CN114525588B - Preparation method of phosphate-substituted single crystal material - Google Patents
Preparation method of phosphate-substituted single crystal material Download PDFInfo
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- CN114525588B CN114525588B CN202210116726.6A CN202210116726A CN114525588B CN 114525588 B CN114525588 B CN 114525588B CN 202210116726 A CN202210116726 A CN 202210116726A CN 114525588 B CN114525588 B CN 114525588B
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- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
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- C30B29/46—Sulfur-, selenium- or tellurium-containing compounds
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
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- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
- C30B11/003—Heating or cooling of the melt or the crystallised material
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Abstract
The application provides a preparation method of a phosphate-substituted single crystal material, which comprises the following steps: 1) Putting the phosphate-substituted polycrystalline material into a sealed container, and vacuumizing; 2) Heating the sealed container containing the hypophosphite polycrystalline material under rotation such that the hypophosphite polycrystalline material is completely melted; 3) Cooling the completely molten phosphate-substitute polycrystalline material in the rotating state in the step 2) to grow crystals; when the crystal growth is finished, the phosphate-substituted single crystal material is obtained; the sealed container is a container resistant to Li corrosion. The growth method and the growth equipment provided by the application break through the size limitation of the chemical vapor transport method for growing the phosphate-substituted single crystal material, and can further carry out size regulation and control on the bulk single crystal by designing the size of the crucible.
Description
Technical Field
The present invention relates to crystal growth for radiation detection, and is especially but not limited to the preparation process of new type single crystal material for direct neutron detection.
Background
Neutron detection has important application in the fields of national security, aerospace and deep space detection, nuclear power energy, oil exploration, medical detection and the like. The development of materials and devices capable of effectively and accurately detecting neutrons is an important research content in the field of nuclear radiation detection. Neutrons are electrically neutral, do not interact with matter coulombs, and cannot ionize atoms directly, so they need to be detected by detecting secondary products or state changes generated by the interaction of the neutrons with atomic nuclei. For example, in a commonly used nuclear reaction method, neutrons are reacted with a certain nuclear species to generate energy-carrying secondary charged particles, and the detection of the neutrons is achieved by recording the ionization effect of the charged particles. Further, neutron detectors can be classified into three major categories according to detection materials and modes: gas detectors, scintillator detectors, and semiconductor detectors.
Traditional gas neutron detectors are based primarily on 3 He，It utilizes 3 The pulse current generated by the proton and tritium nucleus released by the reaction of He and the neutron nucleus detects the neutron. 3 He has a large thermal neutron capture cross-section and is an ideal material for detecting neutrons. However, in China 3 He gas mainly depends on an inlet, and along with the rapid development of the neutron detection field, 3 the problem of He resource supply shortage is becoming more serious, and therefore, new neutron detection materials and devices are urgently needed to be explored. Therein contain 6 Li and 10 the material of B element is a suitable substitute 3 A neutron detection material system of He gas detector. At present, the most studied is 6 Li and 10 b scintillator material, including liquid scintillators (e.g. 6 Li-CH), plastic scintillators (e.g. 10 B-CH Plastic) and glass scintillator: ( 6 Li glass), but is easily decomposed by air, a plastic scintillator has high detection efficiency but has low output light intensity by transmittance, and a glass scintillator has poor irradiation resistance.
The core of the semiconductor detector is a semiconductor device, high-energy charged particles generated by nuclear reaction between neutrons and the semiconductor excite materials to generate electron-hole pairs with a certain proportion, and the neutrons can be detected by applying bias voltage and collecting pulse signals formed by the latter. Compared with gas detectors and scintillator detectors, the semiconductor detector has the advantages of simple structure, small volume, short response time, high detection efficiency and the like, and can be divided into a direct semiconductor detector and an indirect semiconductor detector according to the configuration of devices. The indirect semiconductor detector consists of a conversion layer and a carrier collection layer, and the thermal neutron detection efficiency can only reach 40% at most theoretically (nuclear. The conversion layer and the carrier collecting layer of the direct semiconductor detector are made of the same material layer, the detector is simpler in configuration, and the intrinsic thermal neutron detection efficiency can reach 100% theoretically. However, the direct semiconductor detector requires high material purity and low carrier trap concentration, and only a single crystal sample can meet the requirements. On the other hand, although 6 Li thermal neutron capture cross section less than 3 He (938barns vs 5337barns), butIn the solid 6 Li can reach high atomic density (10) 21 cm -3 Magnitude), significant advantage in effective neutron absorption, which makes it possible to include 6 The single crystal material semiconductor of Li becomes one of the most potential materials for thermal neutron detection. 2020. In the year, chica et al (Nature, vol.577,2020, 346-349) reported a novel compound LiInP 2 Se 6 And preparing the flaky LiInP by a chemical vapor transport method 2 Se 6 The single crystal material has a proper band gap, an energy band structure for effectively transmitting charges, a good thermal neutron capture cross section and high sensitivity to thermal neutrons. However, the chemical vapor transport method adopted in the existing research can only obtain the LiInP with the thickness of sub-millimeter level 2 Se 6 The growth process of the single crystal material is uncontrollable, the process cannot be amplified, and the crystal of the system is seriously hindered from being applied to practical devices.
Disclosure of Invention
The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.
The application provides a large-size and high-quality LiInP 2 Se 6 A method for growing a single crystal material is favorable for application of the single crystal material in the field of neutron semiconductor detectors.
The application provides a preparation method of a phosphate-substituted single crystal material, which comprises the following steps:
1) Putting the phosphate-substituted polycrystalline material into a sealed container, and vacuumizing;
2) Heating the sealed container containing the hypophosphite polycrystalline material under rotation such that the hypophosphite polycrystalline material is completely melted;
3) Cooling the completely molten phosphate-substitute polycrystalline material in the rotating state in the step 2) to grow crystals; when the crystal growth is finished, the phosphate-substituted single crystal material is obtained;
the sealed container is a container resistant to Li corrosion.
In one embodiment provided herein, the chemical formula of the substituted phosphate is LiMP 2 Q 6 ；
The M is selected from any one or more of Ga, in, bi, sb, as and Al;
q is selected from any one or two of S and Se;
in one embodiment provided herein, the salt of hypophosphorous acid is a salt of selenophosphoric acid, more preferably, the salt of hypophosphorous acid is LiInP 2 Se 6 。
In one embodiment provided herein, the Li corrosion resistant container includes any one or more of a fused silica tube, a glassy carbon crucible, and a pyrolytic Boron Nitride (BN) crucible, the surfaces of which are coated with carbon;
in one embodiment provided herein, the fused silica tube with carbon coated surface is a fused silica container with carbon coated surface obtained by cracking carbon-containing organic molecules (acetone, propane, isopropanol, methanol, hexane, etc.) at high temperature (1150 ℃) to generate a dense amorphous carbon layer on the wall of the quartz container (Journal of Crystal Growth, vol.290,2006, 597-601).
In one embodiment provided herein, the fused silica container with carbon coated on the surface thereof may be prepared by dropping 0.5mL to 1mL of a solution containing carbon organic molecules into a silica container with an inner diameter of 12mm, and cracking the solution under the action of oxyhydrogen flame (with a temperature of 2500 ℃ to 3000 ℃) to produce an amorphous carbon layer, wherein the bottom tip portion of the silica container is easily eroded by the molten polycrystalline material, the oxyhydrogen flame is heated for a long time (3 min to 5 min), the oxyhydrogen flame is adapted to be heated for a short time (1 min to 2 min) at the upper end of the container, and the thickness of the coated carbon layer is in a range of 0.1 μm to 0.6 μm.
In one embodiment provided herein, the step 1) is vacuuming to 10% -3 Pa or less.
In one embodiment provided by the present application, the rotation state in step 2) is from 0.1r/min to 23r/min, and the rotation is performed with the vertical direction as the axis;
in one embodiment provided herein, the melting is performed by heating to 50 ℃ to 200 ℃ above the melting point of the phosphate-substitute polycrystalline material at 1 ℃/min to 2 ℃/min, and then maintaining the temperature for 10h to 24h to completely melt the phosphate-substitute polycrystalline material.
In one embodiment provided by the present application, before growing the crystal in step 3), the method further comprises the following steps:
after the phosphate-substituted polycrystalline material is completely melted, cooling the phosphate-substituted polycrystalline material, wherein the temperature of the cooled phosphate-substituted polycrystalline material is within the range of 50-100 ℃ above the melting point of the phosphate-substituted polycrystalline material;
in one embodiment provided herein, the cooling rate is 0.5 ℃/min to 2 ℃/min.
In one embodiment provided herein, step 3) is performed by adjusting the position of the sealed container containing the hypophosphite polycrystalline material such that all or a portion of the hypophosphite polycrystalline material is at an ambient temperature that is 50 ℃ to 100 ℃ below the melting point;
in one embodiment provided herein, the speed of adjustment of the position is 0.5mm/h to 50mm/h;
in one embodiment provided by the application, the rotation speed in the step 3) is 0.1r/min to 23r/min, and the rotation is carried out by taking a vertical direction as an axis;
in one embodiment provided herein, the mono-crystalline material forms a mono-crystalline material at the growth interface when a portion of the mono-crystalline material is in an environment that is 50 ℃ to 100 ℃ below the melting point;
the temperature gradient of the phosphate generation polycrystalline material above the growth interface is 5-30 ℃/cm higher than that of the phosphate generation single crystal material below the growth interface.
In one embodiment provided by the present application, the polycrystalline material is completely melted, and then passes through the upper temperature zone and the lower temperature zone, and is simultaneously cooled to a matching temperature to produce a temperature gradient required for melting polycrystalline crystallization, and then all the melting polycrystalline material is crystallized through the temperature gradient by the speed reduction.
The upper temperature zone is cooled to a temperature point which is 50 ℃ to 100 ℃ higher than the melting point by 0.5 ℃/min to 2 ℃/min, and the lower temperature zone is cooled to a temperature point which is 50 ℃ to 100 ℃ lower than the melting point, so that the temperature gradient reaches 5 ℃/cm to 30 ℃/cm. While the container slowly descends from the upper temperature zone to the lower temperature zone and keeps rotating. After the crystal growth is finished, the phosphate-substituted single crystal material with light transmission, large size and high quality is obtained.
In still another aspect, the present application provides the mono-crystalline phosphate material prepared by the above method for preparing mono-crystalline phosphate material;
in one embodiment provided herein, the dimensions of the mono-crystalline material of the hypophosphite are greater than 10mm in diameter and greater than 40mm in length (depending on the inner diameter of the growth vessel and the amount of packing).
In one embodiment provided herein, the purity of the mono-crystalline material of a hypophosphite is 3N or more.
In yet another aspect, the present application provides a large-sized phosphate-substituted growing apparatus, comprising:
sealing the container;
a heating device, wherein the sealed container is positioned in the heating device;
an actuator configured to control rotation and lowering of the sealed container.
In one embodiment provided herein, the heating device is configured to heat a specific temperature zone to a specific temperature, and the temperature zones are separated by a thermal insulation material.
In one embodiment provided by the present application, the upper and lower temperature regions can be used for independent temperature control. The upper temperature zone is set as a high temperature zone, the lower temperature zone is set as a low temperature zone, and the heating powers of the upper and lower temperature zones are matched with each other to adjust the axial temperature gradient.
Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the application. Other advantages of the present application may be realized and attained by the invention in its aspects as described in the specification.
Drawings
The drawings are intended to provide an understanding of the present disclosure, and are to be considered as forming a part of the specification, and are to be used together with the embodiments of the present disclosure to explain the present disclosure without limiting the present disclosure.
FIG. 1 shows an example of the present application of LiInP 2 Se 6 The structure schematic diagram of the single crystal material growth device;
FIG. 2 shows LiInP prepared in example 1 of the present application 2 Se 6 XRD spectrum of polycrystalline powder;
FIG. 3 shows LiInP prepared in example 1 of the present application 2 Se 6 DSC test curve for polycrystalline material;
FIG. 4 shows LiInP prepared in example 1 of the present application 2 Se 6 A topography of the single crystal material;
FIG. 5 shows LiInP prepared in example 1 of the present application 2 Se 6 A laue spot plot of the single crystal material;
FIG. 6 shows LiInP prepared in example 1 of the present application 2 Se 6 An absorption edge spectrum of the single crystal material;
FIG. 7 is an α -particle response spectrum of the single crystal material obtained in example 1;
fig. 8 is an α -particle response spectrum of the single crystal material obtained in example 2.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, embodiments of the present application are described in detail below. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.
As shown in FIG. 1, the present application provides a large-sized, high-quality LiInP 2 Se 6 The single crystal material growth method, the growth apparatus of the single crystal material used includes crystal growth furnace body 1 specifically, mechanical drive control system 3 and temperature control system 5, the middle part of the said crystal growth furnace body 1 places the glass tube 2, the upper end of the glass tube places the furnace plug 10 with central through hole, the lower end places the solid furnace plug 9; an upper heating zone 6 and a lower heating zone 7 are sequentially arranged in the crystal growth furnace body 1 from top to bottom, and the upper and lower heating zones are independently controlled in temperature by a temperature control system 5; the mechanical transmission control system 3 is controlled by the mechanical transmission device 4The sealed glass crucible 8 with the polycrystalline material rotates and moves up and down. The upper heating zone 6 and the lower heating zone 7 are separated by a heat insulation plate 11.
Example 1:
(1) Providing an initial feedstock comprising elemental lithium (Li, 99.9% Aladdin), elemental indium (In, 99.99% Aladdin), elemental red phosphorus (P, 99.999% Alfa Aesar), and elemental selenium (Se, 99.9999% Alfa Aesar).
(2) Preparation of Li 2 Se precursor: in an argon-filled glove box, 0.2019 g of a Li rod-shaped simple substance and 1.1600g of Se simple substance powder are weighed according to a stoichiometric ratio, the Li rod-shaped simple substance is placed in a molybdenum crucible, the Se simple substance powder is placed at the bottom of a fused quartz crucible, the molybdenum crucible is placed above the Se simple substance powder, and finally the fused quartz crucible is vacuumized to 10 DEG -3 And (6) sealing the pipe by Pa. Putting a plurality of sealed quartz crucibles into a muffle furnace, heating to 300 ℃ at a speed of 0.5 ℃/min, preserving heat for 24 hours, cooling with the furnace, and knocking open the quartz crucibles to obtain Li 2 Se is stored in a glove box.
(3) Preparation of P 2 Se 5 Precursor: weighing 1.5764g of red phosphorus P elementary substance block and 10.0479g of Se elementary substance powder according to stoichiometric ratio, placing the red phosphorus P elementary substance block and the Se elementary substance powder into a fused quartz crucible together, and vacuumizing the fused quartz crucible to 10 g -3 Pa is subjected to tube sealing treatment, the tube is put into a muffle furnace and heated to 500 ℃ at a speed of 0.7 ℃/min, the tube is cooled along with the furnace after heat preservation for 72 hours, and a quartz crucible is knocked open to obtain P 2 Se 5 And placing in a glove box for storage.
(4) Preparation of LiInP 2 Se 6 Polycrystalline materials: weighing 1.2371g Li according to stoichiometric ratio 2 Se precursor 12.1725g P 2 Se 5 Placing the precursor, 2.9705g of simple substance In powder and 1.0522g of simple substance Se powder In a fused quartz crucible, and vacuumizing the fused quartz crucible to 10 DEG -3 After the Pa tube sealing treatment, the tube is put into a muffle furnace and heated to 750 ℃ at a speed of 1 ℃/min, the temperature is kept for 24h and then reduced to 350 ℃ at a speed of 0.5 ℃/min, then the tube is cooled along with the furnace, and a quartz crucible is knocked open to obtain the LiInP 2 Se 6 The polycrystal was stored in a glove box. The polycrystalline material was subjected to powder XRD test, and the result is shown in FIG. 2, wherein the polycrystalline material is pure phase and is shown in the tableThe (00L) crystal face orientation feature is shown. The DSC of the polycrystalline material was measured, and as shown in fig. 3, the melting point of the polycrystalline material was 703 ℃ during the temperature increase as seen from the test curve.
(5) Preparation of LiInP 2 Se 6 Single crystal material: weighing 15g of the LiInP prepared in the step (4) 2 Se 6 Placing the polycrystalline material in a fused quartz crucible after carbon coating treatment, sealing the tube (the outer diameter of the quartz crucible is 15mm, the inner diameter is 12 mm), and vacuumizing to 10% -3 Below Pa, growing in a double-temperature-zone tube furnace to obtain LiInP 2 Se 6 A single crystal material. Firstly, a glass crucible is lowered to the position of a constant temperature area of a tube furnace, the quartz crucible rotates at the speed of 15r/min, the temperature is raised to 850 ℃ at the speed of 2 ℃/min, and the temperature is kept for 10h so that polycrystalline materials are completely melted; the temperature of the upper heating zone is reduced to 800 ℃ at 1 ℃/min, and the temperature of the lower heating zone is reduced to 630 ℃ at 1 ℃/min, so that the temperature gradient of the double-temperature zone tubular furnace reaches 5 ℃/cm to 30 ℃/cm. Meanwhile, the quartz crucible is slowly descended from the high-temperature area to the low-temperature area and keeps rotating by taking the vertical direction as an axis, the descending speed and the rotating speed of the crucible are respectively 1mm/h and 20r/min, and the LiInP 2 Se 6 The polycrystalline material forms LiInP at the growth interface after being cooled 2 Se 6 The temperature gradient of the phosphate generation polycrystalline material above the growth interface is higher than that of the phosphate generation single crystal material below the growth interface by 15 ℃/cm to 22 ℃/cm; after the crystal growth is finished, knocking open the quartz crucible to obtain dark red, light-transmitting and large-size high-quality LiInP 2 Se 6 As shown in the morphology of the single crystal material in FIG. 4 (in which the black portion is a quartz crucible inert carbon layer adhered to the surface), the single crystal material had an outer diameter of 12mm and a length of 50mm (based on the size of the quartz crucible). A photograph of the Laue spots obtained on the (00L) crystal plane by the Laue camera is shown in FIG. 5, which illustrates the LiInP obtained 2 Se 6 Single crystal materials have excellent crystalline quality. Further, by measuring the UV-vis-NIR transmission spectrum, as shown in FIG. 6, liInP was obtained 2 Se 6 The absorption edge of the single crystal material is 593nm, which corresponds to the forbidden band width of 2.09eV.
To evaluate the radiation detection effect of a single crystal material, based on the conventional method in the art, it will be further describedThe single crystal material is made into a prototype device for subsequent testing. Cutting the obtained single crystal material, controlling the thickness between 0.3mm, preparing gold electrodes with the radius of 2mm on the upper end surface and the lower end surface by adopting magnetron sputtering, and respectively connecting with a lead. By 241 Am emits alpha particles with a reaction energy of 5.486MeV, and 6 the nuclear reaction energy of Li and neutron is similar to 4.78MeV, the energy deposition is large, the electron hole pair yield is high, a large signal can be obtained, the range is short (several micrometers in solid), the transportation characteristic of electrons or holes can be conveniently evaluated, and the radiation detection effect of the single crystal material is preliminarily judged by detecting the response of the material to alpha particles. An alpha particle source and a single crystal material device are placed in a detection chamber, high voltage is applied to collect pulse signals generated by alpha particle irradiation, and the obtained pulse signals are transmitted to a multi-channel analyzer after passing through a preamplifier and a main amplifier. The multichannel analyzer records and stores the pulse signal according to the pulse height. The abscissa of the pulse amplitude spectrum obtained after a certain test time is the number of channels and corresponds to the energy value of the particles, and the ordinate represents the particle count recorded in each channel. FIG. 7 shows the LiInP prepared in this example 2 Se 6 The alpha particle response spectrum of the single crystal material corresponds to the electron pulse amplitude spectrum collected under the applied voltage of 200, 300, 400, 500 and 600V. As the voltage increases the charge collection efficiency increases and the corresponding peak shifts to the right gradually. The full energy peaks of alpha particles under different voltages have full energy peak resolution, which indicates that the LiInP 2 Se 6 The single crystal material is capable of efficiently transporting electron carriers generated by reaction with neutrons. In summary, the present application is the LiInP 2 Se 6 The application of the bulk single crystal material in the field of neutron radiation detection opens a brand new development space.
Example 2:
(1) Providing an initial feedstock comprising elemental lithium (Li, 99.9% Aladdin), elemental indium (In, 99.99% Aladdin), elemental red phosphorus (P, 99.999% Alfa Aesar), and elemental selenium (Se, 99.9999% Alfa Aesar).
(2) Preparation of Li 2 Se precursor: in an argon-filled glove box, 0.1979 g of Li rod-shaped simple substance and 1.1371g of Se simple substance powder are weighed according to stoichiometric ratio, and the mixture is preparedPutting the Li rod-shaped simple substance into a molybdenum crucible, putting Se simple substance powder at the bottom of the fused quartz crucible, putting the molybdenum crucible above the Se simple substance powder, and finally vacuumizing the fused quartz crucible to 10 DEG -3 And (6) sealing the pipe by Pa. Putting a plurality of sealed quartz crucibles into a muffle furnace, heating to 300 ℃ at a speed of 0.5 ℃/min, preserving heat for 24 hours, cooling with the furnace, and finally knocking open the quartz crucibles to obtain Li 2 Se is stored in a glove box.
(3) Preparation of P 2 Se 5 Precursor: weighing 1.5195g of red phosphorus P elementary substance block and 9.6853g of Se elementary substance powder according to stoichiometric ratio, placing the red phosphorus P elementary substance block and the Se elementary substance powder into a fused quartz crucible together, and vacuumizing the fused quartz crucible to 10 g -3 Pa is subjected to tube sealing treatment, the tube is put into a muffle furnace and heated to 500 ℃ at a speed of 0.7 ℃/min, the tube is cooled along with the furnace after heat preservation for 72 hours, and a quartz crucible is knocked open to obtain P 2 Se 5 And placing the mixture in a glove box for storage.
(4) Preparation of LiInP 2 Se 6 Polycrystalline materials: weighing 1.1646g Li according to stoichiometric ratio 2 Se precursor 11.4588g P 2 Se 5 Placing the precursor, 2.7963g of simple substance In powder and 0.9905g of simple substance Se powder In a fused quartz crucible, and vacuumizing the fused quartz crucible to 10 DEG -3 After Pa tube sealing treatment, the tube is put into a muffle furnace and heated to 750 ℃ at a speed of 1 ℃/min, the temperature is kept for 24h and then is reduced to 350 ℃ at a speed of 0.5 ℃/min, and then the tube is cooled along with the furnace, and a quartz crucible is knocked open to obtain LiInP 2 Se 6 The polycrystal was stored in a glove box. The melting point of the polycrystalline material was the same as in example 1.
(5) Preparation of LiInP 2 Se 6 Single crystal material: weighing 13g of the LiInP prepared in the step (4) 2 Se 6 Placing the polycrystalline material in a fused quartz crucible after carbon coating treatment, sealing the tube (the outer diameter of the quartz crucible is 15mm, the inner diameter is 12 mm), and vacuumizing to 10% -3 Below Pa, growing in a double-temperature-zone tube furnace to obtain LiInP 2 Se 6 A single crystal material. Firstly, a glass crucible is lowered to the position of a constant temperature area of a tube furnace, the quartz crucible rotates at the speed of 15r/min, the temperature is raised to 840 ℃ at the speed of 2 ℃/min, and the temperature is preserved for 10h to ensure that a polycrystalline material is completely melted; the temperature of the upper heating zone is reduced to 790 ℃ at 1 ℃/min, and the temperature of the lower heating zone is reduced to 1 DEG CAnd/min is reduced to a temperature point of 610 ℃ so that the temperature gradient of the double-temperature-zone tube furnace reaches 5 ℃/cm to 30 ℃/cm. Meanwhile, the quartz crucible slowly descends from a high-temperature area to a low-temperature area and keeps rotating, the descending speed and the rotating speed of the crucible are respectively 1mm/h and 20r/min, and the LiInP 2 Se 6 The polycrystalline material forms LiInP at the growth interface after being cooled 2 Se 6 The temperature gradient of the phosphate generation polycrystalline material above the growth interface is higher than that of the phosphate generation single crystal material below the growth interface by 15 ℃/cm to 22 ℃/cm; after the crystal growth is finished, knocking open the quartz crucible to obtain dark red, light-transmitting and large-size high-quality LiInP 2 Se 6 The single crystal material has an outer diameter of 12mm and a length of 50mm. FIG. 8 shows LiInP 2 Se 6 The single crystal material obtained in this example was evaluated for its radiation detection effect according to the method of example 1. Corresponding to the electron pulse amplitude spectrum collected under the applied voltage of 300V, the full energy peaks of the alpha particles all have full energy peak resolution, which indicates that the LiInP obtained in example 2 2 Se 6 The single crystal material is capable of efficiently transporting electron carriers generated by reaction with neutrons.
Comparative example 1:
this comparative example is Experimental example 1 of US patent US 2021/0206638 A1.
(1) Providing starting materials comprising elemental lithium (Li, 99.9% Sigma Aldrich), elemental indium (In, 99.99% American elements), elemental red phosphorus (P, 99.999%.
(2) Preparation of Li 2 Se precursor: in a nitrogen-filled glove box, the lithium metal was removed from the mineral oil and the oxidized surface layer was cut off. Li and Se are weighed according to a stoichiometric ratio of Li to Se = 2. The reaction is accelerated by continuous stirring until the liquid ammonia is changed from dark blue to clear light orange, and the reaction is finished. Heating to boil liquid ammonia, discharging, placing the reaction container in vacuum for one night, and collecting Li 2 And placing Se in a nitrogen-filled glove box for storage.
(3) Preparation of P 2 Se 5 Precursor: weighing 1.356g of red phosphorus P simple substance block and 8.6437g of Se simple substance particle according to stoichiometric ratio, putting the red phosphorus P simple substance block and the Se simple substance particle into a fused quartz crucible together, and vacuumizing the fused quartz crucible to 2 x 10 -3 mbar is sealed, mixed by simple shaking, placed into an inclined tube furnace, heated to 500 deg.C for 12h, cooled with the furnace after heat preservation for 72h, knocked open quartz crucible in nitrogen-filled glove box, and P is added 2 Se 5 And placing the mixture in a glove box for storage.
(4) Preparation of LiInP 2 Se 6 Polycrystalline materials: 0.437g Li was weighed out In a stoichiometric ratio Li/In/P/Se =1.05/1/2.04/6.12 2 Se、1.030g P 2 Se 5 4.181g In and 0.351g Se were placed In a fused silica crucible after carbon coating treatment, and the fused silica crucible was evacuated to 2X 10 -3 After mbar tube sealing treatment, putting the tube into an inclined tube furnace, heating the tube to 750 ℃ for 10h, keeping the temperature for 24h, then cooling the tube to 350 ℃ in 12h, then cooling the tube along with the furnace, and knocking open a quartz crucible to obtain the LiInP 2 Se 6 Polycrystalline materials.
(5) Preparation of LiInP 2 Se 6 Single crystal material: preparation of LiInP by chemical vapor transport method 2 Se 6 A single crystal material. In consideration of the inner diameter (13 mm to 18 mm) of the fused silica crucible, the LiInP is blended in an amount of 0.5g to 5g 2 Se 6 Preparing polycrystalline material with 16g to 80g I 2 Taking the ratio of LiInP 2 Se 6 Polycrystalline material and I 2 Is arranged at the bottom of the fused silica crucible. During vacuum tube sealing treatment, the bottom of the fused quartz crucible is placed in liquid nitrogen to prevent I 2 Is lost. After sealing, the sealed tube furnace is put into a double-temperature-zone tube furnace, and the bottom of the tube furnace is arranged in a Source area. Source area: heating to 560 ℃ after 6h, keeping the temperature for 12h, heating to 660 ℃ after 6h, keeping the temperature for 168h, and cooling to room temperature after 6 h; a Sink zone: heating to 660 ℃ for 6h, keeping the temperature for 12h, cooling to 560 ℃ for 6h, keeping the temperature for 170h, and cooling to room temperature for 10 h.
After the chemical vapor transport process is finished, deep red flaky LiInP is obtained in a Sink area 2 Se 6 A single crystal material. The area distribution of the sheet-shaped single crystal material is within the range of 1cm multiplied by 1cm, and the thickness distribution is within the range of 0.05mm to 0.5mmAnd the size of the obtained single crystal material is random and uncontrollable.
Comparative example 2:
this comparative example differs from example 1 only in that: the crucible in the step (5) is a fused silica crucible which is not subjected to carbon coating treatment, and other processes and conditions are completely the same; after the growth process is finished, the bottom of the quartz crucible is corroded by the molten polycrystalline material to form a crack, so that gaseous substances generated by the polycrystalline material leak and cannot be crystallized.
Comparative example 3:
this comparative example differs from example 1 only in that: not packing LiInP in the step (5) 2 Se 6 Sealing a crucible of the polycrystalline material, wherein other processes and conditions are completely the same; after the growth procedure is finished, P generated by volatilizing gaseous substances exists between the glassy carbon crucible and the fused quartz crucible x Se y Compounds, causing the molten polycrystalline material to deviate from the normal stoichiometric ratio and fail to crystallize.
Comparative example 4:
this comparative example differs from example 1 only in that: heating the temperature in the step (5) to 850 ℃ at the speed of 2 ℃/min, modifying the temperature to 950 ℃ at the speed of 2 ℃/min, and ensuring that other processes and conditions are completely the same; the final product is produced as crystals having a plurality of different crystallographic orientations.
Compared with a chemical vapor transport method, the method has the following advantages:
the growth method and the growth equipment provided by the application break through the growth of the LiInP by the chemical vapor transport method 2 Se 6 The size of the single crystal material is limited, and the size of the bulk single crystal can be further regulated by designing the size of the crucible. The single crystal obtained by the growth method and the equipment has high repeatability and controllable size, and the single crystal has a large single crystal proportion for practical application.
Claims (11)
1. A method for preparing a phosphate single crystal material comprises the following steps:
1) Putting the phosphate-substituted polycrystalline material into a sealed container, and vacuumizing;
2) Heating the sealed container containing the hypophosphite polycrystalline material under rotation such that the hypophosphite polycrystalline material is completely melted;
3) Cooling the completely molten phosphate-substitute polycrystalline material in the rotating state in the step 2) to grow crystals; when the crystal growth is finished, the phosphate-substituted single crystal material is obtained;
the sealed container is a container resistant to Li corrosion;
the chemical general formula of the phosphate is LiMP 2 Q 6 ；
The M is selected from any one or more of Ga, in, bi, sb, as and Al;
q is selected from Se;
in the step 2), the melting is carried out by heating to 50-200 ℃ above the melting point of the phosphate polycrystalline material;
in step 3), before growing the crystal, the method further comprises the following steps:
after the phosphate-substituted polycrystalline material is completely melted, cooling the phosphate-substituted polycrystalline material, wherein the temperature of the cooled phosphate-substituted polycrystalline material is within the range of 50-100 ℃ above the melting point of the phosphate-substituted polycrystalline material;
adjusting the position of the sealed container containing the phosphate instead of polycrystalline material in the step 3) to ensure that all or part of the phosphate instead of polycrystalline material is in an environment with the temperature 50-100 ℃ lower than the melting point.
2. The method for producing a hypophosphite single crystal material as claimed in claim 1, wherein the container resistant to Li erosion comprises any one or more of a fused silica tube, a glassy carbon crucible, and a pyrolytic boron nitride crucible, the surfaces of which are coated with carbon.
3. According to the rightThe method for producing a mono-crystalline material of a hypophosphite according to claim 2, wherein, in the step 1), the evacuation is performed by evacuating to 10 degrees -3 Pa or less.
4. The method for producing a mono-crystalline material of a hypophosphite according to claim 1, wherein the rotation state in step 2) is from 0.1r/min to 23r/min, and the rotation is performed with the vertical direction as the axis.
5. The method for preparing a mono-crystalline material of a substituted phosphate according to claim 4, wherein the melting is performed by heating to 50 ℃ to 200 ℃ above the melting point of the polycrystalline material of the substituted phosphate at 1 ℃/min to 2 ℃/min, and then keeping the temperature for 10h to 24h so that the polycrystalline material of the substituted phosphate is completely melted.
6. The method for preparing a mono-crystalline material of a hypophosphite according to claim 1, wherein, in step 3), the cooling rate is 0.5 ℃/min to 2 ℃/min before growing the crystal.
7. The method for preparing a mono-crystalline hypophosphite material as claimed in claim 1, wherein in step 3), the speed of adjustment of the position is 0.5 to 50mm/h.
8. The method for producing a mono-crystalline material of a hypophosphite according to claim 1, wherein the rotation speed in step 3) is 0.1 to 23r/min, and the rotation is performed with the vertical direction as the axis.
9. The method for producing a mono-crystalline material of a hypophosphite according to claim 1, wherein the mono-crystalline material of a hypophosphite forms at the growth interface when part of the polycrystalline material of the hypophosphite is in an environment that is 50 ℃ to 100 ℃ below the melting point;
the temperature gradient of the phosphate generation polycrystalline material above the growth interface is 5-30 ℃/cm higher than that of the phosphate generation single crystal material below the growth interface.
10. A mono-crystalline material of a hypophosphite as prepared by the method for preparing a mono-crystalline material of a hypophosphite according to any one of claims 1 to 9;
the size of the phosphate-substitute single crystal material is that the diameter is larger than 10mm, and the length is larger than 40mm.
11. The metaphosphate single crystal material according to claim 10, wherein the purity of the metaphosphate single crystal material is 3N or more.
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| CN1485469A (en) * | 2003-08-08 | 2004-03-31 | 中国科学院上海光学精密机械研究所 | Method for growing near-stoichiometric lithium niobate single crystal |
| CN113430650A (en) * | 2021-06-25 | 2021-09-24 | 黑龙江工程学院 | Middle and far infrared crystal LiGaGe2Se6Polycrystalline raw material synthesis method and single crystal growth method thereof |
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| CN1485469A (en) * | 2003-08-08 | 2004-03-31 | 中国科学院上海光学精密机械研究所 | Method for growing near-stoichiometric lithium niobate single crystal |
| CN113430650A (en) * | 2021-06-25 | 2021-09-24 | 黑龙江工程学院 | Middle and far infrared crystal LiGaGe2Se6Polycrystalline raw material synthesis method and single crystal growth method thereof |
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| Title |
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| "Direct thermal neutron detection by the 2D semiconductor 6LiInP2Se6";Chica等;《Nature》;20200115;第577卷;第346–349页 * |
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