LU503140B1

LU503140B1 - Method for preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite

Info

Publication number: LU503140B1
Application number: LU503140A
Authority: LU
Inventors: Haiying Hu; Lidong Dai
Original assignee: Inst Geochemistry Cas
Priority date: 2022-12-07
Filing date: 2022-12-07
Publication date: 2023-06-07

Abstract

Disclosed is a method for preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite, including: preparing a high-titanium, high-vanadium and high-chromium monticellite cylinder sample using solid magnesium nitrate hexahydrate powder, solid calcium DL-glycerate hydrate, solid chromic nitrate nonahydrate (III), solid vanadium (III)-2,4-pentanedionate, liquid tetraethoxysilane, liquid tetrabutyl titanate, solid natural serpentine powder, solid natural brucite powder, solid natural slaked lime powder and absolute ethyl alcohol as starting materials, pressing serpentine, brucite and slaked lime into two discs on a press according to a weight ratio of 3:3:1, placing the discs to two ends of the monticellite cylinder sample, and sealing the monticellite cylinder sample and the two discs in a gold-palladium alloy sample tube for a high-temperature and high-pressure reaction to obtain high-titanium, vanadium and chromium and high-water single-crystal monticellite. The present invention fills in the technical blank in preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite in the prior art.

Description

HIGH-CHROMIUM AND HIGH-WATER SINGLE-CRYSTAL MONTICELLITE

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention belongs to the technical field of single-crystal mineral sample synthesis under a high-temperature and high-pressure condition, and particularly relates to a method for preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite.

[0003] 2. Description of Related Art

[0004] Olivine minerals are extensively distributed in various geotectonic environments. Monticellite is a silicate mineral existing in the form of a compound salt. To deeply explore the geochemical behaviors, such as migration and enrichment, of alkaline-earth metal elements such as calcium and magnesium in natural monticellite, as well as the physical properties of the natural monticellite under a high pressure, it is of great importance to obtain desired and controllable monticellite samples with variable-valence elements: titanium, vanadium and chromium.

[0005] It is hard to gain consistent research achievements by using natural monticellite samples to simulate the physicochemical properties of substances deep in the earth. Some researchers use artificially synthesized monticellite as samples. However, artificially synthesized pure monticellite is single-component (not containing variable-valence titanium, vanadium and chromium), nano-sized and non-hydrous samples, and cannot meet the requirements of experimental samples for high-temperature and high-pressure experimental simulation.

BRIEF SUMMARY OF THE INVENTION

[0006] The technical issue to be settled by the present invention is to provide a LU503140 method for preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite, so as to solve the above-mentioned problems of the prior art.

[0007] The technical solution of the present invention 1s as follows:

A method for preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite, comprising: preparing, according to monticellite chemometrics, a high-titanium, high-vanadium and high-chromium monticellite cylinder sample using solid magnesium nitrate hexahydrate powder, solid calcium DL-glycerate hydrate, solid chromic nitrate nonahydrate (III), solid vanadium(III)-2,4-pentanedionate, liquid tetraethoxysilane, liquid tetrabutyl titanate, solid natural serpentine powder, solid natural brucite powder, solid natural slaked lime powder and absolute ethyl alcohol as starting materials, pressing serpentine, brucite and slaked lime into two discs on a press according to a weight ratio of 3:3:1, placing the discs at two ends of the monticellite cylinder sample, and sealing the monticellite cylinder sample and the two discs in a gold-palladium alloy sample tube for a high-temperature and high-pressure reaction to obtain high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite.

Preferably, the high-titanium, high-vanadium and high-chromium monticellite cylinder sample is prepared by:

Step 1, using solid magnesium nitrate hexahydrate powder (purity: 99.99%), solid calcium DL-glycerate hydrate (purity: >99.99%), solid chromic nitrate nonahydrate (III) (purity: >99.99%), solid vanadium(IIT)-2,4-pentanedionate (purity: >99.99%), liquid tetraethoxysilane (purity: >99.99%), liquid tetrabutyl titanate (purity: >99.99%), solid natural serpentine powder (purity: >99%), solid natural brucite powder (purity: >99%), solid natural slaked lime powder (purity: >99%) and absolute ethyl alcohol (purity: >99.9%) as the starting materials;

Step 2, placing 100 ml of absolute ethyl alcohol into a 500 ml wide-mouth glass bottle;

Step 3, weiching, according 10 he monticalliie (CAVES! CHF V)0.) dhemometies, g of solid magnesium nitrate hexahydrate powder, 9.7588 g of solid calcium

DL-glycerate hydrate powder, 20 mg of solid chromic nitrate nonahydrate (IIT) and 50 mg of solid vanadium(IIT)-2,4-pentanedionate powder, and adding the weighed starting materials to the 100 ml of absolute ethyl alcohol;

Step 4, respectively adding, with a pipette, 9.1340 ml of liquid tetraethoxysilane and ul of liquid tetrabutyl titanate into the 100 ml of absolute ethyl alcohol according to the monticellite chemometrics;

Step 5, putting a magnetic stirring rotor in the wide-mouth bottle, and sealing a mouth of the wide-mouth bottle with a plastic film with a thickness of 0.5 mm;

Step 6, placing the wide-mouth bottle on a high-temperature magnetic stirring heater coil, and enabling the high-temperature magnetic stirring heater coil to stir a mixed solution for 21 hrs at room temperature and 920 rpm;

Step 7. opening the mouth, sealed with the plastic film, of the wide-mouth bottle to add 42 ml of a 69-70% concentrated nitric acid solution, and then sealing the mouth of the wide-mouth bottle again with the plastic film;

Step 8, poking multiple 0.1 mm holes in a surface of the plastic film;

Step 9, placing the wide-mouth bottle on the high-temperature magnetic stirring heater coil, increasing a temperature of the heater coil to 83° C, and stirring the mixed solution for 26 hrs at 83° C and 1045 rpm;

Step 10, removing the plastic film from the mouth of the wide-mouth bottle, and increasing the temperature of the high-temperature magnetic stirring heater coil to 115° C until the mixed solution in the whole wide-mouth bottle is completely desiccated;

Step 11, taking out the magnetic stirring rotor, taking, with a spoon, all mixed powder out of the wide-mouth bottle, and placing the mixed powder in a platinum crucible;

Step 12, placing the platinum crucible containing the mixed powder in a high-temperature muffle furnace, and increasing a temperature of the high-temperature LU503140 muffle furnace to 1040° C at a rate of 720° C/h to calcine the mixed powder for 1.4 hrs;

Step 13, slowly and naturally cooling the mixed powder to room temperature, and taking out the mixed sample powder;

Step 14, uniformly grinding and mixing a calcined powdery mixture sample in an agate mortar, and pressing the mixture sample into a ® 14.3 mm * 7.2 mm disc on the press, and stacking three discs up in the platinum crucible;

Step 15, hanging the platinum crucible containing the disc-shaped mixture sample in a middle of a high-temperature oxygen atmosphere furnace having an open bottom, with a platinum wire connected to a wall of the platinum crucible, and injecting a gas mixture of hydrogen, argon and carbon dioxide into the platinum crucible from a top of the platinum crucible;

Step 16, placing a cup, 750 ml, of secondary deionized cold water below a furnace body of the oxygen atmosphere furnace;

Step 17, increasing a temperature of the platinum crucible containing the disc-shaped mixture sample to 1680° C at a rate of 700° C/h for constant-temperature calcining for 45 min to melt the disc-shaped mixture sample into glassy-state monticellite;

Step 18, after the sample is calcined at 1680° C for 45 min, applying a 10 A current to the platinum wire connected to the wall of the platinum crucible to fuse the platinum wire, so that the platinum crucible containing the sample falls into the secondary deionized cold water from a hearth of the oxygen atmosphere furnace to realize direct quenching of the sample at a high temperature, thus obtaining monticellite glass with uniform components; and

Step 19, taking the monticellite glass, quenched with the cold water, out of the platinum crucible, and grinding the monticellite glass into uniform sample powder in the agate mortar; placing the sample powder on the press, and pressing the sample powder into a ® 3.8 mm * 3.6 mm cylinder to obtain the high-titanium, vanadium and chromium LU503140 monticellite cylinder sample.

Preferably, sealing the monticellite cylinder sample and the two discs in a gold-palladium alloy sample tube for a high-temperature and high-pressure reaction to obtain high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite is carried out by:

Step 1, pressing the serpentine, the brucite and the slaked lime into two ® 3.8 mm (diameter) * 0.1 mm (thickness) discs on the press according to the weight ratio of 3:3:1;

Step 2, sequentially placing the two ® 3.8 mm (diameter) * 0.1 mm (thickness) discs at two ends of the cylinder sample, and sealing the cylinder sample and the two water-sourced discs in a ® 3.8 mm (inner diameter) * 4.0 mm (height) gold-palladium alloy sample tube with a wall thickness of 0.1 mm;

Step 3. placing the gold-palladium alloy sample tube containing the sample and the two discs on a Kawai-1000t multi-anvil press, setting a pressure rise rate and a temperature rise rate to 3.0 GPa/h and 50° C/min respectively, increasing the pressure and the temperature to 9.0 GPa and 1100° C respectively for hot-pressing sintering, and performing a reaction for 12 hrs under a constant-temperature and constant-pressure condition;

Step 4, after the reaction is performed for 12 hrs under the constant-temperature and constant-pressure condition, decreasing a temperature in a sample cavity to room temperature from 1100° C at a rate of 6° C/min;

Step 5, after the temperature in the sample cavity is decreased to the room temperature, decreasing a pressure in the sample cavity to normal pressure from 9.0 GPa at a rate of 0.90 GPa/h; and

Step 6, at the end of the high-temperature and high-pressure preparation reaction, taking an experimental sample out of the sample cavity, and opening the gold-palladium alloy sample tube with a diamond slicer to obtain the prepared high-titanium, LU503140 high-vanadium, high-chromium and high-water single-crystal monticellite.

Preferably, during the high-temperature and high-pressure reaction, the temperature in the high-pressure sample cavity is calibrated with two sets of high-temperature chromium silicon-nickel silicon N-type metal thermocouples, and each of the two sets of high-temperature chromium silicon-nickel silicon N-type metal thermocouples is composed of a chromium silicon metal alloy wire and a nickel silicon metal alloy wire that are made of different materials; the chemical composition of a positive pole (NP) of each said thermocouple is Nig44%CT142%S114%; the chemical composition of a negative pole (NN) of each said thermocouple is N195.5%S14 40.Mgo 1%; and correspondingly, a diameter of each said positive chromium silicon metal alloy wire (NP) and each said positive nickel silicon metal alloy wire (NN) is 0.25 mm; and each set of high-temperature chromium silicon-nickel silicon N-type metal thermocouples is symmetrically placed on upper and lower sides of an outer wall of the gold-palladium alloy sample tube, so that the temperature in the sample cavity is calibrated.

[0008] The present invention has the following beneficial effects:

[0009] According to the present invention, single-crystal monticellite with a high titanium content (2000-3000 ppm wt%), a high vanadium content (3000-4000 ppm wt%), a high chromium content (1000-2000 ppm wt%) and a high water content (1000-2000 ppm wt%) is synthesized, a synthesized sample contains single-crystal monticellite with the titanium content, vanadium content, chromium content and water content that match the mantle of terrestrial planets, and the obtained high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite is a pure substance and has good chemical stability.

[0010] The method provided by the present invention has the obvious advantages of simple operation process, short reaction time and the like, and the obtained single-erystal monticellite has good properties such as high purity, large size and stable LU503140 chemical properties.

DETAILED DESCRIPTION OF THE INVENTION

[0011] A method for preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite comprises:

[0012] Step 1, solid magnesium nitrate hexahydrate powder (purity: >99.99%), solid calcium DL-glycerate hydrate (purity: >99.99%), solid chromic nitrate nonahydrate (ITT) (purity: >99.99%), solid vanadium (IIT)-2,4-pentanedionate (purity: >99.99%), liquid tetraethoxysilane (purity: >99.99%), liquid tetrabutyl titanate (purity: >99.99%), solid natural serpentine powder (purity: >99%), solid natural brucite powder (purity: >99%), solid natural slaked lime powder (purity: >99%) and absolute ethyl alcohol (concentration: >99.9%) are used as starting materials.

[0013] Step 2, 100 ml of absolute ethyl alcohol is placed into a 500 ml wide-mouth glass bottle.

[0014] Step 3, according to monticellite (CaMg(S1,Cr,Ti,V)O4) chemometrics, 10 g of high-purity solid magnesium nitrate hexahydrate powder, 9.7588 g of high-purity solid calcium DL-glycerate hydrate powder, 20 mg of high-purity solid chromic nitrate nonahydrate (III) and 50 mg of high-purity solid vanadium(IIT)-2,4-pentanedionate powder are accurately weighed with a high-precision analytical balance, and are then carefully added to the 100 ml of absolute ethyl alcohol.

[0015] Step 4, 9.1340 ml of high-purity liquid tetraethoxysilane and 30 ul of high-purity liquid tetrabutyl titanate are carefully added to the 100 ml of absolute ethyl alcohol respectively with a pipette according to the monticellite chemometrics.

[0016] Step 5, a magnetic stirring rotor is put in the wide-mouth bottle containing a mixed solution of the solid magnesium nitrate hexahydrate powder, the solid calcium

DL-glycerate hydrate, the solid chromic nitrate nonahydrate (III), the solid LU503140 vanadium(III)-2,4-pentanedionate, the liquid tetraethoxysilane, the liquid tetrabutyl titanate and the absolute ethyl alcohol, and a mouth of the wide-mouth bottle is sealed with a plastic film with a thickness of 0.5 mm to prevent the initial solution in the wide-mouth bottle from splashing during the high-speed stirring process, which may otherwise compromise the synthesis accuracy of a sample.

[0017] Step 6, the wide-mouth bottle containing the sealed initial mixed solution and magnetic stirring rotor is placed on a high-temperature magnetic stirring heater coil, and in order to dissolve the starting materials, namely the magnesium nitrate hexahydrate, the calcium DL-glycerate hydrate, the chromic nitrate nonahydrate (III), the tetraethoxysilane and the tetrabutyl titanate, as well as tert-butyl chromate in the absolute ethyl alcohol, the high-temperature magnetic stirring heater coil is made to stir the materials at room temperature and 920 rpm for 21 hrs, so that the materials are sufficiently dissolved without residues.

[0018] Step 7, the mouth, sealed with the plastic film, of the wide-mouth bottle is opened, 42 ml of a 69-70% concentrated nitric acid solution is added to the mixed solution to accelerate the preparation reaction of monticellite, and then the mouth of the wide-mouth bottle is sealed again with the plastic film to prevent the initial solution in the wide-mouth bottle from splashing during the high-temperature stirring process, which may otherwise compromise the synthesis accuracy of the sample.

[0019] Step 8, multiple 0.1 mm holes are poked in the surface of the plastic film with sharp tweezers to allow volatile substances such as NH3*H»O, CO, CHa, C2Hy and O» produced during the reaction to be volatilized more easily and to prevent the concentrated nitric acid in the wide-mouth bottle from splashing during the high-temperature stirring process, which may otherwise compromise the synthesis accuracy of the sample.

[0020] Step 9, the wide-mouth bottle is placed on the high-temperature magnetic stirring heater coil, and the temperature of the heater coil is increased to 83° C, and the LU503140 mixed solution is stirred at a high temperature of 83° C and a high speed of 1045 rpm for 26 hrs, so that all initial reagents are thoroughly dissolved in a mixed solution of the absolute ethanol and the concentrated nitric acid.

[0021] Step 10, the plastic film sealing the mouth of the wide-mouth bottle is removed, and the temperature of the high-temperature magnetic stirring heater coil is increased to 115° C until the mixed solution in the whole wide-mouth bottle is completely desiccated.

[0022] Step 11, the magnetic stirring rotor is taken out, and all the mixed powder in the wide-mouth bottle is taken out carefully with a spoon and is placed in a platinum crucible.

[0023] Step 12, the platinum crucible containing the mixed powder is placed in a high-temperature muffle furnace, and the temperature of the high-temperature muffle furnace is increased to 1040° C at a rate of 720° C/h to calcine the mixed powder for 1.4 hrs to remove residual nitric acid and organic matter in the mixed powder; the mixed powder is slowly and naturally cooled to room temperature, and then the mixed sample powder is taken out.

[0024] Step 13, a calcined powder mixture sample is uniformly ground and mixed in an agate mortar, and the mixture sample is pressed into a ® 14.3 mm (diameter) * 7.2 mm (height) disc on the press, and three discs are stacked up in the platinum crucible.

[0025] Step 14, the platinum crucible containing the disc-shaped mixture sample is hung in the middle of a high-temperature oxygen atmosphere furnace having an open bottom, with a platinum wire connected to a wall of the platinum crucible, and a gas mixture of hydrogen, argon and carbon dioxide is injected into the platinum crucible from a top of the platinum crucible to control the oxygen atmosphere in the furnace in the high-temperature calcining process.

© [0026] Step 15, a cup, 750 ml, of secondary deionized cold water is placed below LU503140 the furnace body of the oxygen atmosphere furnace, so that the sample can be directly quenched at a high temperature.

[0027] Step 16, the temperature of the platinum crucible containing the disc-shaped mixture sample is increased to 16809 C at a rate of 700° C/h for constant-temperature calcining for 45 min to melt the disc-shaped mixture sample into glassy-state monticellite. Generally, the melting point of the monticellite is 1600° C, so when the temperature is over 1600° C, the monticellite will be in a glassy state. The high-temperature calcining process under the controlled oxygen atmosphere is carried out to provide a purer mixture initial material, namely the monticellite glass, to realize the synthesis of the high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite; the high-temperature calcination under the oxygen atmosphere can better control the valence state of the variable-valence elements, namely metallic titanium, metallic vanadium and metallic chromium, in the product; and the relatively short calcination time ensures that the monticellite can be quickly melted into a glass phase when the temperature is over 1600° C and possible residual substances that may affect the sample preparation, such as water, organic matter and nitric acid, can be volatilized completely.

[0028] Step 17, after the sample is calcined at 1680° C for 45 min, a 10 A current is applied to the platinum wire connected to the wall of the platinum crucible to fuse the platinum wire, so that the platinum crucible containing the sample instantly falls into the secondary deionized cold water from a hearth of the oxygen atmosphere furnace to realize direct quenching of the sample at a high temperature, thus obtaining monticellite glass with uniform components, wherein fast quenching ensures that the monticellite sample in the glassy state is preserved in a good condition at the high temperature.

[0029] Step 18, the monticellite glass, quenched with the secondary deionized cold water, is taken out of the platinum crucible and is sufficiently ground into uniform sample LU503140 powder in the agate mortar; the sample powder is placed on the press and is pressed into a ® 3.8 mm (diameter) * 3.6 mm (height) cylinder, and in order to obtain high-water monticellite, natural serpentine (molecular formula: MgeSisO10(OH)g), natural brucite (molecular formula: Mg(OH)») and natural slaked lime (molecular formula: Ca(OH)») with a weight ratio of 3:3:1 are used as a water source. The serpentine, brucite and slaked lime, as typical hydrous minerals, will undergo a dehydration reaction at a temperature over 910° C, thus being widely applied to mineral combinations for providing a water source during high-temperature and high-pressure experimental simulation. By setting the weight ratio of the serpentine, the brucite and the slaked lime to 3:3:1, sufficient water can be released by dehydrated products of the hydrous minerals under a high-temperature and high-pressure condition to provide a water source for synthesizing the high-water monticellite, and a large quantity of mineral combinations of forsterite, enstatite, periclase and quartz can be generated to control the silicon activity during the preparation process of the high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite in the sample cavity under the high-temperature and high-pressure condition.

[0030] Step 19, the serpentine, the brucite and the slaked lime with the weight ratio of 3:3:1 for providing the water source are placed on the press and pressed into two ® 3.8 mm (diameter) * 0.1 mm (thickness) discs, which are sequentially placed at two ends of the sample, and the sample and the water-sourced discs (the serpentine, the brucite and the slaked lime with the weight ratio of 3:3:1 for providing the water source) are sealed in a ® 3.8 mm (inner diameter) * 4.0 mm (height) gold-palladium alloy sample tube with a wall thickness of 0.1 mm, wherein the gold-palladium alloy sample tube is made of an optimal sealing material that can effectively prevent water from escaping from the sample tube during the sample preparation process under the high-temperature and high-pressure condition.

[0031] Monticellite is one of the important calcium-containing and LU503140 magnesium-containing silicate minerals in the upper mantle of the earth and other terrestrial planets; in order to truly simulate the growth environment of the monticellite in the upper mantle of the earth and other terrestrial planets and invert the temperature and pressure conditions for the stable existence of the monticellite mineral phase, the gold-palladium alloy sample tube containing the sample and the two water-sourced discs (the serpentine, the brucite and the slaked lime with the weight ratio of 3:3:1 for providing the water source) is placed on a Kawai-1000t multi-anvil press, a pressure rise rate and a temperature rise rate are set to 3.0 GPa/h and 50° C/min respectively, the pressure and the temperature are increased to 9.0 GPa and 1100° C respectively for hot-pressing sintering, and a reaction is performed for 12 hrs under a constant-temperature and constant-pressure condition.

[0032] According to the present invention, the temperature in the high-pressure sample cavity is accurately calibrated with two sets of high-temperature chromium silicon-nickel silicon N-type metal thermocouples, which are the latest internationally standard thermocouples. Because of its advantages of good linearity, large thermoelectromotive force, high sensitivity, good stability and uniformity, high oxidation resistance, low price and immunization to short-range ordering, the high-temperature chromium silicon-nickel silicon N-type metal thermocouples have overall properties superior to those of K-type thermocouples, thus being the most common thermocouples in many high-temperature and high-pressure mineral physics research laboratories at home and abroad and can measure temperatures from -200° C to 1300° C. Each set of high-temperature chromium silicon-nickel silicon N-type metal thermocouples is composed of a chromium silicon metal alloy wire and a nickel silicon metal alloy wire that are made of different materials (the chemical composition of a positive pole (NP) of each thermocouple is Nisa 4% CT14 294511 4%; the chemical composition of a negative pole (NN) of

‘each thermocouple is Nisss%Si44%Mgo.1%; and correspondingly, the diameter of each LU503140 positive chromium silicon metal alloy wire (NP) and each positive nickel silicon metal alloy wire (NN) is 0.25 mm), and each set of high-temperature chromium silicon-nickel silicon N-type metal thermocouples is symmetrically placed on upper and lower sides of an outer wall of the gold-palladium alloy sample tube, so that the temperature in the sample cavity is accurately calibrated.

[0033] When the temperature is increased to 910° C under a pressure of 9.0 GPa, the serpentine, the brucite and the slaked lime with the weight ratio of 3:3:1 sealed at the two ends of the gold-palladium alloy sample tube and used for providing the water source will undergo a dehydration reaction to release sufficient water, so that a good water source is provided. Moreover, when the serpentine, the brucite and the slaked lime undergo the dehydration reaction under the high-temperature and high-pressure condition, a large quantity of mineral combinations of forsterite, enstatite, periclase and quartz will be generated to control the silicon activity during the preparation process of the high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite in the sample cavity under the high-temperature and high-pressure condition.

[0034] After the reaction is performed for 12 hrs under the constant-temperature and constant-pressure condition, the temperature in the sample cavity is decreased to room temperature from 1100° C at a rate of 6° C/min. Compared with the temperature rise rate (50° C/min) for sample preparation, a low temperature fall rate under a constant pressure is more beneficial for crystal growth of large-sized single-crystal monticellite.

[0035] After the temperature in the sample cavity is decreased to the room temperature, the pressure in the sample cavity is decreased to normal pressure from 9.0

GPa at a rate of 0.90 GPa/h.

[0036] At the end of the high-temperature and high-pressure preparation reaction, an experimental sample is taken out of the sample cavity, the gold-palladium alloy sample tube is opened with a diamond slicer, and single-crystal monticellite is picked out under a LUS03140 high-power Olympus microscope.

[0037] The obtained single-crystal monticellite is a single phase without any other impurity phases. A test result obtained with an electron-probe microanalyzer (EPMA) shows that the single-crystal monticellite has a molecular formula of CaMgS104. A test result obtained with multifunctional inductively coupled plasma-mass spectrometry (ICP-MS) shows that the titanium content, vanadium content and chromium content of the single-crystal monticellite are 2261 ppm wt%, 3680 ppm wt% and 1282ppm wt% respectively. A test result obtained with vacuum Fourier transform-infrared spectroscopy (FT-IR) shows that the single-crystal monticellite has a high water content of 3230 ppm wit%.

[0038] The obtained high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite is an orthorhombic system with a space group of

Pnma (no.62), lattice parameters: a = 4.835 A, b= 11.118 A and c = 6.390 À, a unit cell volume of 343.42 A’, an average particle size of 243um, and a maximum particle size of 516 um.

[0039] The high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite obtained through the method provided by the present invention has superior properties such as high purity, large size, and stable chemical properties, and more importantly, the titanium content, the vanadium content, the chromium content and the water content are high and controllable. By changing the chemical dosage of the initial material, liquid tetrabutyl titanate, from 26.5459 ul to 39.8189 ul, the titanium content of the finally obtained high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite is increased from 2000 ppm wt% to 3000 ppm wt%. By changing the chemical dosage of the initial material, solid vanadium (IIT)-2,4-pentanedionate powder, from 40.7491 mg to 54.3321 mg, the vanadium content of the finally obtained high-titanium, high-vanadium, high-chromium and high-water LU503140 single-crystal monticellite is increased from 3000 ppm wt% to 4000 ppm wt%. By changing the chemical dosage of the initial material, solid chromic nitrate nonahydrate powder, from 15.6064 mg to 31.2128 mg, the chromium content of the finally obtained high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite is increased from 1000 ppm wt% to 2000 ppm wt%. By changing the weight ratio of the hydrous minerals, natural serpentine powder, natural brucite powder and natural slaked lime powder, for providing the water source and the different heights of the two corresponding water-sourced discs, the total amount of water generated by the dehydration reaction of the hydrous minerals sealed in the gold-palladium alloy sample tube can be controlled, and thus, the water content of the high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite sample can be adjusted.

The obtained high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite can fully meet the requirements for experimental physics simulation of minerals in the upper mantle of the earth and other terrestrial planets, breaks through the existing technical bottlenecks in the synthesis of single-crystal monticellite, and provides an important experimental sample support for exploring the optimal orientation and crystal axis anisotropy of single-crystal minerals in the upper mantle of the earth and other terrestrial planets under a high-temperature and high-pressure condition.

Claims

What is dlaimedis: LU503140

1. A method for preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite, comprising: preparing, according to monticellite chemometrics, a high-titanium, high-vanadium and high-chromium monticellite cylinder sample using solid magnesium nitrate hexahydrate powder, solid calcium DL-glycerate hydrate, solid chromic nitrate nonahydrate (III), solid vanadrum(lIT)-2,4-pentanedionate, liquid tetraethoxysilane, liquid tetrabutyl titanate, solid natural serpentine powder, solid natural brucite powder, solid natural slaked lime powder and absolute ethyl alcohol as starting materials, pressing serpentine, brucite and slaked lime into two discs on a press according to a weight ratio of 3:3:1, placing the discs at two ends of the monticellite cylinder sample, and sealing the monticellite cylinder sample and the two discs in a gold-palladium alloy sample tube for a high-temperature and high-pressure reaction to obtain high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite.

2. The method for preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite according to Claim 1, wherein the high-titanium, high-vanadium and high-chromium monticellite cylinder sample is prepared by: Step 1, using solid magnesium nitrate hexahydrate powder (purity: >99.99%), solid calcium DL-glycerate hydrate (purity: >99.99%), solid chromic nitrate nonahydrate (III) (purity: >99.99%), solid vanadium(IIT)-2,4-pentanedionate (purity: >99.99%), liquid tetraethoxysilane (purity: >99.99%), liquid tetrabutyl titanate (purity: >99.99%), solid natural serpentine powder (purity: >99%), solid natural brucite powder (purity: >99%), solid natural slaked lime powder (purity: >99%) and absolute ethyl alcohol (purity:

>99.9%) as the starting materials; Step 2, placing 100 ml of absolute ethyl alcohol into a 500 ml wide-mouth glass bottle; Step 3, weighing, according to the monticellite (CaMg(Si, Cr,T1,V)O4) chemometrics,

g of solid magnesium nitrate hexahydrate powder, 9.7588 g of solid calcium LU503140 DL-glycerate hydrate powder, 20 mg of solid chromic nitrate nonahydrate (IIT) and 50 mg of solid vanadium(IIT)-2,4-pentanedionate powder, and adding the weighed starting materials to the 100 ml of absolute ethyl alcohol;

Step 8, poking multiple 0.1 mm holes in a surface of the plastic film;

Step 12, placing the platinum crucible containing the mixed powder in a high-temperature muffle furnace, and increasing a temperature of the high-temperature

‘muffle furnace to 1040° C at a rate of 720° C/h to calcine the mixed powder for 1.4 hrs; LU503140

Step 19, taking the monticellite glass, quenched with the cold water, out of the platinum crucible, and grinding the monticellite glass into uniform sample powder in the agate mortar; placing the sample powder on the press, and pressing the sample powder into a ® 3.8 mm * 3.6 mm cylinder to obtain the high-titanium, vanadium and chromium

FROM EE sees

3. The method for preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite according to Claim 1, wherein sealing the monticellite cylinder sample and the two discs in a gold-palladium alloy sample tube for a high-temperature and high-pressure reaction to obtain high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite is carried out by: Step 1, pressing the serpentine, the brucite and the slaked lime into two ® 3.8 mm (diameter) * 0.1 mm (thickness) discs on the press according to the weight ratio of 3:3:1; Step 2, sequentially placing the two ® 3.8 mm (diameter) * 0.1 mm (thickness) discs at two ends of the cylinder sample, and sealing the cylinder sample and the two water-sourced discs in a ® 3.8 mm (inner diameter) * 4.0 mm (height) gold-palladium alloy sample tube with a wall thickness of 0.1 mm; Step 3. placing the gold-palladium alloy sample tube containing the sample and the two discs on a Kawai-1000t multi-anvil press, setting a pressure rise rate and a temperature rise rate to 3.0 GPa/h and 50° C/min respectively, increasing the pressure and the temperature to 9.0 GPa and 1100° C respectively for hot-pressing sintering, and performing a reaction for 12 hrs under a constant-temperature and constant-pressure condition; Step 4, after the reaction is performed for 12 hrs under the constant-temperature and constant-pressure condition, decreasing a temperature in a sample cavity to room temperature from 1100° C at a rate of 6° C/min; Step 5, after the temperature in the sample cavity is decreased to the room temperature, decreasing a pressure in the sample cavity to normal pressure from 9.0 GPa at a rate of

0.90 GPa/h; and Step 6, at the end of the high-temperature and high-pressure preparation reaction, taking an experimental sample out of the sample cavity, and opening the gold-palladium alloy sample tube with a diamond slicer to obtain the prepared high-titanium, LU503140 high-vanadium, high-chromium and high-water single-crystal monticellite.

4. The method for preparing high-titanium, high-vanadium, high-chromium and high-water single-crystal monticellite according to Claim 3, wherein during the high-temperature and high-pressure reaction, the temperature in the high-pressure sample cavity is calibrated with two sets of high-temperature chromium silicon-nickel silicon N-type metal thermocouples, and each of the two sets of high-temperature chromium silicon-nickel silicon N-type metal thermocouples is composed of a chromium silicon metal alloy wire and a nickel silicon metal alloy wire that are made of different materials; the chemical composition of a positive pole (NP) of each said thermocouple is Nis4.4%Cr14.2%0S11.4%; the chemical composition of a negative pole (NN) of each said thermocouple is Nios 5%S14.44Mgo.1%; and correspondingly, a diameter of each said positive chromium silicon metal alloy wire (NP) and each said positive nickel silicon metal alloy wire (NN) is 0.25 mm; and each set of high-temperature chromium silicon-nickel silicon N-type metal thermocouples is symmetrically placed on upper and lower sides of an outer wall of the gold-palladium alloy sample tube, so that the temperature in the sample cavity is calibrated.