A preparation method of high-purity ferroelastic compound Pb3(PO4)2

Abstract

The present invention discloses a method for preparing a high-purity ferroelastic compound Pb3(PO4)2, comprising: first, grinding and mixing red phosphorus powder and lead oxide powder to obtain a mixed powder; second, sintering the mixed powder in a tubular furnace; and third, cooling the sintered mixed powder in the furnace, removing it from the furnace, and grinding it to obtain a Pb3(PO4)2 polycrystalline powder. The present invention uses a one-step method to synthesize the Pb3(PO4)2 polycrystalline powder. The highly active red phosphorus powder and lead oxide powder are directly mixed and then sintered in an oxygen-containing atmosphere. High-purity Pb3(PO4)2 is generated without introducing any additional substances. The Pb3(PO4)2 polycrystalline powder has extremely strong crystallinity, few impurities, and extremely high purity, making it suitable for the field of microelectronics. Furthermore, the method has high preparation efficiency, does not involve high-concentration acidic solutions, is safer and more environmentally friendly, and is easy to control in each process step, making it suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of ferroelastic material preparation, and in particular relates to a method for preparing a high-purity ferroelastic compound Pb3(PO4)2. Background Art

[0002] As people's demand for miniaturized electronic devices increases, it becomes very important to produce multifunctional components with a length scale of less than 10nm [J.Phys.:Condens.Matter.32(2020)345401]. At present, a series of studies on ferroelastic materials (such as the introduction of domain boundaries, doping, etc.) have proved that due to its good controllability and excellent performance, it is very likely to become the key to the production of extremely small multifunctional components. Pb3(PO4)2 is the first ferroelastic material to be measured to have complete ferroelastic hysteresis, and has become a model compound for ferroelastic deformation [J.Phys.:Condens.Matter.13(2001)5353-5364]. The phase transition of Pb3(PO4)2 occurs at T rans = around 453.6K. At this temperature, the structure of Pb3(PO4)2 changes from trigonal (space group R3m) to monoclinic symmetry (space group C2 / c). This structural change is caused by the deviation of the lead ions from the triaxial center and the subsequent lattice relaxation, including the tilt of the PO4 tetrahedron. The large-scale preparation of Pb3(PO4)2 ferroelastic compounds can not only facilitate related research, but also provide a prerequisite for the possible large-scale application of functional devices in the future. In addition, Pb3(PO4)2 is also a common plastic stabilizer, which is widely used in chemical laboratories, industrial production and environmental fields. Its multiple application functions make Pb3(PO4)2 an indispensable chemical reagent, which has played a positive role in promoting scientific research, promoting industrial development and protecting the environment.

[0003] Regarding the preparation of Pb3(PO4)2 materials, aside from single crystals required for specialized scientific research, the current method for preparing polycrystalline Pb3(PO4)2 for industrial use primarily relies on solid-phase reaction methods. A typical example is the method described in [J. Phys.: Condens. Matter. 13 (2001) 5353-5364], which involves placing a mixture of PbO and (NH4)H2PO4 in a sealed Al2O3 crucible, heating it at 720K for 8 hours, then cooling it to room temperature and grinding it into a powder. However, the polycrystalline powder produced using this method is not sufficiently pure. Furthermore, Chinese patent application number 200610031505.X proposes a polycondensation method for preparing Pb3(PO4)2. Phosphoric acid and lead oxide are mixed in appropriate proportions to undergo a polymerization reaction, followed by aging and a high-temperature condensation reaction at 300°C to 350°C. After cooling, the mixture is pulverized to produce a white Pb3(PO4)2 powder. Although the advantage of the liquid phase method is that the reaction is more complete, the preparation of Pb3(PO4)2 using this method involves the use of high-concentration strong acid and many complex processes, resulting in low preparation efficiency, high risk and environmental pollution. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a method for preparing a high-purity ferroelastic compound Pb3(PO4)2. This method uses a one-step method to synthesize Pb3(PO4)2 polycrystalline powder. Reactive red phosphorus powder is directly mixed with lead oxide powder and then sintered in an oxygen-containing atmosphere. High-purity Pb3(PO4)2 is generated without introducing any additional substances. The prepared Pb3(PO4)2 polycrystalline powder has extremely strong crystallinity, few impurities, and extremely high purity, solving the problems of existing products with low purity, low preparation efficiency, high risk, and environmental pollution.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a high-purity ferroelastic compound Pb3(PO4)2, characterized in that the method comprises the following steps:

[0006] Step 1: Grind red phosphorus powder and lead oxide powder in an agate mortar until they are evenly mixed to obtain a mixed powder;

[0007] Step 2: Place the mixed powder obtained in step 1 into an Al2O3 crucible and place it in a tube furnace for sintering;

[0008] Step 3: Cool the mixed powder sintered in step 2 in the furnace, then take it out and grind it in an agate mortar to obtain Pb3(PO4)2 polycrystalline powder.

[0009] The above-mentioned method for preparing a high-purity ferroelastic compound Pb3(PO4)2 is characterized in that the mass ratio of the red phosphorus powder to the lead oxide powder in step 1 is 1:6~10.

[0010] The method for preparing a high-purity ferroelastic compound Pb3(PO4)2 is characterized in that the grinding time in step 1 is 10 to 60 minutes. The grinding time is controlled to ensure that the red phosphorus powder and the lead oxide powder are fully mixed.

[0011] The above-mentioned method for preparing a high-purity ferroelastic compound Pb3(PO4)2 is characterized in that the sintering atmosphere used in step 2 is air or an argon-oxygen mixture, the sintering temperature is 500°C to 1000°C, and the sintering time is 4 hours to 15 hours. The present invention introduces oxygen into the atmosphere to promote the reaction of red phosphorus to form phosphate ions, ensuring the smooth formation of the ferroelastic compound Pb3(PO4)2 product. Simultaneously, by controlling the sintering temperature and time, the reaction between red phosphorus and oxygen in the atmosphere is fully promoted. More preferably, the sintering temperature is selected to be 900°C, the oxidative melting point of the reactants.

[0012] The above-mentioned method for preparing a high-purity ferroelastic compound Pb3(PO4)2 is characterized in that the grinding time in step three is greater than 2 minutes.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. The present invention adopts a one-step method to synthesize Pb3(PO4)2 polycrystalline powder. The highly active red phosphorus powder is directly mixed with lead oxide powder and then sintered in an oxygen-containing atmosphere, so that the red phosphorus undergoes an oxidation reaction with oxygen to generate phosphate ions, which then fully react with PbO in an in-situ one-step method to generate high-purity Pb3(PO4)2 without introducing other additional substances. The prepared Pb3(PO4)2 polycrystalline powder has extremely strong crystallinity, few impurities, and extremely high purity (phase purity of more than 90%).

[0015] 2. Compared with phosphorus-containing substances such as white phosphorus, which are active and easily oxidized at room temperature and may spontaneously combust in the air, the present invention uses red phosphorus and lead oxide powder as raw materials, which are stable at room temperature and not easily oxidized. It does not involve high-concentration acidic solutions, and the process is safer and more environmentally friendly.

[0016] 3. During the conventional heating reaction of PbO and (NH4)H2PO4, ammonia, water and phosphoric acid dioxide HPO3 are first produced instead of phosphate ions. The reactivity of HPO3 is not as good as that of phosphate ions, which are more acidic and oxidizing, and affects the activity of subsequent reactions. During the one-step synthesis process of the present invention, red phosphorus reacts with oxygen to directly generate highly reactive phosphate ions, which is conducive to obtaining high-purity Pb3(PO4)2, improves the preparation efficiency, avoids the generation of pungent and toxic ammonia, and the preparation method is more environmentally friendly.

[0017] 4. The one-step synthesis method adopted in the present invention has simple operation steps, is easy to implement, and each process link is easy to control, and is suitable for large-scale industrial production.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the XRD pattern of the Pb3(PO4)2 polycrystalline powder prepared in Example 1 of the present invention.

[0020] Figure 2 This is the SEM morphology of the Pb3(PO4)2 polycrystalline powder prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] Example 1

[0022] This embodiment includes the following steps:

[0023] Step 1: Place 0.7 g of red phosphorus powder and 3.5 g of lead oxide powder in an agate mortar and grind for 20 min until the mixture is uniform to obtain a mixed powder;

[0024] Step 2: The mixed powder obtained in step 1 is placed in an Al2O3 crucible and then placed in a tube furnace, and sintered at 900°C in an argon-oxygen atmosphere for 7 hours;

[0025] Step 3: The mixed powder sintered in step 2 is cooled in the furnace, then taken out and ground in an agate mortar for 5 minutes to obtain Pb3(PO4)2 polycrystalline powder with a phase purity of 95.7%.

[0026] Figure 1 The XRD pattern of the Pb3(PO4)2 polycrystalline powder prepared in this embodiment is as follows: Figure 1 It can be seen that the characteristic peaks of the Pb3(PO4)2 polycrystalline powder are completely consistent with the X-ray diffraction characteristic peaks of Pb3(PO4)2 with the number #97-001-4247, and the intensity of the characteristic peaks is very large, indicating that the preparation method of the present invention obtains high-purity and high-crystallinity Pb3(PO4)2 polycrystalline powder.

[0027] Figure 2 This is the SEM morphology of the Pb3(PO4)2 polycrystalline powder prepared in this example. Figure 1 It can be seen that the Pb3(PO4)2 polycrystalline powder presents a lamellar morphology.

[0028] Example 2

[0029] This embodiment includes the following steps:

[0030] Step 1: Place 0.5 g of red phosphorus powder and 3.5 g of lead oxide powder in an agate mortar and grind for 30 min until the mixture is uniform to obtain a mixed powder;

[0031] Step 2: The mixed powder obtained in step 1 is placed in an Al2O3 crucible and then placed in a tube furnace, and sintered at 700°C in an argon-oxygen atmosphere for 6 hours;

[0032] Step 3: The mixed powder sintered in step 2 is cooled in the furnace, then taken out and ground in an agate mortar for 3 minutes to obtain a Pb3(PO4)2 polycrystalline powder with a phase purity of 93.2%.

[0033] After testing, the properties of the Pb3(PO4)2 polycrystalline powder prepared in this example are basically the same as those in Example 1.

[0034] Example 3

[0035] This embodiment includes the following steps:

[0036] Step 1: Place 0.5 g of red phosphorus powder and 4.0 g of lead oxide powder in an agate mortar and grind for 10 min until the mixture is uniform to obtain a mixed powder;

[0037] Step 2: The mixed powder obtained in step 1 was placed in an Al2O3 crucible and then placed in a tube furnace, and sintered at 800°C in an argon-oxygen atmosphere for 10 hours;

[0038] Step 3: The mixed powder sintered in step 2 is cooled in the furnace, then taken out and ground in an agate mortar for 5 minutes to obtain a Pb3(PO4)2 polycrystalline powder with a phase purity of 94.3%.

[0039] After testing, the properties of the Pb3(PO4)2 polycrystalline powder prepared in this example are basically the same as those in Example 1.

[0040] Example 4

[0041] This embodiment includes the following steps:

[0042] Step 1: Place 0.5 g of red phosphorus powder and 5.0 g of lead oxide powder in an agate mortar and grind for 60 min until the mixture is uniform to obtain a mixed powder;

[0043] Step 2: The mixed powder obtained in step 1 is placed in an Al2O3 crucible and then placed in a tube furnace, and sintered at 1000°C for 4 hours in an argon-oxygen atmosphere;

[0044] Step 3: The mixed powder sintered in step 2 is cooled in the furnace, then taken out and ground in an agate mortar for 2 minutes to obtain a Pb3(PO4)2 polycrystalline powder with a phase purity of 93.3%.

[0045] After testing, the properties of the Pb3(PO4)2 polycrystalline powder prepared in this example are basically the same as those in Example 1.

[0046] Example 5

[0047] This embodiment includes the following steps:

[0048] Step 1: Place 0.5 g of red phosphorus powder and 3.2 g of lead oxide powder in an agate mortar and grind for 20 min until the mixture is uniform to obtain a mixed powder;

[0049] Step 2: The mixed powder obtained in step 1 was placed in an Al2O3 crucible and then placed in a tube furnace, and sintered at 500°C in an argon-oxygen atmosphere for 15 hours;

[0050] Step 3: The mixed powder sintered in step 2 is cooled in the furnace, then taken out and ground in an agate mortar for 5 minutes to obtain a Pb3(PO4)2 polycrystalline powder with a phase purity of 91.2%.

[0051] After testing, the properties of the Pb3(PO4)2 polycrystalline powder prepared in this example are basically the same as those in Example 1.

[0052] Example 6

[0053] This embodiment includes the following steps:

[0054] Step 1: Place 0.5 g of red phosphorus powder and 3.0 g of lead oxide powder in an agate mortar and grind for 45 minutes until the mixture is uniform to obtain a mixed powder;

[0055] Step 2: The mixed powder obtained in step 1 was placed in an Al2O3 crucible and placed in a tube furnace, and sintered at 600°C in an air atmosphere for 15 hours;

[0056] Step 3: The mixed powder sintered in step 2 is cooled in the furnace, then taken out and ground in an agate mortar for 4 minutes to obtain Pb3(PO4)2 polycrystalline powder with a phase purity of 92.5%.

[0057] After testing, the properties of the Pb3(PO4)2 polycrystalline powder prepared in this example are basically the same as those in Example 1.

[0058] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a high-purity ferroelastic compound Pb3(PO4)2, characterized in that: The method comprises the following steps: Step 1: Grind red phosphorus powder and lead oxide powder in an agate mortar until they are uniformly mixed to obtain a mixed powder; the mass ratio of the red phosphorus powder to the lead oxide powder is 1:6-10; Step 2: The mixed powder obtained in step 1 is placed in an Al2O3 crucible and then placed in a tube furnace for sintering; the sintering atmosphere is air or argon-oxygen mixed gas, the sintering temperature is 500°C to 1000°C, and the sintering time is 4h to 15h; Step 3: Cool the mixed powder sintered in step 2 in the furnace, then take it out and grind it in an agate mortar to obtain Pb3(PO4)2 polycrystalline powder.

2. The method for preparing a high-purity ferroelastic compound Pb3(PO4)2 according to claim 1, characterized in that: The grinding time in step 1 is 10 min to 60 min.

3. The method for preparing a high-purity ferroelastic compound Pb3(PO4)2 according to claim 1, characterized in that: The grinding time in step 3 is greater than 2 minutes.

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