DE2331257C3 - ferrite - Google Patents

Description

2. Ferrite according to claim 1, characterized in that

b = 0.002.

χ = 0.82.

- = 0.05.

w = 0.12.

α = 0.004.

e = 0.05

is.

3. Ferrite according to claim 1, characterized in that

b = 0.002.

.v = 0.82.

ζ = 0.05,

η = 0.12,

a = 0.004,

e = 0.10

is.

4. Ferrite according to claim 1, characterized in that

h = 0.002,

χ = 0.82.

ζ = 0.05,

μ = 0.12,

α = 0.004.

e = 0.10.

The present invention relates to a ferrite, which can be used in particular in the microwave range.

In US Pat. No. 3,630,912, microwave ferrites are used on the basis of lithium-titanium, to which a small amount of bismuth is added. In addition, these ferrites can also contain small amounts of zinc. Contains copper or manganese. Such Ferrites have good properties and can be used for many applications. Using however, they require too much switching energy in phase shifters. The coercive force of a ferrite can can be reduced by sintering at a relatively high temperature. In general, the Koerzi

50 tivkraft is the smaller, the higher the temperature is. However, if the coercive force is decreased in this way, the remanence ratio is undesirably deteriorated.

The invention underlying studies have shown that such ferrites, which a Containing small amounts of nickel, retain their rectangular hysteresis loop, even if they are at relatively sintered at high temperatures.

Although it is known per se, for example from US-PS 33 72 123, to add lithium ferrites to nickel, However, it was not recognized that only certain cereal amounts of nickel desired the aforementioned Result.

The invention provides a ferrite of the following composition:

3 χ + η + α + 2 ζ + c

Li _0-5 +

(χ - «■ - a - c \ "

0.005 < C. <0.1. 0 < Cl <0.1, 0.0005 < H <0.065 0.30 < X <0.95, 0 < T <0.20, 0 < W. <0.4

b + a + χ + ζ + μM- ι * τ 0.5

-ν-U - t / -f 3 χ + u + u + 2- + e

u + 2- + e \
₂ - -j

The nickel in the ferrite according to the invention therefore does not lead to an increase in the coercive force can use the well-known lithium-titanium-bismuth ferrites (which may contain small amounts of manganese. May contain zinc or cobalt) can be improved by adding a small amount of nickel, whereby ferrites are obtained, which by sintering at high temperatures their rectangular hysteresis loop not lose. The ferrite according to the invention therefore has the desired rectangular shape Hysteresis loop with a relatively small coercive force at the same time. According to the present invention, the coercive force can be adjusted so that it does not exceed 0.6 oersteds located. The amount of nickel that the invention: o appropriate ferrite is added, may be small. By adding an amount less than 0.005 ions An expedient increase in the remanence ratio is obtained per formula unit. Optimal Results are obtained when the nickel concentration is about 0.05 ions per formula unit. Further nickel additions do not improve the remanence ratio; in fact, this relationship begins to fall again at around 0.1 ions per formula unit of nickel.

The ferrite according to the invention is produced by the following process: If possible, oxides are used the metal ions forming the ferrite components are used.

In cases where the chemical instability of the oxide of a special metal ion to one unclean oxide and leads to an unstable compound, the anhydrous carbonate becomes the metal ion used. The raw materials are weighed in stoichiometric proportions and for at least Wet mixed in a ball mill for 1 hour. The resulting sedimentation will then dried at about 100 ° C. The dried raw material mixture then becomes the lighter one Handling sieved through a sieve with a mesh size of 20 mesh.

The screened oxide mixture is placed in refractory boats. These boats are in a box-shaped oven is set and heated to a predetermined temperature. The exact temperature can vary between 700 and 900 C. The purpose of this measure is twofold. Next Sufficient energy should be provided so that the oxide mixture in a solid state reaction a mixture of 70% ferrite and 30% oxide can react. Second, any carbonates used are thermally decomposed in a simple manner.

The mixture subjected to the reaction is generally dominated by a relatively large parallel shape characterized. Before the mixture is molded into a single phase ferrite body and sintered measured the particle size can be reduced. This is done in the manner described above in a Ball mill. The ferrite-oxide slurry is then dried to a fine powder at about 80.degree.

The powder is then mixed with a binder known per se. A big one comes as a binder Number of materials in question. A typical binder is polyvinyl alcohol.

The addition of the binder can either be in a second ball mill process or in a further suitable process step take place, which a uniform distribution of the used as a binder Substance relieved. The powder impregnated with the binder is used in steel molds at a sufficiently high Pressure pressed to form uniform bodies.

The pressed bodies are then at temperatures of 950 to 1150 C in an oxygen or Sintered air atmosphere.

The ferrite according to the invention thus obtained has the following composition:

3 χ

. . / x - w - α - e \
L10.5 + y -y J

b Ti ₁ Co ₁₁ Mn ₁ Zn ^ Ni ₁₁ Bi ₁₁ O _4. ,,.

0.005 < C. <0.1. 0 < a <0.1. 0.0005 < H <0.065 0.30 < X <0.95. 0 < r <0.20, 0 < u- <0.4

• U -

3 χ + vv - a + 2 ζ + e

In the following, further exemplary embodiments 65 of nickel will point to the remanence ratio, if

invention explained. Example 1 is a well-known one. the ferrite is sintered under conditions which

A composition containing nickel is indicated. usually the rectangular shape of the hysteresis loop

while Examples 2, 3 and 4 drastically reduce the beneficial effect.

example 1
A composition! With

b = 0.002 X = 0.82. ζ = 0.05, VV = 0.12. a = 0. (KM e = 0

has the following frequency moderate ¹ and magnetic properties: coercivity = 0.6 Oersteds. Remanence magnetization = 202 Gauss, saturation magnetization = 550 Gauss. Remanence ratio = 0.37. Curie temperature =! 75 C. Resonance line width = 100 Oersted. Dielectric loss tangency = 0.0004 and magnetic loss tanaence = 0.0007.

By S ρ ι e 1 2 A composition With b = 0.002. χ = 0.82. ζ = 0.05. U '= 0.12. (I = 0.004. I '= " 0.05

has the following frequency and magnetic Properties: coercive force = 0.6 Oersted, remanence magnetization = 365 Gauss, saturation magnification - 550 gauss. Rcmancnzverhälnis = 0.66. Curie temperature = 175 C. Resonance line width = 100 oersteds. Tangency of dielectric losses = 0.0004 and tamcence of magnetic Losses = 0.0007.

As Example 2 shows, the remanence ratio for a nickel-containing ferrite is compared to a Ferrite without nickel according to Example 1 improved by a factor of almost 2. Apart from the improvement of the remanence ratio, the properties of the ferrites according to Examples 1 and 2 are identical. The improvement in the remanence ratio is therefore without impairment of the other properties achieved.

By S pi el 3 A composition mil b = 0.002. ν - 0.82. ζ = 0.05, W = 0.12. U = 0.004. e = 0.005

-: - 0.45. Curie temperature = 175 C. Resonance line width - 100 oersteds. Tangence of dielectric losses = O. (KK) 4 and tangence of magnetic Losses - O. (MK) 7.

Example 4
A composition nil

h ■ - = O. (K) 2,

λ = 0.82,

r - 0.05.

η = 0.12.

u = 0, (XM,

ι = - 0.10

has the following frequency and magnetic properties: coercive force = 0.6 Oersted, Remanence magnetization = 325 Gauss. Saturation magnetization = 550 Gauss, remanence ratio = 0.59. Curie temperature = 175 C, resonance line width = HX) Oersted. Tangence of the dielectric Losses = O. (XX) 4 and magnetic loss tangency = 0.0007.

In all examples it was at 1025 C for 5 hours sintered in oxygen, although higher or lower temperatures are also used can come.

To show that the addition of nickel to the in The ferrites in question produced a favorable effect, a series of ferrites of the same type according to the US-PS 33 72 123 produced, which does not contain bismuth. however, contained varying amounts of nickel. The chemical formula of ferrite and the test results are given in the table below.

Li, _is . _x , Zn _0. , Fe ₁₄ ^, NiJTi ₀₇ Q ₁ - O ₂

has the following frequency and magnetic properties: coercive force = 0.6 oersted. Remanence magnetization = 250 Gauss, saturation magnetization = 550 Gauss. Remanence ratio

Compo
nent
worth
of λ lirhil / cu
7 /
<- ' Sld Alms
sphiire
ATM Kocr / i
; /, ; ivkraft
B, 4.1 M, Reehi-
eekig-
keitsvcr
hällnis
B, (Oe) (Gauss) (G-iuB) 4 .-> A /, .ν = 0 1150/5 O: 1.9 653 870 0.75 12 (X); 5 °: 1.5 630 935 0.67 .ν = 0.05 1150 5 1.5 559 686 0.81 1200 5 O ₂ 1.5 600 990 0.61 Λ = 0.1 1150 5 O. 1.5 540 685 0.79 1200/5 O, 1.7 481 800 0.6 It means:

/the temperature.
ί the time.

ß _r the remanent induction,
Λ /, the saturation magnetization.

Claims (1)

Claims: I. Ferrite, characterized by the composition _Lio ^. £.) Fe _2-5 Co _-1 Mn-Zn ₁₁ Ni ₁ Ji ,, O ₁ wherein 0.005 < f <0.1. 0 < ti <0.1. 0.0005 <i · <0.065. 0.30 < x < 0.95, 0 <r <0.20, 0 <"■ <0.4, and ₊ [0.5 ₊ [1 5 (2nd