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Information about Curie Point

The Curie point (Tc), or Curie temperature, is a term in physics and materials science, named after Pierre Curie (1859-1906), and refers to a characteristic property of a ferromagnetic or piezoelectric material.

Curie point in ferromagnetic materials

The Curie point of a ferromagnetic material is the temperature above which it loses its characteristic ferromagnetic ability. At temperatures below the Curie point the magnetic moments are partially aligned within magnetic domains in ferromagnetic materials. As the temperature is increased from below the Curie point, thermal fluctuations increasingly destroy this alignment, until the net magnetization becomes zero at and above the Curie point. Above the Curie point, the material is purely paramagnetic.

At temperatures below the Curie point, an applied magnetic field has a paramagnetic effect on the magnetization, but the combination of paramagnetism with ferromagnetism leads to the magnetization following a hysteresis curve with the applied field strength. The destruction of magnetization at the Curie temperature is a second-order phase transition and a critical point where the magnetic susceptibility is theoretically infinite.

See ferromagnetism for a list of ferromagnetic materials and their Curie temperatures.

The effect is primarily used in magneto-optical storage media, where it is used for erasing and writing of new data. Famous examples include the Sony Minidisc format, as well as the defunct CD-MO format.

Other uses include temperature control in soldering irons such as the Weller WTCPT and, in general, where a temperature-controlled magnetization is desirable.

Curie temperature in piezoelectric materials

In analogy to ferromagnetic materials, the Curie temperature is also used in piezoelectric materials to describe the temperature above which the material loses its spontaneous polarization and piezoelectric characteristics. In lead zirconate titanate (PZT), the material is tetragonal below Tc and the unit cell contains a displaced central cation and hence a net dipole moment. Above Tc, the material is cubic and the central cation is no longer displaced from the centre of the unit cell. Hence, there is no net dipole moment and no spontaneous polarization.

See also

Physics is the science of matter[1] and its motion[2][3], as well as space and time[4][5] —the science that deals with concepts such as force, energy, mass, and charge.
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Materials science or materials engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. This science investigates the relationship between the structure of materials and their properties.
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Pierre Curie

Pierre Curie (1859-1906)
Born May 15, 1859
Paris, France
Died April 19, 1906
Paris, France
Residence France
Nationality French
Field Physicist
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Ferromagnetism is the "normal" form of magnetism with which most people are familiar, as exhibited in horseshoe magnets and refrigerator magnets, for instance. It is responsible for most of the magnetic behavior encountered in everyday life.
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Piezoelectricity is the ability of some materials (notably crystals and certain ceramics) to generate an electric potential[1] in response to applied mechanical stress. This may take the form of a separation of electric charge across the crystal lattice.
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trillion fold).]]

Temperature is a physical property of a system that underlies the common notions of hot and cold; something that is hotter generally has the greater temperature. Temperature is one of the principal parameters of thermodynamics.
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Ferromagnetism is the "normal" form of magnetism with which most people are familiar, as exhibited in horseshoe magnets and refrigerator magnets, for instance. It is responsible for most of the magnetic behavior encountered in everyday life.
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In physics, the magnetic moment or magnetic dipole moment is a measure of the strength of a magnetic source. In the simplest case of a current loop, the magnetic moment is defined as:
where a
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A magnetic domain describes a region within a material which has uniform magnetisation. This means that the individual moments of the atoms are aligned with one another. The regions separating magnetic domains are called domain walls where the magnetisation rotates coherently from
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Magnetization is a property of some materials (e.g. magnets) that describes to what extent they are affected by magnetic fields, and also determines the magnetic field that the material itself creates. Magnetization is defined as the amount of magnetic moment per unit volume.
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Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field. Paramagnetic materials are attracted to magnetic fields, hence have a relative magnetic permeability greater than one (or, equivalently, a positive magnetic
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A system with hysteresis exhibits path-dependence, or "rate-independent memory". Consider a deterministic system with no hysteresis and no dynamics. In that case, we can predict the output of the system at some instant in time, given only the input to the system at that instant.
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phase transition or phase change is the transformation of a thermodynamic system from one phase to another. The distinguishing characteristic of a phase transition is an abrupt change in one or more physical properties, in particular the heat capacity, with a small change in
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critical point, also called a critical state, specifies the conditions (temperature, pressure) at which the liquid state of the matter ceases to exist. As a liquid is heated within a confined space, its density decreases while the pressure and density of the vapor being
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In physics and applied disciplines such as electrical engineering, the magnetic susceptibility is the degree of magnetization of a material in response to an applied magnetic field.
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Ferromagnetism is the "normal" form of magnetism with which most people are familiar, as exhibited in horseshoe magnets and refrigerator magnets, for instance. It is responsible for most of the magnetic behavior encountered in everyday life.
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magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon a magneto-optical disc. Both 130 mm and 90 mm form factors exist. The technology was introduced at the end of the 1980s.
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Sony Corporation
ソニー株式会?

Public (TYO: 6758 ; NYSE:  SNE )
Founded May 7 1946 (adopted current name in 1958) by Masaru Ibuka and Akio Morita[1]
Headquarters Minato-ku, Tokyo, Japan[1]
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MiniDisc

The Sony MZ1 MiniDisc player, the first to hit the market in 1992.
Media type: Magneto-optical disc
Encoding: ATRAC, linear PCM (with Hi-MD)
Capacity: 80 min (standard MiniDisc), up to 45 hours of audio (1 GB capacity) (with Hi-MD)
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soldering iron is a device for applying heat to melt solder for attaching two metal parts.

A soldering iron is composed of a heated metal tip and an insulated handle.
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Piezoelectricity is the ability of some materials (notably crystals and certain ceramics) to generate an electric potential[1] in response to applied mechanical stress. This may take the form of a separation of electric charge across the crystal lattice.
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In classical electromagnetism, the polarization density (or electric polarization, or simply polarization) is the vector field that expresses the density of permanent or induced electric dipole moments in a dielectric material.
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Lead zirconate titanate (Pb[ZrxTi1-x]O3 0<x
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Dipole moment refers to the quality of a system to behave like a dipole. This could be:
  • Electrical dipole moment, the measure of the electrical polarity of a system of charges
  • Magnetic dipole moment, the measure of the magnetic polarity of a system of charges

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Ferroelectricity is a physical property of a material whereby it exhibits a spontaneous electric dipole moment, the direction of which can be switched between equivalent states by the application of an external electric field. Ferroelectrics are key materials in microelectronics.
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The Néel temperature, TN, is the temperature at which an antiferromagnetic material becomes paramagnetic — that is, the thermal energy becomes large enough to destroy the macroscopic magnetic ordering within the material.
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