DE1533206C - Use of compounds of the type Mn deep 3 GaC as a ferromagnetic working medium for energy conversion - Google Patents

Description

The invention relates to the use of a ferromagnetic crystalline material with a perovskite structure as a ferromagnetic working medium for energy conversion. It is a series of compounds of the Mn ₃ GaC type, which have a transition from the antiferromagnetic to the ferromagnetic state.

It is known that nitrogen compounds or carbon compounds M ₄ Z, which have a cubic atomic lattice with centered faces, have different and interesting magnetic properties. With the exception of the well-known nitrogen compounds Fe ₄ N and Mn ₄ N, such compounds are for the most part only hypothetical.

Fe ₄ N is ferromagnetic, _{whereas Mn 4} N has a ferromagnetic structure that can be divided into two antiparallel sublattices, one of which consists of the atoms in the center of the outer surfaces and the other of the atoms at the corners of the cubic lattice.

In the case of the carbon-nitrogen compounds Mn ₄ N _x C _1-,. Ferromagnetism occurs in relief due to the presence of compensation points. It has also been established - which was logically foreseeable - that a total replacement of one of the magnetic sublattices with "non-magnetizable" atoms such as Al, Zn, Sn etc. leads to ferromagnetic compounds such as AlMn ₃ C, ZnMn ₃ C, SnMn ₃ C etc. . Finally, it has been found that in the Mn ₃ ZnC production phase a magnetic conversion takes place at relatively low temperatures and the reason for this has been seen in a ferriferromagnetic transition.

_{The compound stages of the type M 3} M "Z belonging to the alloys used according to the invention, which are derived from nitrogen compounds ^ or carbon compounds of the form M ₄ Z with a face-centered cubic structure through an orderly exchange of transition atoms located at the corners of the cube, on the other hand have a transition from the antiferromagnetic to the ferromagnetic state, which is interesting from various points of view.

Ferromagnetic substances normally have a saturation magnetization, which increases with increasing Temperature decreases monotonically towards the Curie point. We know relatively few substances other than the Curie point have a second transition temperature lower than and at which the Curie point a magnetic transformation occurs, _ in such a way,

that these substances have ferromagnetic properties only in the interval between the two mentioned Have temperature values while their magnetization is below and above this interval is practically zero.

Previously proposed substances with similar characteristics of the saturation magnetization, but which have a Cu ₂ Sb structure and a different composition, however, have the disadvantage that with them only

there is a slight jump in the saturation magnetization, which is 27 Gauss · cm ³ / gram.

The invention is based on the object of providing ferromagnetic working media for converting energy to find and manufacture whose saturation magnetization changes are considerably larger than those already known crystalline materials, and therefore ferromagnetic working materials for ' Energy conversion result with a more favorable efficiency.

The object is achieved according to the invention by using a ferromagnetic crystalline material with a perovskite (CaTiO ₃ ) structure, consisting of 50 to 75 atomic percent chromium, manganese, iron, cobalt, nickel and / or palladium, 16.7 to 25 atomic percent Magnesium, aluminum, copper, zinc, gallium, germanium, silver, indium and / or tin, 0 to 23.3 atomic percent boron, carbon, nitrogen, as a ferromagnetic working medium for energy conversion with a maximum of saturation magnetization in a certain temperature range below the Curie temperature and a significantly lower magnetizability above and below this temperature range.

With such materials, changes in the saturation magnetization at the transition points of 60 Gauss · cm ³ / gram can be achieved, i.e. more than double the values of materials previously recognized as ferromagnetic working media for energy conversion.

Alloys related according to the invention have a perovskite structure and a composition according to the general formula M ₃ M "Z ₀ , where M 'denotes chromium, manganese, iron, cobalt, nickel and / or palladium. M" denotes magnesium, aluminum, Copper, zinc, gallium, germanium, silver, indium and / or tin and also one or more of the insert elements boron, carbon and / or nitrogen, α denotes a number between 0 and 2. This compound shows a transition from the antiferromagnetic to the ferromagnetic state or a narrow antiferro-ferri-ferromagnetic transition zone between the two states mentioned in the direction of increasing temperatures.

Such a compound M ₃ M "Z _a , which is related according to the invention, for example the compound Mn ₃ GaC, is referred to as a compound with a perovskite structure, since its crystal structure is completely analogous to that of the compound TiO ₃ Ca (perovskite). In this last-mentioned compound, the crystal lattice of which is cubic and has centered surfaces, the ions Ca ^{++ are} in the position (0, 0, 0), the ions O ~~ in the

Ίο position, j, j, JJ and lying equal, and further, the ions Ti ^{+ + + +} in the position Q, 5-3) · ^In -> ^Eder any compound according to the invention, one finds a structure and analog arrangements (see Fig. 1) again, in which the same points of the cubic lattice as those mentioned above are correspondingly occupied with metals M ″, in particular Ga, with metals M ', in particular Mn, and elements Z, in particular C.

This structure allows in a very general way deviations in the stoichiometric composition due to a larger or smaller proportion of the elements Z, in particular C, called the insert elements, which is indicated in the formula by the number α , which is preferably a value very close to 1 has, but is not necessarily 1.

If one considers, for example, the compound Mn ₃ GaC, which has this structure, then the parameter of the grating, that is the length α of the edge of the cube, amounts to diffraction images of X-rays according to the classical method of Seemann-B ο h 1 i η measured for the line K ₁ of iron, 3.896 Å at normal temperature.

An investigation of the thermomagnetic properties of this mixed carbon compound led to the finding that below the Curie point of - 22 ° C a transition takes place, which in the direction of increasing temperatures from an antiferromagnetic state to a ferromagnetic state at a temperature Θ, in the vicinity of -115 ° C leads (see Fig. 2). The temperature value Θ depends on the pressure and on magnetic fields of greater intensity. The phenomenon is reversible in the opposite direction.

This transition from the antiferromagnetic to the ferromagnetic state takes place in a very narrow temperature interval (see FIG. 2), in a range with a width of approximately 5 to 6 ^° C. The lattice parameter is shortened by 0.006 Å and by accompanied by a relatively strong endothermic effect. The transition is also evident in a sudden change in certain physical properties of the sample, in particular the specific electrical resistance, which decreases by half in the direction of increasing temperatures (see FIG. 3).

A whole series of compounds with the same perovskite structure, analogous thermomagnetic properties and which correspond to the already mentioned general chemical composition can be derived from the mentioned compound Mn ₃ GaC by an arranged total or partial replacement of the manganese, the gallium and the carbon by the aforementioned elements are formed, and the so-called transition element can also have a slight excess or a slight subset of the standard composition.

There is thus an unlimited number of metal compounds or metal compound levels with continuously variable thermomagnetic properties, in particular the position of the points Θ and 6> _c on the temperature scale and the value of the magnetization intensity at saturation.

The aforementioned transition from the antiferromagnetic to the ferromagnetic state can occur with certain Connections of this type take place via a ferrimagnetic state, i.e. in the sense of increasing temperatures proceed according to a scheme of the following successive states: antiferromagnetic-ferromagnetic-ferromagnetic.

The perovskite structure in these materials for the stated purpose can be obtained by that the interconnected elements and / or binary and / or ternary interconnections all brought together with a high degree of purity and preferably in stages in the specific proportion are, the substances intimately mixed with one another and several longer annealing processes at temperatures between 300 and 900 ° C below-

be thrown, between which the product is each finely chopped and with the newly added elements or intermediate compounds are intimately mixed.

The material with the perovskite structure, which can be produced in the above-mentioned process can, can be used as a material to form a temperature-dependent mechanical or electrical Contact can be used, for example by its arrangement in the attraction area of a magnet. It can also be used as a. Material for the manufacture of a device for the direct conversion of thermal energy in mechanical energy, for example a device with a local heating exposed, with parts of the material occupied disc in a magnetic field with the formation of a Rotary motor can be used. Other possible uses are as a material for the core a solenoid arranged in a permanent magnetic field to generate electricity in the Solenoid with alternating heating and cooling of the core, as a material for one in an electrical one Circle arranged member with one that changes abruptly depending on the temperature specific resistance to determine the ■ temperature or as a material for the core of a inductive electrical circuit element with an abruptly variable depending on the temperature Induction value.

The invention is explained in more detail below with reference to examples and drawings. In detail show

Fig. 1 is a model of the crystal structure of the invention related alloys,

F i g. 2 is a diagram showing the magnetization as a function of the temperature in the case of the carbon compound Mn ₃ GaC,

F i g. 3 is a diagram showing the specific electrical resistance of the carbon compound Mn ₃ GaC as a function of the temperature,

F i g. 4 a comparison of two diagrams in which the magnetization as a function of the temperature for compounds Mn ₃ GaC ₁ - ^ N ^ is drawn once for χ = 0.1 and once for χ = 0.2,

F i g. 5 is a schematic representation of a magnetic bimetal arrangement in which, according to the invention related alloys are incorporated,

F i g. 6 a schematic representation of a thermomechanical Converter with an alloy related to the invention.

Embodiment 1

The task is set to form _{the compound Mn 3 GaC.} For this purpose, a mixture of manganese, gallium and carbon is assumed in a first step, with all three components being of a high degree of purity and proportions corresponding to the stoichiometric composition of the compound being used, i.e. (3 Mn + 1 Ga + 1 C ). The manganese-carbon mixture is thoroughly ground in an agate mortar and the gallium is added in chip form. The mixture is placed in an ampoule made of hard glass, which is sealed in a vacuum and placed in an oven, where a first annealing process is carried out at a temperature of approximately 400 ° C. for at least 100 hours. From then on, the mixture contains only gallium in free form. The ampoule is taken out of the oven and exposed to air cooling. In a second processing step, the homogeneous mixture is again subjected to an intimate grinding in an agate mortar. The mixture is then placed in a quartz ampoule, which is melted shut in a vacuum and which is subjected to a second annealing process for ^{about 100 hours at a temperature of 800 to 900 °} C. The ampoule is then removed from the furnace and subjected to a more or less rapid cooling.

This procedure is relatively straightforward as it has two sections, each of which comprises a crushing process and an annealing process.

_{The compound Mn 3} GaC obtained in this way is obtained in the form of a metallic gray mass that is strongly sintered and hard. It has been found that the melting point of this substance is above 1200 ° C. and that partial decomposition occurs before this temperature is reached, as can be determined by a thermomagnetic analysis.

The purity of the compound Mn ₃ GaC can be controlled in various ways, for example by X-ray diffraction or by thermomagnetic analysis at a temperature of -196 ° C to +1000 ⁰ C. The transition point Θ and the Curie point, the crystal lattice parameters d and The saturation value μ of the magnetic moment in Bohr magnetons on manganese atoms can also be used as physical properties of the compound Mn ₃ GaC as criteria for the purity of the substance.

Embodiment 1 a

The aim is again to form the compound Mn ₃ GaC, but by a second method which differs from the first in that the manganese is first combined with the carbon and then only the gallium is added.

Exactly as in the first exemplary embodiment, a mixture of manganese and carbon in a quantity ratio of approximately 3 Mn + 1 C is thoroughly ground in an agate mortar. This mixture is subjected to a temperature of approximately 650 ° C. for a desired time in a quartz tube which is sealed in a vacuum so that all of the carbon is bound. The result is a mixture of manganese carbides, especially Mn ₅ C ₂ and Mn ₇ C ₃ , which are stable under normal conditions, and the composition of the mixture is determined by analysis.

In a second process step, the manganese-carbide mixture and manganese obtained in the first process step are thoroughly ground in an agate mortar. The last-mentioned manganese is added in such an amount that the total mixture corresponds exactly to the composition (3 Mn + 1 C). This mixture is then subjected in a sealed quartz tube in vacuum for 100 hours to a temperature of about 700 ⁰ C.

In a third process step, the gallium is added in the desired amount, and from there There are two annealing steps separated by a fine comminution step exactly as in the first embodiment accomplished.

With regard to the final composition of the Mn ₃ GaC material, this method is more reliable than that according to exemplary embodiment 1.

Embodiment Ib

The aim is again to produce the compound Mn ₃ GaC, but according to a third method which differs from those described above in that the gallium is added to the manganese first and then the carbon alone.

In a first process step, a mixture of manganese and gallium is brought into the proportions (3 Mn + 1 Ga) under vacuum in a hard glass ampoule for at least 100 hours to a temperature not exceeding 350 ° C. An Mn-Ga alloy is obtained which has the same Corresponds to proportions.

In a second process step, this Mn-Ga alloy is intimately mixed with carbon crushed, the desired proportions are observed, and this mixture is the subjected to the last annealing process of the method according to embodiment 1.

This method is simpler than the one previously described, but the result is less reliable.

Embodiment 2

Zia! is the production of compounds Mn ₃ GaC ₁ _ _x . In order to achieve these compounds with an incomplete carbon content, a mixture of the substance “Mn ₃ Ga” produced in accordance with exemplary embodiment 1 b with a compound Mn ₃ GaC is assumed. The last-mentioned connection can be established in accordance with any one of exemplary embodiments 1 to Ib. The mixture is carried out in the combination χ · »Mn ₃ Ga« + (1 - x) · Mn ₃ GaC corresponding proportions. The mixture is thoroughly comminuted and then subjected to the last annealing process of embodiment 1.

One can also start directly from the three elements Mn, Ga and C and exactly as in one of the exemplary embodiments 1 or 1 b proceed, with the only difference that the carbon content used is so dimensioned that each carbon atom of the compound mentioned earlier is replaced by (1 - x) atoms this element is replaced.

_{Compared to Mn 3} GaC, the connections achieved show changes in parameters, which are listed in the following table:

Table for embodiment 2

links Θ,
(in ⁰ C) © _c
(in ⁰ C) a
(in A) Mn ₃ GaC -115
-128
-140 -22
-20
-18 3.896
3,895
3.894 Mn ₃ GaC, 0.98
Mn ₃ GaC, 0.97

the oxide Ga ₂ O ₃ of white color is placed in a quartz boat, which is inserted into a quartz tube open on both sides, so that a stream of dry NH ₃ gas can be passed through the tube when the tube is in an oven at 900 ° C is arranged. After about 100 hours, the nitrogen compound GaN of yellow color is obtained.

To achieve the nitrogen compound Mn ₃ N, the procedure is initially analogous and Ga ₂ O _{3 is} replaced by Mn and NH ₃ by pure, dry N ₂ , in which case the furnace is kept at a temperature of 550 ° C. After about 100 hours, a nitrogen compound is obtained which is even richer in nitrogen than the compound Mn ₃ N. After metering, the desired amount of manganese is added, the mixture is thoroughly comminuted and subjected to an annealing process at 700 ° C.

In the two manufacturing processes for GaN and Mn ₃ N, a nitrogen content is checked by a microanalysis according to K in each case 1 then 1.

In a second process step the compound Mn ₃ GaN is produced, the discovery of which was reported in the "Comptes Rendus de l'Academie des Sciences", Paris, Vol. 259, pp. 392 and 393 (July 15, 1964).

If one started with GaN, one forms

a mixture of this substance and manganese with the proportions (3 Mn + 1 GaN), comminuted ^: this mixture intimately and subjects it to the last annealing process of embodiment 1.

If you start from Mn ₃ N, you form a mixture of this substance with gallium in the proportions (Mn ₃ N + 1 Ga) and treat this mixture in exactly the same way.

In a third process step, one starts from a mixture of the compound Mn ₃ GaC, which has been obtained according to one of the working examples 1 to Ib, with Mn ₃ GaN, which has been obtained as described above, and assumes proportions that correspond to the composition ( 1 - x) Mn ₃ GaC + χ Mn ₃ GaN. This mixture is subjected to the first annealing process of embodiment 1.

The compounds obtained in this way show _{changes in characteristic values compared to Mn 3} GaC, which are listed in the following table:

Table for embodiment 2a
(see also Fig. 4)

links Θ,
(in ⁰ C) (in ⁰ C) ⁵⁵ Mn ₃ GaC -115
-104
-97 -22
-50
-85 Mn ₃ GaC _{0 9} N ₀₁
Mn ₃ GaC ₀₈ N ₀₂ .. ■

60

Embodiment 2 a

The aim is to produce compounds Mn ₃ GaC ₁ - ^ N _x . In order to achieve these mixed carbon-nitrogen compounds, one begins in a first process step with the formation of one of the nitrogen compounds GaN or Mn ₃ N.

In order to achieve the nitrogen compound GaN, exemplary embodiment 2 b

The aim is to produce compounds Mn ₃ GaC ₁ ^ _x B _x . To obtain such mixed carbon-boron compounds, one begins with the preparation of the compound Mn ₃ GaC ₁ _ ,,. as in embodiment 2. A mixture of this compound and boron is then formed in _{proportions corresponding to the composition Mn 3} GaC ₁ _ _x + xB. This mixture is the last

209 530/119

th annealing process of the method according to embodiment 1 subjected.

You can also start from the four elements Mn, Ga, C and B and proceed exactly as in an exemplary embodiment 1 or 1b, with the only difference that the carbon component used there is replaced by a carbon-boron mixture, in such a way that for each carbon atom an atomically calculated mixture proportion of (1 - x) · C + χ · B is used.

_{In comparison with Mn 3} GaC, the compounds obtained in this way have deviations in characteristic values, which can be seen from the following table:

Table for embodiment 2 b

15th

links Θ,
(in ⁰ C) 6> _c
(in ⁰ C) Mn ₃ GaC -115
-128 -22
-20 Mn ₃ GaC _{0 9} B ₀ j

. It has been found that at a value χ = 0.2, the transition from the antiferrorhagnetic to the ferromagnetic state has disappeared.

Embodiment 3

25th

the goal is

the creation of compounds ₃₁ ^ e _x C; this is based on the four elements Mn, Ga, Ge and C. The procedure is exactly as in one of the exemplary embodiments 1 or 1a, with the only difference that the gallium component used there is replaced by a gallium-germanium mixture, with (1- x) · Ga + x-Ge atoms for each gallium atom added to the mixture.

The compounds obtained in this way have changes in _{characteristic values compared with Mn 3} GaC, which can be seen from the table below.

Table for embodiment 3

links θ,
(in ⁰ C) Θ _c
(in ⁰ C) Mn ₃ OaC -115
-111 CN Ό
(N (N
¹ ι ι Mn ₃ Ga _{0 95} Ge _{0iO 5} C

45

Embodiment 4

The aim here is the production of compounds Mn ₃ - ^ Fe _x GaC. The starting point is again the four elements Mn, Fe, Ga and C and the procedure is exactly as in Example 1, with the only difference that the manganese content is replaced by a mixture of manganese and iron, with three manganese atoms (3 - ^x ) Mn + χ · Fe atoms join the mixture.

Compared to Mn ₃ GaC, the compounds obtained have deviations in characteristic values, which can be seen from the table below.

ίο

Table for Embodiment 4th links
5 (in "C) Mn ₃ GaC -22
-21
-19 Mn, Fe _{94 0 06} GaC
Mn ₂₉₂₅ Fe ₀₀₇₅ GaC .. Θ,
(in "C) -115
.-157
-180

It has been found that for χ = 0.15 there is a transition from the antiferromagnetic state to the ferromagnetic state is omitted.

In the case of the analogous production of connections Mn ₃ _ _x Cr _x GaC, the same observation was made, but in this case with a value of χ = 0.3.

Embodiment 5

The aim is to produce compounds Mn ₃ (^ _x ) Cr _3x C ₁ _ _X N _X. One begins with a first process step for the production of the compound Cr ₃ GaN, the discovery of which was communicated at the same time as that of Mn ₃ GaN in "Comptes Rendus de l'Academie des Sciences de Paris" - as mentioned above.

For this purpose, one starts from GaN, which is obtained as in embodiment 2 a (1st process stage) willi. A mixture is formed from this starting compound and chromium in the proportions (3 Cr + 1 GaN). This mixture is thoroughly crushed and an annealing process according to the subjected to the last annealing process in embodiment 1.

In a second process step, an intimate mixture of the compound Cr ₃ GaN thus obtained is formed with the compound Mn ₃ GaC produced in accordance with one of the exemplary embodiments 1 to 1b with a quantitative composition corresponding to the equation (1 − x) Mn ₃ GaC + χ Cr ₃ GaN. The mixture is thoroughly comminuted and subjected to the last annealing process of embodiment 1.

_{Compared to Mn 3} GaC, the compounds obtained in this way have the characteristic value deviations evident from the table below.

Table for Embodiment 5 50 links (in "C) Mn ₃
Mn ₂
«GaC GaC NJ NJ
Ui NJ , 85 ^ Γο, ₁₅
o, 9sN _0j o ₅ © ι
(in ⁰ C) -115
-105

Embodiment 6

The aim is to produce compounds Mn ₃ Ga _1. ^ Zn _x C ₁ _ _X N _X. The first process step begins with the preparation of the compound Mn ₃ ZnN in two stages. A mixture of powdery zinc and Mn ₃ N is assumed, the latter compound being produced as in embodiment 2 a. It is thoroughly crushed again. The mixture is brought about 100 hours to a temperature of 650 ⁰ C. Then the mixture is again comminuted and intimately brought again about 100 hours to a temperature of 800 ° C.

In a second method step, an intimate mixture is formed from the thus obtained compound Mn ₃ ZnN with the one-of Embodiments 1 prepared according to Ib compound Mn ₃ GaC. The proportions are based on the structure (1 - x) ■ Mn ₃ GaC + Mn ₃ ZnN. The mixture is thoroughly comminuted and subjected to the last annealing process of embodiment 1.

The compounds obtained in this way have _{changes in characteristic values compared with Mn 3} GaC, which can be seen from the table below.

Table for embodiment 6

links Θ,
(in ⁰ C) e _c
(in "C) Mn ₃ GaC -115
-115 -22
-50 Mn ₃ Ga ₀₁₉ Zn ₀₁₁ Co ₁₉ No ₁₁

ok

20th

The thermomagnetic behavior of the compounds according to the present invention, i.e. the practically sudden change in magnetization (in an interval of a few hundredths of a degree) from a value that is practically zero to a relatively high value (of the order of 1, 26 Bohr magnetons per manganese atom in the compound Mn ₃ GaC, for example), in a limited temperature range between the transition point and the Curie point, as well as the equally sudden drop in the specific conduction resistance (for example with Mn ₃ GaC to half of the original value), which makes this transition accompanied, allow a variety of technical applications for compounds according to the invention. In the following exemplary embodiments, it is sufficient to describe only one of numerous application cases in summary.

45 Embodiment 7

(Use case)

According to FIG. 5, an elastically flexible plate 1 made of beryllium bronze with a length of 8 mm, for example, and a width of 2 mm, for example, and another plate 2 carrying a small permanent magnet 3 are connected to one another via an insulating body 4. A thin pellet 5, for example made of Mn ₃ GaC, is glued to the plate 1 with synthetic resin adhesive, the dimensions of which are comparable to those of the magnet.

When the point 0 _{t is} reached as the temperature rises, the _{pellet made of Mn 3} GaC suddenly moves towards the small magnet 3, adheres to it and thus forms a mechanical or electrical contact. If the temperature rises further, this contact will be broken again as soon as the Curie point is reached.

In this way a thermal micro-relay can be produced, which is a kind of "magnetic Bimetal strip "is.

Embodiment 8

(Use case)

As shown in FIG. 6, the stator becomes one Motor formed by a permanent magnet 1 in U-shape, which between its legs is a weak Magnetic field generated, for example from a few hundred Oersted, and that in a container 3 located Bath 2 is immersed in liquid nitrogen so that it is flush with the surface of this bath.

A rotor in the form of a rigid plastic disc 4, for example 2 mm thick and 10 cm radius, protrudes into the gap of this magnet. This disk has two peripheral crowns 5 on both sides, for example 1 cm wide, made of Mn ₂₁₉₄ Fe ₀₀₆ GaC (Θ, - 157 ° C, Θ _c - 21 ° C), which are also glued with synthetic resin adhesive.

The disk can be rotated about an axis 6 on which it is attached and which runs parallel to the magnetic field prevailing in the gap of the magnet and is so far removed from this gap that only the peripheral crowns 5 are immersed in the liquid nitrogen. A heat source, which can be used by the sun or an electric lamp, emits a bundle of heat rays which, by means of a lens 7, act on a point B on the outer cut edge of the rotatable disk. This point B is about 1 cm above the fixed magnet.

A point C of a peripheral crown of the rotor, which is located between the point and the point B and which is brought to the transition point Θ by heating, suddenly becomes magnetic, is attracted to the stator and immersed in the liquid nitrogen, where its magnetization disappears. In this way, the rotor makes one revolution in a few seconds.

Due to the high value of magnetization that occurs at the transition point (of the order of of 1.3 Bohr magnetons per manganese atom), the power of such a motor allows the drive other mechanisms.

Such a motor can be used for the direct transfer of solar energy into mechanical energy will. Its principle also allows its application to spacecraft, where the temperature changes between the sides facing the sun and the sides facing away from the sun very strong and are suddenly.

Embodiment 9

A rod sintered from the carbon compound Mn ₃ GaC serving as a coil carrier is arranged between the poles of a permanent magnet.

If the rod is exposed to sudden temperature changes in an area around its transition point Θ, through alternating heating and cooling, a current is induced in the coil, which is modulated as a function of the cycle of cooling and heating.

In this way, a thermomagnetic generator can be used to generate electrical power realize.

Embodiment 10

The same sintered rod could also be included in a voltage source powered circuit be placed. If the rod has temperature changes in the area around its transition point,

is set, its specific line resistance changes when this transition point is exceeded considerable (half or double the value). As a result, the amount flowing through these rods also fluctuates Current and thus also the achieved voltage drop at a consumer. In this way a temperature sensor can be implemented.

1 sheet of drawings

Claims (7)

Patent claims: 1. Use of a ferromagnetic crystalline material with a perovskite (CaTiO ₃ ) structure, consisting of 50 to 75 atomic percent chromium, manganese, iron, cobalt, nickel and / or palladium, 16.7 to 25 atomic percent magnesium, aluminum, copper, Zinc, gallium, germanium, silver, indium and / or tin, 0 to 23.3 atomic percent boron, carbon, nitrogen, as a ferromagnetic working medium for energy conversion with a maximum of saturation magnetization in a certain temperature range below the Curie temperature and a significantly lower magnetizability above and below this temperature range. 2. Use of a ferromagnetic, crystalline material according to the composition Claim 1, in which a perovskite structure has been established by having the elements to be connected and / or binary and / or ternary interconnections all with high Degree of purity and preferably brought together gradually in the specific proportion, intimately mixed with each other and several longer annealing processes at temperatures between 300 to 900 ° C are subjected, between which the product is each finely crushed and with the newly added elements or intermediate compounds is intimately mixed for the purpose according to claim 1. 3. Using a ferromagnetic crystalline material with a composition and structure according to claim 1, wherein the structure according to claim 2 can be made as material for the formation of a temperature-dependent effective mechanical or electrical contact, for example, by its arrangement in the attraction area of a magnet. 4. Use of a ferromagnetic crystalline material having a composition and structure according to claim 1, wherein the structure according to claim 2 can be made as material for the production of a device for the direct conversion of thermal energy into mechanical Energy, for example a device with a place exposed to heating, with Split the material occupied disk in a magnetic field with the formation of a torque. 5. Use of a ferromagnetic crystalline material of a composition and The structure of claim 1, wherein the structure of claim 2 can be made as a material for the core of a solenoid arranged in a permanent magnetic field to achieve an electricity generation in the solenoid with alternating heating and cooling of the core. 6. Use of a ferromagnetic crystalline material having a composition and structure according to claim 1, wherein the structure according to claim 2 can be made as material for a member arranged in an electrical circuit with a depending on the Temperature volatile resistivity to determine the temperature. 7. Use of a ferromagnetic crystalline material having a composition and structure according to claim 1, wherein the structure according to claim 2 can be made as material for the core of an inductive electrical circuit element with a function of the temperature can change by leaps and bounds.