DE2053899C3 - - Google Patents

Description

3 O ₄

Table chromium dioxide powder according to the invention is 100 atomic percent if all atomic percent of the metal components, which are surprisingly known because they are modified with Te, are added up.
CrO _{2 has} a coercive force of 390 Oersted and the chromium dioxide _{powder according to the invention is modified with Fe CrO 2} only has a coercive force of by intimate mixing of chromium trioxide, metal-73 Oersted, so the skilled person could not stimulate 5 lischen tellurium or any available and which could Modifying agents of this suitable tellurium compound, metallic iron or known chromium dioxide powder to combine. any suitable iron compound and metal-

According to one embodiment of the invention, the lischem tin or any suitable tin

ferromagnetic chromium dioxide powder, according to the marriage compound, so that the desired atomic percent

mix analysis in atomic percent of the metal components are present from the metal atom components,

in terms of essentially 65 bis and heating the mixture at a temperature

99.98 atomic percent chromium, 0.01 to 15 atomic percent from 280 to 480 ⁰ C in an autoclave that has a high

Tellurium and 0.01 to 20 atomic percent iron. Generated by pressure, as explained below,

this embodiment of the invention is achieved that manufactured.

the chromium dioxide powder has a coercive force over 15 Usable tellurium compounds are TeO ₂ , TeO ₃ ,

400 Oersted and a saturation magnetization over H ₂ TeO, H ₆ TeO ₆ , Na ₂ TeO ₄ , K ₂ TeO ₄ . From these

60 emU / g. ties are most preferred to those

According to a further embodiment of the invention in which the tellurium is in the hexavalent state, the ferromagnetic chromium dioxide powder _{is present, ie H 6 TeO 6} or TeO _a . Suitable iron according to the chemical analysis in atomic percent of the ao compounds are Fe ₁ O ₃ , Fe ₃ O ₄ , Fe (OH) ₃ , Fe (NO ₃ ) ₃ , metal components, expressed from 20 to 84 atoms - FeSO ₄ , Fe (SOJ ₃ , FeS, Fe (CrO ₄ ), and Fe ₂ (Cr, O ₇ ) _3rd percent chromium, 1 to 20 atomic percent tellurium and 15 Suitable tin compounds are SnO, SnO ₂ , H ₂ SnO ₃ , up to 60 atomic percent iron Chromium dioxide SnSÖ _4: Sn (COO) ₂ and Sn (CjH ₃ O ₁ J _2. Of these tin powder has a coercive force of over 600 Oersted compounds, H ₂ SnO _{3 is} most preferred,
i as well as a high saturation magnetization. as the mixture is mixed with a small amount of water

According to yet another embodiment of the Er- in a crucible made of platinum or corrosion-resistant steel Finding consists of the powder, entered according to the chemical. The mixture is poured into the crucible Analysis in atomic percent of the metal components placed in the autoclave, which is pressed from corrosion-resistant from 50 to 99.98 atomic percent chromium, metals such. B. corrosion-resistant steel, and 0.01 to 15 atomic percent tellurium, 0.01 to 20 atomic percent with a thermocouple to measure the reac percent Iron and 0.1 to 15 avom percent tin. The tion temperature and with a manometer off-coercive force such a chromium dioxide powder is permitted. The autoclave can with the 50 to 300 oersteds larger than that of the lent mixture according to any suitable VerTellur and iron modified chromium dioxide powder. driving, z. B. by means of an electrical heating on Chromium dioxide powder, which essentially consists of 55 35 devices, can be heated while the temperature of the up to 99.88 atomic percent chromium, 0.01 to 15 atomic mixture is measured. After the reaction percentage Tellurium, 0.01 to 20 atomic percent iron and temperature has been reached, the mixture is used for 0.1 to 10 atomic percent of tin has a suitable length of time that is dependent on the reaction Coercive force over 500 oersted and a pressure and the reaction temperature is maintained Saturation magnetization above 60 emE / g at room temperature and then down to room temperature in the autoclave. The advantage of an Sn content from the cooled. After the mixture has cooled down, Chromium dioxide powder is also distilled the following day it is removed from the autoclave bark 2 to 5. When comparing the water washed and following a suitable method Tables 2 and 4 can be seen that in the case of dried.

Tc (1 atomic percent) + Fe (10 atomic percent) the 45 The coercive force (Hc) is derived from the magnetic

Coercive force is 440 Oersted (Table 2), currency curve measured against the magnetic field curve

rend them with an addition of Sn while maintaining that with a maximum field of 3000 Oersted

Additions of Te (1 atomic percent) 4- Fe (10 atom- using common methods determined.

percent) is over 600 oersteds. The column “Hc ⁺ ” magnetic resonance at room temperature is

in the following table 4 shows this on the 5 ° means of a magnetic balance, which in the work of

Sn additive measure of the increase in H i r ο η e u. A. (Sci. Rep. RITU 6A [1954], 67)

Coercive force. is written, measured.

The following Tables 3 and 5 also show the following examples: A coercive force of preferred embodiments of the invention and 600 oersteds can be achieved in a certain range for 55 not to limit the scope of the invention, the atomic percent of Te and Fe . To the . 11th
For example, the coercive force in the case corresponds to example i
of Te (3 atomic percent) - (- Fe (12.0 atomic percent) Ferromagnetic chromium dioxide powder, the 0.01 600 oersted. In this case, the saturation is up to 20 atomic percent tellurium and 0.01 to 60 atomic magnetization is 62 emE / g, such as the table ) to 60 percent iron was added after taking it. However, by adding Sn, a following process is produced. 5 g of chromium trioxide, increasing the acidity magnetization, and 0.0019 to 4.600 g of telluric acid and 0.0004 to 7.985 g, although the saturation magnetization of an Fe ₂ O ₃ were uniformly mixed so that the Sn- Addition not below 73eniF, g compositions of ZuTable 5. 65 sets given in Table 1. Each of the mixtures was in

The atoni percentages given here relate to a platinum crucible and 1 ml

added to the sum of chromium, tellurium and iron or of water. The mixture was in the crucible

riirnm. Tellurium. Iron and tin, and thus entered into an autoclave, which has an internal volume

of 30 ml. The autoclave was sealed and placed in an electric oven with a diameter of 30 cm. The autoclave was also connected to a high pressure regulator, by means of a stainless steel i-hole pressure tube, which contained a manometer, a push button for an automatic recorder, and a drainage vessel. The oxygen was introduced into the autoclave up to a pressure of 120 kg / cm ² at room temperature. The autoclave was heated to a temperature of 350 ° C. at a rate of up to 100 ° C. per hour and held at that temperature for 2 hours. The internal pressure of the autoclave at 350 ° C was about 350 kg / cm ² . After heating, the autoclave was slowly cooled to room temperature. The system was then depressurized. The reaction product was removed from the autoclave and washed with distilled water. The product was a black magnetic powder, and was dried at a temperature below 15O ⁰ C.

Table 1 shows the coercive forces of the powders obtained as a function of the added Tellurium and iron amounts are shown.

Table 1

Coercive forces of chromium dioxide, which contains various amounts of tellurium and iron

Te Fe Hc (Atomic percent) (Atomic percent) (Oersted) 0.01 40 470 1 15th 460 3 20th 540 5 25th 600 5 40 625 10 40 730 10 60 470 15th 25th 410 20th 30th 400 3 8th 430 3 0.01 400

Example 2

Chromium dioxide powder having coercive forces over 400 oersted and a saturation magnetization over 60 emE / g was obtained by the following method. The mixtures of chromium trioxide, telluric acid and Fe ₂ O ₃ were prepared in such a way that the compositions of the additives given in Table 2 were achieved. The mixtures were treated in the manner described in Example 1. The chromium dioxide powders obtained had the magnetic properties shown in Table 2.

Table 2

additions Fe Hc 61. Te (Atomic percent) (Atomic percent) (Oersted) (emE / g)

15th
10
15th
10
15th

440
440
480
450
540

69

71
69
70
68

Example 3

Iron hydroxide was used as the starting material for the iron addition. 5 g chromium trioxide, 0.116 to 0 356 g telluric acid and 0.422 to 0.892 g iron hydroxide were mixed so that the compositions of the additives given in Table 3 were obtained The chromium dioxide powders were obtained in the manner described in Example 1, ίο The powders obtained had those given in Table 3 magnetic properties.

Table 3

Magnetic properties of tellurium and iron

modified ferromagnetic chromium dioxide powder

Te Fe B e i s ρ i Hc 61. (Atomic percent) (Atomic percent) (Oersted) (emE / g) 1 7.5 470 71 1 12.0 510 64 1 15.0 570 62 3 7.5 550 73 3 12.0 600 62 el 4

Chromium dioxide powder modified with 1 atomic percent tellurium and 10 atomic percent iron was also used modified by adding 0.1 to 15 atomic percent tin. 5 g chromium trioxide, 0.129 to 0.155 g telluric acid, 0.449 to 0.540 g of iron oxide and 0.0095 to

1.710 g of metazinic acid were mixed so that the compositions given in Table 4 of Additions were made. Each of the mixtures was according to the manner described in Example 1 and Treated wisely.

The powders obtained had the coercive forces shown in Table 4. When comparing the Tables 2 and 4, Table 4 clearly shows that an additional addition of tin reduces the coercive force increased by chromium dioxide powders.

Table 4

Coercive force of chromium dioxide, the 1 atomic percent tellurium, 10 atomic percent iron and various amounts Contains tin

Fe

(Atomic (atomic percent) percent)

Sn

(Atomic percent)

Hc (Oersted)

Hc

(Oersted) *)

10
10
10
10
10
10
10
10

0.1 640 200 0.3 630 190 0.5 600 160 1 640 200 3 680 240 5 700 260 10 640 200 15th 600 160

♦) Hc = (Hc value from column 4) -440 Oe. The value of 440 Oc is a coercive force of chromium dioxide powder modified with 1 atomic percent Te and 10 atomic percent Fe, which is found in (Ili second row of Table 2 is given.

Example 5

20 g of chromium dioxide, 0.229 g of telluric acid, 0.242 to 1.263 g of Fe ₂ O ₃ and 0.170 to 0.343 g of metazinic acid were mixed in such a way that the compositions of the additives given in Table 5 were achieved. Each of the mixtures was treated in the manner described in Example 1. The maximum reaction pressure in the production was about 400 kg / cm ⁴ .

The obtained chromium dioxide powders had excellent magnetic properties shown in Table 5 Properties. The powders had a markedly higher coercive force and saturation magnetization than 600 oersted and 75 emU / g.

Table 5

Magnetic properties of chromium dioxide powders modified with tellurium, iron and tin

(Atomic percent)

Fe (atomic percent)

Sn

(Atomic percent)

Hc (Oersted)

61, (emE / g)

0.5 1.5 0.5 600 80 0.5 3.0 0.5 640 74 0.5 4.5 0.5 670 76 0.5 6.0 0.5 630 76 0.5 7.5 0.5 650 75 0.5 1.5 1 640 76 0.5 3.0 1 645 81 0.5 4.5 1 665 76 0.5 6.0 1 660 76 0.5 7.5 1 610 73

609 640/10;

Claims (4)

tables chromium dioxide powder modified with tellurium or antimony. In particular, these chromium dioxide powders have an acicular shape and have 1. Tellurium and iron together containing a large coercive force (Hc) together with a ferromagnetic chromium dioxide powder, consisting of 5 high remanence (Br). Therefore, according to the atomic percent chemical analysis, a magnet containing chromium dioxide exhibits high performance characteristics In terms of metal components, it is essentially valued and, as expected, has in particular borrowed from 20 to 99.98 atomic percent chromium, 0.01 excellent properties as a master band at the up to 20 atomic percent tellurium and 0.01 to 60 atomic magnetic duplication. With the magnetic percent iron. io duplication, the master volume must have a larger one 2. Ferromagnetic chromium dioxide powder after having coercive force as the daughter tape. It is Claim 1, characterized in that the desired that magnetic recording powder for Powder, according to the chemical analysis in atom - a master band in the case of duplication a coercive cent In terms of metal components, it has a tive force of over 600 Oersteds. essentially from 65 to 99.98 atomic percentages 15 Since S. M. Ar i y a succeeded, among other things, Chromium, 0.01 to 15 atomic percent tellurium and 0.01 pure chromium dioxide by thermal decomposition of up to 20 atomic percent iron. Chromium trioxide increases under high oxygen pressure 3. Ferromagnetic chromium dioxide powder after obtained, many attempts are made to develop one Claim 1, characterized in that the powder suitable for magnetic recording Powder, according to chemical analysis, has been made in atomic ao. For example, in the US PS Percentages of metal components expressed, 29 23 683 described that one modifiaus with antimony 20 to 84 atomic percent chromium, 1 to 20 atomic chromium dioxide a large coercive force of percent tellurium and 15 to 60 atomic percent iron 400 Oersted. The US-PS 32 34 260 is to be exempted take that chromium dioxide modified with tellurium 4. Ferromagnetic chromium dioxide powder according to 35 has a large coercive force of 390. In the Claim 1, characterized in that US-PS 29 23 684 is described that with tin Powder, according to chemical analysis in atom-modified chromium dioxide, has a coercive force of Percentage of metal components, owns 250 oersteds. The pure chromium dioxide has one from 50 to 99.88 atomic percent chromium, 0.01 to comparatively low Curie temperature of 116 ° C. 15 atomic percent tellurium, 0.01 to 20 atomic percent 30 The Curie temperature of the chromium dioxide increases Iron and 0.1 to 15 atomic percent tin. with an addition of iron. The common addition of iron and antimony leads to a chromium dioxide with a coercive force of about 400 Oersted and ■ a higher Curie temperature than 116 ⁰ C (US-PS 35 30 34 988). _J " _u .. Furthermore, US-PS 28 85 365 describes with Ru Summary of the Description Modified CrO ₂ , US Pat. No. 2,923,683 with Sb Chromium dioxide modified with tellurium and iron, modified CrO ₂ , US-PS 29 23 685 with alkali with a greater coercive force, is obtained by a metal-modified CrO ₂ , US-PS 30 34 988 with the joint addition of tellurium and iron. 40 3d transition metal modified CrO ₄ and the US-PS of chemical analysis an atomic percent ratio of 30 68 176 with F modified CrO ₂ . In addition, it is in the metal components that essentially the US-PS 34 23 320 indicates that Fe, Sb or Te 20 to 99.98 atomic percent chromium, 0.01 to 20 atomic percent are used as a modifier for CrO ₄ and tellurium 0.01 to 60 atomic percent iron can. In the example 1 of US-PS 30 34 988 corresponding to the intrinsic coercivity is greater than 45 also indicated that with Fe modified CrO ₂₄₀₀ Oersted. Has the coercive force of with tellurium and a coercive force of only 73 oersteds.
Iron-modified chromium dioxide is further The invention is based on the object of ferro- Addition of 0.1 to 15 atomic percent tin increased. magnetic chromium dioxide powder with large coercivity The ferromagnetic chromium dioxide powders of earth force and high saturation magnetization, which are used to find a large coercive force and high density recording, have high saturation magnetization. Every particle of the can to make available.
Powder has a uniform needle-like shape. In addition, the invention is based on the object and is useful as a magnetic recording medium. a ferromagnetic chromium dioxide powder with a The invention relates to tellurium and iron together with a coercive force higher than 600 oersteds together with the ferromagnetic chromium dioxide powder they contain. 55 to create a large saturation magnetization. This ferromagnetic chromium dioxide powder has a coercive force that is suitable ^{for a master tape for magnetic ve r much large and a high saturation magnetization.} tization. Such a powder is for tapes, plates. This object is achieved according to the invention by a and high-density recording drums suitable for ferromagnes containing tellurium and iron together and especially for main bands at the 60 table chromium dioxide powder dissolved, which, according to the magnetic reproduction useful. chemical analysis in atomic percent of the metal The more recent development in the field of on-components, essentially from 20 to high density drawing, requires a magnetic 99.98 atomic percent chromium, 0.01 to 20 atomic percent oxide powder with a large magnetic coercive tellurium, and 0.01 to 60 atomic percent Atomic percent of Fisen,
power and a high saturation magnetization. For a ferrotile purpose, various magnetic powders, magnetic chromium dioxide powder with high coercivity have been developed, for example a magnetic iron oxidative force and high saturation magnetization for vermilver, which is doped with cobalt and is ferromagnetic . These properties of the ferromagnetic