A method for preparing BiMg2PO6 material with prismatic structure

Abstract

This invention belongs to the field of inorganic non-metallic material preparation technology, and discloses a method for preparing BiMg2PO6 material with a prismatic structure. Using MgO, Bi2O3, and NH4H2PO4 as raw materials, NaCl and KCl are mixed and ground with the raw materials as a mixed molten salt to obtain a precursor. The obtained precursor is calcined at 750~900℃ for 0.5~3h. After calcination, it is naturally cooled to room temperature to obtain a BiMg2PO6-salt mixture. The BiMg2PO6-salt mixture is washed multiple times with deionized water to remove the salt components, filtered, and dried to obtain the BiMg2PO6 material. The preparation method of this invention has a short cycle time, high purity, and the obtained material has a prismatic structure with a lateral length of 6~91μm and a corresponding width of 1.7~16.7μm. This preparation method has easily controllable process conditions, simple operation, inexpensive raw materials, and is easy to scale up for production.

Description

Technical Field

[0001] This invention belongs to the field of inorganic non-metallic material preparation technology, and relates to a method for preparing BiMg2PO6 material with a prismatic structure. Background Technology

[0002] Micro- and nanomaterials refer to materials whose size is in the nanometer to micrometer range in at least one dimension, and whose physicochemical properties are significantly different from those of macroscopic bulk materials. Furthermore, micro- and nanomaterials possess high specific surface area, small size, good thermal stability, and photothermal and electromagnetic response characteristics. These properties make them promising for applications in energy storage, biomedicine, nanoelectronic devices, and environmental remediation. With the rapid development of micro- and nanotechnology, researchers have discovered that many micro- and nanomaterials with special morphologies and structures (such as rod-shaped, flower-shaped, sheet-like, and polyhedral materials) exhibit excellent performance. For example, rod-shaped MgO nanomaterials, due to their unique optical, magnetic, and mechanical properties, are significantly different from their bulk or nanoparticle forms and have broad application prospects in fields such as electronic devices, environmental protection, fire safety, and the ceramics industry; rod-shaped mesoporous SiO2 nanomaterials have the advantages of being easily biodegradable and non-toxic, and are therefore widely used in fields such as medicine and new material synthesis; hexagonal prism-shaped ZnO photocatalysts with a high proportion of high-index crystal faces exhibit excellent photocatalytic activity and can efficiently degrade organic pollutants such as methylene blue; triangular prism-shaped tubular [Ag4Ni(L)3]·3.5H2O shows potential application value in microcapillary devices.

[0003] BiMg2PO6 is a novel bismuth-magnesium phosphate functional material. Due to its unique crystal structure and composition characteristics, it shows important application prospects in fields such as dielectric materials, solid electrolytes, photocatalysis, and rare earth-doped luminescent materials. For example, in the literature "Crystal structure and microwave dielectric properties of novel BiMg2MO6(M=P, V) ceramics with low sintering temperature (Zhang P, Hao M, Xiao M, et al. Journal of Materiomics, 2021, 7(6): 1344-1351)," alcohol was used as the ball milling medium. The mixed raw materials were placed in a planetary ball mill and ground for 4 hours. After the ball milling slurry was dried, it was passed through a 40-mesh sieve. Then, the mixed powder was placed in an alumina crucible and pre-fired at a suitable temperature. The pre-fired powder was granulated with 6-8 wt% paraffin and pressed into shape. After debinding at 550℃, it was sintered at 925℃ for 4 hours to obtain BiMg2PO6 ceramic material with excellent microwave dielectric properties. In the literature "Optical properties and electronic band structure of BiMg2PO6, BiMg2VO6, BiMg2VO6: Pr 3+ and BiMg2VO6: Eu 3+The luminescent properties of BiMg2PO6 were reported in "(Barros A, Deloncle R, Deschamp J, et al. Optical Materials, 2014, 36(10):1724-1729)". Since the properties of a material are closely related to the morphology, size, and dimensions of its crystals, preparing BiMg2PO6 materials with special morphologies can broaden its applications in other fields. For example, the literature "Triangularprism-shaped p-type 6H-SiC nanowires" (Gao F, Feng W, Wei G, et al. Crystengcomm, 2012, 14(2): 488-491) reported that triangular prism-shaped 6H-SiC nanowires exhibited strong visible light luminescence, indicating their potential application in optoelectronic devices. The literature "Controlled growth of CdS nanostep structured arrays to improve photoelectrochemical performance" (Jiang J, Wang H, An H, et al. Frontiers in Chemistry, A CdS array consisting of a rod-shaped framework and surface nanostep structures was reported in 2020, 8: 577582. The nanosteps in this structure not only increase the contact area between the CdS film and the electrolyte and promote the surface reaction, but also enable photogenerated electrons and holes to easily migrate to the edges and grooves of the nanostep structures on the CdS array surface, thereby significantly improving the photoelectrochemical performance.

[0004] Currently, the preparation of BiMg2PO6 materials both domestically and internationally mostly employs solid-state methods. This typically involves mixing raw materials, ball milling for an extended period, and then calcining at high temperatures to obtain BiMg2PO6 powder. However, this method results in a long preparation time and difficulty in controlling the material's morphology. In the literature "Synthesis and characterization of bismuthmagnesium phosphate and arsenate: BiMg2PO6 and BiMg2AsO6" (Huang J, Gu Q, Sleight A W. Journal of Solid State Chemistry, 1993, 105(2):599-606), the raw materials are mixed, initially ground, and then heated at 400℃ for 2 hours to decompose (NH4)2HPO4. After grinding, the materials are then successively heated at 700℃, 800℃, and 1000℃ for 12 hours each, with grinding performed at the end of each heating cycle to finally obtain BiMg2PO6 material. However, there are few reports on the synthesis of BiMg2PO6 materials within a shorter preparation cycle. Therefore, it is of great significance to study how to prepare BiMg2PO6 materials with specific morphologies under conditions of shorter preparation time.

[0005] my country is rich in magnesium, bismuth, and phosphorus resources, and researching and utilizing these resources effectively is of significant practical importance. This invention employs a novel approach to prepare BiMg2PO6 materials with a prismatic structure. This method enables the rapid preparation of BiMg2PO6 materials with regular morphology, a short preparation cycle, and good dispersibility. Even with prolonged high-temperature reactions, the prismatic BiMg2PO6 materials do not crumble, maintaining their excellent morphology, and the preparation temperature range is wide. The preparation method is easy to control, simple to operate, and readily scalable, thus possessing significant application value. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing BiMg2PO6 material with a prismatic structure. This method has a wide preparation temperature range, is simpler to operate, and the process conditions are easy to control. It is also suitable for large-scale production and can solve the problems of long preparation cycles, irregular product morphology, and even if there is a regular morphology, it is easy to break after long-term high-temperature reaction.

[0007] The technical solution of this invention is as follows: A method for preparing a BiMg2PO6 material with a prismatic structure includes the following steps: (1) Weigh MgO, Bi2O3 and NH4H2PO4 as raw materials according to the stoichiometric ratio of BiMg2PO6, and use the Mg in the raw materials as raw materials. 2+ with Bi3+ Based on the total molar amount, NaCl and KCl were weighed as the mixed molten salt required for the reaction. The raw materials and the mixed molten salt were mixed and ground to obtain the precursor. The molar fraction of NaCl in the mixed molten salt was 12.5%, and the molar fraction of KCl was 87.5%. (2) The precursor obtained in step (1) is transferred to a box-type resistance furnace and calcined in an air atmosphere. After the calcination time is over, it is naturally cooled to room temperature to obtain a BiMg2PO6-salt mixture. (3) The BiMg2PO6-salt mixture obtained in step (2) is washed multiple times with deionized water to remove the salt components, and then filtered and dried to obtain BiMg2PO6 material.

[0008] Furthermore, in step (1), the Mg in the raw material 2+ with Bi 3+ The ratio of the total molar amount to the total molar amount of the mixed molten salt is 1: (1.5~9).

[0009] Furthermore, in step (2), the calcination temperature is 750~900℃ and the calcination time is 0.5~3h.

[0010] A method for preparing BiMg2PO6 material with a prismatic structure. The BiMg2PO6 material obtained has a prismatic structure with a length of 6~91μm and a width of 1.7~16.7μm on the lateral side.

[0011] The beneficial effects of this invention are: 1. This invention employs a novel preparation method to prepare BiMg2PO6 material with a prismatic structure. The length of the prism side faces ranges from 6 to 91 μm, and the corresponding width ranges from 1.7 to 16.7 μm, exhibiting good dispersibility.

[0012] 2. This invention can prepare BiMg2PO6 material with a prism structure under a reaction time of 0.5 h. Compared with the traditional solid-state method, this method shortens the material preparation cycle, uses inexpensive and readily available raw materials, and significantly reduces the cost of material preparation, providing technical conditions for its large-scale production and application.

[0013] 3. The prism-structured BiMg2PO6 material prepared by this invention does not crack even after long-term high-temperature reaction, such as above 850℃ or even 2 hours at 900℃, and the prism structure morphology is well maintained.

[0014] 4. The preparation method of the present invention is characterized by simple operation and strong controllability of conditions. The resulting material has high purity and excellent microstructure, and is easy to scale up for production. Attached Figure Description

[0015] Figure 1 The image shows the XRD pattern of the BiMg2PO6 material prepared in Example 1.

[0016] Figure 2 The images show the XRD patterns of BiMg2PO6 materials prepared in Examples 2 and 3 at different calcination temperatures, where a represents 750℃, b represents 800℃, and c represents 900℃.

[0017] Figure 3 The images show the XRD patterns of BiMg2PO6 materials prepared in Example 4 under different calcination times, where d represents 0.5 h, e represents 1 h, and f represents 3 h.

[0018] Figure 4 The XRD patterns of BiMg2PO6 materials prepared in Examples 5 and 6 with different amounts of molten salt are shown, where g is 1:1.5, h is 1:4.5, and i is 1:9.

[0019] Figure 5 The image shows the XRD pattern of the material prepared in Comparative Example 1.

[0020] Figure 6 The image shows a SEM image of the BiMg2PO6 material prepared in Example 1.

[0021] Figure 7 SEM images of BiMg2PO6 materials prepared in Examples 2 and 3 at different calcination temperatures; where (a) 800℃; (b) 900℃.

[0022] Figure 8 SEM images of BiMg2PO6 materials prepared in Example 4 at different calcination times; where (a) 1h; (b) 3h.

[0023] Figure 9 SEM images of BiMg2PO6 materials prepared in Example 6 with different amounts of molten salt; where (a) 1:4.5; (b) 1:6.

[0024] Figure 10 The images show SEM images of the BiMg2PO6 materials prepared in Examples 3 and 4; where (a) is the SEM image at 825℃ in Example 3, and (b) is the SEM image at 0.5h in Example 4. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0026] Example 1: MgO, Bi₂O₃, and NH₄H₂PO₄ were weighed out according to stoichiometric ratio as raw materials. Simultaneously, 12.5% ​​NaCl and 87.5% KCl were measured out as a mixed molten salt. The Mg content in the raw materials was used as the molten salt. 2+ with Bi 3+ Based on the total molar amount, make Mg 2+ with Bi 3+ The ratio of the total molar mass to the total molar mass of the mixed molten salt is 1:3 (in Mg). 2+ with Bi 3+ (The total molar amount is taken as 1). The weighed raw materials are uniformly mixed with the mixed molten salt and ground for 18 min to obtain the precursor. The obtained precursor is placed in a box-type resistance furnace and calcined in air atmosphere. The calcination temperature is set at 850℃ and the calcination time is 2 h. After calcination, the material is allowed to cool naturally to room temperature with the furnace to obtain a BiMg2PO6-salt mixture. Subsequently, the BiMg2PO6-salt mixture is washed multiple times with deionized water to remove the salt components. The washed product is filtered and dried at 118℃ for 1.9 h to obtain a BiMg2PO6 material with a prismatic structure. The sides of some prismatic structures have growth lines parallel to the crystal extension direction. The side length of the prismatic structure is 10.4~64 μm, and the corresponding width is 3.3~11.8 μm. See Figure 6 .

[0027] Example 2: The difference between this embodiment and Example 1 is that the calcination temperatures are 750℃, 775℃, and 800℃, respectively. All of these calcination temperatures yielded BiMg2PO6 materials with a prismatic structure. When the calcination temperature was 800℃, growth lines parallel to the crystal extension direction were distributed on the side surfaces of some prismatic structures. The side surface length of the prismatic structure was 6~34μm, and the corresponding width was 2.2~8.5μm. (See...) Figure 7 (a) in the middle.

[0028] Example 3: The difference between this embodiment and Example 1 is that the calcination temperatures are 825℃, 875℃, and 900℃, respectively. All of these calcination temperatures yielded BiMg2PO6 materials with a prismatic structure. The BiMg2PO6 material obtained at 825℃ exhibits growth lines parallel to the crystal extension direction on the lateral sides of some prisms. The lateral side lengths are 14–45 μm, and the corresponding widths are 3–10 μm. (See...) Figure 10 (a).

[0029] When the calcination temperature is 900℃, the lateral surface length of the prismatic structure of the prepared BiMg2PO6 material is 12~58μm, and the corresponding width is 3.3~11μm. (See...) Figure 7 (b) in the middle.

[0030] Example 4: The main difference between this embodiment and Example 1 is that the calcination times are 0.5 h, 0.75 h, 1 h, and 3 h, respectively. All of these different calcination times yielded BiMg2PO6 materials with a prismatic structure. The 0.5 h calcination time yielded BiMg2PO6 materials with a prismatic structure, the lateral side length of which is 13.2–68 μm, and the corresponding width is 1.7–16.7 μm. (See [link to example]). Figure 10 (b).

[0031] When the calcination time was 1 hour, growth lines parallel to the crystal extension direction were distributed on the lateral surfaces of some prismatic structures. The lateral surface length of the prismatic structures was 8.2–55 μm, and the corresponding width was 2.6–14.4 μm. (See...) Figure 8 In (a); when the calcination time is 3 h, the lateral surface length of the prism structure is 9~91 μm, and the corresponding width is 2.4~11.6 μm, see [reference]. Figure 8 (b) in the middle.

[0032] Example 5: The main difference between this embodiment and Example 1 is that the Mg content in the raw materials... 2+ with Bi 3+ The ratio of the total molar amount of the molten salt to the total molar amount of the mixed molten salt is 1:1.5. At this molar ratio, a BiMg2PO6 material with a prismatic structure is obtained.

[0033] Example 6: The main difference between this embodiment and Example 1 is that the Mg content in the raw materials... 2+ with Bi 3+ The ratios of the total molar amount to the total molar amount of the mixed molten salt were 1:4.5, 1:6, 1:7.5 and 1:9, respectively. All of these molar ratios resulted in BiMg2PO6 materials with a prismatic structure.

[0034] When Mg in the raw material 2+ with Bi 3+ When the ratio of the total molar amount to the total molar amount of the mixed molten salt is 1:4.5, the resulting prism structure has a lateral length of 17.4–72 μm and a corresponding width of 2.6–13.5 μm. (See...) Figure 9 (a) in the middle.

[0035] When Mg in the raw material 2+ with Bi 3+ When the ratio of the total molar amount to the total molar amount of the mixed molten salt is 1:6, the resulting prism structure has a lateral length of 12.4–61 μm and a corresponding width of 2.2–12.4 μm. (See...) Figure 9 (b) in the middle.

[0036] Comparative Example 1: The main difference between this embodiment and Embodiment 1 is that the calcination temperature is 720℃.

[0037] Figure 1-4 The XRD patterns of the BiMg2PO6 materials prepared in Examples 1-6 show that the diffraction peaks of the obtained products are sharp, indicating that they have good crystallinity and high-purity BiMg2PO6 materials were successfully prepared.

[0038] Figure 5 The image shows the XRD pattern of the material prepared in Comparative Example 1. As can be seen from the image, there are obvious impurity peaks in the diffraction peaks of the product, indicating that high-purity BiMg2PO6 material was not successfully prepared. The possible reason is the low calcination temperature; the mixed molten salt containing 12.5% ​​NaCl and 87.5% KCl did not fully assist the reaction system at this temperature.

[0039] Figure 6-10 The images show SEM images of the BiMg2PO6 materials prepared in Examples 1-4 and Example 6. These SEM images show that the prepared BiMg2PO6 materials exhibit a prismatic structure, with prism side lengths ranging from 6 to 91 μm and corresponding widths ranging from 1.7 to 16.7 μm. Further observation reveals growth lines parallel to the crystal extension direction on the sides of some prisms. These growth lines are growth step textures. The absence of explicit mention of growth lines does not necessarily mean that they are not observed in the materials in question.

Claims

1. A method for preparing a BiMg2PO6 material with a prismatic structure, characterized in that, Includes the following steps: (1) Weigh MgO, Bi2O3 and NH4H2PO4 as raw materials according to the stoichiometric ratio of BiMg2PO6, and use the Mg in the raw materials as raw materials. 2+ with Bi 3+ Based on the total molar amount, NaCl and KCl were weighed as the mixed molten salt required for the reaction. The raw materials and the mixed molten salt were mixed and ground to obtain the precursor. The molar fraction of NaCl in the mixed molten salt was 12.5%, and the molar fraction of KCl was 87.5%. (2) The precursor obtained in step (1) is transferred to a box-type resistance furnace and calcined in an air atmosphere. After the calcination time is over, it is naturally cooled to room temperature to obtain a BiMg2PO6-salt mixture. (3) The BiMg2PO6-salt mixture obtained in step (2) is washed multiple times with deionized water to remove the salt components, and then filtered and dried to obtain BiMg2PO6 material.

2. The method for preparing BiMg2PO6 material with a prismatic structure according to claim 1, characterized in that, In step (1), Mg in the raw material 2+ with Bi 3+ The ratio of the total molar amount to the total molar amount of the mixed molten salt is 1: (1.5~9).

3. The method for preparing BiMg2PO6 material with a prismatic structure according to claim 1, characterized in that, In step (2), the calcination temperature is 750~900℃ and the calcination time is 0.5~3h.

4. The BiMg2PO6 material obtained by any one of the preparation methods according to claims 1-3 has a prism structure, wherein the length of the lateral side of the prism structure ranges from 6 to 91 μm and the width ranges from 1.7 to 16.7 μm.

Images