Preparation method of monodisperse yttrium oxide with controllable morphology

Abstract

The application discloses a preparation method of monodisperse yttrium oxide with controllable morphology and belongs to the technical field of rare earth materials. The preparation method of the monodisperse yttrium oxide with controllable morphology comprises the following steps: adding a surfactant into an aqueous solution of a precipitant, stirring under heating, slowly adding an aqueous solution of yttrium nitrate, adjusting the pH value to 6.5-7.5, stirring and reacting, and preparing the yttrium oxide through aging, suction filtration, washing, drying, calcination, cooling, grinding and sieving. The prepared yttrium oxide has a narrow particle size distribution and good monodispersity, and the morphology and particle size can be controlled.

Description

Technical Field

[0001] This invention relates to the field of rare earth materials technology, and specifically to a method for preparing monodisperse yttrium oxide with controllable morphology. Background Technology

[0002] Yttrium oxide (Y₂O₃) is an important rare earth oxide material with excellent corrosion resistance, heat resistance, dielectric properties, and optical properties, and is widely used in optoelectronic devices, advanced ceramics, catalysts, and coatings. With the increasing demands for powder performance in related fields, the particle size uniformity, morphological controllability, and dispersibility of yttrium oxide powder have become crucial factors affecting its performance. Currently, yttrium oxide powder is typically prepared using a precipitation method. This method uses yttrium salts such as yttrium nitrate as raw materials and ammonium carbonate, ammonium bicarbonate, or oxalate as precipitants to first generate a yttrium-containing precipitate precursor, which is then dried and calcined to obtain yttrium oxide. This method is simple, has mild conditions, and is suitable for industrial production. However, during the precipitation process, the reaction between yttrium ions and the precipitant is rapid, making it difficult to control local supersaturation. This can easily lead to inconsistent nucleation and growth of the precursor, resulting in yttrium oxide powder with problems such as wide particle size distribution, unstable morphology, and particle agglomeration.

[0003] Chinese invention patent CN101698609A discloses a method for preparing spherical, monodisperse, single-size yttrium oxide nanoparticles. This method involves adding urea to a solution containing yttrium ions and using a homogeneous precipitation method to prepare spherical, monodisperse rare-earth ion-doped yttrium oxide nanoparticles. Monodisperse nanoceramic powders with a single size are crucial for preparing high-transmittance transparent ceramics. This invention utilizes the slow decomposition of urea in water upon heating to alter the pH value of the solution, causing the yttrium salt solution containing rare-earth ions to precipitate monodisperse, single-size spherical particles. Calcination then produces single-size spherical nanoparticles suitable for sintering transparent ceramics. After molding and sintering, rare-earth ion-doped yttrium oxide transparent ceramics can be obtained. However, this invention has shortcomings in the morphology control of yttrium oxide. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing monodisperse yttrium oxide with controllable morphology.

[0005] A method for preparing monodisperse yttrium oxide with controllable morphology includes the following steps: adding a surfactant to an aqueous precipitant solution, heating and stirring, slowly adding an aqueous yttrium nitrate solution, adjusting the pH to 6.5-7.5, stirring the reaction, and then aging, filtering, washing, drying, calcining, cooling, grinding, and sieving to obtain yttrium oxide;

[0006] The surfactant is a compound of lauroyl glutamate ammonium and hexadecyltrimethylammonium bromide;

[0007] The lauroyl glutamate ammonium is obtained by acidification and ammoniation of sodium lauroyl glutamate.

[0008] The mass ratio of the compounded lauroyl glutamate ammonium to hexadecyltrimethylammonium bromide is (1.4-3):1.

[0009] The precipitant is one of ammonium carbonate and ammonium bicarbonate.

[0010] The concentration of the precipitant aqueous solution is 0.6-1 mol / L; the concentration of the yttrium nitrate aqueous solution is 0.3-1 mol / L.

[0011] The molar ratio of the precipitant to yttrium nitrate is (2-5):1.

[0012] The surfactant is added at a rate of 40-80g per 1mol of yttrium nitrate.

[0013] The temperature for heating and stirring is 60-70℃, and the time is 30-60 minutes.

[0014] The stirring reaction is carried out at a temperature of 60-70℃ for 1-2 hours.

[0015] The drying temperature is 90-120℃, and the time is 12-15h.

[0016] The calcination procedure is as follows: heat the temperature to 500-600℃ at a heating rate of 2-5℃ / min, calcin for 1-2 hours, and then heat the temperature to 800-900℃ at a heating rate of 2-5℃ / min, and calcin for 1-2 hours.

[0017] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0018] This invention employs a morphology modifier composed of ammonium lauroyl glutamate and hexadecyltrimethylammonium bromide. It utilizes the coordination adsorption of carboxylates and amide groups onto the surface of yttrium ions or yttrium oxide precursors, as well as the electrostatic association and hydrophobic synergistic effect between the two surfactants, to simultaneously regulate the nucleation, growth, and dispersion processes of yttrium oxide precursors. This method can suppress disordered particle aggregation and uneven growth, resulting in yttrium oxide with a narrow particle size distribution and good monodispersity. Furthermore, by adjusting the ratio of the compound surfactants, the amount of precipitant, and the reaction conditions, a controllable transformation of yttrium oxide from a nanosheet structure to a cuboid-like polyhedral structure can be achieved. Attached Figure Description

[0019] Figure 1 The infrared spectra of sodium lauroyl glutamate and ammonium lauroyl glutamate in Example 1 are shown below.

[0020] Figure 2Scanning electron microscope image of monodisperse yttrium oxide prepared in Example 2;

[0021] Figure 3 Scanning electron microscope image of monodisperse yttrium oxide prepared in Example 3;

[0022] Figure 4 Scanning electron microscope image of monodisperse yttrium oxide prepared in Example 4;

[0023] Figure 5 A scanning electron microscope image of the monodisperse yttrium oxide prepared in Example 5;

[0024] Figure 6 The image shown is a scanning electron microscope (SEM) image of the monodisperse yttrium oxide prepared in Example 6. Detailed Implementation

[0025] Example 1: Preparation of ammonium lauroyl glutamate

[0026] Mix 100 ml anhydrous ethanol, 100 ml deionized water, and 10 g sodium lauroyl glutamate. Stir at 25 °C and 200 rpm for 30 min. Adjust the pH to 2.5 with 0.5 mol / L hydrochloric acid solution. Stir at 25 °C and 200 rpm for 1 h. Filter and collect the precipitate. Wash with deionized water (3 × 80 ml). Then redisperse the precipitate in a mixture of 50 ml anhydrous ethanol and 100 ml deionized water. Stir at 30 °C and 300 rpm for 20 min. Adjust the pH to 7 with 0.5 mol / L ammonia solution. Stir at 30 °C and 300 rpm for 1.5 h. Concentrate under reduced pressure at 40 °C for 2 h. Dry under vacuum at 40 °C for 12 h to obtain ammonium lauroyl glutamate.

[0027] Figure 1 The figures show the infrared spectra of sodium lauroyl glutamate and ammonium lauroyl glutamate. As can be seen from the figures, sodium lauroyl glutamate has a wavelength of 2921 cm⁻¹. -1 2851cm -1 An aliphatic -CH2- stretching vibration absorption peak appears nearby, at 1645 cm⁻¹. -1 An absorption peak for amide I appears nearby, at 1554 cm⁻¹. -1 and 1412cm -1 COO appeared nearby - Absorption peaks for antisymmetric and symmetric stretching vibrations. After acidification and amination treatment, the resulting product shows an absorption peak at 2922 cm⁻¹. -1 2852cm -1 The aliphatic CH2- absorption peak is retained nearby, at 1642 cm⁻¹. -1 The presence of a retained amide I absorption peak nearby indicates that the lauroyl chain and amide skeleton were not destroyed; simultaneously, the product showed an absorption peak at 1455 cm⁻¹. -1 NH4 appeared nearby +The absorption peaks related to the overlap of bending vibration and aliphatic chain -CH2- vibration, and COO - The antisymmetric stretching vibration peak is 1554 cm⁻¹ -1 Moved to 1592cm -1 COO - The symmetrical stretching vibration peak is 1412 cm⁻¹ -1 Moved to 1392cm -1 This indicates that the counter-ion environment of the carboxylate has changed (based on this preparation process, it is inferred that the counter-ion environment of the carboxylate is changed by Na). + Transformed into NH4 + The above results indicate that sodium lauroyl glutamate was converted into ammonium lauroyl glutamate after acidification and ammoniation treatment.

[0028] Example 2 Preparation of Monodisperse Yttrium Oxide

[0029] Add surfactant (1.4 g of ammonium lauroyl glutamate prepared in Example 1 and 1 g of hexadecyltrimethylammonium bromide) to 100 ml of 0.6 mol / L ammonium carbonate aqueous solution, heat to 60 °C, stir at 300 rpm for 60 min, sonicate (200 W, 20 kHz) for 10 min, and slowly add 100 ml of [the solution]. A 0.3 mol / L yttrium nitrate aqueous solution (with the pH adjusted to 7.5 using 0.25 mol / L nitric acid solution or 0.25 mol / L ammonia solution during the dropwise addition) was added over 30 min. The mixture was then stirred at 60℃ and 400 rpm for 2 h. After standing and aging at 60℃ for 3 h, the mixture was filtered. The filter cake was washed with deionized water until neutral, then washed with anhydrous ethanol (2 × 50 ml). The cake was then dried in a forced-air drying oven at 90℃ for 15 h. The temperature was increased to 500℃ at a rate of 2℃ / min and calcined for 2 h. The temperature was then increased to 800℃ at a rate of 2℃ / min and calcined for 2 h. The mixture was allowed to cool naturally to room temperature, ground for 5 min, and then passed through a 300-mesh sieve to obtain monodisperse yttrium oxide.

[0030] Example 3 Preparation of Monodisperse Yttrium Oxide

[0031] Add surfactant (2g of lauroyl glutamate ammonium prepared in Example 1 and 1g of hexadecyltrimethylammonium bromide) to 300ml of 0.8mol / L ammonium bicarbonate aqueous solution, heat to 65℃, stir at 300rpm for 45min, sonicate (200W, 20kHz) for 10min, and slowly add 100ml of [the solution]. A 0.6 mol / L yttrium nitrate aqueous solution (with the pH adjusted to 7.0 using 0.25 mol / L nitric acid solution or 0.25 mol / L ammonia solution during the dropwise addition) was added over 40 min. The mixture was then stirred at 65℃ and 400 rpm for 1.5 h. After standing and aging at 65℃ for 2.5 h, the mixture was filtered. The filter cake was washed with deionized water until neutral, then washed with anhydrous ethanol (2 × 50 ml). The cake was then dried in a forced-air drying oven at 100℃ for 14 h. The temperature was increased to 550℃ at a rate of 3℃ / min and calcined for 1.5 h. The temperature was then increased to 850℃ at a rate of 3℃ / min and calcined for 1.5 h. The mixture was allowed to cool naturally to room temperature, ground for 5 min, and then passed through a 300-mesh sieve to obtain monodisperse yttrium oxide.

[0032] Example 4 Preparation of Monodisperse Yttrium Oxide

[0033] Add surfactant (3g of ammonium lauroyl glutamate prepared in Example 1 and 1g of hexadecyltrimethylammonium bromide) to 500ml of 1mol / L ammonium bicarbonate aqueous solution, heat to 70°C, stir at 300rpm for 30min, sonicate (200W, 20kHz) for 10min, and slowly add 100ml of [the solution]. A 1 mol / L yttrium nitrate aqueous solution (with the pH adjusted to 6.5 using 0.25 mol / L nitric acid solution or 0.25 mol / L ammonia solution during the dropwise addition) was added over 1 hour. The mixture was then stirred at 70°C and 400 rpm for 1 hour. After standing and aging at 70°C for 2 hours, the mixture was filtered. The filter cake was washed with deionized water until neutral, then washed with anhydrous ethanol (2 × 50 ml). The cake was then dried in a forced-air drying oven at 120°C for 12 hours. The temperature was increased to 600°C at a rate of 5°C / min and calcined for 1 hour. The temperature was then increased to 900°C at a rate of 5°C / min and calcined for 1 hour. The mixture was then allowed to cool naturally to room temperature, ground for 5 minutes, and passed through a 300-mesh sieve to obtain monodisperse yttrium oxide.

[0034] Example 5 Preparation of Monodisperse Yttrium Oxide

[0035] Add surfactant (1.75 g of ammonium lauroyl glutamate prepared in Example 1 and 1.25 g of cetyltrimethylammonium bromide) to 300 ml of 0.8 mol / L ammonium bicarbonate aqueous solution, heat to 65 °C, stir at 300 rpm for 45 min, disperse by ultrasonication (200 W, 20 kHz) for 10 min, and slowly add 100 ml of [the solution]. A 0.6 mol / L yttrium nitrate aqueous solution was added dropwise (the pH was adjusted to 7.0 using 0.25 mol / L nitric acid solution or 0.25 mol / L ammonia solution during the dropwise addition process), and the mixture was stirred at 50℃ and 400 rpm for 1.5 h. The mixture was then allowed to stand and age at 50℃ for 2.5 h, filtered, and the filter cake was washed with deionized water until neutral. It was then washed with anhydrous ethanol (2 × 50 ml) and dried in a forced-air drying oven at 100℃ for 14 h. The temperature was then increased to 550℃ at a rate of 3℃ / min and calcined for 1.5 h. The temperature was then increased to 850℃ at a rate of 3℃ / min and calcined for 1.5 h. The mixture was allowed to cool naturally to room temperature, ground for 5 min, and then passed through a 300-mesh sieve to obtain monodisperse yttrium oxide.

[0036] Example 6 Preparation of Monodisperse Yttrium Oxide

[0037] Add surfactant (2.25 g of ammonium lauroyl glutamate prepared in Example 1 and 0.75 g of cetyltrimethylammonium bromide) to 300 ml of 0.8 mol / L ammonium bicarbonate aqueous solution, heat to 65 °C, stir at 300 rpm for 45 min, disperse by ultrasonication (200 W, 20 kHz) for 10 min, and slowly add 100 ml of [the solution]. A 0.6 mol / L yttrium nitrate aqueous solution was added dropwise (the pH was adjusted to 7.0 using 0.25 mol / L nitric acid solution or 0.25 mol / L ammonia solution during the dropwise addition process), and the mixture was stirred at 50℃ and 400 rpm for 1.5 h. The mixture was then allowed to stand and age at 50℃ for 2.5 h, filtered, and the filter cake was washed with deionized water until neutral. It was then washed with anhydrous ethanol (2 × 50 ml) and dried in a forced-air drying oven at 100℃ for 14 h. The temperature was then increased to 550℃ at a rate of 3℃ / min and calcined for 1.5 h. The temperature was then increased to 850℃ at a rate of 3℃ / min and calcined for 1.5 h. The mixture was allowed to cool naturally to room temperature, ground for 5 min, and then passed through a 300-mesh sieve to obtain monodisperse yttrium oxide.

[0038] Comparative Example 1

[0039] The preparation method of monodisperse yttrium oxide with controllable morphology is basically the same as that in Example 3, except that lauroyl glutamate ammonium is replaced with an equal weight of sodium lauroyl glutamate.

[0040] Comparative Example 2

[0041] The preparation method of monodisperse yttrium oxide with controllable morphology is basically the same as that in Example 3, except that lauroyl glutamate ammonium is replaced with an equal weight of lauroyl sarcosine ammonium.

[0042] Comparative Example 3

[0043] The preparation method of monodisperse yttrium oxide with controllable morphology is basically the same as that in Example 3, except that hexadecyltrimethylammonium bromide is not added, but only 3g of lauroylglutamate ammonium is added.

[0044] Comparative Example 4

[0045] The preparation method of monodisperse yttrium oxide with controllable morphology is basically the same as that in Example 3, except that lauroyl glutamate ammonium is not added, but only 3g of hexadecyltrimethylammonium bromide is added.

[0046] Comparative Example 5

[0047] The preparation method of monodisperse yttrium oxide with controllable morphology is basically the same as that in Example 3, except that the amount of lauroyl glutamate ammonium added is replaced with 1g and the amount of hexadecyltrimethylammonium bromide added is replaced with 2g.

[0048] Comparative Example 6

[0049] The preparation method of monodisperse yttrium oxide with controllable morphology is basically the same as that in Example 3, except that the amount of lauroyl glutamate ammonium added is replaced with 2.4g and the amount of hexadecyltrimethylammonium bromide added is replaced with 0.6g.

[0050] Comparative Example 7

[0051] The preparation method of monodisperse yttrium oxide with controllable morphology is basically the same as that in Example 3, except that "300 ml 0.8 mol / L ammonium bicarbonate aqueous solution" is replaced with "430 ml 0.8 mol / L ammonium bicarbonate aqueous solution".

[0052] The particle size distribution of yttrium oxide was tested using a laser particle size analyzer. Before testing, 0.1 g of yttrium oxide was added to 10 ml of a 0.1 wt% sodium hexametaphosphate aqueous solution with a pH of 8.5 and ultrasonically dispersed for 5 min at 200 W and 20 kHz using an ultrasonic oscillator. The sample was then added to the circulation chamber of the laser particle size analyzer, and the sample addition amount was adjusted to ensure a light-blocking rate of 12%. The most probable particle size of yttrium oxide was recorded, along with the D10, D50, and D90 particle size values. The particle size distribution width was calculated using the formula Span = (D90 - D10) / D50. Each sample was tested in triplicate, and the average value was taken as the test result. The smaller the Span value, the narrower the particle size distribution and the better the monodispersity of the yttrium oxide powder. The test results are shown in Table 1.

[0053] Table 1 Performance Test Data

[0054]

[0055] Figure 3 , 5 Figures 1 and 6 show scanning electron microscope (SEM) images of Examples 3, 5, and 6. As can be seen from the images, yttrium oxide forms nearly quadrilateral nanosheets. Table 1 shows that its most probable particle sizes are 517, 329, and 643 nm, exhibiting a narrow particle size distribution. The only difference between Examples 3, 5, and 6 is the feed ratio of ammonium lauroylglutamate to hexadecyltrimethylammonium bromide, demonstrating that monodisperse yttrium oxide nanosheets of different particle sizes can be prepared by controlling the feed ratio.

[0056] Figure 2 , 4 The images are scanning electron microscope (SEM) images of Examples 2 and 4. As can be seen from the images, yttrium oxide has a polyhedral structure that is approximately rectangular, and its thickness is significantly increased compared to Example 3.

[0057] In Comparative Example 1, after replacing ammonium lauroyl glutamate with sodium lauroyl glutamate, although the long-chain alkyl and carboxylate structures were still retained, Na... + counterions and NH4 + Differences in hydration capacity, interfacial adsorption state, and calcination residue behavior weaken the electrostatic association and complex adsorption between the ammonium lauroyltrimethylammonium bromide and the crystal facet confinement effect, resulting in a wider particle size distribution. In Comparative Example 2, lauroylsarcosine ammonium has fewer hydrophilic groups and coordination sites than lauroylglutamate ammonium, which affects the Y... 3+ The insufficient selective adsorption capacity of the precursor crystal facets makes it difficult to stably induce uniform sheet-like growth, leading to an increase in the Span value. In Comparative Example 3, the system does not contain hexadecyltrimethylammonium bromide, lacking the electrostatic association and template stabilization provided by the cationic surfactant, making it easy for particles to aggregate randomly during precipitation and aging. In Comparative Example 4, only hexadecyltrimethylammonium bromide is added, lacking the coordination adsorption and crystal facet selective inhibition of lauroylglutamate ammonium, making it difficult to control the orientation growth of the precursor, resulting in greater particle size differences. In Comparative Example 5, the excessive proportion of hexadecyltrimethylammonium bromide leads to an excessive number of local micelles or associated structures, easily causing instantaneous nucleation and uneven precipitation; in Comparative Example 6, the excessive proportion of lauroylglutamate ammonium and insufficient cationic surfactant result in an imbalance between particle growth and dispersion stability, easily forming large particles or agglomerates. In Comparative Example 7, the increased amount of ammonium bicarbonate increases the supersaturation and ionic strength of the system, causing the precipitation rate to be too fast and the local concentration fluctuations to increase, resulting in inconsistent nucleation time and growth degree of different particles.

[0058] Unless otherwise stated, this invention relates to controlling the pH of a system within a target pH value ± 0.2 during pH adjustment.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing monodisperse yttrium oxide with controllable morphology, characterized in that, Includes the following steps: A surfactant was added to the aqueous solution of the precipitant, the temperature was raised and stirred, and yttrium nitrate aqueous solution was slowly added dropwise to adjust the pH to 6.5-7.

5. The reaction was stirred, and the mixture was aged, filtered, washed, dried, calcined, cooled, ground and sieved to obtain yttrium oxide. The surfactant is a compound of lauroyl glutamate ammonium and hexadecyltrimethylammonium bromide; The lauroyl glutamate ammonium is obtained from sodium lauroyl glutamate through acidification and ammoniation. The mass ratio of the compounded lauroyl glutamate ammonium to hexadecyltrimethylammonium bromide is (1.4-3):1; The precipitant is one of ammonium carbonate and ammonium bicarbonate; The amount of surfactant added is 40-80g per 1mol of yttrium nitrate; The calcination process is as follows: heat the temperature to 500-600℃ at a heating rate of 2-5℃ / min, calcin for 1-2 hours, and then heat the temperature to 800-900℃ at a heating rate of 2-5℃ / min, and calcin for 1-2 hours.

2. The method for preparing monodisperse yttrium oxide with controllable morphology according to claim 1, characterized in that, The concentration of the precipitant aqueous solution is 0.6-1 mol / L; the concentration of the yttrium nitrate aqueous solution is 0.3-1 mol / L.

3. The method for preparing monodisperse yttrium oxide with controllable morphology according to claim 1, characterized in that, The molar ratio of the precipitant to yttrium nitrate is (2-5):

1.

4. The method for preparing monodisperse yttrium oxide with controllable morphology according to claim 1, characterized in that, The temperature for heating and stirring is 60-70℃, and the time is 30-60 minutes.

5. The method for preparing monodisperse yttrium oxide with controllable morphology according to claim 1, characterized in that, The stirring reaction is carried out at a temperature of 60-70℃ for 1-2 hours.

6. The method for preparing monodisperse yttrium oxide with controllable morphology according to claim 1, characterized in that, The drying temperature is 90-120℃, and the time is 12-15h.

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