DE1519844C3 - Process for removing inclusions from crystals - Google Patents

Description

The invention relates to a method for removing inclusions from crystals resulting from compounds exist whose components form mixed crystals with the compound in a limited area can, wherein the inclusions consist of one or more components of the compound, by annealing in the presence of an additional material.

The term "crystals" should be understood here in a very broad sense and does not apply to single-crystalline bodies limited, but also includes crystals in polycrystalline bodies, the crystals also very can have small dimensions, such as B. in a powder. Crystals of compounds were already there manufactured in many ways. A simple method is to heat a mixture of the Components. In many cases you can e.g. B. melt the components together, the Compound forms or when cooling from the. Melt is created. You can use the components melt together in equivalent quantities; however, it is also possible to use an excess of one of the components to choose, after which the formed crystals of the compound of the superfluous component be separated. Furthermore, the compound can be vaporized directly by reaction from the Components are represented. Crystals of such compounds were often not homogeneous, and the Physical properties could be, provided they counteract deviations from the stoichiometric composition were sensitive, generally difficult or impossible to reproduce. It turned out found that where a homogeneous product was expected, there were often crystals with parts with different parts physical properties had been formed.

It is already a treatment of crystals of two component compounds became known (Journal of Chemical Physics 32 [1960] 6, pp. 1826 to 1831), in which such a crystal is heated in a closed vessel, this vessel as a whole at a certain temperature is brought, while also an additional material, ίο namely mixture of the compound in question and another phase in equilibrium with this compound at this temperature, which is richer one of these components is present in the vessel. This mixture forms vapor stresses the components in the vessel that are in equilibrium with the crystalline phase of the compound, which has the highest possible content of that component in the mixture in the second phase Excess is present.

so through exchange with the surrounding atmosphere and diffusion of the components into the crystal, the said crystal becomes homogeneous in the long run Edge composition, which while maintaining the crystalline structure, the highest possible concentration of the last-mentioned component.

It was found, however, that even such a treatment often does not lead to a crystal with either invariable reproducible physical properties, and the invention lies among others the task underlying to remedy this evil. The invention is based, among other things, on the knowledge that a crystal obtained in a known manner is one consisting of several components Compound inclusions may contain one or more of one or more other phases Components of the connection exist. These inclusions can be used when making the connection be formed, e.g. B. in the formation from a melt with as precisely as possible a stoichiometric composition due to errors in the quantities of components used. If at least some of these inclusions contains precisely that component in excess which is also present in excess in the mixture, such an inclusion is at most partially converted into the compound, but it remains one of the second phase of the mixture, so that the crystal remains inhomogeneous.

The stated object is achieved in the above-mentioned method in that as an additional So material either

a) a mixture of the compound and at least one component of the compound, which is in the heating temperature is in equilibrium with each other, or

b) a compound, the composition of which is selected so that it is on the Silodus curve of the to cleaning compound is in the phase diagram (edge composition),

is used and that it is tempered as many times until the equilibrium is reached, until all Inclusions in the crystals are eliminated by diffusion, with each tempering in the additional material either

a) at least one component of the compound in the mixture is replaced by another or

b) a connection with a different edge composition

is used.

Because in general there is a considerable difference in the composition of the various phases exists in the mixture, the ratio between the amounts of these phases is not particularly critical. This ratio and the total amount applied must be so large that one of the phases cannot go through Transition of components to the treated crystals and to the intermediate space within the Vessel can disappear. The total amount of the mixture is preferably large compared to Amount of the crystals to be treated, which leads to the establishment of the equilibrium composition in the intermediate space that is not occupied by the mixture and the crystals are required Component quantities are essentially supplied by the mixture. The volume of the vessel will preferably kept as small as possible so that the intermediate space, which is thus not of the crystals or is ingested by the mixture, is as small as possible, which leads to the build-up of equilibrium concentrations of the components in this space required component quantities remain small and further the occurrence of temperature gradients in the vessel is greatly reduced.

The cooling after the heating treatment is preferably carried out in such a way that new inclusions are formed is prevented as completely as possible. It is therefore preferable to cool down quickly to a temperature in which there is no diffusion of the components into the crystal, so that at the treatment temperature obtained equilibrium state of the treated crystals solidified. You can also go to a treatment at a higher temperature stabilize the whole at a lower temperature, whereby of course, the composition is generally changed somewhat, followed by rapid cooling can. In this way, the risk of re-formation of inclusions can be reduced because the spontaneous formation of inclusion nuclei at low temperature is lower and the temperature can fall more quickly to a value at which diffusion of the components practically no longer occurs can. For crystals made of two components, two treatments are sufficient, the first with one Mixture that is richer in one of the two components, and a second with a mixture that is richer the other component is.

For crystals with three or more than three components, more than two treatments are generally required necessary.

A condition for the possibility of treatment of the crystalline compounds by the process of the invention is that the compound in the Temperatures is stable at which diffusion of the components is possible and at which stable condensed Phases, d. H. solid or liquid phases, can consist of one or more of the components, those at the temperature in question in thermodynamic Can be in equilibrium with the crystalline compound.

If the phase system of the components is not known, it can be examined beforehand and then the required compositions of the mixtures are determined from the test results will.

It is possible that at the treatment temperature stable composition of the crystal at dn-tr low temperature looks more stable, but at this low temperature this composition can very well persist, so that a very long service life can be achieved. When using a crystal treated in this way, if this has particular electrical properties, e.g. B. consists of a semiconductor compound to electrical In many cases, the properties can persist for a very long time because there are no inclusions are. If such inclusions are present, they could possibly be too much from the surrounding material to eliminate one component by ingesting that component, making the crystal very much its composition could slowly and partly locally change, then the electric ones would also change Change properties of the crystal. In the absence of such inclusions, the risk is lower because in In this case, nuclei of inclusions must be formed in the crystal. This nucleation is in generally more difficult than growing existing inclusions. It is also possible that a Edge composition stable at the treatment temperature, as described with the inventive Process is achievable, is stable even at low temperature, but in the latter case no edge composition forms. Any inclusion that has a different composition and only one If the edge composition of the crystal is in equilibrium, the crystal would be used frequently for electrical purposes and for other reasons, e.g. B. as a result of temperature fluctuations, the surrounding Change the material in the direction of this edge composition and thus also the physical Change properties of this material. In the absence of such inclusions, the composition remains because the whole crystal is stable in this composition and has no internal contact with has other phases with which this composition is not in equilibrium.

In general, the total amount of material in the inclusions is compared to the amount of material in the crystal extremely low. Therefore, one or more of the treatments can only be used with the method described perform with an edge composition of the joint rather than a mixture. The resulting The composition of the crystal after such a treatment can be somewhat different Edge composition differ when using a sufficient excess of this edge composition however, this deviation is only very small.

Although the described process according to the invention can be used to obtain crystals that are free of inclusions, these crystals are on edge composites or hardly differ in edge composites differing compositions limited, with the exact composition of the temperature used and the composition of the mixture during the last treatment is. In order to also produce crystals with other compositions, one or more crystals are used of the compound in a molten vessel in precisely metered amounts of at least two different edge compositions of this compound attached, after which the whole on one Temperature is heated high enough to allow diffusion of the components into the treated crystal to enable and so long is maintained until the whole material has a homogeneous composition had received.

5 6

The amounts of the edge aggregates are preferably determined by the content of the relevant component

compositions chosen so that the heating component in the crystalline compound is conditional. Through

treatment results in a composition that, when there are differences in the compositions between

Room temperature is stable. two crystals of the crystalline compound can be one

The starting materials are preferably previously 5 transport of the component in question through the intermediate space in the form of the volatile compound for obtaining edge compositions that take place through application of the method according to the invention. Transport break free of inclusions are produced. This is particularly important for the transport of solids in gas, especially when the connection is visible - or the form of vapor is known per se, but temperature gradients have been used to date, depending on the possible variation in their composition,
only has a narrow range of existence. To conclude, the invention will be explained with reference to the drawing and the vessel, some crystals to be treated of some exemplary embodiments can be refined in more detail below together with a powdery mixture of the.
Edge compositions are applied; it is it shows

however, it is also possible to use only the crisis to be treated.

to include stalls, with crystals of different systems, in which the abscissa represents the

Edge compositions in the correct ratio, dislocation in atomic or molar ratios of the

be turned. both components and the temperature as the ordinate

A second important advantage of the invention is applied;

The method is that a precise knowledge of the existence of 20 Fig. 2 a part of the diagram of Fig. 1, at

area of the connection in the phase diagram from which the dimensions in the abscissa direction

is not necessary in advance and that these are enlarged;

drive can also be used if this Fig. 3 is a phase diagram of a two-component

Existence area in the phase diagram is very narrowly limited t system of another type in which the

and is consequently difficult to determine precisely. 25 settlement and temperature in a manner similar to that in

The method according to the invention results in a diagram of FIG. 1;

Edge composition, in which the last used Fig. 4 is a diagram in which the abscissa in

Mixture determines which component in ratio- Fig. 2 specified compositions and as

moderately higher concentration will be present the corresponding concentrations of the ordinate

or which components are shown in relatively higher 3 ° components in the intermediate space

Concentrations will be present. are;

For the application of the edge composition in FIG.
Solutions on the obtained crystals favorable ratios- Fig. 1 shows a phase diagram of a system to determine nisse experimentally. Favorable temperatures 35 of two components A and B, _{between which only and treatment times} can also be formed by a crystalline compound A x By can be determined, with data from the phase where χ and y represent integers. The connection diagram and measurements on the obtained crystals A _x By is in the present case a congruent melt can be used. substance and forms eutectic melting temperatures

It is also advantageous if the intermediate not occupied by the 40 doors with both A and B, the two normal crystalline compounds, can melt. The crystalline phase A _x By has to be kept as small as possible in the space in the vessel, so that each temperature has a thermodynamically stable one, so that the area of existence required to form the equilibrium concentrations, in which the content of the components in this space can vary at the treatment temperature. This area of existence can, however, be as small as possible in such component quantities. 45 can be very narrow and can often hardly be determined exactly - this space can be used to further adjust this space if necessary. One possible form of the existence area is to reduce it, that it is indicated with an indifferent, preferential in Fig. B. FIG. 1, which contains the atomic ratio A _x By , is filled in in the form of a powder. If only one is shown, the scales on the abscissa of the components being greatly enlarged with almost no concentration in the 5 °. The boundary composition of the intermediate space can build up, so that practically connection A _x By, ie the most extreme combinations no transfer of this component through these settlements, in which the connection is still stable, space can take place, the desired equal- through the lines 1 and 2 indicated (Fig. 2). Just weight nevertheless by transferring the other these compositions can be achieved with other component or components. 55 liquid or solid phases of the phase system of A. B. possible, the transfer of only one and B are in thermodynamic equilibrium, poorly evaporable ble component with the help of a Fig. 3 relates to a two-component system in the chemical means of transport, ie with a further crystalline in addition to the crystalline phase A _x B _y ' Treatment temperature vaporizable or gaseous phases occur, namely the crystalline phase of the moderate substance, which with this component under BiI- ⁶ ° compound A _x ! B _y ! with a higher content of the formation of a volatile compound of this component component A ' than the compound A _x ¹ By and which can enter into a reversible reaction. crystalline phase of the compound A _x .. 'B _y ..' with a The concentration ratio between this sub- higher content of component B ' than the substance and this volatile compound in the same bond A _x ' B _y '. While in the weight state shown in FIG. 1, the composition ⁶ 5 phase diagram at temperature 3 determines the connection of the crystalline compound with which this equation A _x By of the edge combination shown in FIG. 2 is obtained. Said composition 4 or 5 with a liquid of the composition is of course at least in composition 6 (FIG. 1) with a higher content of the composition

7 8

Component A or with a liquid as indicated in FIG. 2, at the temperature 3 composition 7 with a higher content of the shown schematically. The horizontal parts 31 and component B can be in equilibrium, at 30 of the two lines in Fig. 4 can give the concentrator temperature 20 (Fig. 3) the compound A _x 'B _y ' ions of the relevant components in the gas phase with the crystalline Connections A _x ! B _y . ' or 5 be in equilibrium with a liquid of the composition A _x,. 'By ..' be in equilibrium. The areas of existence settlement 6 (Fig. 1) and / or a solid in the mentioned three crystalline compounds are not shown in A _x By-Phast with the edge composition 4 (Fig. 2) Fig. 3, but it must be assumed. The boundary composition of the solid A _x By are that these three compounds can all have a phase 5 with a maximum B content with the boundary of such a range of existence of the boundary composition 7 of the liquid phase, which consists of the conditions in which the contents of the components are Component B consists in which a maximum amount can change. At the temperature 20, the component A dissolved can be in equilibrium. Edge phase of a connection A _x 'By'- ,. The corresponding vapor concentrations are in the content of the component A , with the edge phase horizontal parts 32 and 33 of the lines in Fig. 4 of the compound A _x ZBy. ', which shows the highest content of 15. The concentration of A in the vapor is the component B ' has to be in equilibrium, or lower, and that of B is higher than in the preceding it can be the edge phase of the compound A _x ¹ By, the trap. The compositions of the compound A _x B _y , which has the highest content of the component B ' , with the boundary phase of the: compound Ax-'B _y ..', which are the settlements 4 and 5, can be used in the Temperature 3 has the highest content of component A ' , so it is not in equilibrium with liquid phases, but in equilibrium. ;. rend the corresponding concentrations of the

Both at. the connection A _x B _y in the phase diagram- components in this phase, in the direction of the gram of A and B at temperature 3 (Fig. 1 and edge composition 4 to the edge together-Fig. 2) as well as in the connection A _x By in the phase setting 5, gradually change, with the concentration of component A decreasing in the gas diagram of A and B ' at the temperature 20 25 phase (FIG. 3), it applies that the edge composition of the loading and that of the component B increases . In Fig. 4, appropriate compounds with a highest content of these curves are drawn in the relevant middle parts, one of the components in the next phase (liquid with 34 and 35, as a straight line, or solid) with a higher content of this component , but in principle different forms are possible, namely with an edge composition with the 30 but without maximum values and minimum values, that is, the lowest content of this component can be in weight in the same direction from left to right in FIG. ■: ■ middle part the curve 34 showing the concentrations

Furthermore, if in addition to these solid or liquid A in the gas phase indicates, always falls and the phases a gaseous phase is present, the only curve 35, which indicates the concentrations of B in the gas from a phase containing the components A and B 35, always increases .:

Vapor is built up and a certain temperature If a crystal A _x By unknown is selected, the content of each component composition which contains inclusions, the thes of which are not known in the gas phase in equilibrium with the compositions, depends, however, from Compositions of the solid or liquid present consist of one or more phases that are composed of the solid phases. Are z. B. in the case of phase 40 phase A _x By , occur when heating this diagram of A and B at the temperature 3 crystal to a temperature 3 in a vented (Fig. 1 and Fig. 2) a liquid phase and a space , in which there is also a vapor phase consisting of A _x By and the combined mixture with the initial equilibrium of the liquid phase from point 8 to point 6 is phase with a higher content of A , the following changes in the phase diagram of FIG. 1, so 45 appearances changes on. The two phases in the mixture in the state of equilibrium, the vapor composition, form an equilibrium, with the liquid phase gradually decreasing, namely the concentration edge composition 6 (FIG. 1) and the solid A _x By of component A gradually decreasing and the concentration phase assumes composition 4 (FIG. 2). In the tion of component B gradually up until point 6 of the vented space, concentrations of the liquid composition are reached where the 5 ° of components A and B , which give the horizontal liquid an edge composition with maxima- parts 30 and 31 of the curves of the 4 correspond to the content of B has reached. Another addition of B If the composition of the crystalline material changes neither the composition of the liquid in the crystal with A _x B _y -? Has from the edge together nor the vapor concentration of the components, settlement 4, the crystal takes from the gas but causes the formation of the solid Compound A _x By 55 phase the component A and releases the component in an edge composition 4 with a maximum of B to the gas phase until a thermodynamic malern content of the component A (FIG. 2). The equilibrium is reached. Because at the same time due to concentrations of the two components in the gas interaction of the vapor phase with the two-phase phase, there is no change. Steam with this mixture the concentrations of the components sen concentrations of components A and B 60 in the gas phase always to the values indicated in Fig. 4 by 30 and 31 can thus be brought back with a melt of the marginal values, changes the composition 6 (Fig. 1) as well as with a solid A _x By crystal its composition until it has reached the same-edge composition 4 with an edge composition 4 (Fig. 2). Be an eventual weight. In Fig. 4 are the concentrations in the inclusion of a phase which is richer in B than that of the gas phase of the components A (solid line) 65 Compound A _x By, strives with the adjacent and B (dash-dot line) for the corresponding crystal material of the phase A _x By remain in equilibrium with the compositions of the solid and liquid phases, which is only possible if this material would assume the same composition ratios as the composition 5. because

9 10

however, can be dissolved by evaporation of B and by one-component, two condensed

diffuse from A from the gas phase, the combined phases 44 and 45 of the compounds C _x , E _x , and

Settlement of the crystal towards the composition D _y ..E _z .. and a crystalline phase 46 of the compound

shifts towards setting 4, the included B- C _x D _y E _z , where _x , _x ., _v , _y ", _z , z- and _z .. integers

rich phase strives to represent the component B to the um- 5. The stoichiometric composition

release and component A due to these compounds are shown in FIG. 5 with 47, 48

take what is designated exclusively by implementing the or 49.

enclosed phase in the A -rich A _x B _y phase The phase of the compound C _x D _y E _z , whose stoichio-

can be done so that the inclusion disappears. metric composition in the phase diagram

However, if the crystal contains inclusions, which is indicated by an io through 49, has a phase of existence which is richer in A , then this changes within the boundary composition, which changes through the phase to the surrounding crystalline material in the A _x By- closed curve which connects the points 50, phase by exchanging the components A and B in 51, 52, 53, 54 and 50 with one another. The composition 4 (FIG. 2), while the edge composition 50 itself can be condensed with the composition 6 (FIG. 1). Because the 15 phase of C with the boundary composition 55 and all crystalline material of the A _x B _y phase through with the condensed phase of D with the boundary-to-interaction with the gas phase and, via this composition 57, are in equilibrium. The ZuPhase, with which the mixture contains the composition 54 of the crystalline CiDy-Ez phase, the inclusion cannot disappear from the phase with the condensed phase D with the edge that is richer in A can disappear. If the thus treated ao composition 58 and with the condensed phase crystal is then treated in a similar way, now the compound D _y ..E _t .. with the composition 63, however, using a mixture which is to be in equilibrium. Each of the edge compositions of the phase A _X B _V and the closest phase consisting of tongues richer in B on the portion delimited by 50 and 54, so is similar to those in the closed curve, may appear with an edge above The crystal 25 is the composition of the condensed phase of D striving to take on the composition 5, being the equilibrium lying on the curve vanishing the points 57 and 58 inclusions of a phase richer in A , the straight lines showing the the. The crystal treated in this way is now homogeneous between the line segment 50-54 and the line segment and has a composition which corresponds to the line segment 57-58 drawn in FIG. 2, each two possible compositions 5 given. 30 mutually in equilibrium marginal relationships

The two treatments described can also set the crystalline phase of the compound

take place in reverse order, in which case manure C _X D _V E _Z on the one hand and the condensed phase

the. treated crystal also free from inclusions of D on the other hand. The representation type of a

but has obtained Composition 4. Three-component system at a certain temperature

From Fig. 2 it can be seen that crystals of the temperature is common per se, and the figure clearly shows

composition 4 or 5 in the case of the in this figure for each composition of components C, D

drew curves showing the edge compositions and E at the temperature on which the diagram is based

of the compound A _x B _y , depending on the temperature, which condensed phase or which

specify the temperature at which room-condensed phases specified by 10 can occur,

temperature are thermodynamically unstable and possible 40 The connection CDE when a Randzusam-

It is only possible to quench the frozen composition 51, is in equilibrium with the compo-

State are achievable. component C with the edge composition 56 and the

Inclusion-free crystals with compositions Compound CE with rim composition 61.
between the two edge Compositions 4 and _{5, for} producing a crystal to the phase C _x D _y E, can be prepared by that a set of 45 is free of inclusions, may, for. B. such crystals with the edge composition 4 together crystal initially at this temperature in a gem with a metered amount of crystals with the closed vessel in the presence of a mixture of edge composition 5 in a closed the condensed phases C _x DyE _z , C _x , E ₁ , and E space are heated to a temperature 3 at which the edge compositions indicated by points 52, 62 and 59, respectively, via the vapor phase, assume a mutual transfer 5 °. In the components A and B takes place until the two of the intermediate gas phase build each other with these types of crystals have the same composition boundary compositions in equilibrium and in the gas phase concentrations borrowed concentrations of components C, D and E of the components have been formed, those with this on. By interaction of the treated crystal composition are in equilibrium. If in 55 with this gas phase the crystal assumes composition 52, if one or more of the crystals are still small amounts of the crystalline C _x D ₁₁ E _z -? H & sQ , the margins of inclusions of other phases are present with this gas phase they also disappear during the treatment. Balance is. Any included phases of By a suitable choice of the amounts of both C, D and D _y ..E _z .. disappear, so that only possible compositions is a final composition 60 included phases of C _x . E ₂ . achievable with the combination that lies between the compositions 11, setting 62 and E with the composition 59 and 12, and thus remains at room temperature 10. In the case of a similar following, it is stable. treatment with a mixture that consists of the condensate

Fig. 5 shows schematically a three-component satiated phases C _x D _y E _z , D _y ..E _z .. and E with the

system at a certain temperature, which consists of six 65 edge compositions 53, 64 and 60, respectively,

may contain condensed phases, namely three, the treated crystal takes the composition

condensed phases 41, 42 and 43 of the components 53, while any included C _x -E ₁ . ver

C, D or E, in which small amounts of the others shrink and only consisting of the Is phase

11 12

Conclusions can remain. In a subsequent powdery mixture of zinc telluride and elemental treatment with a tellurium from the phases C _x D _y E _z , C , in which the atomic ratio between and D disappear, this last tellurium and zinc was about 2: 1, during one week Inclusions completely, so that one of the inclusions heats up to 850 ° C. In the crystal thus treated, free crystal with the edge composition 50 5 showing no decrease in the number of dark spots was noticeable. After that the crystal was on similar

Obviously, by appropriate choice, other ways can be treated, but now using one

Consequences of treatments and other mixtures - powdery mixture of zinc telluride and zinc in

if inclusion-free crystals C _{x DyE 1} are produced, an atomic ratio between tellurium and zinc of

den, the composition again by the io about 1: 2. It turned out that after the latter

Composition of the mixture in the last treatment, the dark points from the treated

action is determined. Crystal were gone. From this one can deduce

The mixtures used can also derive from two that the dark points in the present case

Phases exist. due to inclusions consisting of tellurium

It is also possible to use a 15 instead of a mixture.

Boundary composition of the compound C _x DyEz to The method described was also using, wherein the crystal after the treatment using powdery zinc tellurides with a tellurium need not have received a boundary composition, boundary composition without the second tellurium but a slightly different composition phase in the first treatment and rich may have under. Even with such treatments, the use of powdery zinc tellurides with zinc inclusions can disappear. rich edge composition without the second zinc

The three-component phase shown schematically in FIG. 5 was carried out in the second treatment.

nent system leads at a certain temperature, after which it was also found that the input

a three-component compound, conclusions in the treated crystal had disappeared,

is only given as a system that is possible in principle. 35 _R.

It should be evident that there are very many types of three- Example 2

component systems are possible in which this example relates to the treatment of the crystalline

Principle of the method according to the invention application of a ferromagnetic compound of manganese anti-

Can be found. monid (MnSb). Asked from X-ray examinations

It is also clear that, starting from mixtures 30, it emerges that the area of existence of this compound from different edge compositions is the spread and at 70O ⁰ C between 45.8 and 49.2 atomic bond C _x DyEz, very percent within the area of existence Sb lies. For the former, many compositions together are achievable. Settlement became a Curie temperature of about 440 ° K

From those described with reference to FIGS. 1 to 5 and for the latter a Curie temperature of about

Found principles for carrying out the 35 590 ° K according to the invention. Powder of these two compositions

Process reveals that the invention in principle also tongues were prepared by making mixtures of

in crystals of compounds from more than three weighed amounts of manganese and antimony in

Components is applicable. heated to 700 ° C under the correct conditions and

Furthermore, instead of a vacuum in the intermediate, quenching was carried out, after which the crystals obtained were powdered with an inert gas or another inert gas. Crystals with unknown composition medium, e.g. For example, an indifferent liquid, usage and dimensions of about 4 · 2 · 1 mm ³ can be found. Also an inert gas or one that has been treated in the following manner,
In a quartz ampoule, a powdery mixture was placed at the treatment temperature in the supercritical state, which is made up of weighed amounts of the two states. If the term "indifferent" 45 was used here. On which is used, it is to be understood that the powder was a little boat made of quartz glass with the medium no chemical reactions with the crystal to be treated, after which compound or its components enter into. That the ampoule was vented and melted. However, the medium may be heated to 700 ° C for two weeks at the treatment temperature.Other concentrations of the components in the inter- 50 and then quenched to room temperature,
bring about medial space. A) Such a treatment was carried out with a powder-furthermore dopants can be used, mixture which consists of 3 parts by weight of 45.8 µm doped physically pure crystals. Manganese antimonide containing atomic percent Sb and

Some exemplary embodiments of the process follow, containing 1 part by weight of 49.2 atomic percent Sb

rens according to the invention. 55 manganese antimonide. It was found that

the Curie temperature of the crystal after the treatment

^ßels P ^iel V development was about 490 ° K.

Single crystals of zinc telluride (ZnTe) were carried out by B) A similar treatment was carried out with a melting together of equivalent amounts of zinc powder ^mixture , which was produced from the same mass and tellurium, after which from the obtained 6o parts by weight of powders of the two materials mentioned under A) Sublimation single crystals were obtained from compositions. It turns out that. It was found that this moreover was transparent, that the Curie temperature of the crystal after the operation crystals received dark points. The dimension was about 520 ° K.

Solutions to these points were of the order of magnitude. C) A similar treatment was given with a

of 1 μm, and the points were on average at intervals 65 powder mixture carried out, which consists of 1 part by weight

of 50 μιη from each other. A crystal of manganese antimonide containing about 45.8 atomic percent Sb

4 x 2 x 2 mm ³ was contained in a closed vented and 3 parts by weight 49.2 atomic percent Sb-

Quartz ampoule, in which there was also about 30 g of one of the manganese antimonide. It was found,

13 14

that the Curie temperature of the crystal was obtained according to the accuracy such that it was about 545 ° K during the treatment. Treatment of crystal compositions within the It should be noted that after the above handle existence range resulted. In general, however, the Curie temperatures of the powder used are also measured more precisely and, in the case of a narrow range of existence, powders, practically the same 5 more reliable results being achieved by previously using the method according to the first AusKristalle found using values as for those treated with these powders became. .. embodiment of the invention, the edge assemblies-From this example it can be seen that the Curie settlements are established. .
temperature of the treated crystal gradually increases with the antimony content of the mixture used, because it increases the results of the invention. . according to the method can be clearly demonstrated, but similar treatments to that in Example 2 are obviously not limited to the type described in these examples were with crystals of the ferromagne- Examples of the compounds mentioned, sontic compound Cr ₃ Te ₄ carried out, whereby Krid it can also be obtained from other connections at which the Curie temperatures 15 turn, z. B. in compounds of the type for compositions between 54.65 and 58.82 A ^lll B ^y in which A ^{m is} one of the elements aluminum, atomic percent Te. or between about 65 ° C and -10 ° C gallium or indium and BY one of the elements. Phosphorus, arsenic or antimony can be, connec- It should be noted that the second example relates to a fertilizer of the type A ^ll B ^vl , in which A ^a refers to one of the crystalline compounds which, in terms of their 20 elements, are zinc, cadmium or mercury and B ^V1 composition has a wide range of existence. be one of the elements sulfur, selenium or tellurium.In this case, the two boundary can be combined, compounds such as CrSb, FeSb, CoSb, and dislocations of the powders used in the mixture through bonds such as SnS and SnSe, or compounds by simply weighing the starting components three components, e.g. B. CdIn ₂ S ₄ , AgSbTe ₂ .

1 sheet of drawings

Claims (1)

Claim: Method of removing inclusions from crystals consisting of compounds whose Components with the connection in one. restricted Area mixed crystals can form, the inclusions of one or more Components of the connection consist, by annealing in the presence of an additional material, characterized in that either as additional material a) a mixture of the compound and at least one component of the compound which are in equilibrium with each other at the heating temperature, or b) a compound, the composition of which is selected so that it appears on the solidus curve the connection to be cleaned is in its phase diagram (edge composition), is used and that it is tempered until the equilibrium is reached until all inclusions in the crystals are eliminated by diffusion, with each tempering in the additional material either a) at least one component of the compound in the mixture is replaced by another or b) a connection with a different edge composition is used.