and other polycrystalline functional material applications.

Example systems, apparatuses, and methods are disclosed sensing a flow of fluid using a thermopile-based flow sensing device. An example apparatus includes a flow sensing device comprising a heating structure having a centerline. The flow sensing device may further comprise a thermopile. At least a portion of the thermopile may be disposed over the heating structure. The thermopile may comprise a first thermocouple having a first thermocouple junction disposed upstream of the centerline of the heating structure. The thermopile may further comprise a second thermocouple having a second thermocouple junction disposed downstream of the centerline of the heating structure.

An apparatus and method perform supersonic cold-spraying to deposit N and P-type thermoelectric semiconductor, and other polycrystalline materials on other materials of varying complex shapes. The process developed has been demonstrated for bismuth and antimony telluride formulations as well as Tetrahedrite type copper sulfosalt materials. Both thick and thin layer thermoelectric semiconductor material is deposited over small or large areas to flat and highly complex shaped surfaces and will therefore help create a far greater application set for thermoelectric generator (TEG) systems. This process when combined with other manufacturing processes allows the total additive manufacturing of complete thermoelectric generator based waste heat recovery systems. The processes also directly apply to both thermoelectric cooler (TEC) systems, thermopile devices, and other polycrystalline functional material applications.

Materials and systems and methods of manufacture thereof that function as thermoelectric materials both in and near a cryogenic temperature range. In particular, the synthesis of heavy fermion materials that exhibit higher ZTs than previously achieved at cryogenic and near-cryogenic temperatures.

Better thermoelectric characteristics of a thermoelectric material containing nanoparticles are achieved. The thermoelectric material contains a plurality of nanoparticles distributed in a mixture of a first material having a band gap and a second material different from the first material. The first material contains Si and Ge. A concentration of atoms of the second material and a composition ratio of Si to Ge satisfy relational expressions in expressions (1) and (2) below with c representing a concentration of atoms (unit of atomic %) of the second material in the thermoelectric material and r representing the composition ratio of Si to Ge:
r0.62c0.25(1)
r0.05c0.06(2).

The present invention provides a thermoelectric conversion material represented by the following chemical formula (I):
Ba.sub.8+aCu.sub.6bGe.sub.40+6 (I) wherein the values of a is not less than 0.1 and not more than 0.47; the values of b is not less than 0 and not more than 0.43; the thermoelectric conversion material has a clathrate crystal structure; and the thermoelectric conversion material is of p-type. The present invention provides a p-type BaCuGe clathrate thermoelectric conversion material having high thermoelectric conversion performance index.

Temperature sensor devices and corresponding methods are provided. A temperature sensor may include a first layer being essentially non-conductive in a temperature range and a second layer having a varying resistance in the temperature range.

A heat exchanger may include a flow chamber able to be flowed through by a first fluid, a fin structure arranged in the flow chamber, a heat transfer chamber, and a thermoelectric temperature-control system. The temperature-control system may include at least one Peltier element with a plurality of p-doped p-type semiconductors and a plurality of n-doped n-type semiconductors electrically contacting one another. On a side of the fin structure, a plurality of connecting structures may be arranged. A respective connecting structure may include an electrically insulating base layer and an electrically conductive connecting layer. The fin structure may include the base layer. The connecting layer may be applied on a side of the base layer facing away from the fin structure. One such p-type semiconductor and one such n-type semiconductor may be mounted on the connecting layer. The fin structure may be provided with the base layer via oxidation.