Moderately dispersed Dy2O3 particles

Abstract

Nanoparticle-scale Dy2O3 particles have beneficial properties for ceramic and electronic applications. Disclosed herein are well-dispersed Dy2O3 particles with regular morphology and lateral sizes ranging from about 10 nm to 1 μm. The Dy2O3 particles are 10 and D 90 The DyO particles may exhibit a narrow particle size distribution, with a difference in particle size of about 0.1 μm to 1 μm. Furthermore, methods for producing these well-dispersed DyO particles are disclosed. These methods do not involve grinding to obtain the particles. Also disclosed are uses for the DyO particles.

Description

[Technical Field]

[0001] The present application relates to well-dispersed DyO particles having regular morphology and desirably small lateral sizes. These lateral sizes may range from about 10 nm to 1 μm. Also disclosed herein are methods for producing well-dispersed DyO particles and their uses. [Background technology]

[0002] Introduction Dysprosium oxide (Dy2O3) is a trioxide compound of the rare earth metal dysprosium. It is used in ceramics, glass, phosphors, lasers, multilayer ceramic capacitors, and other specialized applications. In particular, it is used as a light-storing or heat-storing material, a contrast agent in magnetic resonance imaging, and as an additive to improve the capacitance of barium titanate, the dielectric of multilayer ceramic capacitors.

[0003] For these applications, it is necessary to obtain small particle size dysprosium oxide without crushing. The particle size of dysprosium oxide is generally about 7 to 8 microns.

[0004] Increasing efforts are being made to prepare nano-Dy2O3 materials whose size, shape, crystalline structure, and surface chemistry meet the requirements of such technological applications.

[0005] Achieving high-yield synthesis of nano-DyO3 while precisely controlling its morphology (size, shape, surface chemistry, particle size distribution, etc.) has been a challenging task. U.S. Patent No. 6,677,262 discloses the synthesis of narrowly dispersed DyO3 via a urea route using low precursor concentrations (8-10 g / L). However, the resulting product yields were low. To synthesize DyO3 in high yields, the precursor concentration must be significantly increased. However, at such high concentrations, the intermediates undergo further growth via Ostwald ripening or oriented attachment growth. See S. Deng et al., “Reduced Graphene Oxide Conjugated CuO Nanowire Mesocrystals for High-Performance NO2 Gas Sensors,” J. Am. Chem. Soc., 2012, 134(10), pp. 4905-4917. Thus, the synthesized DyO3 does not retain the desired discrete and well-dispersed particles. Using known synthetic methods, concentrations cannot be linearly extrapolated to produce nanoparticles in high yields due to the influence of the thermodynamics of particle growth. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there remains a need to develop a simple and efficient method for preparing dispersed Dy2O3 in high yield. [Means for solving the problem]

[0007] overview As disclosed herein, the compositions comprise well-dispersed DyO particles having a regular morphology and a lateral size ranging from about 10 nm (0.01 μm) to 1000 μm. In certain embodiments, the compositions comprise well-dispersed DyO particles having a regular morphology and a lateral size ranging from about 10 nm to 1 μm. In certain embodiments, the dispersed DyO particles have a lateral size ranging from about 40 nm (0.04 μm) to 100 μm. In some embodiments, the dispersed DyO particles have a lateral size ranging from about 40 nm (0.04 μm) to 1 μm. In other embodiments, the dispersed DyO particles have a lateral size ranging from about 100 nm (0.1 μm) to 1 μm.

[0008] In any of these embodiments regarding lateral size, the Dy2O3 particles may be 10 and D 90 It is possible for the particle size distribution to be relatively narrow, such that the particle size distribution is between about 0.1 μm and 1 μm.

[0009] The present method for producing well-dispersed DyO particles includes the steps of: (a) mixing a dysprosium salt, a polymeric additive, and a chelating agent in water to provide a dysprosium precursor solution, (b) heating the dysprosium precursor solution to form a precipitate, and (c) calcining the precipitate to provide well-dispersed DyO particles, from which well-dispersed DyO particles can be isolated.

[0010] In embodiments of the method, the chelating agent may be selected from the group consisting of diethanolamine, 2-amino-2-(hydroxymethyl)-1,3-propanediol, triethanolamine, ethylenediamine, 6-aminohexanoic acid, L-histidine, L-lysine, and mixtures thereof.

[0011] In embodiments of the method, the polymer additive may be selected from the group consisting of polyvinylpyrrolidone (PVP), poly(vinyl alcohol) (PVA), polyethyleneimine (PEI), and mixtures thereof.

[0012] Also disclosed herein are DyO particles produced by this method, which can provide for large-scale production of these DyO particles and also provide high yields. Importantly, these methods do not include any milling step. [Brief explanation of the drawings]

[0013] Brief description of the drawings [Figure 1] FIG. 1 is a flow chart illustrating one embodiment of a method for producing well-dispersed Dy2O3 particles.

[0014] [Figure 2] Figure 2A is an SEM of nano-Dy2O3 prepared by the chloride precursor / hydrothermal method.

[0015] FIG. 2B is a graph of the particle size distribution of nano-Dy2O3 prepared by the chloride precursor / hydrothermal method.

[0016] [Figure 3] Figure 3A shows an SEM of nano-DyO prepared by the nitrate precursor / hydrothermal method. These particles were prepared using aminohexanoic acid as a chelating agent and polyvinylpyrrolidone (PVP) as a polymer additive.

[0017] FIG. 3B is a graph of the particle size distribution of nano-Dy2O3 produced by the nitrate precursor / hydrothermal method and chelating agent and polymeric additives described for FIG. 3A.

[0018] [Figure 4]FIG. 4A is an SEM of Dy2O3 synthesized using nitrate precursors with room temperature precipitation followed by supercritical drying, as described in Comparative Example 1.

[0019] FIG. 4B is a graph of the particle size distribution of Dy2O3 described in FIG. 4A and Comparative Example 1.

[0020] [Figure 5] FIG. 5A is an SEM of Dy2O3 synthesized using nitrate precursors with precipitation at room temperature followed by heating in isopropanol, as described in Comparative Example 2.

[0021] FIG. 5B is a graph of the particle size distribution of Dy2O3 described in FIG. 3E and Comparative Example 2.

[0022] [Figure 6] FIG. 6A is an SEM of Dy2O3 synthesized using a nitrate precursor with precipitation at room temperature in the presence of a carboxylic acid, as described in Comparative Example 3.

[0023] FIG. 6B is a graph of the particle size distribution of Dy2O3, as described in FIG. 3G and Comparative Example 3.

[0024] [Figures 7A-8B] Figure 7A shows a transmission electron micrograph (TEM) and a selected area electron diffraction (SAED) pattern image of a precipitate that was hydrothermally reacted and dried using polyethyleneimine (PEI) as a polymer additive.

[0025] Figure 7B shows TEM and SAED of Dy2O3 with polyethyleneimine as a polymer additive after calcination.

[0026] Figure 8A shows TEM and SAED images of a precipitate obtained by hydrothermal reaction and drying using polyvinyl alcohol (PVA) as a polymer additive.

[0027] Figure 8B shows the TEM and SAED of Dy2O3 with PVA as the polymer additive after calcination.

[0028] [Figure 9] FIG. 9 is an X-ray diffraction diagram of calcined Dy2O3.

[0029] [Figure 10] FIG. 10 is an explanatory diagram showing the size in the horizontal direction. DETAILED DESCRIPTION OF THE INVENTION

[0030] Detailed explanation Before the moderately dispersed DyO particles and methods are disclosed and described, it will be understood that the present disclosure is not limited to the specific structures, method steps, or materials disclosed herein, but extends to equivalents thereof that would be recognized by one of ordinary skill in the relevant art. It should also be understood that the terminology employed herein is used solely for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, it should be noted that the singular forms "a," "one," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, a reference to "a step" can include multiple steps, and a reference to the "product" or "product" of a reaction or process should not be considered to include all of the products of the reaction / process, and a reference to "processing" can include reference to one or more of such processing steps. Thus, a processing step can include multiple or repeated processing of similar materials / fluids to produce a specified processing product.

[0031] Numerical values ​​with "about" include typical experimental variations. As used herein, the term "about" means within a statistically meaningful range of values, such as a stated particle size, concentration range, time frame, molecular weight, temperature, or pH. Such ranges can be within one order of magnitude, typically within 10%, and more typically within 5% of the indicated value or range. Sometimes, such ranges can be within the typical experimental error of the standard method used to measure and / or determine a given value or range. The allowable variation encompassed by the term "about" depends on the particular system under study and can be readily understood by one of ordinary skill in the art. Whenever a range is referred to in this application, any integer within that range is also contemplated as an embodiment of the invention.

[0032] The present invention relates to well-dispersed DyO particles. Here, dispersibility is an index of the heterogeneity (or uniformity) of particle sizes in a mixture. This can be indicated by the polydispersity index (PDI) parameter obtained from dynamic light scattering (DLS), a technique commonly used to determine the size distribution of particles in a suspension by measuring fluctuations in the intensity of scattered light. Specifically, the mean and standard deviation (stddev) are calculated from the particle size distribution (PSD) profile, and the PDI is calculated as (stddev / mean). 2 When expressed in the form: PDI, the PDI value is obtained. Information regarding this analytical technique can also be found at https: / / www.materials-talks.com / blog / 2017 / 10 / 23 / polydispersity-what-does-it-mean-for-dls-and-chromatography / , which is incorporated herein by reference where appropriate.

[0033] [Table 1] A completely uniform sample would have a PDI value of 0.0, as shown in Table 1. As used herein, "moderately dispersed" means that the Dy2O3 particles have a PDI value in the range of about 0.1 to 0.4.

[0034] As used herein, "well-dispersed Dy2O3 particles" refers to D 10 From D 90 In some embodiments, the particles have a particle size distribution where D 10 and D 90 The particle size distribution is about 0.1 μm to 1 μm.

[0035] As used herein, "regular morphology" means that the particle properties, including size, shape, and structure, are well-defined and consistent among different particles within the same batch. This includes small aspect ratio configurations, such as uniform spheres, ellipses, or cubes, and high aspect ratio configurations, such as uniform rods or wires.

[0036] As used herein, in a two-dimensional nanostructure, the "lateral size" refers to the length extending from one surface to the other. Figure 10 is a diagram illustrating the lateral size and how to measure it. Here, the lateral size of a particle can be measured from electron microscope images, specifically, transmission electron microscope and scanning electron microscope (TEM and SEM) images.

[0037] Disclosed herein are compositions comprising moderately dispersed DyO particles having a regular morphology and a lateral size ranging from about 10 nm (0.01 μm) to 1000 μm. In certain embodiments, the compositions comprise moderately dispersed DyO particles having a regular morphology and a lateral size ranging from about 10 nm to 1 μm. In certain embodiments, the dispersed DyO particles have a lateral size ranging from about 40 nm (0.04 μm) to 100 μm. In some embodiments, the dispersed DyO particles have a lateral size ranging from about 40 nm (0.04 μm) to 1 μm. In other embodiments, the dispersed DyO particles have a lateral size ranging from about 100 nm (0.1 μm) to 1 μm. In these embodiments, the particles have a lateral size of about 100 nm (0.1 μm) to 1 μm. 10 and D 90The particle size distribution is about 0.1 μm to 1 μm.

[0038] In all the above set forth embodiments relating to particle size distribution and lateral size, the Dy2O3 particles have a D of about 10 nm to 100 nm. 10 , D of about 0.1 μm to about 0.8 μm 50 , and D of approximately 0.25 μm to 10 μm 90 In some embodiments, the DyO particles can have a D of about 10 nm to 100 nm. 10 , D of about 0.1 μm to about 0.8 μm 50 , and D of about 0.25 μm to 5 μm 90 In certain of these embodiments, the DyO particles may have a D of about 0.25 μm to 1 μm. 90 may have:

[0039] In certain embodiments, the DyO particles have a D of about 10 nm to 0.2 μm. 50 , D of about 0.2 μm to about 1 μm 90 In certain of these embodiments, the Dy2O3 particles have a D of about 10 nm to 0.15 μm. 50 and D of approximately 0.2 μm to 0.75 μm 90 It has the following characteristics.

[0040] The DyO particles disclosed herein can have a round or faceted shape and are not significantly aggregated. Furthermore, the DyO particles disclosed herein have a crystalline structure. In certain embodiments, the X-ray diffraction pattern of the DyO particles illustrates a single cubic phase, which can serve as a fingerprint of the periodic atomic arrangement in the material.

[0041] In any of the above embodiments, the DyO particles can also have a low chloride content, and in certain of these embodiments, the chloride content can be about 0 to 50 ppm. Such a low chloride content prevents or reduces the potential for corrosion, which is particularly important for the use of DyO particles in multilayer ceramic capacitors. Therefore, achieving a low chloride content is an important characteristic of the DyO particles.

[0042] The well-dispersed DyO particles as disclosed herein are produced by a method comprising: (a) mixing a dysprosium salt, a polymeric additive, and a chelating agent in water to provide a dysprosium precursor solution; (b) heating the dysprosium precursor solution to form a precipitate; and (c) calcining the precipitate to provide the well-dispersed DyO particles, from which the well-dispersed DyO particles as disclosed herein can be isolated.

[0043] It is important to note that the methods disclosed herein do not involve a grinding or milling step. As such, the disclosed DyO particles are obtained without a grinding or milling step. Thus, the disclosed methods provide DyO particles as disclosed and described above.

[0044] The starting dysprosium salt is water-soluble, and in this process, the dysprosium salt is dissolved in water. The salt can be a salt of an inorganic or organic acid, such as a chloride, sulfate, nitrate, acetate, etc. In certain embodiments, the dysprosium salt can be either a chloride salt or a nitrate salt. The starting dysprosium salt can affect the particle shape, particle size, and particle size distribution achieved.

[0045] The chelating agent used in the methods described herein can be any chelating agent. A chelating agent is an organic compound capable of linking metal ions to form a chelate. In certain embodiments, the chelating agent can be advantageously selected from diamines (e.g., ethylenediamine), alkanolamines (e.g., diethanolamine, 2-amino-2-(hydroxymethyl)-1,3-propanediol, and triethanolamine), or amino acids (e.g., 6-aminohexanoic acid, L-histidine, L-lysine), and mixtures thereof. More than one chelating agent can also be present in the same reaction mixture. During calcination, the chelating agent is removed.

[0046] The polymer additive can be any polymer that aids in the processability of the dysprosium precursor solution and is removed during calcination. Here, the role of the polymer additive is to influence particle size and morphology by selective surface stabilization and / or providing access to kinetically controlled growth conditions. The polymer additive can be selected from the group consisting of polyvinylpyrrolidone (PVP), poly(vinyl alcohol) (PVA), polyethyleneimine (PEI), and mixtures thereof.

[0047] The chelating agent and polymeric additive are dissolved in water when added to the process. The chelating agent may be added as a water mixture at a concentration of about 0.1-2 M, in some embodiments about 0.5-1 M, and the polymeric additive may be added as a water mixture at a concentration of about 2-15 g / L, in some embodiments about 6.25-12.5 g / L.

[0048] To form the dysprosium precursor solution, the chelating agent, polymeric additive, and dysprosium salt can be added simultaneously or individually while mixing. If not added simultaneously, any order of addition can be used. In some embodiments, about 2-3 moles of chelating agent are added per mole of dysprosium in step (a) of the method.

[0049] In certain embodiments, the dysprosium precursor solution of step (a) has a dysprosium concentration of about 0.2 mol / L to 1.5 mol / L.

[0050] The dysprosium precursor solution of step (a) may have a concentration of dysprosium oxide of about 25 to 75 g / L.

[0051] In step (b), the dysprosium precursor solution is heated to form a precipitate. Heating can be carried out at a temperature of about 100°C to 350°C for about 15 minutes to 24 hours. In certain embodiments, heating can be carried out at a temperature of about 120°C to 160°C for about 45 minutes to 2 hours. Heating can provide a crystalline precipitate. In particular, heating can provide a single-crystal precipitate.

[0052] The crystalline precipitate from the heating step of step (b) can be washed with water to remove residual amounts of bound or adsorbed ions, such as nitrates and chlorides, and then dehydrated with a suitable solvent, such as ethanol, before calcination. In certain embodiments, the crystalline precipitate is particularly pure in anionic impurities, as characterized by a conductivity of less than about 10 mS / cm after washing.

[0053] The crystalline precipitate is calcined in step (c) to form DyO particles as disclosed and described herein. Calcination can be carried out at a temperature ranging from about 400°C to 1000°C for about 15 minutes to 24 hours. Calcination should be sufficient to remove the polymeric additives and chelating agents. In certain embodiments, calcination can be carried out at a temperature of about 600°C to 800°C for about 1 hour to 4 hours.

[0054] This calcination results in DyO particles having the properties as defined herein. Similar to the precipitate of step (b), the calcined product can exhibit single-crystal SAED (selected area (electron) diffraction).

[0055] The firing can be carried out by any method that can produce a uniform material.

[0056] For the particle size distribution (PSD) measurements described here, approximately 0.1 g of powder was dispersed in 10 mL of 2% sodium hexametaphosphate by sonication for 3 minutes. PSD measurements were then performed using a Microtrac S3500. The sample solution was added dropwise to a sample delivery controller filled with pure water and sonicated for 3 minutes. The solution was then flowed into a transparent cell at a flow rate of 49 mL / sec (75% flow rate). The signal was captured and the sample particle size was calculated automatically.

[0057] FIG. 1 is a flow chart of one embodiment of a method for producing well-dispersed Dy2O3 particles.

[0058] 2 and 3 show the typical morphology of the Dy2O3 of the present invention by A) SEM or B) Microtrac.

[0059] In the following, examples are given to illustrate the inventive method for the preparation of Dy2O3 particles and their characterization in more detail, but the scope of the present invention is in no way limited thereby.

[0060] example Example 1: Nano Dy 2 O 3 Synthesis of The following was done: 1) Weigh out the polymer additive PVA and the chelating agent diethanolamine, then dissolve them in water while heating at 50°C. 2) A stock solution of DyCl3 (415 g / L, 2.225 M) was added to the above mixture to a final concentration of 0.4 M (74.6 g / L). 3) The solution was poured into the Teflon liner of an autoclave, and the autoclave was heated to 160°C and held at this temperature for 1 hour. 4) The result was a sticky white substance (wet cake / sediment). 5) The wet cake was then centrifuged and the supernatant was removed. The wet cake was then washed with deionized water until the conductivity was less than 8 mS / cm. 6) Wash twice with ethanol and dehydrate the wet cake. 7) The wet cake was calcined at 700°C for 2 hours. Scanning electron microscopy revealed that the dysprosium oxide consisted of discrete, non-aggregated particles with rounded, faceted morphology (Fig. 2A). 50 The particle size is 0.13 μm (Figure 2B). TEM and SAED of Dy2O3 showed that the material has a single crystalline structure.

[0061] Example 2: Nano Dy 2 O 3 Synthesis of The following was done: 1) 8 g / L of PVP (MW=40K) and PVP (MW=1300K), 0.06 M of aminohexanoic acid, and 0.8 M of DEA were dissolved in water. 2) A stock solution of Dy(NO3)2 (415 g / L, 2.225 M) was added to the above mixture to a final concentration of 0.4 M (74.6 g / L). 3) The solution was then poured into the Teflon liner of an autoclave, heated to 160°C, and held at this temperature for 1 hour. 4) The result was a sticky white substance (wet cake / sediment). 5) The wet cake was centrifuged and the supernatant removed. The remaining material was washed with deionized water until the conductivity was less than 8 mS / cm. 6) Then, it was dehydrated by washing twice with ethanol and centrifuged to obtain the final wet cake. 7) The wet cake was calcined at 700°C for 2 hours. SEM of the obtained dysprosium oxide showed discrete, non-aggregated particles with flat morphology and lengths of less than 500 nm (Figure 3A). The PSD of the obtained Dy2O3 was 50 was 0.137 μm (Figure 3B).

[0062] Comparative Example 3: Dy 2 O 3 Synthesis of The following was done: 1) Prepare 1083 ml of 4.5 M NH4OH. 2) 900 ml of a stock solution of Dy(NO3)3 (100 g / L, 2.225 M) was prepared and added to the above ammonia solution to a final concentration of 0.4 M (74.6 g / L). 3) The solution was stirred at room temperature for 1 hour. 4) The final pH was 9.90 and the temperature was 24.1°C. 5) The supernatant was decanted, and the filtrate was replenished with deionized water several times until the conductivity of the filtrate became less than 8 mS / cm, and the precipitate was recovered. 6) Two-thirds of the precipitate obtained in step 5 was dehydrated with ethanol and dispersed in a total volume of 600 ml of ethanol. 7) The slurry was dried at 300°C and 130-140 bar. 8) The obtained oxide was calcined at 700°C for 2 hours. The resulting Dy2O3 was an agglomeration of fine needle-like particles (Figure 4A). The PSD of this material was D 50 showed that the granules were composed of 3.18 μm particles (Fig. 4B).

[0063] Comparative Example 4: Dy 2 O 3 Synthesis of The following was done: 1) Steps 1 to 5 of Comparative Example 1 were followed. 6) One-third of the obtained precipitate was dehydrated with isopropanol and dispersed in a total amount of 500 ml of isopropanol. 7) The slurry was heated to 80°C for 24 hours. 8) The obtained wet cake was calcined at 700°C for 2 hours. The resulting Dy2O3 was large irregular aggregates consisting of clumps and clusters (Figure 5A). The PSD of these aggregates was 7.08 μm. 50 (Figure 5B).

[0064] Comparative Example 5: Dy 2 O 3 Synthesis of The following was done: 1) 120 ml of 4.5 M NH4OH was prepared, and 5 g of lauric acid was dissolved in this ammonia solution. 2) A stock solution of Dy(NO3)3 (100 g / L, 2.225 M) was prepared and added to the above mixture. 3) The solution is stirred at room temperature for 1 hour. 4) The final pH was 9.73 and the temperature was 21.8°C. 5) The supernatant was decanted, and the filtrate was replenished with deionized water several times until the conductivity of the filtrate became less than 8 mS / cm, and the precipitate was recovered. 8) The wet cake was collected by suction filtration using a Bühner funnel. 9) The obtained wet cake was calcined at 700°C for 2 hours. Clusters of Dy2O3 aggregates of various sizes were formed (Figure 6A). The PSD showed that they had a D of 21.54 μm. 50 (Figure 6B). Example 6 - Moderately dispersed Dy 2 O 3 Formation of multilayer ceramic capacitors using particles 1. Mix the moderately dispersed Dy2O3 particles prepared here with barium titanate powder (main component) and other raw material powders (e.g., MgO, Y2O3, V2O5, Ho2O3). 2. A polyvinyl butyral (PVB) resin solution is wet mixed with a mixed solvent system of toluene and ethanol to form a ceramic slurry, which is then cast onto a ceramic green sheet using the doctor blade method. 3. The internal electrode pattern is transferred to the ceramic green sheets and laminated onto the top and bottom sheet surfaces. 4. The ceramic green sheets are pressed together using a press, and the sheet laminate is cut to the specified size. 5. The sheet laminate is fired at 1120-1135°C for 2 hours to form the capacitor body, and an external electrode paste containing Cu powder and glass is applied to both ends of the fired capacitor body and printed at 850°C to form the external electrodes. 6. Ni and Sn are plated sequentially using an electrolytic barrel device to produce a multilayer ceramic capacitor.

[0065] Unless otherwise indicated, numerical values ​​expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and the like used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained.

[0066] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present technology are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible, but any numerical values ​​necessarily contain certain errors resulting from the standard deviation found in their respective testing measurements.

[0067] It will be apparent that the compositions and methods described herein are well adapted to achieve the objects and advantages mentioned, as well as those inherent therein. Those skilled in the art will recognize that the methods and systems herein can be embodied in many ways and, as such, should not be limited by the illustrative embodiments and examples set forth above. In this regard, any number of the features of the different embodiments described herein may be combined into one single embodiment, and alternative embodiments having fewer or more than all of the features described herein are possible.

[0068] While various embodiments have been described for purposes of this disclosure, various changes and modifications can be made that are well within the scope contemplated by this disclosure. Numerous other variations may be made that will readily suggest themselves to those skilled in the art and are encompassed by the spirit of this disclosure. The following is further disclosed in relation to the present invention. [1] Moderately dispersed Dy with regular morphology and lateral size ranging from about 10 nm to 1 μm 2 O 3 A composition comprising particles. [2] The composition according to [1], wherein the lateral size is in the range of about 40 nm to 1 μm. [3] The composition according to [1], wherein the lateral size is in the range of about 100 nm to 1 μm. [4] The particle is D 10 and D 90 The composition according to [1], having a particle size distribution of about 0.1 μm to 1 μm. [5] The particles are approximately 10nm to 100nm in diameter. 10 , D of about 0.1 μm to about 0.8 μm 50 , D of about 0.25 μm to 10 μm 90 The composition according to [1], [6] D with particles of approximately 0.25 μm to 5 μm 90 The composition according to [5], [7] D with particles of approximately 0.25 μm to 1 μm 90 The composition according to [5], [8] The composition according to [1], wherein the particles are spherical, ellipsoidal, or cubic. [9] The composition according to [1], comprising about 0 to 50 ppm of chloride.

[10] The composition according to [1], wherein the particles have a single cubic phase.

[11] Moderately dispersed Dy, including: 2 O 3 Method for producing particles: (a) mixing a dysprosium salt, a polymeric additive, and a chelating agent in water to provide a dysprosium precursor solution; (b) heating the dysprosium precursor solution to form a precipitate; and (c) The precipitate was calcined to obtain a well-dispersed Dy 2 O 3 Providing particles.

[12] 11. The method of claim 10, wherein the chelating agent is selected from the group consisting of diethanolamine, 2-amino-2-(hydroxymethyl)-1,3-propanediol, triethanolamine, ethylenediamine, 6-aminohexanoic acid, L-histidine, L-lysine, and mixtures thereof.

[13]

[11] The method according to

[11] , wherein the polymer additive is selected from the group consisting of polyvinylpyrrolidone (PVP), poly(vinyl alcohol) (PVA), polyethyleneimine (PEI), and mixtures thereof.

[14] The method according to

[11] , wherein the dysprosium salt is a water-soluble salt.

[15] The method according to

[14] , wherein the water-soluble salt of dysprosium is a chloride salt or a nitrate salt.

[16] The method according to

[11] , wherein the dysprosium precursor solution in step (a) has a dysprosium concentration of about 0.2 mol / L to 1.5 mol / L.

[17] The method according to

[11] , wherein the dysprosium precursor solution in step (a) has a dysprosium oxide concentration of about 25 to 75 g / L.

[18] The method according to

[11] , wherein in step (a), about 2 to 3 moles of a chelating agent are mixed per mole of dysprosium.

[19] The method according to

[11] , wherein the heating is carried out at a temperature in the range of about 100°C to 350°C for about 15 minutes to 24 hours.

[20] The method according to

[11] , in which the heating in (b) results in a single-crystal precipitate before calcination.

[21] The method according to

[11] , wherein the firing is carried out at a temperature in the range of about 400°C to 1000°C for about 15 minutes to 24 hours.

[22] Calcination yielded well-dispersed Dy nanoparticles with regular morphology and lateral sizes ranging from approximately 40 nm to 1 μm. 2 O 3 The method according to

[11] , wherein particles are provided.

[23] The method according to

[11] , wherein the method does not involve grinding.

[24] Dysprosium oxide particles produced by the method described in

[11] .

Claims

1. Non-aggregated and moderately dispersed Dy with regular morphology and lateral size ranging from 10 nm to 1 μm. ２ O ３ 1. A composition comprising particles, "Properly dispersed" means that Dy ２ O ３ A composition wherein the particles have a polydispersity index value of 0.1 to 0.

4.

2. The composition of claim 1, wherein the lateral size ranges from 40 nm to 1 μm.

3. The composition of claim 1, wherein the lateral size ranges from 100 nm to 1 μm.

4. The particle is D １０ and D ９０ 2. The composition of claim 1, wherein both of said particles have a particle size distribution of 0.1 μm to 1 μm.

5. The particles are D １０ , D of 0.1 μm to 0.8 μm ５０ , D of 0.25 μm to 1 μm ９０ 10. The composition of claim 1, wherein

6. The composition of claim 1 , wherein the particles are spherical, ellipsoidal, or cubic.

7. The composition of claim 1 comprising 0 to 50 ppm chloride.

8. The composition of claim 1 , wherein the particles have a single cubic phase.

9. The composition of claim 1, wherein the particles have a D 50 of 10 nm to 0.2 μm and a D 90 of 0.2 μm to 1 μm.

10. The composition of claim 1, wherein the particles have a D 50 of 10 nm to 0.15 μm and a D 90 of 0.2 μm to 0.75 μm.

11. Moderately dispersed Dy, including: ２ O ３ Method for producing particles: (a) mixing a dysprosium salt, a polymeric additive, and a chelating agent in water to provide a dysprosium precursor solution; (b) heating the dysprosium precursor solution to form a precipitate; and (c) The precipitate is calcined to obtain a well-dispersed Dy ２ O ３ Providing particles; "Properly dispersed" means that Dy ２ O ３ This means that the polydispersity index value of the particles is between 0.1 and 0.

4.

12. 12. The method of claim 11, wherein the chelating agent is selected from the group consisting of diethanolamine, 2-amino-2-(hydroxymethyl)-1,3-propanediol, triethanolamine, ethylenediamine, 6-aminohexanoic acid, L-histidine, L-lysine, and mixtures thereof.

13. 12. The method of claim 11, wherein the polymeric additive is selected from the group consisting of polyvinylpyrrolidone (PVP), poly(vinyl alcohol) (PVA), polyethyleneimine (PEI), and mixtures thereof.

14. 12. The method of claim 11, wherein the dysprosium salt is a water-soluble salt.

15. 15. The method of claim 14, wherein the water-soluble salt of dysprosium is a chloride salt or a nitrate salt.

16. 12. The method of claim 11, wherein the dysprosium precursor solution of step (a) has a dysprosium concentration of 0.2 mol / L to 1.5 mol / L.

17. 12. The method of claim 11, wherein the dysprosium precursor solution of step (a) has a dysprosium oxide concentration of 25 to 75 g / L.

18. 12. The method according to claim 11, wherein in step (a), 2 to 3 moles of chelating agent are mixed per mole of dysprosium.

19. 12. The method of claim 11, wherein the heating is carried out at a temperature in the range of 100°C to 350°C for 15 minutes to 24 hours.

20. The method of claim 11, wherein the heating in (b) results in a single-crystal precipitate before calcination.

21. The method of claim 11, wherein the calcination is carried out at a temperature in the range of 400°C to 1000°C for 15 minutes to 24 hours.

22. Calcination yielded well-dispersed Dy nanoparticles with regular morphology and lateral sizes ranging from 40 nm to 1 μm. ２ O ３ The method of claim 11 wherein particles are provided.

23. 12. The method of claim 11, wherein the method does not include grinding.

24. The composition of claim 1, wherein the particles are round or faceted.

25. The composition of claim 1, wherein the particles have a crystalline structure.

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