RU2291509C1 - Ferrite material - Google Patents

Abstract

FIELD: metallurgy; ferrite materials for microwave engineering.

SUBSTANCE: proposed Li-ferrospinel based ferrite material characterized in reduced saturation temperature coefficient TKJ_s, enhanced saturation stability J_s in operating temperature range of -60 to +85 °C at high J_s value and low dielectric and magnetic loss tangent in extremely-high frequency band has in its composition lithium, titanium, zinc, manganese, ferric, and lithium fluoride oxides, proportion of ingredients being as follows, mass percent: lithium oxide Li₂O, 2.753-3.39; titanium oxide TiO₂, 0.001-5,71; zinc oxide ZnO, 7.67-7.903; manganese oxide MnO₂, 4.12-6.21; ferric oxide, Fe₂O₃, 76.98-83.285; lithium fluoride LiF, 0.20-0.40.

EFFECT: enhanced yield of nonreciprocal microwave devices.

1 cl, 1 tbl, 5 ex

Description

The invention relates to microwave technology, in particular to ferrite materials, designed to create non-reciprocal decoupling microwave devices: valves, circulators operating in the temperature range of -60- + 85 ° C, millimeter wavelength range.

The creation of these non-reciprocal decoupling microwave devices requires ferrite materials having:

- high values of saturation magnetization - J _{s of the} order of 380 kA / m;

- low values of the temperature coefficient of saturation magnetization - TKJ _{s of the} order of less than 0.1% / deg in the operating temperature range of -60- + 85 ° C millimeter wavelength range;

- high stability of saturation magnetization values in the above temperature range;

- low values of the tangent of the angle of the total dielectric and magnetic losses - (tanδ = ∑ (tanδ _∑ + tanδ _μ )) of the order of 6 × 10 ^-4 .

Ferritic materials of the parametric series LiZn in combination with other components can provide these parameters.

Known ferrite material based on Li-ferrospinel [1], containing the following components, wt.%:

Lithium oxide Li ₂ O 3.01-3.53 Titanium oxide TiO ₂ 0.1-2.97 Zinc Oxide ZnO 4.11-4.22 Manganese Oxide MnO ₂ 2.21-6.47 Niobium oxide Nb ₂ O ₅ 1.32-2.36 Iron oxide Fe ₂ O ₃ 81.48-88.21

X-ray diffraction analysis of this ferrite material shows the presence of the main phase of spinel and the second phase, LiNbO ₃ , resulting from the interaction of lithium and niobium oxides, which:

- firstly, being distributed along the grain boundaries, it prevents their growth and thereby ensures high uniformity of the microstructure - graininess, low porosity and high density,

- secondly, lithium niobate (LiNbO ₃ ) is a good dielectric with a resistance of 10 ¹⁴ Ohm / cm and its presence in a ferrite material together with manganese oxide provides the ferrite material with low values of the angle tangent of the total dielectric and magnetic losses (tgδ = ∑ (tanδ _∑ + tanδ _μ )) of the order of 6 × 10 ^-4 in the millimeter wavelength range.

The presence of titanium oxide in a ferrite material in combination with zinc oxide increases, on the one hand, the saturation magnetization values - J _s , but on the other hand decreases the Curie temperature - and, therefore, increases the temperature coefficient of saturation magnetization - TKJ _s .

Thus, this ferrite material has high saturation magnetization values - J _{s of the} order of 360 kA / m, low values of the angle tangent of the total dielectric and magnetic losses (tanδ = ∑ (tanδ _∑ + tanδ _μ )) of the order of 6 × 10 ^-4 and high values temperature coefficient of saturation magnetization - TKJ _{s of the} order of 0.15% / deg, the latter complicates the use of this ferrite material in non-reciprocal decoupling microwave devices operating in the temperature range of -60- + 85 ° C, the millimeter wavelength range, due to:

- firstly, increasing the requirements for tuning the parameters of non-reciprocal decoupling microwave devices associated with a margin for direct and reverse losses in the working frequency band at room temperature,

- secondly, low yield of non-reciprocal decoupling microwave devices capable of operating in the above temperature range.

Known ferrite material based on Li-ferrospinel, containing, wt.%:

Lithium oxide Li ₂ O 2.62-3.5 Titanium oxide TiO ₂ 0.09-2.95 Zinc Oxide ZnO 3.76-3.98 Manganese Oxide MnO ₂ 2.14-5.77 Niobium oxide Nb ₂ O ₅ 1.31-2.06 Molybdenum oxide MoO ₃ 0.78-1.11 Iron oxide Fe ₂ About ₃ 84.60-85.35

prototype [2].

The X-ray diffraction analysis of this ferrite material shows, as in the first analogue, the presence of the main spinel phase and the second phase — LiNbO ₃ , which provides the above-mentioned advantages of the ferrite material — the analogue, namely, rather high saturation magnetization values — J _s , low values of the total dielectric tangent and magnetic losses (tanδ = ∑ (tanδ _∑ + tanδ _μ )) of the order of 6.8 × 10 ^-4 and this ferrite material.

In addition, the presence of additional molybdenum oxide in this ferrite material provides an even higher saturation magnetization, J _{s, of the} order of 380 kA / m, as well as a decrease in the temperature coefficient of saturation magnetization, TKJ _{s, of the} order of 0.1% / deg compared to the analog.

However, these values of the temperature coefficient of saturation magnetization coefficient - TKJ _{s of} ferrite material are insufficient for using this ferrite material in nonreciprocal decoupling microwave devices operating in the temperature range of -60- + 85 ° С, of the millimeter wavelength range.

In addition, this ferrite material is characterized by low stability of saturation magnetization values - J _s in the above temperature range, which determines the low yield of suitable nonreciprocal decoupling microwave devices.

The technical result of the invention is to reduce the temperature coefficient of saturation magnetization coefficient - TKJ _s , increase the yield of non-reciprocal decoupling microwave devices by increasing the stability of saturation magnetization values - J _s in the operating temperature range of -60- + 85 ° C while maintaining high values of saturation magnetization - J _s and low values of the angle tangent of the total dielectric and magnetic losses (tanδ = ∑ (tanδ _∑ + tanδ _μ )) of the millimeter wavelength range.

The technical result is achieved by the fact that the known ferrite material based on Li-ferrospinel, containing oxides of lithium, titanium, zinc, manganese, iron, additionally contains lithium fluoride in an amount of 0.20-0.40 in the following ratio of components, wt.%:

Lithium oxide Li ₂ O 2,753-3,39 Titanium oxide TiO ₂ 0.001-5.71 Zinc Oxide ZnO 7.67-7.903 Manganese Oxide MnO ₂ 4.12-6.21 Iron oxide Fe ₂ About ₃ 76.98-83.285 Lithium Fluoride LiF 0.20-0.40

The presence of lithium fluoride in an amount of 0.20-0.40 in combination with other components and their indicated ratio in a ferrite material provides:

- firstly, a decrease in the temperature coefficient of saturation magnetization coefficient - TKJ _s in the operating temperature range of -60- + 85 ° С,

- secondly, the stability of the saturation magnetization values - J _s in the above temperature range.

This became possible as a result of the replacement of oxygen ions with a negative valence of O ^-2 with a more electronegative fluorine ion F ^1- , which leads to the formation of chains in the crystal lattice in the form of octahedrons (FeO _6-x F _x ) and tetrahedrons (Fe ₃ O _{4- x} F _x ), and, as a result, a decrease in the crystal lattice parameters from 8.375 to 8.361-8.367 Å, which in turn leads to an increase in the exchange process of interaction between the above chains and, as a result, as was said above:

- firstly, a decrease in the temperature coefficient of saturation magnetization coefficient - TKJ _s in the working temperature range of -60- + 85 ° С,

- secondly, to increase the stability of saturation magnetization values - J _s in the above temperature range.

Moreover, the specified ratio of the components ensures the preservation of high values of saturation magnetization - J _s and low values of the tangent of the angle of the total dielectric and magnetic losses (tanδ = ∑ (tanδ _∑ + tanδ _μ )) of the millimeter wavelength range.

The latter are provided, among other things, by a decrease in the electrical conductivity of the ferrite material due to the presence of lithium fluoride in it.

The presence of lithium fluoride in an amount of less than 0.20 and more than 0.40 wt.% Is undesirable, as it leads to:

- firstly, to the formation of low uniformity of the microstructure - heterogeneity, increase porosity and decrease density,

- secondly, to increase the values of the temperature coefficient of saturation magnetization - TKJ _s ,

thirdly, an increase in the values of the tangent of the angle of the total dielectric and magnetic losses (tanδ = ∑ (tanδ _∑ + tanδ _μ )).

Example 1

Ferrite material is made using standard ceramic technology.

Take lithium oxide, titanium oxide, zinc oxide, manganese oxide, iron oxide, lithium fluoride in an amount in weight% of 3.18, 3.78, 7.67, 4.12, 81.25, 0.3, respectively.

In this case, lithium fluoride is taken in superstoichiometric composition.

Then the mixture of the starting components is calcined sequentially at the following temperatures and over time:

400 ° C - 1 hour,

500 ° C - 2 hours,

725 ° C - 5 hours,

after which the mixture is ground, a solution of polyvinyl alcohol is introduced into it, the preforms are pressed from it, and their final sintering is carried out sequentially at the following temperatures and over time:

100 ° C - 1 hour,

200 ° C - 1 hour,

350 ° C - 2 hours,

1050-1125 ° C - 7 hours, with a heating rate of 100 ° C / hour.

After sintering, the samples of ferrite material are cooled to 700 ° C, at a cooling rate of 100 ° C / h.

Examples 2-5.

Similarly, samples of ferrite material were made, but with different ratios of components, both indicated in the claims (examples 2-3), and beyond it (examples 4-5).

Also, samples of ferrite material were made according to the ratio of the components of the prototype.

On the fabricated samples of ferrite material, the values of the temperature coefficient of saturation magnetization - TKJ _s were measured in the working temperature range of -60- + 85 ° C, the values of saturation magnetization - J _s , the angle tangent of the total dielectric and magnetic losses

(tanδ = ∑ (tanδ _∑ + tanδ _μ )).

The results are shown in table 1.

As can be seen from the table, samples of ferrite material made at a ratio of components, including lithium fluoride, indicated in the claims (examples 1-3) have:

- low values of the temperature coefficient of saturation magnetization - TKJ _{s of the} order of 0.058% / deg,

- high saturation magnetization - J _{s of the} order of 380 kA / m,

- low values of the angle tangent of the total dielectric and magnetic losses (tanδ = ∑ (tanδ _∑ + tanδ _μ )) of the order of (7.0-8.2) × 10 ^-4 .

Samples of the same ferrite material manufactured at a ratio of components, including lithium fluoride, exceeding the limits specified in the claims (examples 4-5), have high values of the temperature coefficient of saturation magnetization - TKJ _{s of the} order of 0.13% / deg. Furthermore, there is a significant increase in the total angle tangent values of dielectric and magnetic losses _{(tgδ = Σ (tgδ Σ +} tgδ μ)) ( the order of (1,3-1,7) × 10 ^-3.

Thus, the proposed ferrite material in comparison with the ferrite material described in the prototype has:

- firstly, low values of the temperature coefficient of saturation magnetization - TKJ _{s of the} order of 0.058% / deg (prototype of the order of 0.07% / deg) in the operating temperature range of -60- + 85 ° C,

- secondly, it ensures the stability of saturation magnetization values - J _s , and therefore, increase the yield of non-reciprocal decoupling microwave devices operating in the above temperature range.

Moreover, the proposed ferrite material retains:

- high saturation magnetization - J _{s of the} order of 380 kA / m,

- low values of the angle tangent of the total dielectric and magnetic losses (tanδ = ∑ (tanδ _∑ + tanδ _μ )) of the order of (7.0-8.2) × 10 ^-4 .

This will make it possible to use the proposed ferrite material to create non-reciprocal decoupling microwave devices: valves, circulators operating in the temperature range of -60- + 85 ° С, millimeter wavelength range.

Information sources

1. RF patent No. 2247436, IPC ⁷ H 01 F 1/34, publ. 02/27/05, bull. No. 6.

2. RF patent No. 2247437, IPC ⁷ H 01 F 1/34, publ. 02/27/05, bull. No. 6.

№№ The ratio of components, wt.% The results of measurements of the parameters of samples of ferrite material Li ₂ O TiO ₂ Zno MnO ₂ Fe ₂ O ₃ LiF MoO ₃ Nb ₂ O ₅ TKJ _s % / degree -60- + 85 ° С J _s kA / m (tanδ = ∑ (tanδ _∑ + tanδ _μ )) one 3.18 3.78 7.67 4.12 81.25 0.30 0.08 360 7.6 × 10 ^-4 2 2,753 0.001 7,903 6,058 83,285 0.20 0.11 380 8.2 × 10 ^-4 3 3.39 5.71 7.71 6.21 76.98 0.40 0.058 340 7.0 × 10 ^-4 four 3.18 3.78 7.67 4.12 81.25 0.08 0.15 360 1.3 × 10 ^-3 5 3.18 3.78 7.67 4.12 81.25 0.50 0.13 350 1.7 × 10 Prototype 2.95 1.3 3.85 4.03 85.09 - 0.93 1.85 0.1 380 6.8 × 10 ^-4 2.62 0.09 3.76 5.77 84.60 - 1,11 2.06 0.13 405 7.5 × 10 ^-4

Claims (1)

Ferrite material based on Li-ferrospinel containing oxides of lithium, titanium, zinc, manganese, iron, characterized in that the ferrite material additionally contains lithium fluoride in the following ratio, wt.%: Lithium oxide Li ₂ O 2,753-3,39 Titanium oxide TiO ₂ 0.001-5.71 Zinc Oxide ZnO 7.67-7.903 Manganese Oxide MnO ₂ 4.12-6.21 Iron oxide Fe ₂ O ₃ 76.98-83.285 Lithium Fluoride LiF 0.20-0.40