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Article

Synthesis, Evolution of Morphology, Transport Properties for Bi2Te3 Nanoplates

by
Yu-Jing Zhao
1,2,3,† and
Fang Zhou
2,3,*,†
1
School of Physics, Electronictechnology and Intelligent Manufacturing, Huaihua University, Huaihua 418008, China
2
Department of Criminal Science and Technology, and Department of Foundation Course, Hunan Police College, Changsha 410138, China
3
Synergetic Innovation Center for Quantum Effects and Application, Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Key Laboratory for Matter Microstructure and Function of Hunan Province, Institute of Interdisciplinary Studies, School of Physics and Electronics, Hunan Normal University, Changsha 410081, China
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Crystals 2022, 12(11), 1668; https://doi.org/10.3390/cryst12111668
Submission received: 31 July 2022 / Revised: 10 November 2022 / Accepted: 13 November 2022 / Published: 19 November 2022
(This article belongs to the Special Issue Raman Scattering in Optical Crystals)
Browse Figures
Versions Notes

Abstract

:
Bi2Te3 has an extensive application as thermoelectric materials. Here, large scale Bi2Te3 single-crystal hexagonal nanoplates(NPs) with size of 0.4–0.8 μm were synthesized successfully by hydro-thermal method. X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) were used to characterize the Bi2Te3 nanoplates, which confirm the single crystal quality and smooth surface morphology with large size. We discussed the morphology-evolution in detail the influence of various reaction factors which including: the reaction temperature, the reaction time, the surfactants of the polyvinyl pyrrolidone (PVP) and pH value. The synthesis method is not only green, but also shortens the reaction time and improves the reaction efficiency. The Bi2Te3 nanopowders were hot-pressed into solid state pellets through spark plasma sintering (SPS). The values of the electrical conductivity σ were about 0.16 × 10−5 Sm−1 and 0.22 × 10−5 Sm−1 at room temperature and 530 K, respectively. The values of the Seebeck coefficient S were around −81 μVK−1 and −118 μVK−1 at room temperature and 530 K, respectively.

1. Introduction

The discovery of topological materials has evolved rapidly in the past 15 years, going through non-magnetic topological insulators (TI), crystalline insulators (TCI) and three-dimensional (3D) topological semimetals (TSM) [1,2,3,4,5,6,7]. Recently reported 3D-framed nanomaterials, BiSbTeSe2 had Dirac-type surface states and low bulk carrier density [8]; Bi1.1Sb0.9Te2S had recombination and layered structure [9]; the mesoporous TiO2 and macroporous 3D-framed graphene aerogel (TGM) consisting of several layers of MoS2 on a hierarchical porous structure, as a high-performance, robust, noble metal-free CO2 reduction photocatalysts [10]. 3D-framed graphene has been used for H2 precipitation reactions due to its unique structure and properties, including its hierarchical network, large specific surface area, diverse pore distribution, excellent light absorption ability, and excellent electrical conductivity [11].
In the last decade, Bismuth is a pioneer in topologically insulating nanomaterials (TIs), from strong or weak of 3D TI, topological metals TIs, semimetals TIs to magnetic TIs, while retaining the usual layered structural patterns [12,13,14,15,16,17,18,19,20,21,22,23,24,25]. Bi2Se3 TI thin films and nanoribbons with 1D Mohr stripe films on the surface, having a strongly enhanced surface density of states TI 1D cloudy superstructure due to weak coupling between the layers, became ideal candidates for van der Waals structures 3D TI [15]; 3D TI of Bi2Se3 nanoribbons due to their very high mobility of surface Dirac states and low bulk carrier density [19]. (Bi, Sb)2(Te, Se)3 TI films, eliminating crystal defects, reducing bulk carrier concentration, tuning the Fermi energy level to the Dirac point, and fabricating TI/superconductor pelletss completely in situ [17].
3D-framed of Bi2Te3 grown on molecular-beam epitaxy (MBE), new in-situ and Milestone flexiWAVE MW system, respectively [12,13,26,27]. Bi2Se3 TI thin films and nanoribbons were using catalyst free physical vapor deposition (PVD) [19]. MnBi2Te4 produced by a 2 mL alumina growth crucible of a Canfield crucible set [20,21,22,23,24,25,26,27]. These instruments are not only very advanced but also very expensive [19,20,21,22,23,24,25]. The solvothermal method has been successfully used to change the morphology and size structure of nanomaterials, and it has become one of the commonly used methods to prepare Bi2Te3 and Bi2Se3 nanomaterials because of its simple preparation method, easy operation, low cost, cheap equipment and low-temperature synthesis [26,27,28,29,30,31,32,33,34,35].
Till date, a number of papers have reported the preparation of bismuth telluride nanosheets by solvothermal method [36,37,38,39,40,41,42,43,44,45,46,47,48,49,50]. Among them, some reported the effect of temperature on the morphology of the products [51,52,53,54,55,56], some reported the effect of pH on the morphology of the products [57,58,59,60,61], and some reported the effect of surface complexing agent on the morphology of the products [62,63,64,65,66,67,68,69,70,71,72,73]. However, there are a few articles on the effect of all reaction factors on the morphology.
Herein, we discuss the morphology in detail for the effect of various reaction factors, which including: the reaction temperature, the varion surfactants, the weight of NaOH, and the reaction time. The Bi2Te3 nano-powders hot pressed into solid state pellets by SPS.The solid state pellets the values of the electrical conductivity σ and the Seebeck coefficient S were measured.

2. Experimental Sections

2.1. Preparation of Bi2Te3 Nanoplates

All of the reagents used in the experiment were of analytical purity and used without further purication. The typical synthesis procedure is as follows. First, 6 mmol TeO2, 2 mmol Bi2O3, 0.8 g of NaOH, and 1 g of PVP (K-30) were dissolved in ethylene glycol (EG). Second, this solution was transferred into a stainless steel autoclave, which was heated at 180 °C for 7 h and then cooled to room temperature. The precipitates were centrifuged, washed with distilled water, acetone, and absolute ethanol for several times, and finally dried at 60 °C for 6 h.

2.2. Sample Characterization

The crystallographic phase structure of as—prepared sample was determined by X-ray powder diffraction (XRD, Bruker D8 Advance). The size and morphology of the final product were characterized by scanning electron microscope (SEM, FEI, NovaSEM-450). The chemical composition and elemental mapping were analyzed by energy-dispersive X-ray (EDX) spectroscopy. Transmission electron microscope (TEM) image, high-resolution TEM (HRTEM) image, and selected area electron diffraction (SAED) pattern were characterized by TEM (FEI Tecnai F20) operating at 200 kV. Raman spectra were measured by high resolution Raman spectrometer (LabRAM HR Evolution, Horiba JY) using continuous wave laser with wavelength of 514.5 nm (5 mW excitation power) as excitation light source.

3. Results and Discussion

3.1. Structure and Morphology of Bi2Te3 Nanoplates

Figure 1 is the XRD pattern of as—prepared Bi2Te3 nanostructures. All the diffraction peaks in the XRD pattern match well with the Bi2Te3 rhombohedral lattice phase (JCPDS: 15-0863). The six main peaks can be easily indexed to (015), (1, 0, 10), (110), (205), (0, 2, 10) and (1, 1, 15) planes of Bi2Te3 rhombohedral lattice phase [47,50].
Figure 2a is SEM image of Bi2Te3 nanoplates, which shows the uniform hexagonal morphology in large scale. Figure 2b is low magnification TEM image of single Bi2Te3 nanoplate, which has a typical flat surface and sharp edges. These Bi2Te3 nanoplates have size of 0.6–0.8 μm, which is large enough to be observed in the optical microscopy for Raman measurement. The selected area electron diffraction (SAED) pattern shown in Figure 2b exhibits a hexagonal symmetry diffraction spot pattern and indicates the single crystal nature of Bi2Te3 nanoplates. Figure 2c is high-resolution TEM (HRTEM) image [50,52]. The plane spacings were measured to be 0.22 nm. Figure 2b,c gives the single-crystal nanoplates grow along the [0001] zone axis projection of the hexagonal Bi2Te3 reciprocal lattice [50,51]. Raman spectrum of single Bi2Te3 nanoplate at room temperature is shown in Figure 2d. The peak positions are consistent with the previously measured bulk crystalline Bi2Te3 [52].

3.2. Influences of the Reaction Temperature

The structures and the morphologies of the Bi2Te3 products can be affected by a variety of factors: a reaction temperature, a weight of NaOH, different surfactants, etc. A reaction temperature is one of the most important factors. We discussed a series of the reaction temperatures (140 °C, 160 °C, 180 °C, and 200 °C) of single factor with other conditions unchanged [50]. At 140 °C, the morphologies of the products was nanoparticles, as shown in Figure 3a. At 160 °C, the main products contain two different morphologies: nanoparticles and hexagon nanoplates, as shown in Figure 3b. As temperatures increased above 180 °C, pure Bi2Te3 hexagon nanoplates, as shown in Figure 3c. Further increasing temperature 200 °C did not change the morphology, as shown in Figure 3d. The appropriate temperature of Bi2Te3 hexagon nanoplates is 180 °C. Influences of the reaction temperature are listed in Table 1.
As shown in Table 1, the morphology of the product changed from nanoparticles to nanoplates with temperature increases. Smaller crystallites possess larger Gibbs free energy, based on the Gibbs-Thomson effect. Thus, chemical reaction for making Bi2Te3 nanoplates takes higher energy, for lower temperature cannot provide sufficient energy for reactants to be fully converted into Bi2Te3 nanoplates [64].

3.3. Influences of the Weight of NaOH

In order to discuss the necessity and effect of NaOH for the morphology of product, the nanoplates synthesized at NaOH for (0 g, 0.2 g, 0.4 g, 0.8 g, 1.6 g and KOH) [50,67,68]. When the weight of NaOH is 0 g, a large amount of fine nanoparticles and nanorods could be observed, no nanoplates were found, as shown in Figure 4a. When the weight of NaOH is 0.2 g, the nanorods was increasing, no nanoplates were found, as shown in Figure 4b. When the weight of NaOH is 0.4 g, the nanorods was decreasing, the nanoplates could be observed, as shown in Figure 4c. When the weight of NaOH is 0.8 g, the nanoplates were completely crystallized, as shown in Figure 4d. When the weight of NaOH is 1.6 g, the nanoplates were incompletely crystallized again, as shown in Figure 4e. When NaOH be replaced by KOH, nanowires and nanoplates could be observed, as shown in Figure 4f. So we choose 0.8 g of NaOH. Influences of the weight of NaOH are listed in Table 2.
Thus, an alkaline substance is needed to reduce the acid hydrolysis of the reaction. Therefore, the morphology of product comprises the nanowires or nanoparticles, if NaOH is not enough. When the weight of NaOH increases, the hexagonal Bi2Te3 NPs that have a uniform size, sharp outlines, and sharp edges, as displayed in Figure 3a–d. It indicates that OH− can make the release the cations in solution easier, guiding the crystals to grow towards a particular crystal plane, amid non-equilibrium crystal growth with higher monomer concentration [62,67,68,69].

3.4. Influences of the Surfactants

We designed a surfactants experiment of single factor with other conditions unchanged. Bi2Te3 nanoplates synthesized with other surfactants (PVP was replaced with no surfactant, the cetyltrimethylammonium bromide (CTAB), the ethylenediaminetetraacetic acid disodium salt (EDTA), and the sodium dodecyl benzene sulfonate (SDBS)) [49]. When the reaction was carried out no surfactant, many nanoparticles and nanowires with irregular shapes could be observed, as shown in Figure 5a. When PVP was replaced by CTAB, EDTA, and SDBS, the morphologies of the products were quite similar to the products synthesized without any surfactants, as shown in Figure 5b–d. So we choose 1.0 g of PVP as the optimal value. Influences of the surfactants are listed in Table 3.
The above experiments indicate that surfactants impact the morphology and the composition of the product. For example, surfactants like CTAB and EDTA can make the product contain a large amount of Te elementary substances. The reason might be that the surfactants adsorb and coat the initially produced Te nanocrystals, which greatly reduces the combination of Te and Bi [70,71,72,73].

4. Influences of the Reaction Time

The rhombohedral crystal structure of Bi2Te3 belongs to the R 3 ¯ m(166) space group symmetry [53]. There are five atoms per unit cell in the Bi2Te3. This compound contains sandwich structure of the five layers [Te(1)-Bi-Te(2)-Bi-Te(1)], which are held together by van der Waals force. Therefore, Bi2Te3 crystal grows faster in the a or b axis direction than in the C-axis direction, formed a hexagonal plates morphology at the end. Bi2Te3 nanoplates have an orientation along the (001) direction by the HRTEM image. On the basis of these results and other related works, Ref. [47] illustrated a possible growth mechanism, and proved assumption that three stages of the process of Bi2Te3 crystal growth. Ref. [50] put forward the possible proposal that two steps for the process of Bi2Te3 crystal growth.
It is a series of reaction time is 3 h, 5 h, 7 h, 9 h, and 11 h [54,64,65,66,67]. At 3 h, a large amount of fine Bi2Te3 nanoplates and nanowires could be observed as shown in Figure 6a. At 5 h, the nanowire is in middle of thin hexagon Bi2Te3 nanopate, as shown in Figure 6b. At 7 h, the Bi2Te3 hexagon nanoplates shown in Figure 6c. At 9 h, the hole is in middle of thin hexagon Bi2Te3 nanopate shown in Figure 6d. At 11 h, every things vanished from sight, as shown in Figure 6e. The statistical results show nanoplates length range from about 0.4 μm to 0.8 μm, the average length of nanoplates is 0.54 μm in Figure 6f. The process of life on Bi2Te3 are listed in Table 4.
The intrinsic growth morphology of Bi2Te3 NPs is a layered structure under relatively mild environment due to the lattice structure. At the beginning of the reaction, the generated Bi2Te3 nuclei adsorbed some Bi2Te3 grains and built into a hexagonal prototype. Then, due to the surfactant PVP, the hydrophobic end adsorbs on the (001) surface, which inhibits the growth of Bi2Te3 on the (001) surface, the growth rate of Bi2Te3 NPs along the a-axis and b-axis is larger than that of the c-axis, thus forming hexagonal nanosheets. Finally, the nanostructure of hexagonal Bi2Te3 NPs was formed [70,72,73]

5. Transport Properties of Bi2Te3 Solid-State Pellets

By analyzing the factors affecting the synthesis, a suitable synthesis formula was determined, and well-dispersed and homogeneous hexagonal Bi2Te3 NPs with an average particle size distribution of 0.40 μm were obtained.

5.1. Density Determination of Solid-State Pellets

Through the analytical discussion of controlled synthesis, The Bi2Te3 nanopowders were hot-pressed into solid state pellets through SPS. The Bi2Te3 powder was vacuum hot pressed into a 20 mm diameter and 5 mm height disc-shaped specimen in Figure 7. The disc-shaped specimens were polished to a standard size of 12.51 mm in diameter and 1.94 mm in thickness as shown in Figure 7a–c.
The mass M 0 , diameter D and thickness H of the block were measured 3 times for each parameter using a balance and vernier calipers, respectively, and then the average values were taken. And the measured values were substituted into the density formula to obtain the volume, density and relative density of the circular block as shown in Table 5.
The density of the circular Bi2Te3 solid-state pellets was 7.241938 g/cm3 compared with the pure Bi2Te3 block density of 7.7 g/cm3, and the relative density of the block of the specimen is calculated to be 94.1%. It indicates that the hot-pressed Bi2Te3 solid-state pellets had good dense density, which is beneficial to improve its electrical conductivity.

5.2. The Electrical Conductivity σ of Bi2Te3 Solid-State Pellets

The conductivity of the hot-pressed Bi2Te3 bulk specimens is plotted against the temperature. From the Figure 8, the conductivity of Bi2Te3 solid-state pellets is positively correlated with the temperature range from room temperature to 550 K. The conductivity keeps increasing with the temperature, before reaching the maximum conductivity σ which is about 0.16 × 10 − 5 Sm−1 and 0.22 × 10−5 Sm−1 at room temperature and 530 K, respectively. The conductivity of Bi2Te3 solid-state pellets increases with the temperature in the study. Because of the semiconductor materials at low and medium temperatures, carrier rises exponentially with impurity excitation and the conductivity also increases exponentially when temperatures increases. The electrical conductivity σ was very similar to the σ reported in Refs. [58,59].

5.3. The Seebeck Coefficient S of Bi2Te3 Solid-State Pellets

As the Seebeck coefficients S are negative in shown the Figure 9, the Bi2Te3 solid-state pellets is an N-type semiconductor material. The conductivity keeps decreasesing with the temperature, before reaching the minimum coefficient S were around −81 μVK−1 and −118 μVK−1 at room temperature and 530 K, respectively. The Seebeck coefficient S of the sample decreases with the increase of temperature, for the grain size of the sample powder is very small at the nanometer level, which causes many defects and enhances the scattering of carriers, thus increasing the scattering factor and finally the Seebeck coefficient. The temperature dependence of S was very similar to the S reported in Refs. [60,61].

6. Conclusions

In summary, we have successfully synthesized Bi2Te3 single crystals nanoplates via hydro-thermal method. The average length of these nanoplates is 0.40 μm. The reaction temperature, the weight of NaOH, and various surfactants play important roles on the growth of Bi2Te3 nanocrystals. PVP and NaOH are a first and necessary one for synthetics of Bi2Te3 nanoplates.The thickness of Bi2Te3 nanoplates via adjusting the weight of NaOH. The reaction time 7 h was not only shortens the reaction time but also improves the reaction efficiency. The transport properties compared with that of Refs. [58,59,60,61], just reached the level of those did not improve it.

Author Contributions

Conceptualization, Y.-J.Z. and F.Z.; methodology, Y.-J.Z.; validation, Y.-J.Z. and F.Z.; formal analysis, Y.-J.Z.; investigation, Y.-J.Z.; data curation, F.Z.; writing—original draft preparation, Y.-J.Z.; writing—review and editing, F.Z.; visualization, Y.-J.Z.; project administration, F.Z.; funding acquisition, Y.-J.Z. and F.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the National Natural Science Foundation of China (Grant No. 22175062, 21671064), the Natural Science Foundation of Hunan Province of China (Grant No. 2020JJ5446, 2021JJ30232), the Scientific Research Fund of Hunan Provincial Education Department (Grant No.19B448, 19B183, 20C0754, 16B048) and the High-level-talent Initiation Research Fund of Hunan Police Academy (Grant No. 2021KYQD16).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

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Crystals 12 01668 g001 550
Figure 1. XRD pattern of as-prepared Bi2Te3 nanostructures.
Figure 1. XRD pattern of as-prepared Bi2Te3 nanostructures.
Crystals 12 01668 g001
Crystals 12 01668 g002 550
Figure 2. (a) SEM image. (b) Low magnification TEM image and SAED pattern. (c) HRTEM image. (d) Raman spectrum at room temperature of single Bi2Te3 nanoplate.
Figure 2. (a) SEM image. (b) Low magnification TEM image and SAED pattern. (c) HRTEM image. (d) Raman spectrum at room temperature of single Bi2Te3 nanoplate.
Crystals 12 01668 g002
Crystals 12 01668 g003 550
Figure 3. A series of temperatures (a) 140 °C, (b) 160 °C, (c) 180 °C, (d) 200 °C.
Figure 3. A series of temperatures (a) 140 °C, (b) 160 °C, (c) 180 °C, (d) 200 °C.
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Crystals 12 01668 g004 550
Figure 4. A series of the weight of NaOH (a) 0 g, (b) 0.2 g, (c) 0.4 g, (d) 0.8 g, (e) 1.6 g, (f) KOH.
Figure 4. A series of the weight of NaOH (a) 0 g, (b) 0.2 g, (c) 0.4 g, (d) 0.8 g, (e) 1.6 g, (f) KOH.
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Crystals 12 01668 g005 550
Figure 5. A series of the surfactants (a) no surfactant, (b) CTAB, (c) EDTA, (d) SDBS.
Figure 5. A series of the surfactants (a) no surfactant, (b) CTAB, (c) EDTA, (d) SDBS.
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Crystals 12 01668 g006 550
Figure 6. A series of reaction time (a) 3 h, (b) 5 h, (c) 7 h, (d) 9 h, (e) 11 h, (f) nanoplate length length size.
Figure 6. A series of reaction time (a) 3 h, (b) 5 h, (c) 7 h, (d) 9 h, (e) 11 h, (f) nanoplate length length size.
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Crystals 12 01668 g007 550
Figure 7. (a) Bi2Te3 solid-state pellets; (b) The diameter of solid-state pellets; (c) The thickness of solid-state pellets.
Figure 7. (a) Bi2Te3 solid-state pellets; (b) The diameter of solid-state pellets; (c) The thickness of solid-state pellets.
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Crystals 12 01668 g008 550
Figure 8. Temperature dependence of the electrical conductivity σ.
Figure 8. Temperature dependence of the electrical conductivity σ.
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Crystals 12 01668 g009 550
Figure 9. Temperature dependence of the Seebeck coefficient S.
Figure 9. Temperature dependence of the Seebeck coefficient S.
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Table
Table 1. A series of temperatures influenced on the morpholoy of Bi2Te3.
Table 1. A series of temperatures influenced on the morpholoy of Bi2Te3.
TeO2Bi2O3NaOHPVP (K-30)t (h)T (°C)Morphology
(a)6 mmol2 mmol0.8 g1 g7 h140 °Cnanoparticles
(b)6 mmol2 mmol0.8 g1 g7 h160 °Cnanoparticles and nanoplates
(c)6 mmol2 mmol0.8 g1 g7 h180 °Cnanoplates
(d)6 mmol2 mmol0.8 g1 g7 h200 °Cnanoplates and nanoclusters
Table
Table 2. A series of the weight of NaOH influenced on the morpholoy of Bi2Te3.
Table 2. A series of the weight of NaOH influenced on the morpholoy of Bi2Te3.
TeO2Bi2O3PVP (K-30)T (°C)t (h)NaOHMorphology
(a)6 mmol4 mmol1 g180 °C7 h0 gnanoparticles and nanowires
(b)6 mmol4 mmol1 g180 °C7 h0.2 gnanoparticles, nanowires and nanoplates
(c)6 mmol4 mmol1 g180 °C7 h0.4 gnanowires and nanoplates
(d)6 mmol4 mmol1 g180 °C7 h0.8 gnanoplates
(e)6 mmol4 mmol1 g180 °C7 h1.6 gnanoparticles and nanoplates
(f)6 mmol4 mmol1 g180 °C7 hKOHnanoparticles and nanoplates
Table
Table 3. A series of the surfactants influenced on the morpholoy of Bi2Te3.
Table 3. A series of the surfactants influenced on the morpholoy of Bi2Te3.
TeO2Bi2O3T (°C)t (h)NaOHSurfactantsMorphology
(a)6 mmol4 mmol180 °C7 h0.8 g0 gnanoplates and nanowires
(b)6 mmol4 mmol180 °C7 h0.8 gCTABnanoplates and nanowires
(c)6 mmol4 mmol180 °C7 h0.8 gEDTAnanoplates and nanowires
(d)6 mmol4 mmol180 °C7 h0.8 gSDBSnanoparticles, nanoplates and nanowires
Table
Table 4. Influences of the reaction time.
Table 4. Influences of the reaction time.
TeO2Bi2O3NaOHPVP (K-30)T (°C)t (h)Morphology
(a)6 mmol2 mmol0.8 g1 g180 °C3 hnanoparticles
(b)6 mmol2 mmol0.8 g1 g180 °C5 hnanoparticles andnanoplates
(c)6 mmol2 mmol0.8 g1 g180 °C7 hnanoplates
(d)6 mmol2 mmol0.8 g1 g180 °C9 hnanoplates
(e)6 mmol2 mmol0.8 g1 g180 °C11 hnothing
Table
Table 5. The density of the circular Bi2Te3 solid-state pellets.
Table 5. The density of the circular Bi2Te3 solid-state pellets.
Parameters NameM 0 (g)D (mm)H (mm)V (cm3)ρ (g/cm3)Relative Density
Measured value1.72612.511.940.2383347.24193894.1 %
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Zhao, Y.-J.; Zhou, F. Synthesis, Evolution of Morphology, Transport Properties for Bi2Te3 Nanoplates. Crystals 2022, 12, 1668. https://doi.org/10.3390/cryst12111668

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Zhao Y-J, Zhou F. Synthesis, Evolution of Morphology, Transport Properties for Bi2Te3 Nanoplates. Crystals. 2022; 12(11):1668. https://doi.org/10.3390/cryst12111668

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Zhao, Yu-Jing, and Fang Zhou. 2022. "Synthesis, Evolution of Morphology, Transport Properties for Bi2Te3 Nanoplates" Crystals 12, no. 11: 1668. https://doi.org/10.3390/cryst12111668

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