1461 results about "Curie temperature" patented technology

Certain embodiments provide a heater. The heater includes a ferromagnetic member. The heater also includes an electrical conductor electrically coupled to the ferromagnetic member. The electrical conductor is configured to conduct a majority of time-varying electrical current passing through the heater at about 25° C. The heater is configured to provide a first heat output below the Curie temperature of the ferromagnetic member. The heater is configured to automatically provide a second heat output approximately at and above the Curie temperature of the ferromagnetic member. The second heat output is reduced compared to the first heat output.

Techniques for ultrahigh density writing on an erasable magnetic medium include using a micromachined mechanism having two probes for writing to the medium. Use of the two probe embodiment eliminates the need to change the magnetic orientation of the probe. In another embodiment, a single probe is provided which is heated to the vicinity of its Curie temperature to enable the magnetic orientation of the probe to be switched. The probe may be heated to its Curie temperature through the use of a heating element or a focused laser. In another embodiment of the present invention, either the magnetic orientation of the probe or the magnetic orientation of the medium may be switched through the combination of a static magnetic field, a radio frequency magnetic field and, under certain circumstances, the magnetic field of the probe. In all cases, the writing techniques enable information to be written to a magnetic medium in a manner which enables the information to be erased and the medium rewritten.

Magnetic nanoparticle compositions are provided which provide an inherent temperature regulator for use in magnetic heating, particularly for use in magnetic hyperthermia medical treatments. The composition includes magnetic nanoparticles having a Curie temperature of between 40 and 46° C., preferably about 42° C., and may further include a polymeric material and optionally a drug or radiosensitizing agent. Methods of hyperthermia treatment of a patient in need thereof are provided which include the steps of administering to the patient a composition comprising magnetic nanoparticles having a Curie temperature of between 40 and 46° C.; and exposing the magnetic nanoparticles in the patient to an alternating magnetic field effective to generate hysteresis heat in the nanoparticles.

A heat pump system is provided that uses multiple stages of MCMs with different Curie temperature ranges. An adjustable fluid flow path is used whereby the number of stages through which a heat transfer fluid passes can be varied depending upon e.g., the amount of heating or cooling desired. In certain embodiments, a magnetic field used to activate the MCMs can be manipulated so that the number of stages of MCMs that are activated also be adjusted. These and other features can improve the operating efficiency of the heat pump.

Small, low-cost wireless temperature sensors (26,64,96) are provided for sensing the temperature of an object (44). The temperature sensors (26,64,96) preferably include a plurality of individual, magnetically susceptible temperature sensor elements (28-34,66,92), as well as optional magnetic field-responsive data elements (38,40,20) adapted for attachment to object (44) or to a substrate (82) in turn attached to object (44). The temperature sensor elements (28-34,66,92) preferably have magnetic bodies (22,70) exhibiting a re-magnetization response under the influence of an applied alternating magnetic field, which is different below and above a set point temperature, normally the Curie temperature of the magnetic body (22) or an adjacent sheath (74,94). The temperature sensors (26,64,96) are used in conjunction with a detector (46) operable to generate a magnetic field of magnitude sufficient to cause re-magnetization responses of the temperature sensor elements (28-34,66,92) and optional data elements (38,40,20), to detect such responses, and to use the detected responses to determine the temperature of object (44) by means of a decoding algorithm. The temperature sensors (26,64,96) can be used in closed-loop heating systems (98) capable of controlling the heating of an object (114).

A method of improving the physical and/or electrical and/or magnetic properties of a thin film material formed on a substrate, wherein the properties of the thin film material are stress-dependent, by selectively applying force to the substrate during the film formation and/or thereafter during the cooling of the film in the case of a film formed at elevated temperature, to impose through the substrate an applied force condition opposing or enhancing the retention of stress in the product film. The method of the invention has particular utility in the formation of ferroelectric thin films which are grown at temperature above the Curie temperature, and which may be placed in tension during the cooling of the film to provide ferroelectric domains with polarization in the plane of the film.

A method in which at least one piezoceramic sensor, which converts every mechanical force to which it is subjected into an electrical signal and having a Curie temperature higher than 200° C., is solidarized directly onto the surface of a metal support element of a vehicle braking element, which during use faces a vehicle element to be braked. While in contact with such a surface, an electrical circuit is implemented that picks up and eventually processes the electrical signal, the electrical circuit being connected with a connector integrated with the metal support element. An electrically insulating layer sandwiches the at least one piezoceramic sensor and the electrical circuit, and a block of friction material with an underlying damping layer is formed upon the electrically insulating layer. After forming the block of friction material, the piezoceramic sensor is polarized by applying a predetermined potential difference thereto by means of the connector.

A thermal-assist magnetic recording medium is provided which can accomplish a surface recording density of 1 Tbit/inch². The thermal-assist magnetic recording medium includes: a substrate; a plurality of underlying layers formed on the substrate; a first magnetic layer formed on the underlying layers; a coupling control layer formed on the first magnetic layer and formed of a ferromagnetic alloy; and a second magnetic layer formed on the coupling control layer. Here, Curie temperatures of the first magnetic layer and the second magnetic layer are higher than the Curie temperature of the coupling control layer, an anisotropy magnetic field of the first magnetic layer is greater than the anisotropy magnetic field of the second magnetic layer, and a saturation magnetic field has a minimum value at a temperature of 350° C. or lower.

The present invention relates to a new method and apparatus for converting heat to electric energy. The invention exploits the rapid changes in spontaneous polarization that occur in ferroelectric materials during phase change. The invention permits robust and economical generation of electric energy from thermal energy, and it can be used in many different applications. In one aspect, the present invention relates to an apparatus for converting heat to electric energy comprising a pair of electrodes; a ferroelectric layer formed there between with a ferroelectric material characterized with a Curie temperature, T_c, such that when the temperature of the ferroelectric material is lower than T_c, the ferroelectric material is in a ferroelectric phase in which very powerful polarization is established spontaneously in the unit cells of the ferroelectric material, and when the temperature of the ferroelectric material is greater than T_c, spontaneous polarization is not established in the unit cells of the ferroelectric material; and a means for alternately delivering a flow of cold fluid and a flow of hot fluid to the ferroelectric layer so as to alternately cool the ferroelectric layer at a first temperature T_L that is lower than T_c, and heat the ferroelectric layer at a second temperature T_H that is higher than T_c, thereby the ferroelectric material of the ferroelectric layer undergoes alternating phase transitions between the ferroelectric phase and the paraelectric phase with temperature cycling.

A thin film structure comprises a first layer including a first plurality of grains of magnetic material having a first intergranular exchange coupling, and a second layer positioned adjacent to the first layer and including a second plurality of grains of magnetic material having a second intergranular exchange coupling, wherein the second intergranular exchange coupling is larger than the first intergranular exchange coupling and wherein the Curie temperature of the first layer is greater than the Curie temperature of the second layer. A data storage system including the thin film structure is also provided.

According to the present invention, powder coating compositions comprise one or more than one thermoplastic or thermosetting polymer or resin and one or more than one finely divided magnetic material, such as a ferromagnetic material. Preferred magnetic materials include Ni_1−xZn_xFe₂O₄ compounds, wherein 0.4≦X≦0.75, piezoelectric compounds, ferrimagnetic δFeOOH, Fe—Ni—B, Cu₂MnIn, transparent polymer-Cobalt oxide nanocomposites and soft ferrites. In addition, the present invention provides methods of making powder coatings on a substrate comprising applying to a substrate a resinous powder coating composition comprising one or more than one magnetic material to form a powder coating layer, followed by induction heating to melt the applied powder coating to form a coating film and, optionally, to cure the powder coating. The powder coatings remain at a pre-selected temperature equal to or less than the Curie temperature (T_C) of the one or more than one finely divided magnetic material during induction heating of the powder coating without directly heating the substrate. Powder coatings on metal parts may also be induction heat cured.

A magnetic recording system is provided having a write head employing a combination of magnetic write field gradient and thermal gradient to write data on a ‘thermal spring’ magnetic recording media. The write head comprises a magnetic element using a write current to induce a magnetic write field at the magnetic media and a thermal element using a very small aperture laser to heat a portion of the media. The thermal spring magnetic media comprises [comprises] first and second stacks providing two exchange coupled ferromagnetic layers having different Curie temperatures [The first stack has a high magneto-crystalline anisotropy, a relatively low saturation magnetization and a low Curie temperature.] [The second stack has a relatively low magneto-crystalline anisotropy, a high saturation magnetization and a high Curie temperature.] The magnetic field gradient and the thermal gradient are arranged to substantially overlap at the trailing edge of the heated portion of the magnetic media allowing data at high density with high thermal stability to be recorded on the rapidly cooling thermal spring magnetic recording media.

An aerosol-generating article (10) comprises an aerosol-forming substrate (20) and a susceptor (1, 4) for heating the aerosol-forming substrate (20). The susceptor (1, 4) comprises a first susceptor material (2, 5) and a second susceptor material (3, 6) having a Curie temperature, the first susceptor material being disposed in intimate physical contact with the second susceptor material. The first susceptor material may also have a Curie temperature, the second Curie temperature being lower than 500 DEG C, and lower than the Curie temperature of the first susceptor material, if the first susceptor material has a Curie temperature. The use of such a multi-material susceptor allows heating to be optimised and the temperature of the susceptor to be controlled to approximate the second Curie temperature without need for direct temperature monitoring.

To provide a wafer, made from a lithium tantalate single crystal or a lithium niobate single crystal, wafer which is charge restrained without impairing the piezoelectricity. Moreover, to provide a processing method and a processing apparatus therefor. It is characterized in that a wafer 50, made from a lithium tantalate single crystal or a lithium niobate single crystal, and a reducing agent 60, including an alkali metal or an alkali metal compound, are accommodated in a processing tank 2, and the inside of the processing tank 2 is held at a temperature of from 200° C. or more to less than a Curie temperature of the single crystal under decompression, thereby reducing the wafer 50.

A thermally-assisted MRAM structure which is programmable at a writing mode operating temperature is presented and includes an anti-ferromagnet, an artificial anti-ferromagnet, a barrier layer, and a free magnetic layer. The anti-ferromagnet is composed of a material having a blocking temperature T_b which is lower than the writing mode operating temperature of the magnetic random access memory structure. The artificial anti-ferromagnet is magnetically coupled to the anti-ferromagnet, and includes first and second magnetic layers, and a coupling layer interposed therebetween, the first and second magnetic layers having different Curie point temperatures. The barrier layer is positioned to be between the second magnetic layer and the free magnetic layer.

A piezoelectric member of uniaxial crystal or uniaxial crystal and the piezoelectric member has perovskite type oxide described to be ABO₃ in a general formula with a main component of the A being Pb and a main component of the B containing at least three kinds of elements selected from the group consisting of Mg, Zn, Sc, In, Yb, Ni, Nb, Ti and Ta and film thickness of the piezoelectric member is not less than 1 μm and not more than 10 μm and the piezoelectric member fulfills a predetermined conditions on relative dielectric constant or Curie temperature.