A method for synthesizing a yttrium-containing carbonate apatite (Ca 5-x Y x )[(PO4) 3-x (CO3) 2x ]F at high temperature and high pressure

Abstract

The application discloses a method for synthesizing yttrium-containing carbonate apatite (Ca 5‑x Y x )[(PO4) 3‑x (CO3) 2x ]F at high temperature and high pressure. Analytically pure calcium phosphate Ca3(PO4)2 and analytically pure nano calcium fluoride CaF2 are mixed at a molar ratio of 3:1, uniformly ground and uniformly mixed, and a precursor undoped apatite Ca5(PO4)3F powder is obtained at high temperature. The undoped apatite, analytically pure calcium carbonate, analytically pure yttrium phosphate YPO4 and nano calcium fluoride are mixed according to a molar ratio of a reaction equation to prepare a sample, and a reaction is carried out at high temperature and high pressure, wherein a synthesis pressure is 3 GPa, a temperature is 1050-1100 DEG C, and a reaction time is 2 h. A white yttrium-containing carbonate apatite powder is obtained, no other impurities are contained, a crystal structure is monoclinic P63 / m, and with an increase of a doping amount x of yttrium, a crystal lattice parameter linearly increases, and the doping amount x of yttrium ranges from 0

Description

Technical Field

[0001] This invention relates to the field of earth science and mineralogy research, and specifically to a high-temperature, high-pressure synthesis method for yttrium-containing carbonate apatite (Ca). 5-x Y x )[(PO4) 3-x (CO3) 2x The method of F. Background Technology

[0002] Rare earth apatite is a common mineral in igneous and metamorphic rocks, and an important carrier of rare earth elements, serving as a crucial mineral raw material for rare earth extraction. Its natural formation mechanism involves the formation of a complex rare earth carbonate-phosphate complex from monazite (YPO4) and carbonates under high temperature and pressure in a water environment, namely yttrium carbonate apatite (Ca). 5-x Y x )[(PO4) 3-x (CO3) 2x Due to the significant differences in crystal forms between carbonates and phosphates, the composite crystal form of carbonate apatite cannot form a continuous solid solution and thus has a limiting solid solubility. Therefore, the Y content (x) of carbonate apatite has an upper limit, which is crucial for predicting the rare earth content in apatite deposits. Currently, most studies on the properties of yttrium-bearing carbonate apatite use natural minerals, while the quantification of the upper limit of solid solubility in artificial synthesis remains a gap. Summary of the Invention

[0003] The technical problem to be solved by this invention is: to provide a high-temperature and high-pressure synthetic yttrium carbonate apatite (Ca 5-x Y x )[(PO4) 3-x (CO3) 2x The method of F was used to determine the doping range of rare earth Y in apatite.

[0004] The technical solution of this invention is: a high-temperature and high-pressure synthesis method for yttrium carbonate apatite (Ca 5-x Y x )[(PO4) 3-x (CO3) 2x The method of F includes the following steps:

[0005] Step 1: Analytical grade calcium phosphate Ca3(PO4)2 and analytical grade nano-calcium fluoride CaF2 are mixed and ground evenly at a molar ratio of 3:1. Using a powder press, the mixture powder is placed in a Φ10mm mold and pressed into a Φ10mm×10mm cylindrical shape. The cylindrical shape is placed on a ceramic boat lined with platinum sheets and sintered in a silicon molybdenum rod furnace at 1000℃ for 24 hours. The precursor undoped apatite Ca5(PO4)3F powder is obtained by grinding. The synthesis reaction is: 3Ca3(PO4)2 + CaF2 → 2Ca5(PO4)3F.

[0006] Step 2: The precursor phases synthesized in Step 1, undoped apatite Ca5(PO4)3F, analytical grade calcium carbonate CaCO3, analytical grade yttrium phosphate YPO4, and analytical grade nano-calcium fluoride CaF2, are mixed in molar proportions according to the left side of the reaction equation to obtain a mixture: (2-4x / 3)Ca5(PO4)3F + 2xYPO4 + 4xCaCO3 + (2x / 3)CaF2 → 2(Ca 5-x Y x )[(PO4) 3-x (CO3) 2x ]F, where x is the doping amount of rare earth yttrium Y. The mixture is ground evenly and then pressed into a Φ6mm×5mm cylinder using a powder presser. The cylinder is wrapped with a 0.02mm thick platinum foil and placed in an h-BN tube, with h-BN as the pressure transmission medium.

[0007] Step 3: Assemble the h-BN tube containing the sample from Step 2 into the high-pressure synthesis assembly block and place it in a six-sided top press for high-temperature and high-pressure reaction;

[0008] Step 4: After the high-temperature and high-pressure reaction is completed, the cylindrical tube wrapped in platinum foil is removed. A diamond cutter is used to cut the platinum tube, and the sample is extracted and ground to obtain yttrium carbonate apatite powder (Ca). 5-x Y x )[(PO4) 3-x (CO3) 2x ]F.

[0009] Furthermore, the specific operation of the h-BN tube in step 2 is as follows: drill a Φ6mm hole in the center of an h-BN rod with a size of Φ10mm on a lathe to make an h-BN tube, insert the sample into the tube, and seal both ends with Φ6mm and 2mm thick h-BN sheets.

[0010] Furthermore, the method for assembling the h-BN tube in the high-pressure synthesis assembly block as described in step 3 specifically includes: selecting a pyrophyllite block and drilling a Φ12mm circular through hole in the center of the pyrophyllite block; fitting a circular graphite heating furnace with an outer diameter of 12mm and an inner diameter of Φ10mm inside the circular through hole; placing a 10mm h-BN tube-sealed sample in the middle of the graphite heating furnace; and sealing the upper and lower ends of the circular graphite heating furnace with pyrophyllite plugs.

[0011] Furthermore, the high-temperature and high-pressure reaction conditions described in step 3 are as follows: first, the pressure is increased to 3 GPa, then the temperature is increased to 1000-1100℃, and the pressure and temperature are maintained for 2 hours before quenching.

[0012] Further, the yttrium-doped carbonate apatite sample obtained in Step 4 is a white powder without other impurities. Its crystal structure is monoclinic P63 / m, and the lattice parameters α = 90°, β = 90°, γ = 120°. As the doping amount x of yttrium increases, the lattice parameters increase linearly.

[0013] Further, the doping amount x of yttrium in the yttrium-doped carbonate apatite sample obtained in Step 4 ranges from 0 < x ≤ 0.15; when x > 0.15, a yttrium phosphate YPO4 impurity phase appears in the synthesized product.

[0014] Beneficial effects: This application provides a method for artificially synthesizing yttrium-doped carbonate apatite (Ca 5-x Y x )[(PO4) 3-x (CO3) 2x F, which fills the gap in the prior art without yttrium-doped carbonate apatite and finds the solid solution upper limit of artificially synthesized yttrium-doped carbonate apatite. Detailed implementation manners

[0015] Example 1:

[0016] A method for synthesizing yttrium-doped carbonate apatite (Ca 4.95 Y 0.05 )[(PO4) 2.95 (CO3) 0.10 F by high temperature and high pressure includes the following steps:

[0017] Step 1: Mix analytical pure calcium phosphate Ca3(PO4)2 and analytical pure nano calcium fluoride CaF2 in a molar ratio of 3:1 and grind them evenly; use a powder press to press the mixture powder into a Φ10mm×10mm cylindrical shape in a Φ10mm mold, place it on a porcelain boat covered with a platinum sheet, and sinter it in a silicon molybdenum rod furnace at 1000°C for 24h, then grind it to obtain the precursor undoped apatite Ca5(PO4)3F powder. The synthesis reaction is: 3Ca3(PO4)2 + CaF2 - 2Ca5(PO4)3F.

[0018] Step 2: Mix the precursor undoped apatite Ca5(PO4)3F synthesized in Step 1, analytical pure calcium carbonate CaCO3, analytical pure yttrium phosphate YPO4, and analytical pure nano calcium fluoride CaF2 according to the molar ratio of the reaction equation: 29 / 15Ca5(PO4)3F + 1 / 10YPO4 + 1 / 5CaCO3 + 1 / 30CaF2 → 2(Ca 4.95 Y 0.05 )[(PO4) 2.95 (CO3) 0.10F, wherein the doping amount of rare earth yttrium Y is 5%. The mixture is ground uniformly, and the powder is pressed into a Φ6mm×5mm cylinder using a powder press. The cylinder is then wrapped with a 0.02mm thick platinum foil. The platinum foil-wrapped sample cylinder is placed in an h-BN tube, with h-BN as the pressure transmission medium.

[0019] Step 3: Assemble the h-BN tube containing the sample from Step 2 into the high-pressure synthesis assembly block and place it in a six-sided top press for high-temperature and high-pressure reaction;

[0020] Step 4: After the high-temperature and high-pressure reaction is completed, the cylindrical tube wrapped in platinum foil is removed. A diamond cutter is used to cut the platinum tube, and the sample is extracted and ground to obtain yttrium carbonate apatite powder (Ca). 4.95 Y 0.05 )[(PO4) 2.95 (CO3) 0.10 ]F;

[0021] The specific operation of the h-BN tube in step 2 is as follows: drill a 6mm hole in the center of an h-BN rod with a size of 10mm on a lathe to make an h-BN tube, insert the sample into the tube, and seal both ends with 6mm thick h-BN sheets.

[0022] The method for assembling the h-BN tube in the high-pressure synthesis assembly block as described in step 3 includes the following steps: selecting a pyrophyllite block and drilling a Φ12mm circular through hole in the center of the pyrophyllite block; fitting a circular graphite heating furnace with an outer diameter of 12mm and an inner diameter of Φ10mm inside the circular through hole; placing a 10mm h-BN tube-sealed sample in the middle of the graphite heating furnace; and sealing the upper and lower ends of the circular graphite heating furnace with pyrophyllite plugs.

[0023] The high-temperature and high-pressure reaction conditions described in step 3 are as follows: first, the pressure is increased to 3 GPa, then the temperature is increased to 1000℃, and the pressure and temperature are maintained for 2 hours before quenching.

[0024] Example 2:

[0025] A high-temperature, high-pressure synthesis method for yttrium carbonate apatite (Ca 4.90 Y 0.10 )[(PO4) 2.90 (CO3) 0.20 The method of F includes the following steps:

[0026] Step 1: Analytical grade calcium phosphate Ca3(PO4)2 and analytical grade nano-calcium fluoride CaF2 are mixed and ground evenly at a molar ratio of 3:1. Using a powder press, the mixture powder is placed in a Φ10mm mold and pressed into a Φ10mm×10mm cylindrical shape. The cylindrical shape is placed on a ceramic boat lined with platinum sheets and sintered in a silicon molybdenum rod furnace at 1000℃ for 24 hours. The precursor undoped apatite Ca5(PO4)3F powder is obtained by grinding. The synthesis reaction is: 3Ca3(PO4)2 + CaF2 - 2Ca5(PO4)3F.

[0027] Step 2: Mix the precursor phases synthesized in Step 1—undoped apatite Ca5(PO4)3F, analytical grade calcium carbonate CaCO3, analytical grade yttrium phosphate YPO4, and analytical grade nano-calcium fluoride CaF2—in molar ratio according to the reaction equation: 28 / 15Ca5(PO4)3F + 1 / 5YPO4 + 2 / 5CaCO3 + 1 / 15CaF2 → 2(Ca 4.90 Y 0.10 )[(PO4) 2.90 (CO3) 0.20 F, wherein the doping amount of rare earth yttrium Y is 10%. The mixture is ground uniformly, and the powder is pressed into a Φ6mm×5mm cylinder using a powder press. The cylinder is then wrapped with a 0.02mm thick platinum foil. The platinum foil-wrapped sample cylinder is placed in an h-BN tube, with h-BN as the pressure transmission medium.

[0028] Step 3: Assemble the h-BN tube containing the sample from Step 2 into the high-pressure synthesis assembly block and place it in a six-sided top press for high-temperature and high-pressure reaction;

[0029] Step 4: After the high-temperature and high-pressure reaction is completed, the cylindrical tube wrapped in platinum foil is removed. A diamond cutter is used to cut the platinum tube, and the sample is extracted and ground to obtain yttrium carbonate apatite powder (Ca). 4.90 Y 0.10 )[(PO4) 2.90 (CO3) 0.20 ]F;

[0030] The specific operation of the h-BN tube in step 2 is as follows: drill a 6mm hole in the center of an h-BN rod with a size of 10mm on a lathe to make an h-BN tube, insert the sample into the tube, and seal both ends with 6mm thick h-BN sheets.

[0031] The method for assembling the h-BN tube in the high-pressure synthesis assembly block as described in step 3 includes the following steps: selecting a pyrophyllite block and drilling a Φ12mm circular through hole in the center of the pyrophyllite block; fitting a circular graphite heating furnace with an outer diameter of 12mm and an inner diameter of Φ10mm inside the circular through hole; placing a 10mm h-BN tube-sealed sample in the middle of the graphite heating furnace; and sealing the upper and lower ends of the circular graphite heating furnace with pyrophyllite plugs.

[0032] The high-temperature and high-pressure reaction conditions described in step 3 are as follows: first, the pressure is increased to 3 GPa, then the temperature is increased to 1050℃, and the pressure and temperature are maintained for 2 hours before quenching.

[0033] Example 3:

[0034] A high-temperature, high-pressure synthesis method for yttrium carbonate apatite (Ca 4.85 Y 0.15 )[(PO4) 2.85 (CO3) 0.30 The method of F includes the following steps:

[0035] Step 1: Analytical grade calcium phosphate Ca3(PO4)2 and analytical grade nano-calcium fluoride CaF2 are mixed and ground evenly at a molar ratio of 3:1. Using a powder press, the mixture powder is placed in a Φ10mm mold and pressed into a Φ10mm×10mm cylindrical shape. The cylindrical shape is placed on a ceramic boat lined with platinum sheets and sintered in a silicon molybdenum rod furnace at 1000℃ for 24 hours. The precursor undoped apatite Ca5(PO4)3F powder is obtained by grinding. The synthesis reaction is: 3Ca3(PO4)2 + CaF2 - 2Ca5(PO4)3F.

[0036] Step 2: Mix the precursor phases synthesized in Step 1—undoped apatite Ca5(PO4)3F, analytical grade calcium carbonate CaCO3, analytical grade yttrium phosphate YPO4, and analytical grade nano-calcium fluoride CaF2—in molar proportions according to the reaction equation: 9 / 5 Ca5(PO4)3F + 3 / 10 YPO4 + 3 / 5 CaCO3 + 1 / 10 CaF2 → 2(Ca 4.85 Y 0.15 )[(PO4) 2.85 (CO3) 0.30 F, wherein the doping amount of rare earth yttrium Y is 15%. The mixture is ground uniformly, and the powder is pressed into a Φ6mm×5mm cylinder using a powder press. The cylinder is then wrapped with a 0.02mm thick platinum foil. The platinum foil-wrapped sample cylinder is placed in an h-BN tube, with h-BN as the pressure transmission medium.

[0037] Step 3: Assemble the h-BN tube containing the sample from Step 2 into the high-pressure synthesis assembly block and place it in a six-sided top press for high-temperature and high-pressure reaction;

[0038] Step 4: After the high-temperature and high-pressure reaction is completed, the cylindrical tube wrapped in platinum foil is removed. A diamond cutter is used to cut the platinum tube, and the sample is extracted and ground to obtain yttrium carbonate apatite powder (Ca). 4.85 Y 0.15 )[(PO4) 2.85 (CO3) 0.30 ]F;

[0039] The specific operation of the h-BN tube in step 2 is as follows: drill a 6mm hole in the center of an h-BN rod with a size of 10mm on a lathe to make an h-BN tube, insert the sample into the tube, and seal both ends with 6mm thick h-BN sheets.

[0040] The method for assembling the h-BN tube in the high-pressure synthesis assembly block as described in step 3 includes the following steps: selecting a pyrophyllite block and drilling a Φ12mm circular through hole in the center of the pyrophyllite block; fitting a circular graphite heating furnace with an outer diameter of 12mm and an inner diameter of Φ10mm inside the circular through hole; placing a 10mm h-BN tube-sealed sample in the middle of the graphite heating furnace; and sealing the upper and lower ends of the circular graphite heating furnace with pyrophyllite plugs.

[0041] The high-temperature and high-pressure reaction conditions described in step 3 are as follows: first, the pressure is increased to 3 GPa, then the temperature is increased to 1100℃, and the pressure and temperature are maintained for 2 hours before quenching.

[0042] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-temperature, high-pressure synthesis method for yttrium carbonate apatite (Ca 5-x Y x )[(PO4) 3-x (CO3) 2x The method of F is characterized in that, Includes the following steps: Step 1: Mix and grind analytical grade calcium phosphate (Ca3(PO4)2) and analytical grade nano-calcium fluoride (CaF2) at a molar ratio of 3:1 until homogeneous. Using a powder press, place the powder mixture into a Φ10mm × 10mm cylindrical shape in a Φ10mm mold, place it on a ceramic boat lined with platinum sheets, and press at 1000°C. o Sintering of silicon molybdenum rods in furnace C for 24 hours, grinding to obtain precursor undoped apatite Ca5(PO4)3F powder, synthesis reaction: 3Ca3(PO4)2+ CaF2→2Ca5(PO4)3F; Step 2: The precursor phases synthesized in Step 1, undoped apatite Ca5(PO4)3F, analytical grade calcium carbonate CaCO3, analytical grade yttrium phosphate YPO4, and analytical grade nano-calcium fluoride CaF2, are mixed in molar proportions according to the left side of the reaction equation to obtain a mixture: (2-4x / 3)Ca5(PO4)3F + 2xYPO4 + 4xCaCO3 + (2x / 3)CaF2 → 2(Ca 5-x Y x )[(PO4) 3-x (CO3) 2x ]F, where x is the doping amount of rare earth yttrium Y. The mixture is ground evenly and then pressed into a Φ6mm×5mm cylinder using a powder presser. The cylinder is wrapped with a 0.02mm thick platinum foil and placed in an h-BN tube, with h-BN as the pressure transmission medium. Step 3: Assemble the h-BN tube containing the sample from Step 2 into the high-pressure synthesis assembly block and place it in a six-sided top press for high-temperature and high-pressure reaction; Step 4: After the high-temperature and high-pressure reaction is completed, the cylindrical tube wrapped in platinum foil is removed. A diamond cutter is used to cut the platinum tube, and the sample is extracted and ground to obtain yttrium carbonate apatite powder (Ca). 5-x Y x )[(PO4) 3-x (CO3) 2x The obtained yttrium carbonate apatite sample is a white powder, free of other impurities, with a monoclinic P63 / m crystal structure, lattice parameters a = 9-10 Å, b = 9-10 Å, c = 6-7 Å, α = 90°. 。 β=90 。 γ=120 。 As the doping concentration x of yttrium increases, the lattice parameter increases linearly, and the range of yttrium doping concentration x is 0. <x≤0.15。 2. A high-temperature, high-pressure synthetic yttrium carbonate apatite (Ca) method according to claim 1. 5-x Y x )[(PO4) 3-x (CO3) 2x The method of F is characterized in that, The specific operation of the h-BN tube in step 2 is as follows: drill a 6mm hole in the center of an h-BN rod with a size of 10mm on a lathe to make an h-BN tube, insert the sample into the tube, and seal both ends with 6mm thick h-BN sheets.

3. A high-temperature, high-pressure synthetic yttrium carbonate apatite (Ca) method according to claim 1. 5-x Y x )[(PO4) 3-x (CO3) 2x The method of F is characterized in that, The method for assembling the h-BN tube in the high-pressure synthesis assembly block as described in step 3 includes the following steps: selecting a pyrophyllite block and drilling a Φ12mm circular through hole in the center of the pyrophyllite block; fitting a circular graphite heating furnace with an outer diameter of 12 mm and an inner diameter of Φ10 mm inside the circular through hole; placing a 10 mm h-BN tube-sealed sample in the middle of the graphite heating furnace; and sealing the upper and lower ends of the circular graphite heating furnace with pyrophyllite plugs.

4. A high-temperature, high-pressure synthetic yttrium carbonate apatite (Ca) method according to claim 1. 5-x Y x )[(PO4) 3-x (CO3) 2x The method of F is characterized in that, The high-temperature and high-pressure reaction conditions described in step 3 are as follows: first, the pressure is increased to 3 GPa, then the temperature is increased to 1000-1100℃, and the pressure and temperature are maintained for 2 hours before quenching.