CN1654424A - Process for preparing yttrium aluminum garnet powder - Google Patents
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- CN1654424A CN1654424A CN 200410075856 CN200410075856A CN1654424A CN 1654424 A CN1654424 A CN 1654424A CN 200410075856 CN200410075856 CN 200410075856 CN 200410075856 A CN200410075856 A CN 200410075856A CN 1654424 A CN1654424 A CN 1654424A
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Abstract
The present invention is the homogeneous phase microwave urea radiating synthesis process of preparing well dispersive nanometer level monophase YAG powder. The synthesis conditions includes molar ratio between urea and Y-Al ion of 15 and amorphous precursor calcining temperature of 900 deg.c to crystallize directly to produce monophase YAG powder. Into the reaction system, proper amount of ammonium sulfate to improve the granulation distribution and sintering performance of YAG powder. When the ammonium sulfate adding amount is 8 %, the YAG powder has excellent sintering performance and average diameter of 10-200 nm.
Description
The technical field is as follows:
the invention belongs to the field of preparation methods of yttrium aluminum garnet powder, and particularly relates to the field of preparation methods of yttrium aluminum garnet powder synthesized by microwaves.
Background art:
yttrium aluminum garnet of formula Y3Al5O12YAG has high melting point, high hardness, low creep rate at high temperature, low electrical conductivity and stable chemical and thermal properties, is a very excellent high-temperature structural material, is particularly used for insulating or refractory coatings, and attracts a plurality of researchers to research and develop (ceramics, Eng, Sci, Proc., 1994, 14 (7-8): 181-. Pure YAG is transparent in visible and near infrared regions, the dodecahedron interstitial position can be partially doped or completely replaced by rare earth element cations, and the pure YAG can be used as fluorescent powder of a solid laser and a cathode ray tube, and is an important optical functional material. YAG powder prepared by traditional solid-phase reaction method is subjected to YAM (Y) in the reaction process4A2O9) And YAP (YAlO)3) Transition phase, which makes the temperature of the YAG phase to be above 1400 ℃, and the sinterability of the obtained YAG powder is poor (Chinese non-ferrous metals bulletin, 2003, 13(2), 432-. In recent years, the research on the synthesis of YAG by various wet chemical methods has attracted more and more attention, and the significant effect is that the temperature for producing YAG is reduced to 1000 ℃ or below, the wet chemical synthesis conditions directly affect the performance of theYAG precursor, and finally determine the calcination temperature for producing the YAG phase and the performance of the powder thereof. Searching for more appropriate synthesis conditions, making the synthesized precursor finer in particle size and more uniform in components, and effectively avoiding hard agglomeration of the precursor in the drying and calcining processes, is the key to obtain good sinterability YAG powder. As an important structural and functional material, studies on the preparation of YAG nanopowders have been reported in many documents in recent years, and compared to conventional solid-phase high-temperature reaction methods, improvements are made to some extent in the YAG phase formation temperature, powder activity, uniformity of components, and the like, but each of them has its own disadvantages. YAG powder obtained by a high-energy ball milling method has large particles and serious agglomeration. The combustion method is easy to introduce carbon element in the combustion process, so that the purity of the product is reduced, and the sinterability is reduced. In addition, the shape and size of the product particles are not easily controlled due to the severity and explosiveness of the combustion process. The solvothermal process has a very low yield and expensive equipment. In the polymer network gel methodThe used organic reagent is not easy to be thoroughly removed, so that the purity of the powder is influenced; in addition, the process of the method is relatively complicated. Although the sol-gel method uses inorganic salt to replace metal alkoxide, the synthesis cost is reduced, but oxides are connected by bridge oxygen bonds, hard agglomeration is easily formed after drying, and the sinterability of products is influenced. The eutectic method is due to Al (NO)3)3And Y (NO)3)3Has different melting point and thermal decomposition temperature, and although the solution is mixed to molecular level in the initial stage, Al is in the subsequent treatment2O3And Y2O3Gradually separates, thus raising the synthesis temperature. Compared with other methods, the precipitation method has the advantages of simpler synthetic route, lower cost and easy and accurate control. However, in the coprecipitation method, the uniformity of the microscopic composition cannot be realized due to the difference in concentration and precipitation speed generated by precipitation among the components; the conventional water-bath heating homogeneous precipitation method achieves uniform mixing of reactant atomic sizes, but has long synthesis time, large energy consumption, high required ratio of urea concentration to mixed metal ion concentration (e.g. 150: 1), low efficiency, and is not suitable for industrial production (Materials Letters, 2002, 56: 344-.
The microwave synthesis of ultramicro materials not only has the advantages of uniform and rapid heating, simple operation and the like, but also has the characteristic of inducing or promoting certain chemical reactions by the microwave effect, and further shows the unique advantages (Jinchanghan. microwave chemistry, first edition. Beijing: science publishers, 2001.110-112). Meanwhile, the research results of the literature (Journal of Alloys and composites, 1998, 275-.
The invention content is as follows:
in order to accomplish the task of the present invention, the present inventors have succeeded in preparing yttrium aluminum garnet powder of a nanometer size using the following technical features. The method for preparing the nano-sized yttrium aluminum garnet powder of the present invention will be described in detail.
A preparation method of yttrium aluminum garnet powder comprises the following steps:
(1) dissolving Y2O3 powder with the purity of 95-99.99% in nitric acid, and adding distilled water to prepare 1000ml of Y (NO3)3 solution with the concentration of 0.05-6M;
(2) analytically pure Al (NO) is added to the prepared solution3)3·9H2O, according to the molar ratio of Y to Al of 0.1-5, stirring and dissolving the mixture until the mixture is uniform to obtain mother liquor;
(3) adding distilled water into a certain amount of mother liquor, diluting to 2-8 times according to ((Al)3++Y3+) Adding 0.01-0.5 mol of (NH) based on the sum of the mol numbers of 14)2SO4(ii) a Adding 2-40 mol of urea, and stirring to prepare a uniform reaction solution;
(4) heating the reaction solution in a microwave oven for 30-45 min, taking out, washing with water and/or absolute ethyl alcohol, and filtering; drying the product obtained by suction filtration in a drying oven for 6-8 hours;
(5) calcining the dried product at the temperature of 800-1100 ℃;
the average diameter of the yttrium aluminum garnet powder obtained by the preparation method is 10-200 nm, and the best average diameter is 40-90 nm.
According to the preparation method of the yttrium aluminum pomegranate powder, the urea solution generates the following reactions in the heating process:
OH produced by ionization-And CO3 2-The anion is combined with yttrium aluminum cation in the solution to generate a precursor, so that the dosage of urea and the synthesis reaction process are of great importance to the influence of the product. The dosage of the urea is too low, and single-phase YAG cannot be obtained; the useamount of the urea is too high, so that the concentration of metal ions is reduced too low, and the efficiency of synthesizing YAG is extremely low. FIG. 1 is an XRD spectrum of a calcined product of precursors synthesized with different amounts of urea at 1100 ℃ under the action of microwave irradiation, from which it can be seen that when the molar ratio of urea to yttrium aluminum ions is 15: 1, the precursor synthesized by microwave irradiation is kept at 1100 ℃ for 2 hours to obtain single-phase YAG, which is completely the same as the result obtained at 20: 1, while when the molar ratio of urea to yttrium aluminum ions is 10: 1, only a small amount of YAG is generated in the calcined product, and the main crystal phases are mainly YAP and YAM, which may be caused by that the anions generated by decomposition of urea cannot completely precipitate metal cations due to too low concentration of urea. The yield of YAG is greatly improved by adopting microwave irradiation, and because the microwave irradiation not only can quickly and uniformly heat the reaction solution, but also can promote urea to be quickly ionized and hydrolyzed by the microwave effect, the concentration of the anion of the precipitator is kept above the critical concentration of the nucleation of the precursor, so that the dosage of the urea is obviously reduced.
The microwave irradiation can promote the urea solution to be ionized and hydrolyzed rapidly, and single-phase YAG powder is successfully synthesized under the condition of low urea dosage with the mole ratio of urea to yttrium aluminum ions being 15: 1, thereby greatly improving the yield of YAG; adding a proper amount of (NH) into a reaction system4)2SO4The particle size distribution of the YAG powder after calcination can be obviously improved along with (NH)4)2SO4The addition amount is increased from 2 percent to 8 percent, and the particle size distribution of the producedYAG powder reaches the best; the chemical formula of the synthesized nano amorphous precursor is (NH)4)0.2AlY0.6(OH)2(CO3)1.4(SO4)0.1·0.4H2O, the precursor is directly crystallized by calcining at 900 DEG CForming a YAG polycrystalline phase; adding 8% of (NH)4)2SO4The YAG powder produced has good sinterability, and is pressureless sintered in 1500 ℃ air, and the relative density of the sintered body reaches 97.5%.
The testing instrument adopts an American Bio-Rad FIS-165 infrared spectrometer, a German relaxation-resistant STA-409-EP type comprehensive thermal analyzer and a Japanese science D/max-RA type X-ray diffractometer to analyze the chemical composition of a precursor and the phase change process of the precursor; the particle size distribution of the powder is analyzed by adopting an American Coulter Beckmann LS13320 laser diffraction particle tester, and the morphology and the particle size of the powder are observed by adopting a Japanese JEOL-2 type transmission electron microscope.
The invention has the advantages that: by adopting a microwave homogeneous synthesis method, the common advantages of microwave irradiation and homogeneous precipitation are exerted, not only is the synthesis efficiency improved, but also the uniform mixing of microcosmic components in the reaction process is realized; according to the invention, cheap inorganic ammonium sulfate is used as a raw material, the nano-scale single-phase YAG powder with good dispersibility is successfully prepared by adopting a microwave irradiation urea method homogeneous synthesis technology, the dispersibility of a synthesized YAG precursor is improved by adding a proper amount (a small amount) of ammonium sulfate, the obvious effect is achieved, and the defects that the YAG precursor is easy to agglomerate and difficult to wash, and is easy to gel after being dried to cause hard agglomeration and the like in the existing wet preparation technology are effectively overcome; the granularity of YAG powder is 10-120 nm, optimally 70-90 nm by adopting LD (laser diffraction) and TEM, and the YAG powder has good sintering performance.
Description of the drawings:
FIG. 1 is an XRD curve of a calcined product of the precursor synthesized in different embodiments at 1100 ℃;
FIG. 2 Infrared Spectrum of YAG precursor in example 2;
FIG. 3 DTA/TG curve of YAG precursor in example 2;
FIG. 4 TEM results of YAG precursors and their calcined product YAG powder particles at 1100 deg.C: (a) a precursor, (b) YAG powder, (c) an ED pattern of YAG particles;
figure 5 XRD curves of the precursor of example 2 and its calcined product at different temperatures.
The specific implementation mode is as follows:
mixing Y with purity of 99.99%2O3Dissolving the powder in nitric acid, adding distilled water to obtain 0.3M Y (NO)3)31000ml of solution; accurately weighing analytically pure Al (NO) according to the molar ratio of Y to Al of 3: 53)3·9H2O is added to Y (NO)3)3The solution was dissolved with stirring and homogenized for use as a stock mother salt solution.
80ml of mother salt solution is weighed and diluted to 320ml by adding water, and urea (CO (NH)2)2) And (Al)3++Y3+) The total molar weight ratio is within the range of 10-30, urea withdifferent dosage is added, and (NH) is added according to different percentages of the mother salt mass4)2SO4The reaction solutions were prepared as shown in Table 1, and the reaction solutions were heated for 30 minutes in a WD700 type microwave oven having a microwave frequency of 2.45GHz and an output of 900W.
Washing the precursor synthesized by microwave with distilled water and absolute ethyl alcohol respectively for three times, drying the precursor after suction filtration in a thermostat at 60 ℃ for 8 hours, and then calcining at different temperatures within the temperature range of 500-1100 ℃.
And carrying out dry die pressing on the YAG powder obtained after calcination under the pressure of 200MPa to form a wafer with the diameter of 13mm and the thickness of 2mm, sintering the wafer in the air at 1500 ℃ for 2 hours under no pressure, and then measuring the density of a sintered body by adopting an Archimedes method.
TABLE 1 reaction solution proportioning Table
Reaction solution [ urine [ Y]3+][Al3+][ Urea]][(NH4)2SO4]/[Y3++Al3+]
Liquid composition]/[Y3++Al3+]Molal concentration mol% concentration
Parts by weight: degree of molar ratio
Example 1100.0750.12524
Examples 2150.0750.12530, 2, 4, 6, 8, 12, 16
Example 3200.0750.12544
FIG. 1 is an XRD spectrum of a calcined product of a precursor synthesized by different urea dosages at 1100 ℃ under the action of microwave irradiation, when the molar ratio of urea to yttrium aluminum ions is 15: 1, the precursor synthesized by the microwave irradiation is kept at 1100 ℃for 2 hours to obtain single-phase YAG, the result is completely the same as that of the calcined product at 20: 1, and when the molar ratio of urea to yttrium aluminum ions is 10: 1, only a small amount of YAG is generated in the calcined product, and main crystal phases are mainly YAP and YAM, which is probably caused by that the anions generated by the decomposition of the urea cannot completely precipitate metal cations due to the low concentration of the urea. As in document [ j.am.ceram.soc., 1999, 82 (8): 1977-1984]the molar ratio of urea to yttrium aluminum ions reported in YAG preparation by a water-bath heating urea method is 150: 1, the urea dosage is reduced by 10 times, the concentration of metal ions is increased by 15 times, and the synthesis reaction time is greatly shortened, so that the YAG yield is greatly improved by adopting microwave irradiation, the microwave irradiation not only enables the reaction solution to be rapidly and uniformly heated, but also enables the urea to be rapidly ionized and hydrolyzed by the microwave effect, so that the concentration of precipitator anions is kept above the critical concentration of precursor nucleation, and the urea dosage is remarkably reduced.
Different contents of (NH) were added by analyzing the reaction system4)2SO4The particle size distribution accumulation curve of YAG powder obtained by calcining the synthesized precursor at 1100 ℃ is obtained to obtain No (NH)4)2SO4The added YAG precursor is subjected to hard agglomeration in the calcining process, so thatThe granularity of the calcined YAG powder is coarse and the distribution is wide; and (NH)4)2SO4The addition of (A) can obviously improve the particle size distribution of the YAG powder after calcination, along with (NH)4)2SO4The addition amount is increased from 2 percent to 8 percent, the particlesize distribution of the produced YAG powder is optimal, and the average particle size is 87 nm.
From the results of infrared spectroscopic analysis of the precursor of example 2 in fig. 2, in combination with the DTA/TG curve of example 2 in fig. 3, reference [ j.mater.res., 2000, 15 (9): 1864-1867.]Similar analysis can be used to obtain the approximate formula of the amorphous precursor: (NH)4)0.2AlY0.6(OH)2(CO3)1.4(SO4)0.1·0.4H2And O, the theoretical weight loss of the YAG generated by the method is 45.7 percent, and is basically consistent with the actual measurement result. FIG. 5 shows that the precursor is amorphous below 600 ℃, YAG phase begins to crystallize and separate out at 800 ℃, all the calcined product at 900 ℃ is YAG phase, and the diffraction peak of the YAG phase becomes sharper and sharper as the calcination temperature is increased to 1100 ℃, which shows that the crystallization degree of the YAG phase is further increased. The amorphous precursor synthesized under the action of microwave irradiation is pyrolyzed and directly crystallized to form a YAG phase, intermediate phases YAM and YAP are not generated, and the forming temperature of the YAG phase at 900 ℃ is obviously reduced compared with that of a conventional urea heating method. Compared with the conventional method, under the action of microwave irradiation, a great amount of precursor crystal nuclei germinate in an exploding mode, yttrium aluminum cations and related anions nucleate simultaneously, the generation of distribution precipitation of yttrium aluminum ions in conventional heating is avoided, and the forming rate of the crystal nuclei is greater than the growing rate of the crystal nuclei, so that the particle size of the synthesized precursor is smaller and more uniform, and in addition, because the two components of yttrium aluminum are uniformly distributed at the atomic level, the combined diffusion path is shortened, and the precursor directly generates a YAG phase at a low temperature.
FIG. 4 shows the reaction system of example 2 with 8% addition of (NH)4)2SO4The synthesized precursor and the TEM morphology of the YAG powder particles calcined at 1100 ℃ show that the precursor particles are spherical, the particle size is about 40nm basically, and certain soft agglomeration characteristics are presented. YAG powder particles formed by sintering crystal at 1100 deg.C are spherical or spindle-shaped, the short axis diameter is about 60nm, and the long axis diameter is 60-200nm are different.
The microwave irradiation can promote the urea solution to be ionized and hydrolyzed rapidly, and single-phase YAG powder is successfully synthesized under the condition of low urea dosage with the mole ratio of urea to yttrium aluminum ions being 15: 1, thereby greatly improving the yield of YAG; adding a proper amount of (NH) into a reaction system4)2SO4The particle size distribution of the YAG powder after calcination can be obviously improved along with (NH)4)2SO4The addition amount is increased from 2 percent to 8 percent, and the particle size distribution of the produced YAG powder reaches the best; the chemical formula of the synthesized nano amorphous precursor is (NH)4)0.2AlY0.6(OH)2(CO3)1.4(SO4)0.1·0.4H2O, calcining the precursor at 900 ℃ and directly crystallizing to generate YAG polycrystalline phase; adding 8% of (NH)4)2SO4The YAG powder produced has good sinterability, and is pressureless sintered in 1500 ℃ air, and the relative density of the sintered body reaches 97.5%.
Claims (3)
1. A preparation method of yttrium aluminum garnet powder is characterized by comprising the following steps:
(1) mixing Y with purity of 95-99.99%2O3Dissolving the powder in nitric acid, adding distilled water to obtain 0.05-6M Y (NO)3)3The volume of the solution is 1000ml,
(2) analytically pure Al (NO) is added to the prepared solution3)3·9H2O, according to the molar ratio of Y to Al of 3: 5, stirring and dissolving the mixture until the mixture is uniform to obtain mother liquor,
(3) adding distilled water into a certain amount of mother liquor, diluting to 2-8 times, and adding (Al)3++Y3+) Adding 0.01-0.5 mol of (NH) based on the sum of the mol numbers of 14)2SO4(ii) a Adding 2-40 mol of urea, stirring to prepare a uniform reaction solution,
(4) heating the reaction solution in a microwave oven for 30-45 min, taking out, washing with water and/or absolute ethyl alcohol, and filtering; drying the product obtained by suction filtration in a drying oven for 6-8 hours,
(5) the dried product was calcined at a temperature of 800-.
2. The method of claim 1, wherein: according to (Al)3++Y3+) The sum of the number of moles is 1, and the number of moles of urea added is 15.
3. The method of claim 1, wherein: according to (Al)3++Y3+) The sum of the number of moles of ammonium sulfate added was 1, and the number of moles of ammonium sulfate added was 0.08.
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| CZ302642B6 (en) * | 2010-06-18 | 2011-08-10 | Ceské vysoké ucení technické v Praze Fakulta jaderná a fyzikálne inženýrská | Process for preparing powder ceramic material Y3AI5O12 (YAG) |
| CN102585826A (en) * | 2011-12-23 | 2012-07-18 | 彩虹集团公司 | Preparation method for rare earth doped yttrium aluminum garnet crystal precursor |
| CN101386784B (en) * | 2008-09-05 | 2013-06-26 | 陈哲 | Method for synthesizing nano fluorescent powder by microwave excited low-temperature liquid phase combustion |
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| CN1204083C (en) * | 2002-08-28 | 2005-06-01 | 中国科学院上海硅酸盐研究所 | Prepn of ion doped yttrium aluminium garnet nano-powder |
| CN1442364A (en) * | 2003-04-15 | 2003-09-17 | 山东大学 | Preparation method of spherical agglomeration less yttrium aluminium garnet nano micropowder |
| CN1249275C (en) * | 2003-06-27 | 2006-04-05 | 中国科学院上海硅酸盐研究所 | Preparation method of yttrium aluminium garnet nano-powder |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101386784B (en) * | 2008-09-05 | 2013-06-26 | 陈哲 | Method for synthesizing nano fluorescent powder by microwave excited low-temperature liquid phase combustion |
| CZ302642B6 (en) * | 2010-06-18 | 2011-08-10 | Ceské vysoké ucení technické v Praze Fakulta jaderná a fyzikálne inženýrská | Process for preparing powder ceramic material Y3AI5O12 (YAG) |
| CN102585826A (en) * | 2011-12-23 | 2012-07-18 | 彩虹集团公司 | Preparation method for rare earth doped yttrium aluminum garnet crystal precursor |
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