Ultrafine samarium-iron composite oxide, and preparation method and application thereof

Abstract

The application belongs to the technical field of magnet materials, and provides a superfine samarium-iron composite oxide as well as a preparation method and application thereof. The method comprises the following steps: mixing nitrate, samarium salt and iron salt, and heating to obtain an intermediate substance; mixing the intermediate substance with alkali metal oxide to obtain the superfine samarium-iron composite oxide. The application has the advantages of short preparation time, simple preparation method, low cost, large-scale preparation, no introduction of new impurities, and high purity of the obtained product. The superfine samarium-iron composite oxide prepared by the application has small and uniform grain size and high specific surface area, provides a good precursor for preparing samarium-iron alloy, and has wide application prospects in the fields of energy storage and solar cells.

Description

Technical Field

[0001] This invention relates to the field of magnet materials technology, and in particular to an ultrafine samarium iron composite oxide, its preparation method, and its application. Background Technology

[0002] With the widespread application of permanent magnet motors in electronics and electric vehicles, improving their magnetic properties has become a critical issue. Currently, neodymium iron boron (NdFeB) magnets are used in these motors; however, due to neodymium's scarcity and increasing cost, there is an urgent need to find a new material to replace NdFeB magnets. Samarium iron nitride (SamFeNi) magnets have a lower samarium content than NdFeB magnets, and their theoretical maximum energy product (BH) is also higher. max 472 kJ·m -3 Samarium iron nitride (SamFeNi) magnets have a Curie temperature as high as 470℃, which is 160℃ higher than that of NdFeB magnets. Furthermore, SamFeNi magnets exhibit superior oxidation and corrosion resistance compared to NdFeB magnets. Therefore, using SamFeNi magnets to replace NdFeB magnets has broad application prospects.

[0003] Samarium iron nitride (Samarium ferromagnetic oxide) magnets are generally prepared by nitriding Samarium ferromagnetic alloys. The main methods for preparing Samarium ferromagnetic alloys include mechanical alloying, rapid quenching, hydrogen disproportionation, and reduction-diffusion. Among these, the reduction-diffusion method uses Samarium oxide and iron oxide as raw materials, eliminating the three processes of pure metal preparation, alloy smelting, and coarse crushing of steel ingots, making it a promising preparation technology. However, the typical reduction-diffusion process still requires the preparation of iron oxide and Samarium oxide, and the preparation temperature is relatively high, resulting in relatively coarse oxide grains. Consequently, the Samarium ferromagnetic alloy grains formed after reduction-diffusion are also relatively large. As is well known, larger grains result in lower coercivity and poorer high-temperature resistance. Currently, commonly used methods for preparing Samarium ferromagnetic composite oxides include solid-state methods, sol-gel methods, and hydrothermal methods. The sol-gel and hydrothermal methods involve reaction temperatures exceeding 200℃, resulting in particles with minimum sizes of tens of nanometers. The solid-phase method, with reaction temperatures reaching as high as 1200℃, produces larger particles (mostly in the micrometer range). Furthermore, the sol-gel and hydrothermal methods require more raw materials, increasing processing costs and producing impure products. Therefore, providing a simple, convenient, environmentally friendly, and pollution-free method for preparing ultrafine samarium-iron composite oxides is of great significance. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems existing in the prior art and to provide an ultrafine samarium iron composite oxide, its preparation method and application.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing ultrafine samarium-iron composite oxide, comprising the following steps:

[0007] (1) Mix nitrate, samarium salt and iron salt and heat to obtain an intermediate substance;

[0008] (2) The intermediate substance is mixed with an alkali metal oxide to obtain the ultrafine samarium iron composite oxide.

[0009] Preferably, the nitrate in step (1) comprises lithium nitrate and potassium nitrate; the molar ratio of lithium nitrate to potassium nitrate is 3-7:3-7.

[0010] Preferably, the samarium salt in step (1) is samarium nitrate, samarium chloride, samarium bromide or samarium sulfate, and the iron salt is ferric nitrate, ferrous nitrate, ferric chloride, ferrous chloride, ferric bromide, ferric sulfate or ferrous sulfate.

[0011] Preferably, the molar ratio of nitrate, samarium salt and iron salt in step (1) is 8-12 g: 0.4-0.6 mmol: 0.4-0.6 mmol.

[0012] Preferably, the heating rate in step (1) is 4-6℃ / min, the target temperature is 140-200℃, and the holding time after reaching the target temperature is 25-35min.

[0013] Preferably, the alkali metal oxide in step (2) is lithium oxide, sodium oxide, sodium peroxide or potassium oxide.

[0014] Preferably, the molar ratio of the alkali metal oxide in step (2) to the samarium salt in step (1) is 1.4-1.6:0.4-0.6.

[0015] Preferably, the stirring speed in step (2) is 550-650 r / min and the time is 3-5 min.

[0016] The present invention also provides an ultrafine samarium-iron composite oxide obtained by the preparation method described above.

[0017] The present invention also provides the application of the ultrafine samarium iron composite oxide in permanent magnet motors, energy storage or solar cells.

[0018] The beneficial effects of this invention are:

[0019] (1) This invention provides a method for preparing ultrafine samarium-iron composite oxide, comprising the following steps: mixing nitrate, samarium salt and iron salt, and heating to obtain an intermediate substance; mixing the intermediate substance with an alkali metal oxide to obtain ultrafine samarium-iron composite oxide. This invention has a short preparation time, a simple preparation method, low cost, and can be prepared on a large scale. Furthermore, this invention does not introduce new impurities, and the obtained product has high purity.

[0020] (2) The ultrafine samarium iron composite oxide prepared by this invention has small and uniform grain size (particle size less than 15nm) and high specific surface area, providing a good precursor for the preparation of samarium iron alloys. It also has broad application prospects in energy storage, solar cells and other fields. Attached Figure Description

[0021] Figure 1 X-ray diffraction patterns (2theta(°)—2θ(°), Intensity(au)—intensity(au)) of the ultrafine samarium iron composite oxide and the sintered ultrafine samarium iron composite oxide in Example 1;

[0022] Figure 2 This is a transmission electron micrograph of the ultrafine samarium iron composite oxide in Example 1;

[0023] Figure 3 Transmission electron microscopy image of the ultrafine samarium iron composite oxide in Example 2;

[0024] Figure 4 Transmission electron microscopy image of the ultrafine samarium iron composite oxide in Example 3;

[0025] Figure 5 This is a transmission electron micrograph of the ultrafine samarium iron composite oxide in Example 4. Detailed Implementation

[0026] This invention provides a method for preparing ultrafine samarium-iron composite oxide, comprising the following steps:

[0027] (1) Mix nitrate, samarium salt and iron salt and heat to obtain an intermediate substance;

[0028] (2) The intermediate substance is mixed with an alkali metal oxide to obtain the ultrafine samarium iron composite oxide.

[0029] In this invention, the nitrate in step (1) comprises lithium nitrate and potassium nitrate; the molar ratio of lithium nitrate and potassium nitrate is preferably 3-7:3-7, more preferably 4-6:4-6, and even more preferably 4.5-5:4.5-5.

[0030] In this invention, nitrate is used as a reaction solvent in step (1) to reduce the reaction temperature.

[0031] In this invention, the samarium salt in step (1) is samarium nitrate, samarium chloride, samarium bromide or samarium sulfate, and the iron salt is ferric nitrate, ferrous nitrate, ferric chloride, ferrous chloride, ferrous bromide, ferric sulfate or ferrous sulfate.

[0032] In this invention, the preferred molar ratio of nitrate, samarium salt and iron salt in step (1) is 8-12g:0.4-0.6mmol:0.4-0.6mmol, more preferably 9-11g:0.45-0.55mmol:0.45-0.55mmol, and even more preferably 9.5-10g:0.47-0.5mmol:0.47-0.5mmol.

[0033] In this invention, the heating rate in step (1) is preferably 4-6℃ / min, more preferably 4.5-5.5℃ / min, and even more preferably 5-5.3℃ / min; the target temperature is preferably 140-200℃, more preferably 150-190℃, and even more preferably 160-170℃; and the holding time after reaching the target temperature is preferably 25-35min, more preferably 27-33min, and even more preferably 28-30min.

[0034] In this invention, the alkali metal oxide in step (2) is lithium oxide, sodium oxide, sodium peroxide or potassium oxide.

[0035] In this invention, the molar ratio of the alkali metal oxide in step (2) to the samarium salt in step (1) is preferably 1.4-1.6:0.4-0.6, more preferably 1.45-1.55:0.45-0.55, and even more preferably 1.47-1.5:0.47-0.5.

[0036] In this invention, the stirring speed for mixing in step (2) is preferably 550-650 r / min, more preferably 570-630 r / min, and even more preferably 580-600 r / min; the mixing time is preferably 3-5 min, more preferably 3.5-4.5 min, and even more preferably 3.9-4 min.

[0037] In this invention, after the mixing in step (2) is completed, the resulting system is naturally cooled, and then centrifuged and washed with water in sequence. The centrifugation and washing steps are repeated, and finally dried to obtain the ultrafine samarium iron composite oxide.

[0038] In this invention, the target temperature for natural cooling is preferably 20–30°C, more preferably 22–28°C, and even more preferably 23–25°C; the centrifugation speed is preferably 10,000–15,000 r / min, more preferably 11,000–14,000 r / min, and even more preferably 12,000–13,000 r / min; the centrifugation time is preferably 8–12 min, more preferably 9–11 min, and even more preferably 9.5–10 min; the number of repetitions is preferably ≥1 time, more preferably ≥2 times, and even more preferably ≥3 times; the drying temperature is preferably 50–70°C, more preferably 55–65°C, and even more preferably 58–60°C; the drying time is preferably 10–14 h, more preferably 11–13 h, and even more preferably 12–12.5 h.

[0039] The present invention also provides an ultrafine samarium-iron composite oxide obtained by the preparation method described above.

[0040] The present invention also provides the application of the ultrafine samarium iron composite oxide in permanent magnet motors, energy storage or solar cells.

[0041] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1

[0043] 10g of nitrate (containing lithium nitrate and potassium nitrate in a molar ratio of 4:6), 0.5mmol of samarium nitrate and 0.5mmol of ferric nitrate were mixed and heated to 150℃ at a heating rate of 5℃ / min and held for 30min to obtain an intermediate substance.

[0044] The intermediate material was mixed with 1.5 mmol of lithium oxide at 600 r / min for 4 min. After mixing, the resulting system was naturally cooled to 25 °C and centrifuged at 13000 r / min for 10 min. Then it was washed with water. The centrifugation and water washing steps were repeated twice. Finally, it was dried at 60 °C for 12 h to obtain ultrafine samarium iron composite oxide.

[0045] The obtained ultrafine samarium iron composite oxide was sintered at 800℃ to obtain the sintered ultrafine samarium iron composite oxide.

[0046] The ultrafine samarium iron composite oxide was sintered at 800°C to increase the crystallinity of the oxide. This is because the ultrafine samarium iron oxide particles prepared in this embodiment are very small and have low crystallinity. After sintering at 800°C, the crystallinity is improved and the grain size is increased, which is beneficial for characterizing its purity by XRD.

[0047] The ultrafine samarium iron composite oxide obtained in this embodiment and the sintered ultrafine samarium iron composite oxide were characterized by X-ray diffraction, and the X-ray diffraction patterns of the ultrafine samarium iron composite oxide and the sintered ultrafine samarium iron composite oxide in this embodiment were obtained, as shown below. Figure 1 As shown. From Figure 1 As can be seen from the data, the ultrafine samarium iron composite oxide prepared in this embodiment, after sintering at 800℃, only showed the SmFeO3 phase compared with the standard PDF card, with no other impurity phases generated. This indicates that the product obtained in this embodiment has a very high purity.

[0048] The ultrafine samarium-iron composite oxide obtained in this embodiment was characterized using transmission electron microscopy, resulting in a transmission electron micrograph of the ultrafine samarium-iron composite oxide in this embodiment, as shown below. Figure 2 As shown. From Figure 2 As can be seen from the data, the ultrafine samarium iron composite oxide particles prepared in this embodiment are small in size and uniformly distributed, with an average size of about 8 nm.

[0049] Example 2

[0050] 9g of nitrate (containing lithium nitrate and potassium nitrate in a molar ratio of 4.5:5), 0.47mmol of samarium sulfate and 0.47mmol of ferric sulfate were mixed and heated to 160℃ at a heating rate of 4.5℃ / min and held for 28min to obtain an intermediate substance.

[0051] The intermediate substance was mixed with 1.47 mmol of sodium peroxide at 580 r / min for 3.5 min. After mixing, the resulting system was naturally cooled to 23 °C and centrifuged at 12000 r / min for 11 min. Then it was washed with water. The centrifugation and washing steps were repeated 3 times. Finally, it was dried at 55 °C for 13 h to obtain ultrafine samarium iron composite oxide.

[0052] The ultrafine samarium-iron composite oxide obtained in this embodiment was characterized using transmission electron microscopy, resulting in a transmission electron micrograph of the ultrafine samarium-iron composite oxide in this embodiment, as shown below. Figure 3 As shown. From Figure 3 As can be seen from the data, the ultrafine samarium iron composite oxide particles prepared in this embodiment are small in size and uniformly distributed, with an average size of about 9 nm.

[0053] Example 3

[0054] 11g of nitrate (containing lithium nitrate and potassium nitrate in a molar ratio of 5:5.5), 0.55mmol of samarium chloride and 0.55mmol of ferric chloride were mixed and heated to 170℃ at a heating rate of 5.5℃ / min and held for 27min to obtain an intermediate substance.

[0055] The intermediate substance was mixed with 1.55 mmol of sodium oxide at 630 r / min for 4.5 min. After mixing, the resulting system was naturally cooled to 27 °C and centrifuged at 13000 r / min for 9.5 min. Then it was washed with water. The centrifugation and water washing steps were repeated 3 times. Finally, it was dried at 65 °C for 11 h to obtain ultrafine samarium iron composite oxide.

[0056] The ultrafine samarium-iron composite oxide obtained in this embodiment was characterized using transmission electron microscopy, resulting in a transmission electron micrograph of the ultrafine samarium-iron composite oxide in this embodiment, as shown below. Figure 4 As shown. From Figure 4 As can be seen from the data, the ultrafine samarium iron composite oxide particles prepared in this embodiment are small in size and uniformly distributed, with an average size of about 10 nm.

[0057] Example 4

[0058] 12g of nitrate (containing lithium nitrate and potassium nitrate in a molar ratio of 5:5), 0.58mmol of samarium nitrate and 0.6mmol of ferrous nitrate were mixed and heated to 200℃ at a heating rate of 6℃ / min and held for 30min to obtain an intermediate substance.

[0059] The intermediate material was mixed with 1.6 mmol of lithium oxide at 650 r / min for 5 min. After mixing, the resulting system was naturally cooled to 30 °C and centrifuged at 15000 r / min for 8 min. Then it was washed with water. The centrifugation and water washing steps were repeated twice. Finally, it was dried at 70 °C for 10 h to obtain ultrafine samarium iron composite oxide.

[0060] The ultrafine samarium-iron composite oxide obtained in this embodiment was characterized using transmission electron microscopy, resulting in a transmission electron micrograph of the ultrafine samarium-iron composite oxide in this embodiment, as shown below. Figure 5 As shown. From Figure 5 As can be seen from the data, the ultrafine samarium iron composite oxide particles prepared in this embodiment are small in size and uniformly distributed, with an average size of about 14 nm.

[0061] As shown in the above embodiments, this invention provides an ultrafine samarium-iron composite oxide, its preparation method, and its applications. The method includes the following steps: mixing nitrate, samarium salt, and iron salt, and heating to obtain an intermediate substance; mixing the intermediate substance with an alkali metal oxide to obtain the ultrafine samarium-iron composite oxide. This invention features a short preparation time, a simple preparation method, low cost, and large-scale production capability. Furthermore, this invention does not introduce new impurities, and the resulting product has high purity. The ultrafine samarium-iron composite oxide prepared by this invention has small and uniform grain size and a high specific surface area, providing a good precursor for the preparation of samarium-iron alloys. It also has broad application prospects in energy storage, solar cells, and other fields.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing ultrafine samarium-iron composite oxide, characterized in that, Includes the following steps: (1) Mix nitrate, samarium salt and iron salt and heat to obtain an intermediate substance; (2) The intermediate substance is mixed with an alkali metal oxide to obtain the ultrafine samarium iron composite oxide; The nitrate in step (1) comprises lithium nitrate and potassium nitrate; the molar ratio of lithium nitrate to potassium nitrate is 3-7:3-7; The heating rate in step (1) is 4-6℃ / min, and the target temperature is 140-200℃; the holding time after reaching the target temperature is 25-35min. The alkali metal oxide mentioned in step (2) is lithium oxide, sodium oxide, sodium peroxide, or potassium oxide; The mixing speed in step (2) is 550-650 r / min, and the mixing time is 3-5 min.

2. The preparation method according to claim 1, characterized in that, The samarium salt in step (1) is samarium nitrate, samarium chloride, samarium bromide or samarium sulfate, and the iron salt is ferric nitrate, ferrous nitrate, ferric chloride, ferrous chloride, ferric bromide, ferric sulfate or ferrous sulfate.

3. The preparation method according to claim 2, characterized in that, The mass molar ratio of nitrate, samarium salt and iron salt in step (1) is 8-12 g: 0.4-0.6 mmol: 0.4-0.6 mmol.

4. The preparation method according to claim 1, characterized in that, The molar ratio of the alkali metal oxide in step (2) to the samarium salt in step (1) is 1.4-1.6:0.4-0.

6.

5. The ultrafine samarium iron composite oxide obtained by the preparation method according to any one of claims 1 to 4.

6. The application of the ultrafine samarium iron composite oxide of claim 5 in permanent magnet motors, energy storage, or solar cells.

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