DE2243975A1 - LITHIUM-TITANIUM-WISMUTH-COBALT-FERRITE - Google Patents

Description

Patent attorneys Dipl.-Ing. R ¥ eicf.vann »

Dipl.-Ing. H.Weickmann, Dipl.-Phys. Dr. K. Fincke Dipl.-Ing. R A.Weickmann, Dipl.-Chem. B. Huber

8 MUNICH 86, POST BOX 860 820

MÖHLSTRASSE 22, NUMBER 48 39 21/22

<983921/22>

CORPORATION, 401 Broadways, Redwood City, CaUf ₀ 94063, USA

Idthium ~ titanium-bismuth-cobalt-ferrite

Grenades are currently commonly used in the microwave frequency range. Grenades, however, are very expensive and have poor temperature behavior. Although the use of gerrites has already been proposed, their losses are high, their densities are low or their ICoercitive field strengths are too high. j

To avoid this disadvantage, it has also already been proposed to use ferrite in the microwave frequency range. narrow resonance line widths, good temperature behavior, low losses, little effort and rectangular hysteresis loops. Corresponding ferrites contain lithium and titanium with a small amount of bismuth, and copper, zinc and manganese may also be added. Proving see ₉ that these Perrite are useful only special microwave low power disadvantageous.

309812/1125

At powers above 1 to 2 kW instabilities occur in the ferrite activities that cause a great loss of power.

The present invention has for its object to provide a ferrite, in particular the above does not have the disadvantage mentioned, i.e. it can also be used for higher power microwave ovens.

To achieve this object, the invention provides a lithium-titanium-bismuth-cobalt ferrite of the following composition from

.s

where 0.001 <* r <0.1
O0OOO5 <p <0.065

O £ »£ 0.20 O <w < 0.4

and p + tj, + x + ζ + w

0.5 + V 2 1 A 2.

Advantageously, 06 = 0x006, in particular 0.002,

The ferrite can also contain a small amount of zinc or Contain manganese.

The invention is explained below on the basis of preferred exemplary embodiments the subject of the invention explained.

For the production of the ferrite material are usually Oxides of the ferrite-forming metal ions are used. If the constant instability of the oxide of a

309812/1125. ₃ ■ "

If the correct metal ion causes this oxide to form an impure and unstable compound, the anhydrous carbonate of the metal ion is used. The starting materials are weighed in a btoichiometric ratio and mixed in a wet ball mill for one or more hours. The sludge obtained is then dried at about 100 ° and pressed through a sieve with a mesh size of 20 (US sieve size) for easy processing. The sieved oxide mixture is filled into refractory boats. The boats are transported into a box-like melting furnace and heated to a certain temperature. The exact temperature can be between 700 ° G and 900 ° 0. The purpose of this heat treatment is twofold. On the one hand, sufficient energy is to be generated to cause the oxide mixture to react by a solid-state reaction to form a mixture of 70% ferrite and 30 % oxide. On the other hand, all carbonates used should be thermally offset «

The mixture brought to reaction is usually distinguished by a relatively large particle size. Before the mixture can be pressed into molds and sintered into a single-phase ferrite body ₉ , the particle size must be reduced, which is done in the manner already mentioned above by ball mills. The ferrite oxide Sohlamm is then dried at about 80 ° 0 to a fine powder "The powder is mixed in to check a known manner with a binder, said binder numerous, Z ₀ as polyvinyl alcohol, suitable Sindo

The binder can be added in the second grinding process or in another process which is uniform Distribution of the binder guaranteed. The powder impregnated with the binder is then placed in compression molds made of tool steel and made under appropriate pressure

108812/1128

shapes to create an even density. The pellets are in oxygen or air at a Sintered temperature between 950 ° C and 1150 ° C.

The ferrites obtained in this way are characterized by the following composition:

^Li 0.5 +1 2 J ^Fe 2.5 -Λ ¥ / -ß ¹¹ X ⁰⁰ CG ¹ W ¹ P

X OC ZWp 4 «v

where 0.001 £ 04 £ 0 _e 1

Ο »0005 £ β <0.065
0.30 <x <0.95
Oi ζ i Ο «20

⁰ < ^w ^ 0 4
and p + 06- + χ + z + w + I 0.5 + * 2 "/ | + 2" 5

Dx + w + 06f 2z l l - \ 2- ^ 1) "Ρ =

Examples are mentioned below from which the advantages of the ferrite according to the invention can be seen, with example 1 treated a Co-free ferrite and Example 2 a OO-containing ferrite and from a comparison of these two Ferrites which can be recognized by the addition of cobalt advantages.

example 1

A ferrite treated in the aforementioned manner was manufactured, its thermal pretreatment was carried out at 800 ° 0 and its sintering at 1025 ° 0 in air.

The composition was ß »0« 002

χ = 0 "66 ζ = 0.05 w = 0.10 oc = 0

- 5 309812/1125

This ferrite was characterized by the following microwave properties: tangent of dielectric losses = 0.0005, tangent of magnetic losses = 0 _o 0005, resonance line width = 215 Oe, spin wave line width = 2o5 Oe, peak power = 1.3 kW «

Example 2

The composition of this ferrite was

= 0.002

, - = {/ χ = Oo 66

'SO! ^{Z = Oo05}

{J ^ fw = O ₆ 10

tj Qt = 0.006

p. I This ferrite had the following microwave properties5 CI Tangent of the dielectric losses = 0.0005, tangent Π F; of magnetic losses = 0.0007 »resonance line width" O l | = 210 Oe, spiral / wave line width = 6.2 Oe, peak % I power = 7.0 kW.

The Oo-containing ferrite according to Example 2 has one around the A factor of 5 greater peak power than the Co-free ferrite according to example 1. The ferrite according to example 2 has something greater magnetic losses than the ferrite according to example 1, the usability of the ferrite according to example 2 as microwave ferrite was not affected by the addition of cobalt "

Examples 3 to 8

Bs was made of a number of ferrites, where

p = 0.002

χ = 0.66

ζ = 0.05

w = O ₀ 10 and

06 from 0 to 0.01, each in steps

was changed from 0.002. 309812/1 125

.; It became the square of the spiral wave line width that

ti f ^ '

nff-i directly proportional to the load capacity of a microwave

iij °: ferrits is, measured and in the attached figure above the

«Ü ^ j: Co content of the ferrite discharged. Over the range of f ^: \ examined eu values, the square of the

y Spiral wave line width by a factor of 1S.

- patent claims -

BATH ORIGINAL

- 7 - 30981 2 / Π

Claims (2)

Claims 1. lithium-titanium-bismuth-cobalt-ferrite, marked by the following composition: T.-i (χ- π - * λ ¹¹ 0.5+ Γ ^ I ™ ^le X + W- where 0.001 <<* - < Od 0.0005 <β <0.065 0c30 $ x 1 Oc95 0 < ζ <0o20 0 <w C 0.4 and ß + o £> + x +2 3 "x + w + © 0 + 2 ζ 2.5- \ 2 - S = 3 2 ο ferrite according to claim 1, because, through, marked ze.ich.net that D ^ = 0 "006 _o 3 · ferrite after. Claim 1, characterized. labeled in characterized in that 06 = 0.002. 309812/1125 Blank page