A method for optimizing the growth of centimeter-scale ZrTe5 single crystals by tellurium flux method

Abstract

The application discloses a method for growing a centimeter-level ZrTe5 single crystal by optimizing a tellurium flux method, and belongs to the technical field of crystal growth. The method comprises the following steps: purifying and pretreating a tellurium source, assembling a growth device, high-temperature melting, heat oscillation temperature control growth, and separating and collecting the ZrTe5 single crystal; through the process chain of the tellurium source purification pretreatment-pre-necking quartz tube crucible-free charging-heat oscillation temperature control growth, the two problems of exogenous pollution inhibition and crystal size increase are solved synchronously, the commercial Te block is annealed and purified under the condition of vacuum high temperature by using activated carbon, the traditional Canfield crucible device is removed by using the pre-necking quartz tube, the introduction of Te oxidation impurities and exogenous metal impurities is effectively reduced, the high-purity single crystal with low carrier concentration is stably obtained, and the heat oscillation program of slow cooling nucleation-fast remelting-slow cooling epitaxy is designed in the narrow phase formation temperature window of the ZrTe5, the single crystal size is increased from the traditional millimeter level to the centimeter level, and a reliable material platform is provided for topological transport research and device processing.

Description

Technical Field

[0001] This invention belongs to the field of crystal growth technology, specifically relating to an optimized method for growing centimeter-scale ZrTe5 single crystals using tellurium flux. Background Technology

[0002] ZrTe5 (zirconium pentatellite) is a layered topological material with a quasi-one-dimensional chain structure, belonging to the orthorhombic crystal system with space group Cmcm (No. 63). Located near the phase boundary between strong and weak topological insulators, it can form bulk Dirac nodes, making it an important candidate system for studying topological properties, the three-dimensional quantum Hall effect, and low-dimensional quantum states. Experimentally, abundant quantum transport phenomena have been observed in ZrTe5 single crystals, including a nontrivial Berry phase, chiral anomaly-related negative longitudinal magnetoresistance, an anomalous Hall effect, and the three-dimensional quantum Hall effect, making it valuable for fundamental physics research and the development of topological electronic devices.

[0003] High-quality ZrTe5 single crystals are the key material foundation for conducting the aforementioned intrinsic topological transport research and device fabrication. Currently, the main methods for preparing ZrTe5 single crystals include chemical vapor transport (CVT) and tellurium flux method. Studies have shown that ZrTe5 single crystals grown by the tellurium flux method are closer to the ideal stoichiometry and have a lower carrier concentration. Therefore, it is currently considered the preferred approach for obtaining high-quality ZrTe5 single crystals.

[0004] The typical process for growing ZrTe5 single crystals using the existing tellurium flux method is as follows: the raw materials are prepared according to a molar ratio of Zr:Te = 1:49, placed in a Canfield crucible and sealed in a quartz tube; heated to 1000℃ in a tube furnace and held for 12 hours to fully melt the raw materials; then slowly cooled at a rate of 3℃ / h within a temperature range of 460-650℃; after cooling, centrifugation is performed to obtain ZrTe5 single crystals.

[0005] However, the traditional tellurium flux method still has the following significant drawbacks, which restrict the further improvement of ZrTe5 single crystal quality and its large-scale application: First, there is the issue of contamination from raw materials and equipment. Commercially available Te blocks are easily oxidized in air to form impurities such as TeO2. The Canfield crucible equipment itself may introduce exogenous impurities (Al, Si, etc.). These impurities, once they enter the melt, will form Te vacancies and additional scattering centers, leading to an increase in crystal carrier concentration, a decrease in mobility, and large performance fluctuations between batches, making it difficult to stably obtain high-quality samples with low carrier concentration.

[0006] Second, there is the issue of limited crystal size. ZrTe5 exhibits an extremely narrow stable phase-forming temperature window in Te-rich melts, coexisting in liquid phase equilibrium only within approximately 100℃ (450-550℃). Traditional methods employ a single, continuous, and slow cooling process within this narrow temperature range. This results in poor controllability of supersaturation changes in the melt, easily triggering numerous spontaneous nucleations and parallel competitive growth of polycrystalline nuclei, leading to insufficient solute supply for individual nuclei. Consequently, the typical size of ZrTe5 single crystals obtained using traditional methods is only approximately 2 × 0.2 × 0.05 mm. 3 The uniform regions available for property characterization and device fabrication are very limited, making it difficult to meet the demand for large-size, high-quality single-crystal substrates in the fabrication of micro and nano devices.

[0007] Chinese patent CN119776993B discloses a method for preparing zirconium pentatellite thin films, specifically including the following steps: First, ZrTe5 crystals are grown using a flux method, ground into powder, and intercalated with a dispersant to weaken the van der Waals forces between ZrTe5 crystal layers; then, an ultrasonic dispersion technique is used to prepare a ZrTe5 dispersion with good dispersibility. To improve the stability of the dispersion, a stabilizer is further added, significantly enhancing the dispersion and stability of ZrTe5 particles in the solution. Finally, a uniform thin film is deposited using spin coating or drop coating techniques. However, existing methods do not perform purification pretreatment on the Te source to eliminate oxide impurities, nor do they design a temperature control strategy for the narrow phase-forming temperature window of ZrTe5, still using the traditional one-time cooling method. This cannot solve the problem of single crystal size limitation caused by polynuclear competitive growth, thus failing to obtain high-quality ZrTe5 bulk single crystals with centimeter-scale and low carrier concentration. To address these issues, we propose an optimized method for growing centimeter-scale ZrTe5 single crystals using the tellurium flux method. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing technologies by providing an optimized method for growing centimeter-scale ZrTe5 single crystals using the tellurium flux method.

[0009] This invention is implemented as follows: an optimized method for growing centimeter-sized ZrTe5 single crystals using a tellurium flux method, the optimized method for growing centimeter-sized ZrTe5 single crystals using a tellurium flux method includes: S10, Tellurium source purification pretreatment: Place the Te block and activated carbon together in a quartz tube, and evacuate to 10. -3 After the Pa level is reached, the tube is sealed, heated to 650-750℃ at a heating rate of 3℃ / min and held at that temperature for 6-10 hours. After natural cooling or cooling to room temperature at a rate of 5℃ / min, the purified Te block is removed and set aside for later use. The purity of the Te block is ≥99.9999%. S20, Assembly of growth device: Take the pretreated quartz tube, mix the Zr raw material and the obtained purified Te block at a Te:Zr molar ratio of 50:1-500:1, place them in the lower area of ​​the quartz tube, set the porous alumina plate filter medium at the necking point, and place the crucible on top. Then, evacuate the quartz tube and seal it. S30, high temperature melting: The sealed quartz tube is placed in a tube furnace and heated to 850-1000℃ at a rate of 3-5℃ / min and kept at a constant temperature for 24-72h, so that Zr and Te can be completely melted to form a uniform Zr-Te melt. S40, thermal oscillation temperature-controlled growth: The Zr-Te melt is cooled to 580-620℃ at 1-3℃ / min, then cooled to 460-480℃ at 0.5-3℃ / h, and then rapidly heated to 500-550℃ within 5-20min, and then cooled to 460-480℃ at 0.5-3℃ / h. This constitutes one thermal oscillation cycle, and 1-5 thermal oscillation cycles are completed. S50, centrifugal separation: After rapidly heating the quartz tube to 480-510℃, remove it and separate the ZrTe5 single crystal with the Te flux by centrifugation, and collect the ZrTe5 single crystal.

[0010] Preferably, in step S10, the temperature is increased to 700°C at a heating rate of 3°C / min and held at that temperature for 8 hours.

[0011] Preferably, in step S20, the quartz tube is a pre-necked quartz tube that has undergone acid washing, ultrasonic cleaning and drying treatment, the purity of the Zr raw material is ≥99.9%, and the inner diameter of the necked part of the pre-necked quartz tube is 3-8mm; the pore size of the porous alumina plate is 50-200μm.

[0012] Preferably, in step S20, the Zr raw material and the obtained purified Te block are in a Te:Zr molar ratio of 200:1-350:1.

[0013] Preferably, in step S30, the sealed quartz tube is placed in a tube furnace and heated to 900°C at a rate of 5°C / min and kept at that temperature for 48 hours.

[0014] Preferably, in step S10, the quartz tube has a length of 150-200 mm and an outer diameter of 20 mm.

[0015] Preferably, in step S40, during the thermal oscillation temperature-controlled growth, the Zr-Te melt is cooled to 600°C at 2°C / min, then cooled to 469°C at 1°C / h, and then rapidly heated to 509°C within 10 min, and then cooled to 469°C at 1°C / h, which constitutes one thermal oscillation cycle.

[0016] Preferably, in step S50, when ZrTe5 single crystal and Te flux are separated by centrifugation, the centrifugation speed is 300-5000 rpm and the centrifugation time is 1-10 min.

[0017] Compared with the prior art, the embodiments of this application have the following main advantages: This invention addresses two major issues simultaneously: suppressing exogenous contamination and increasing crystal size. It employs a complete process chain: tellurium source purification pretreatment, crucible-free charging via pre-necked quartz tube, and temperature-controlled thermal oscillation growth. Firstly, activated carbon is used to anneal and purify commercially available Te blocks under vacuum and high temperature conditions. Combined with the removal of traditional Canfield crucible devices using pre-necked quartz tubes, this effectively reduces the introduction of Te oxide impurities and exogenous metal impurities, stably obtaining high-purity single crystals with low carrier concentration. Secondly, a thermal oscillation program is designed within the narrow phase-forming temperature window (450-550℃) of ZrTe5, involving slow cooling nucleation, rapid remelting, and slow cooling epitaxy. By cyclically dissolving secondary nuclei and retaining and promoting the preferential epitaxial growth of the primary nuclei, the single crystal size is reduced from the traditional millimeter level (approximately 2×0.2×0.05mm). 3 Improved to the centimeter level (approximately 10×2×1mm) 3 This significantly expands the uniform machinable region, providing a reliable material platform for topological transport research and device fabrication. Attached Figure Description

[0018] Figure 1 A schematic diagram of the process for optimizing the tellurium flux method to grow centimeter-scale ZrTe5 single crystals is shown.

[0019] Figure 2 The diagram shows a sealed Te block after tellurium source purification pretreatment in Embodiment 1 of the present invention.

[0020] Figure 3 A schematic diagram of the assembled growth apparatus in Embodiment 1 of the present invention is shown.

[0021] Figure 4 A schematic diagram of the temperature-time program for thermal oscillation temperature-controlled growth in Embodiment 1 of the present invention is shown.

[0022] Figure 5 A schematic diagram of the growth apparatus after centrifugal separation of single crystals in Embodiment 1 of the present invention is shown. Detailed Implementation

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0024] Example 1

[0025] This invention provides an optimized method for growing centimeter-scale ZrTe5 single crystals using a tellurium flux method. Figure 1 A schematic diagram illustrating the implementation process of an optimized tellurium flux method for growing centimeter-sized ZrTe5 single crystals is shown. The optimized tellurium flux method for growing centimeter-sized ZrTe5 single crystals specifically includes: S10, Tellurium source purification pretreatment: Te blocks and activated carbon are placed together in a quartz tube, with the Te blocks placed at the bottom of the quartz tube, followed by the activated carbon. The two are separated by quartz wool. After filling, appropriate remaining space is left in the tube to facilitate the reaction. Figure 2 This diagram illustrates the sealing of a purified Te block after tellurium source purification pretreatment in Embodiment 1 of the present invention. Figure 2 In the process, the purified Te block, activated carbon, and quartz wool are encapsulated within a quartz tube. The quartz wool, located in the middle of the quartz tube, is white and fibrous. Its function is to isolate the activated carbon from the purified Te block (preventing the activated carbon powder from directly contacting the Te block to avoid secondary pollution, while ensuring the "channel" for gas / impurity adsorption remains unobstructed). A vacuum of 10... -3 After sealing the tube at the Pa level, heat it to 700℃ at a heating rate of 3℃ / min and maintain the temperature for 8 hours. After natural cooling or cooling down to room temperature at a rate of 5℃ / min, remove the purified Te block for later use. The purity of the Te block (Prmat) is ≥99.9999%; the quartz tube is 150-200mm long and 20mm in outer diameter. In this embodiment of the invention, the quartz tube, after being heated to 700°C at a heating rate of 3°C / min and held at that temperature for 8 hours, is placed in a single-zone tube furnace and heated from room temperature to 700°C at a heating rate of 3°C / min, and held at 700°C for 8 hours. During this process, activated carbon adsorbs volatile impurities and tellurium oxides in the Te block, and the purified Te block exhibits a more pronounced metallic luster compared to the original Te block. After annealing, the Te block is cooled to room temperature naturally or at a rate of 5°C / min, the tube is opened, and the purified Te block is separated and collected. The obtained purified Te is used as the Te raw material for subsequent ZrTe5 single crystal growth.

[0026] It should be noted that traditional methods directly use commercial Te blocks with an inner crucible. Commercial Te is easily oxidized, and the crucible setup may introduce exogenous impurities. These impurities, once inside the crystal, form Te vacancies and scattering centers, leading to large batch-to-batch performance fluctuations. This invention, in step S10, places the Te block and activated carbon together in a quartz tube and anneals and purifies them under vacuum at 650-750℃ for 6-10 hours, effectively removing volatile impurities and tellurium oxides from the Te block. In step S20, a pre-necked quartz tube, treated with acid washing, ultrasonic cleaning, and drying, is used as the growth container, with a porous alumina plate filter medium at the necking point. This eliminates the need for the lower crucible in traditional Canfield crucible setups, avoiding exogenous impurity contamination introduced by the crucible. This invention connects tellurium source purification pretreatment – ​​crucible-free loading of the pre-necked quartz tube – thermal oscillation temperature-controlled growth into a complete process chain, simultaneously suppressing exogenous contamination and promoting crystal growth. The parameters are clearly connected, and the mechanism is clear, thus enabling the repeated acquisition of high-quality single crystals with similar performance.

[0027] S20, Assembly of the growth device: Take the pretreated quartz tube, mix the Zr raw material and the obtained purified Te block at a Te:Zr molar ratio of 300:1, place them in the lower region of the quartz tube, set a porous alumina plate filter medium at the necking point, and place a crucible on top. Then, evacuate the quartz tube and seal it.

[0028] The quartz tube is a pre-necked quartz tube that has undergone acid washing, ultrasonic cleaning and drying treatment. The purity of the Zr raw material is ≥99.9%, and the inner diameter of the necked part of the pre-necked quartz tube is 5mm. The pore size of the porous alumina plate is 150μm.

[0029] In this step, a quartz tube is used as the growth container. A pre-necking treatment is performed in the middle of the quartz tube to form a necked structure, dividing the quartz tube into two connected regions. The inner diameter of the necked section is 5mm, which can be controlled according to the melt filtration requirements. Before use, the quartz tube is sequentially rinsed with dilute acid, ultrasonically cleaned, and dried to remove surface contaminants. Zr raw material with a purity of not less than 99.9% is mixed with the purified Te obtained in step S10 at a flux ratio of 300:1 (Te:Zr molar ratio). During loading, the Zr raw material and purified Te are placed in the lower region of the quartz tube. A porous alumina plate with a pore size of 150μm is placed at the necked section as a filter medium, and a crucible is placed on top. Then, the quartz tube is evacuated and sealed. Figure 3 A schematic diagram of the assembled growth apparatus in Embodiment 1 of the present invention is shown, as follows: Figure 3As shown, the growth apparatus uses a quartz tube as the overall growth container. The quartz tube undergoes a pre-necking treatment in the middle to form a pre-necked structure, dividing the interior of the quartz tube into two interconnected regions. In the lower region of the quartz tube, a raw material mixture with a Zr:purified Te molar ratio of 1:300 is placed, including Zr raw material and Te blocks pretreated in step S10. At the pre-neck, an Al2O3 filter plate (porous alumina plate) is placed. This filter plate serves as a filter medium, blocking the passage of ZrTe5 single crystals during the subsequent centrifugal separation stage, while allowing liquid Te flux to migrate upwards through the filter plate under centrifugal force. In the upper region of the quartz tube, a crucible is placed to catch the liquid Te flux passing through the filter plate during centrifugal separation. After the growth apparatus is assembled, the entire growth unit is in a vacuum-sealed state and can then be transferred to a tube furnace for subsequent high-temperature melting, thermal oscillation temperature-controlled growth, and centrifugal separation operations. In this embodiment of the invention, the growth apparatus eliminates the lower crucible in the traditional Canfield crucible apparatus by pre-necking, directly using a pre-necked quartz tube as the growth container. After assembly, the entire growth unit is in a vacuum-sealed state and can then be transferred to a tube furnace for subsequent temperature-controlled growth.

[0030] S30, high temperature melting: The sealed quartz tube is placed in a tube furnace and heated to 900℃ at 5℃ / min and kept at a constant temperature for 48h, so that Zr and Te are completely melted to form a uniform Zr-Te melt. In this embodiment of the invention, the quartz tube assembled and sealed in step S20 is placed at an angle in a single-zone tubular furnace for high-temperature melting, so that the charging zone is located at the center of the effective temperature zone of the furnace. Figure 4 A schematic diagram of the temperature-time program for thermal oscillation-controlled growth in Embodiment 1 of the present invention is shown. The temperature-time program is designed for the narrow phase-forming temperature window of ZrTe5 in Te-rich melt, which is only about 100°C (450-550°C). Traditional methods employ a single, continuous, slow cooling within this narrow temperature range, which easily triggers a large number of spontaneous nucleations and parallel competitive growth of polycrystalline nuclei, resulting in limited single-crystal size. The present invention, through a thermal oscillation program, first uses an extremely slow cooling rate to suppress spontaneous nucleation in each cycle, then rapidly heats up to remelt and eliminate secondary nuclei, and finally slowly cools again to promote the preferential epitaxial growth of the primary nuclei. Through multiple cycles, the growth process changes from polynuclear competition to mononuclear growth, thereby significantly increasing the single-crystal size. Figure 4 The temperature-time program shown is used for temperature control: first, the temperature is increased from room temperature to 900℃ at a rate of 5℃ / min, and then held at 900℃ for 48 hours. During this stage, the Zr raw material and purified Te completely melt to form a Zr-Te melt with uniform composition. After melting, the melt remains in a liquid phase state much higher than the ZrTe5 phase formation temperature, preparing it for subsequent entry into the effective growth temperature zone.

[0031] S40, thermal oscillation temperature-controlled growth: The Zr-Te melt is cooled to 600℃ at 2℃ / min, then cooled to 469℃ at 1℃ / h, and then rapidly heated to 509℃ within 10min, and then cooled to 469℃ at 1℃ / h. This is one thermal oscillation cycle, and three thermal oscillation cycles are completed. In embodiments of the present invention, such as Figure 4 As shown, after high-temperature melting, the temperature is cooled from 900℃ to 600℃ at a relatively fast rate of 2℃ / min, allowing the melt to quickly enter the upper part of the effective phase-forming temperature range of ZrTe5, avoiding prolonged residence in excessively high temperature ranges. During the thermal oscillation growth stage, within the effective phase-forming temperature window of ZrTe5 (450-550℃), a thermal oscillation procedure of slow cooling nucleation-fast heating remelting-slow cooling epitaxy is adopted, specifically including: Slow cooling nucleation: The temperature was reduced from 600℃ to 469℃ at an extremely slow rate of 1℃ / h to control the initial nucleation of ZrTe5, so that only a small number of crystal nuclei were formed in the system; Rapid thermal remelting: When the temperature drops to 469℃, the temperature is rapidly raised to 509℃ within 10 minutes to remelt the small grains and defect nuclei that have formed in the melt, retaining only the main nuclei with larger size and better crystal quality. Slow cooling epitaxy: The temperature is then slowly reduced from 509℃ to 469℃ at a rate of 1℃ / h, allowing the ZrTe5 solute to grow epitaxially on the retained high-quality crystal nuclei.

[0032] A thermal oscillation cycle is defined as a slow cooling from 469℃ to 509℃ followed by a rapid heating to 469℃. This embodiment repeats this cycle three times. Figure 4 The three consecutive oscillation waveforms are shown in the figure. The furnace temperature uniformity and temperature control accuracy should be ensured throughout the entire thermal oscillation growth stage. The temperature-time curve of the whole process should be recorded in real time by program temperature control or thermocouples so as to facilitate batch comparison and process reproduction.

[0033] Traditional methods for ZrTe5 typically employ a single, slow cooling process within a narrow phase-forming temperature window of approximately 450-550℃. Due to the limited adjustability of supersaturation and undercooling, multiple nuclei can easily form simultaneously and grow in parallel within the melt, resulting in typical sample sizes of only about 2mm × 0.2mm × 0.05mm. In step S40 of this invention, spontaneous nucleation is first suppressed by extremely slow cooling at 0.5-3℃ / h within the range of 460–480℃, leaving only a small number of high-quality nuclei in the system. Then, the temperature is rapidly increased to 500-550℃ within 5-20 minutes, causing small grains and defect nuclei to redissolve, leaving only the main nuclei. Subsequently, the temperature is slowly cooled again at 0.5-3℃ / h to 460-480℃, allowing the solute to epitaxially grow on the main nuclei. This process is repeated 1-5 times through alternating slow cooling at 460-480℃ and rapid heating at 500-550℃, achieving the goal of dissolving small nuclei and promoting the growth of the main nuclei. As the growth process changes from multi-nucleus competition to selective growth, the single crystal size is increased from the millimeter level to the centimeter level (approximately 10mm×2mm×1mm), meeting the device processing requirements.

[0034] S50, centrifugal separation: After rapidly heating the quartz tube to 490℃, remove it and separate the ZrTe5 single crystal from the Te flux by centrifugation. Collect the ZrTe5 single crystal. When separating the ZrTe5 single crystal from the Te flux by centrifugation, the centrifugation speed is 2000 rpm and the centrifugation time is 6 min.

[0035] After thermal oscillation growth, the tube furnace is rapidly heated to 490°C within 5 minutes to facilitate subsequent separation. The quartz tube is then quickly removed from the furnace and immediately centrifuged at 2000 rpm for 6 minutes to achieve clear stratification of the ZrTe5 single crystal and Te flux within the tube. Figure 5 A schematic diagram of the centrifugal growth apparatus for single crystals in Embodiment 1 of this invention is shown. During centrifugation, the denser ZrTe5 single crystals are deposited at one end of the quartz tube, while the remaining Te flux remains at the other end, thus achieving separation of the single crystals and the flux. The collected ZrTe5 single crystals are stored in a dry environment, and the porous Al2O3 filter plate effectively blocks the passage of the single crystals at the pre-necked section. Under centrifugal force, the liquid Te flux migrates through the filter plate to the right end of the quartz tube and is collected by the crucible, thereby achieving complete separation of the ZrTe5 single crystals and the Te flux. This verifies the effectiveness of the apparatus design of the pre-necked quartz tube combined with the porous alumina plate filter medium in the centrifugal separation process.

[0036] This invention addresses two major issues simultaneously: suppressing exogenous contamination and increasing crystal size. It employs a complete process chain: tellurium source purification pretreatment, crucible-free charging via pre-necked quartz tube, and temperature-controlled thermal oscillation growth. Firstly, activated carbon is used to anneal and purify commercially available Te blocks under vacuum and high temperature conditions. Combined with the removal of traditional Canfield crucible devices using pre-necked quartz tubes, this effectively reduces the introduction of Te oxide impurities and exogenous metal impurities, stably obtaining high-purity single crystals with low carrier concentration. Secondly, a thermal oscillation program is designed within the narrow phase-forming temperature window (450-550℃) of ZrTe5, involving slow cooling nucleation, rapid remelting, and slow cooling epitaxy. By cyclically dissolving secondary nuclei and retaining and promoting the preferential epitaxial growth of the primary nuclei, the single crystal size is reduced from the traditional millimeter level (approximately 2×0.2×0.05mm). 3 Improved to the centimeter level (approximately 10×2×1mm) 3 This significantly expands the uniform machinable region, providing a reliable material platform for topological transport research and device fabrication. Furthermore, the process concept of Te source purification-inner crucible-thermal oscillation temperature control in the embodiments of this invention can also be applied to other growth-sensitive topological materials such as Bi2Te3 and Bi2Te2Se, and has broad applicability.

[0037] Example 2

[0038] This invention provides an optimized method for growing centimeter-scale ZrTe5 single crystals using a tellurium flux method. The optimized method for growing centimeter-scale ZrTe5 single crystals using a tellurium flux method specifically includes: S10, Tellurium source purification pretreatment: Place the Te block and activated carbon together in a quartz tube, and evacuate to 10. -3 After sealing the tube at the Pa level, heat it to 650℃ at a heating rate of 3℃ / min and maintain the temperature for 6 hours. After natural cooling or cooling down to room temperature at a rate of 5℃ / min, remove the purified Te block for later use. The purity of the Te block is ≥99.9999%; the quartz tube is 150-200mm long and 20mm in outer diameter. S20, Assembly of the growth device: Take the pretreated quartz tube, mix the Zr raw material and the obtained purified Te block at a Te:Zr molar ratio of 50:1, place them in the lower region of the quartz tube, set a porous alumina plate filter medium at the necking point, and place a crucible on top. Then, evacuate the quartz tube and seal it.

[0039] The quartz tube is a pre-necked quartz tube that has undergone acid washing, ultrasonic cleaning and drying treatment. The purity of the Zr raw material is ≥99.9%, and the inner diameter of the necked part of the pre-necked quartz tube is 3mm. The pore size of the porous alumina plate is 50μm.

[0040] S30, high temperature melting: The sealed quartz tube is placed in a tube furnace and heated to 850℃ at 3℃ / min and kept at a constant temperature for 24h, so that Zr and Te are completely melted to form a uniform Zr-Te melt; S40, thermal oscillation temperature-controlled growth: The Zr-Te melt is cooled to 580℃ at 1℃ / min, then cooled to 460℃ at 0.5℃ / h, and then rapidly heated to 500℃ within 5min, and then cooled to 460℃ at 0.5℃ / h. This constitutes one thermal oscillation cycle, and one thermal oscillation cycle is completed. S50, centrifugal separation: After rapidly heating the quartz tube to 480℃, remove it and separate the ZrTe5 single crystal from the Te flux by centrifugation. Collect the ZrTe5 single crystal. When separating the ZrTe5 single crystal from the Te flux by centrifugation, the centrifugation speed is 300 rpm and the centrifugation time is 1 min.

[0041] Example 3

[0042] This invention provides an optimized method for growing centimeter-scale ZrTe5 single crystals using a tellurium flux method. The optimized method for growing centimeter-scale ZrTe5 single crystals using a tellurium flux method specifically includes: S10, Tellurium source purification pretreatment: Place the Te block and activated carbon together in a quartz tube, and evacuate to 10. -3 After sealing the tube at the Pa level, heat it to 750℃ at a heating rate of 3℃ / min and maintain the temperature for 10 hours. After natural cooling or cooling down to room temperature at a rate of 5℃ / min, remove the purified Te block for later use. The purity of the Te block is ≥99.9999%. The quartz tube is 150-200mm long and 20mm in outer diameter. S20, Assembly of the growth device: Take the pretreated quartz tube, mix the Zr raw material and the obtained purified Te block at a Te:Zr molar ratio of 500:1, place them in the lower region of the quartz tube, set a porous alumina plate filter medium at the necking point, and place a crucible on top. Then, evacuate the quartz tube and seal it.

[0043] The quartz tube is a pre-necked quartz tube that has undergone acid washing, ultrasonic cleaning and drying treatment. The purity of the Zr raw material is ≥99.9%, and the inner diameter of the necked part of the pre-necked quartz tube is 8mm. The pore size of the porous alumina plate is 200μm.

[0044] S30, high temperature melting: The sealed quartz tube is placed in a tube furnace and heated to 1000℃ at 5℃ / min and kept at a constant temperature for 72h, so that Zr and Te are completely melted to form a uniform Zr-Te melt. S40, thermal oscillation temperature-controlled growth: The Zr-Te melt is cooled to 620℃ at 3℃ / min, then cooled to 480℃ at 3℃ / h, and then rapidly heated to 550℃ within 20min, and then cooled to 480℃ at 3℃ / h. This constitutes one thermal oscillation cycle, and 5 thermal oscillation cycles are completed. S50, centrifugal separation: After rapidly heating the quartz tube to 510℃, remove it and separate the ZrTe5 single crystal from the Te flux by centrifugation. Collect the ZrTe5 single crystal. When separating the ZrTe5 single crystal from the Te flux by centrifugation, the centrifugation speed is 5000 rpm and the centrifugation time is 10 min.

[0045] Example 4

[0046] This invention provides an optimized method for growing centimeter-scale ZrTe5 single crystals using a tellurium flux method. The optimized method for growing centimeter-scale ZrTe5 single crystals using a tellurium flux method specifically includes: S10, Tellurium source purification pretreatment: Place the Te block and activated carbon together in a quartz tube, and evacuate to 10. -3 After sealing the tube at the Pa level, heat it to 660℃ at a heating rate of 3℃ / min and maintain the temperature for 7 hours. After natural cooling or cooling down to room temperature at a rate of 5℃ / min, remove the purified Te block for later use. The purity of the Te block is ≥99.9999%; the quartz tube is 150-200mm long and 20mm in outer diameter. S20, Assembly of the growth device: Take the pretreated quartz tube, mix the Zr raw material and the obtained purified Te block at a Te:Zr molar ratio of 150:1, place them in the lower region of the quartz tube, set a porous alumina plate filter medium at the necking point, and place a crucible on top. Then, evacuate the quartz tube and seal it.

[0047] The quartz tube is a pre-necked quartz tube that has undergone acid washing, ultrasonic cleaning and drying treatment. The purity of the Zr raw material is ≥99.9%, and the inner diameter of the necked part of the pre-necked quartz tube is 4mm. The pore size of the porous alumina plate is 70μm.

[0048] S30, high temperature melting: The sealed quartz tube is placed in a tube furnace and heated to 890℃ at 4℃ / min and kept at a constant temperature for 30h, so that Zr and Te can be completely melted to form a uniform Zr-Te melt. S40, thermal oscillation temperature-controlled growth: The Zr-Te melt is cooled to 590℃ at 2.5℃ / min, then cooled to 462℃ at 0.5℃ / h, then rapidly heated to 510℃ within 6 min, and then cooled to 465℃ at 1℃ / h. This constitutes one thermal oscillation cycle, and four thermal oscillation cycles are completed. S50, centrifugal separation: After rapidly heating the quartz tube to 483℃, remove it and separate the ZrTe5 single crystal from the Te flux by centrifugation. Collect the ZrTe5 single crystal. When separating the ZrTe5 single crystal from the Te flux by centrifugation, the centrifugation speed is 2000 rpm and the centrifugation time is 6 min.

[0049] Example 5

[0050] This invention provides an optimized method for growing centimeter-scale ZrTe5 single crystals using a tellurium flux method. The optimized method for growing centimeter-scale ZrTe5 single crystals using a tellurium flux method specifically includes: S10, Tellurium source purification pretreatment: Place the Te block and activated carbon together in a quartz tube, and evacuate to 10. -3 After sealing the tube at the Pa level, heat it to 740℃ at a heating rate of 3℃ / min and maintain the temperature for 9 hours. After natural cooling or cooling down to room temperature at a rate of 5℃ / min, remove the purified Te block for later use. The purity of the Te block is ≥99.9999%; the quartz tube is 150-200mm long and 20mm in outer diameter. S20, Assembly of the growth device: Take the pretreated quartz tube, mix the Zr raw material and the obtained purified Te block at a Te:Zr molar ratio of 450:1, place them in the lower region of the quartz tube, set a porous alumina plate filter medium at the necking point, and place a crucible on top. Then, evacuate the quartz tube and seal it.

[0051] The quartz tube is a pre-necked quartz tube that has undergone acid washing, ultrasonic cleaning and drying treatment. The purity of the Zr raw material is ≥99.9%, and the inner diameter of the necked part of the pre-necked quartz tube is 7mm. The pore size of the porous alumina plate is 180μm.

[0052] S30, high temperature melting: The sealed quartz tube is placed in a tube furnace and heated to 960℃ at 4℃ / min and kept at a constant temperature for 60h, so that Zr and Te are completely melted to form a uniform Zr-Te melt. S40, thermal oscillation temperature-controlled growth: The Zr-Te melt is cooled to 615℃ at 2.5℃ / min, then cooled to 475℃ at 2.5℃ / h, and then rapidly heated to 545℃ within 16min, and then cooled to 475℃ at 2.5℃ / h. This constitutes one thermal oscillation cycle, and three thermal oscillation cycles are completed. S50, centrifugal separation: After rapidly heating the quartz tube to 505℃, remove it and separate the ZrTe5 single crystal from the Te flux by centrifugation. Collect the ZrTe5 single crystal. When separating the ZrTe5 single crystal from the Te flux by centrifugation, the centrifugation speed is 3000 rpm and the centrifugation time is 9 min.

[0053] In summary, this invention provides an optimized method for growing centimeter-sized ZrTe5 single crystals using the tellurium flux method. This invention simultaneously addresses two major issues: suppressing exogenous contamination and increasing crystal size, through a complete process chain of tellurium source purification pretreatment – ​​crucible-free charging with a pre-necked quartz tube – and temperature-controlled thermal oscillation growth. Firstly, activated carbon is used to anneal and purify commercially available Te blocks under vacuum and high temperature conditions, combined with the removal of traditional Canfield crucible devices using a pre-necked quartz tube, effectively reducing the introduction of Te oxide impurities and exogenous metal impurities, and stably obtaining high-purity single crystals with low carrier concentration. Secondly, a thermal oscillation program of slow cooling nucleation – rapid heating remelting – slow cooling epitaxy is designed within the narrow phase formation temperature window of ZrTe5 (450-550℃). By cyclically dissolving secondary nuclei and retaining and promoting the preferential epitaxial growth of the main nuclei, the single crystal size is reduced from the traditional millimeter level (approximately 2 × 0.2 × 0.05 mm). 3 Improved to the centimeter level (approximately 10×2×1mm) 3 This significantly expands the uniform machinable region, providing a reliable material platform for topological transport research and device fabrication.

[0054] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of the present invention according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of the present invention. These technical solutions also fall within the scope of protection of the present invention.

Claims

1. A method for growing centimeter-scale ZrTe5 single crystals using an optimized tellurium flux method, characterized in that, The method includes: S10, Tellurium source purification pretreatment: Place the Te block and activated carbon together in a quartz tube, and evacuate to 10. -3 After sealing the tube at the Pa level, heat it to 650-750℃ at a heating rate of 3℃ / min and maintain the temperature for 6-10 hours. After natural cooling or cooling down to room temperature at 5℃ / min, remove the purified Te block for later use. S20, Assembly of growth device: Take the pretreated quartz tube, mix the Zr raw material and the obtained purified Te block at a Te:Zr molar ratio of 50:1-500:1, place them in the lower area of ​​the quartz tube, set the porous alumina plate filter medium at the necking point, and place the crucible on top. Then, evacuate the quartz tube and seal it. S30, high temperature melting: The sealed quartz tube is placed in a tube furnace and heated to 850-1000℃ at a rate of 3-5℃ / min and kept at a constant temperature for 24-72h, so that Zr and Te can be completely melted to form a uniform Zr-Te melt. S40, thermal oscillation temperature-controlled growth: The Zr-Te melt is cooled to 580-620℃ at 1-3℃ / min, then cooled to 460-480℃ at 0.5-3℃ / h, and then rapidly heated to 500-550℃ within 5-20min, and then cooled to 460-480℃ at 0.5-3℃ / h. This constitutes one thermal oscillation cycle, and 1-5 thermal oscillation cycles are completed. S50, centrifugal separation: After rapidly heating the quartz tube to 480-510℃, remove it and separate the ZrTe5 single crystal with the Te flux by centrifugation, and collect the ZrTe5 single crystal.

2. The method for growing centimeter-scale ZrTe5 single crystals using the optimized tellurium flux method as described in claim 1, characterized in that: In step S10, the temperature is increased to 700°C at a heating rate of 3°C / min and held at a constant temperature for 8 hours.

3. The method for growing centimeter-scale ZrTe5 single crystals using the optimized tellurium flux method as described in claim 1, characterized in that: In step S20, the quartz tube is a pre-necked quartz tube that has undergone acid washing, ultrasonic cleaning and drying treatment, the purity of Zr raw material is ≥99.9%, and the inner diameter of the necked part of the pre-necked quartz tube is 3-8mm; the pore size of the porous alumina plate is 50-200μm.

4. The method for growing centimeter-scale ZrTe5 single crystals using the optimized tellurium flux method as described in claim 3, characterized in that: In step S20, the Zr raw material and the obtained purified Te block are mixed at a Te:Zr molar ratio of 200:1-350:

1.

5. The method for growing centimeter-scale ZrTe5 single crystals using the optimized tellurium flux method as described in claim 4, characterized in that: In step S30, the sealed quartz tube is placed in a tube furnace and heated to 900°C at a rate of 5°C / min and kept at that temperature for 48 hours.

6. The method for growing centimeter-scale ZrTe5 single crystals using the optimized tellurium flux method as described in claim 1, characterized in that: In step S10, the quartz tube has a length of 150-200 mm and an outer diameter of 20 mm.

7. The method for growing centimeter-scale ZrTe5 single crystals using the optimized tellurium flux method as described in any one of claims 2-6, characterized in that: In step S40, during the thermal oscillation temperature-controlled growth, the Zr-Te melt is cooled to 600°C at 2°C / min, then cooled to 469°C at 1°C / h, and then rapidly heated to 509°C within 10 min, and then cooled to 469°C at 1°C / h. This constitutes one thermal oscillation cycle.

8. The method for growing centimeter-scale ZrTe5 single crystals using the optimized tellurium flux method as described in claim 7, characterized in that: In step S50, when ZrTe5 single crystals and Te flux are separated by centrifugation, the centrifugation speed is 300-5000 rpm and the centrifugation time is 1-10 min.

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