Crystal Growth and the Magnetic Properties of Na2Co2TeO6 with

Subscriber access provided by UNIV AUTONOMA DE COAHUILA UADEC

Article

Crystal growth and the magnetic properties of Na2Co2TeO6 with quasi-two-dimensional honeycomb lattice Guiling Xiao, Zhengcai Xia, Wanwan Zhang, Xiaoyu Yue, Sha Huang, Xiaoxing Zhang, Feng Yang, Yujie Song, Meng Wei, Han Deng, and Dequan Jiang Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.8b01770 • Publication Date (Web): 12 Apr 2019 Downloaded from http://pubs.acs.org on April 12, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Crystal Growth & Design

Crystal growth and the magnetic properties of Na2Co2TeO6 with quasi-two-dimensional honeycomb lattice Guiling Xiao1, Zhengcai Xia*1, Wanwan Zhang2, Xiaoyu Yue1, Sha Huang1, Xiaoxing Zhang1, Feng Yang1, Yujie Song1, Meng Wei1, Han Deng1, Dequan Jiang1 1.Wuhan National High Magnetic Field Center & School of Physic, Huazhong University of Science and Technology, Wuhan 430074. China 2. State Key Laboratory of Structure Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, P. R. China Abstract The single crystal Na2Co2TeO6 has been successfully grown by self-flux method and its lattice structure and basic magnetic properties were characterized. As determined by single crystal X-ray Diffraction (XRD), Na2Co2TeO6 belongs to space group P6322 (182) with a = b = 5.2709(2) Å, c = 11.2615(15) Å and V = 270.95 (4) Å3, the crystal structure is layered honeycomb formed by CoO6 octahedra and the TeO6 octahedra in the center of the honeycomb layers, the NaO6 octahedra is between the honeycomb layers. Magnetic susceptibility measurements indicate that the single crystal sample displays a distinct anisotropic behavior and the spin parallels to the honeycomb plane (ab-plane). In a lower temperature region, a series of antiferromagnetic (AFM) like phase transitions were observed, which may result from the spin-reorientation of Co2+ ions. The different magnetization behavior between the polycrystalline and the single crystal (with the magnetic field parallel to and perpendicular to ab-plane) reveals obvious magnetic anisotropy of single crystal Na2Co2TeO6. The special honeycomb planes formed by CoO6 octahedra and the AFM interaction inter- and intrahoneycomb planes may lead to the obvious anisotropy and complicated magnetic phase transitions. Key words: Na2Co2TeO6, spin-reorientation, honeycomb, anisotropic

* Corresponding author: E-mail address: [email protected] (Zhengcai Xia) 1

ACS Paragon Plus Environment

Crystal Growth & Design 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

INTRODUCTION In recent years, the potentially unconventional electronic and magnetic properties of the honeycomb structure formed by magnetic atoms have attracted much attention in condensed matter physics. A series of layered compounds have been prepared by solid-state reaction or flux method, and their basic magnetic properties have been investigated. 1-6 As a honeycomb-type layered oxide, it is found that Na3Co2SbO6 adopted a ‘zig-zag’ AFM structure at low temperatures, which results in increasing the complex influence of next-nearest-neighbor exchange in determining the ground state. 3 Recently, some studies have done on the field-induced magnetization processes of extended Heisenberg-Kitaev models for the honeycomb lattice, such as α-RuCl3 and Na2IrO3.2 For the new layered honeycomb tellurates, BiMTeO6 (M = Cr, Mn, Fe), were synthesized and characterized.7 The electronic and magnetic properties of quasi-two-dimensional (2D) honeycomb compounds A3Ni2SbO6 (A = Li, Na) have been investigated by a comprehensive experimental and theoretical study, 8 in which the honeycomb planes, intra-layer spin exchange couplings between magnetic ions, contain both AFM and ferromagnetic (FM) interactions, which supporting a zig-zag AFM ground state with complicated magnetic phase diagrams. As a typical of low dimensional honeycomb system, Na2Co2TeO6 has been investigated in the synthesis, structure, basic magnetic properties and magnetodielectric characterization with polycrystalline sample. 9, 10 The powder neutron diffraction shows a long-range AFM ordering below 24.8 K, and the magnetic ground state with a zig-zag AFM chain. 11 The effective magnetic moments of the magnetic Co2+ ion are 2.77(3) μB/Co(1)2+ and 2.45(2) μB/Co(2)2+ at 1.8 K, which is considered as the persistent spin fluctuations in the ordered state. The previous studies also show the presence of short-range magnetic correlations.11 Considering to the P6322 space group of Na2Co2TeO6, the non-centrosymmetric is a necessary condition for ferroelectricity. It is thus expected that, depending on the stabilized magnetic order, this compound could display interesting multiferroic and/or magnetoelectric properties.12 The dielectric measurements reveal the presence of magnetodielectric coupling in Na2Co2TeO6.10 So far, all investigates of the Na2Co2TeO6 is based on the polycrystalline samples. 11, 12 However, as quasi-two-dimensional honeycomb lattice layer structure, the polycrystalline has the average effect in many performance, especially, the phase transition field and the phase transition temperature are sensitive on the sample quality and affected by the lattice defects in the polycrystalline sample. In order to determine the more detail interaction inter- and intrahoneycomb planes formed by the magnetic ion CoO6 octahedra, the synthesized of the single crystal Na2Co2TeO6 is in demand. On the other hand, Na2Co2TeO6 is highly anisotropic both in crystal structure and 2


Page 2 of 17

Page 3 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


magnetic coupling, and thus a study of single crystals is indispensable to clarify the detailed magnetic properties, including the coupling between dielectric properties and the AFM ordering. In the present, we concentrate on the synthesis of the single crystal sample of quasi-two dimension Na2Co2TeO6. In order to confirm the quality of sample, a full characterization of the crystal structure and the anisotropic magnetic coupling were performed using the as the grown single crystals. The results show that the single crystal sample is in high quality, and obvious anisotropic magnetic properties were observed, which provides good conditions for the further investigation on Na2Co2TeO6. EXPERIMENTAL SECTION Single crystal growth and magnetization measurement Na2Co2TeO6 polycrystalline sample was synthesized by a conventional solid-state reaction method, starting materials Na2O (99.95%), Co3O4 (99.95%) and TeO2 (99.95%) were mixed in appropriate stoichiometric molar ratio, the mixture was ground fully and sintered at 800 ℃ in air for 100 h with a platinum crucible, To obtain single phase sample, the mixture was ground and sintered several times. Na2Co2TeO6 single crystal sample was synthesized by a self-flux method. The obtained polycrystalline sample Na2Co2TeO6 and the flux of Na2O and TeO2 were mixed in molar ratio of 1:0.5:2. Ground the mixture fully and then gradually heated to 900 ℃ at 5℃/min in the air. Remaining the temperature of 900 ℃ for 30 h, then cooled the temperature to 500 ℃ at the rate of 3 ℃/h. When temperature decreases to room temperature, the Na2Co2TeO6 flaky crystals with typical size of 1-5 mm in diameter and 0.5 mm thickness with light purple color were obtained. In order to wash off the excess of the flux, the hot NaOH (1 M) solution was used. The magnetization measurements both of polycrystalline and single crystal samples have been done with a superconducting quantum interference device magnetometer (SQUID Quantum Design). Single crystal structure characterization A high quality single crystal with size of 0.2*0.2*0.2 mm3 was selected for the structure analysis, in which the data collection using the Oxford Diffraction Rigaku XtaLAB miniTM diffractometer with graphite-monochromated Mo-Ka radiation (λ = 0.71073 Å) at 293 K. The cell determination, refinement and data reduction were applied using CrysAlisPro software with an empirical absorption correction. The program Olex2 was used as an interface to invoke program SHELXS and SHELXL executables, where direct methods were applied to resolve crystal structure in solution program SHELXS, and used full-matrix least squares on F2 to refine anisotropic atomic displacement parameters of all non-hydrogen atoms in refinement program SHELXL. Crystallographic data, atomic coordinates and anisotropic displacement 3



Page 4 of 17

parameters for Na2Co2TeO6 are given in tables 1-2. The CCDC number is 1882240. Table 1 Details of the crystal data collection and structure refinement of Na2Co2TeO6.

Temperature Crystal system

Na2Co2TeO6 387.44 293(2) K hexagonal

Space group

P6322

a b c α β γ Volume Z ρcalc μ F(000) Crystal size Radiation Mo-Kα 2Θ range for data collection Reflections collected Independent reflections Data/restraints/parameters Goodness-of-fit on F2 Final R indexes [all data] Largest diff. peak and hole

5.2709(2) Å 5.2709(2) Å 11.2615(15) Å 90.00° 90.00° 120.00° 270.95(4) Å3 2 4.749 g/cm3 11.520 mm‐1 352.0 0.2× 0.2 × 0.2 mm3 λ = 0.71073 (Å) 7.24° to 52.68° 543 196 [Rint = 0.0254, Rsigma = 0.0261] 196/0/21 1.099 R1 = 0.0475, wR2 = 0.1261 3.84 and -1.15 e /Å3

Empirical formula Formula weight

Table 2 Fractional atomic coordinates (×104) and equivalent isotropic displacement parameters (Å2×103) for Na2Co2TeO6. Ueq is defined as 1/3 of the trace of the orthogonalised UIJ tensor.

atom

x

y

z

U(eq)

Te

-3333

-6667

-2500

8.0(6)

Co(1)

0

0

-2500

5.8(8)

Co(2)

-6667

-3333

-2500

10.0(9)

O

-247(11)

-3592(10)

-3442(4)

12.3(11)

Na

-3200(20)

-3200(20)

-5000

88(5)

4


Page 5 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


RESULTS AND DISCUSSED The structure analysis of single crystal XRD shows that the Na2Co2TeO6 in the hexagonal symmetry with space group P6322, the unit-cell parameters are a = b = 5.2709(2) Å and c = 11.2615(15) Å. The crystal structure of Na2Co2TeO6 is shown in figure 1, which can be viewed as a 2D honeycomb lattice as shown in figure 1(a), the honeycomb layers are separated by Na layers, the layers of honeycomb formed by CoO6 octahedra and the non-magnetic TeO6 octahedra. Figure 1(b) views perpendicular to the honeycomb layers, in which the 2D honeycomb lattice forms by CoO6 octahedra and the TeO6 octahedra in the center of the honeycomb layers.

Figure1 (a) crystal structure of Na2Co2TeO6, (b) view perpendicular to the honeycomb layer, in which the layer of honeycomb formed by CoO6 octahedra and the non-magnetic TeO6 octahedra.

The structural refinement of Na2Co2TeO6 was performed on powder XRD data based on the same structural model. Figure 2(a) show the room temperature XRD patterns of the powder sample (Crushed single crystal sample), and the refinement with General Structure Analysis System are shown in figure 2(a), in which the experimental value, calculate value, background, difference and ref1 are marked with different symbols. According to the Rietveld refinement, the lattice parameters of a = 5



b = 5.26844(16) Å, c = 11.23708(26) Å, and V = 270.115(13) Å3 were obtained, which is almost coincide with the results from single crystal structure characterization as listed in table 1, the different between the refinement parameters may result mainly from the different strain in single and crushed single samples. In figure 2(a), all diffraction peaks can be indexed by the non-centrosymmetric space group P6322, no extra diffraction peak is found, which is in agreement with the previous reports .13 Figure 2(b) shows the XRD measured with a single crystal at room temperature, the diffraction peaks of (0 0 2), (0 0 4), (0 0 6) and (0 0 8) indicate the normal vector of the surface of the measured sample is c-axis. Both the XRD studies reveals that obtained Na2Co2TeO6 samples have the hexagonal structure and good crystallinity.

Figure 2 (a) room temperature X-ray diffraction patterns and the refinement results of the polycrystalline sample (crushed single sample) with General Structure Analysis System. (b) X-ray diffraction pattern of the single crystal sample, inset is the morphology of the measured single crystal sample.

In order to investigate the magnetic properties of polycrystalline and the single crystal samples, the temperature dependence of magnetization were measured in the temperature region of 2 K to 300 K under the magnetic field of 0.01 T. As shown in figure 3(a), above 150 K the magnetization curves show similar temperature dependence, but when temperature decreasing below 150 K, the magnetization behaviors of polycrystalline and single crystal (with magnetic field along and 6


Page 6 of 17

Page 7 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3(a) Temperature dependence of magnetization measured at 0.01 T in the temperature region of 2 K to 300 K for polycrystalline and single crystal (magnetic field perpendicular to and parallel to ab-planes). (b), (c) and (d) show the zoom in of temperature range from 2 to 30 K, the spin reorientation transitions are marked with (blue) arrows. The curves of ZFC and FC are marked by solid symbols and open symbols respectively.

perpendicular to ab-plane) are obvious different. The lower temperature magnetization curves of the polycrystalline and single crystal with magnetic field perpendicular to and parallel to the honeycomb planes (ab-plane) are shown in figures 3(b), 3(c) and 3(d) respectively. For polycrystalline as shown in figure 3(b), three magnetic phase transitions were observed in FC (ZFC) mode at TpolyN1 ~ 27 K (26.5 K), TpolyN2 ~ 15.4 K (15 K) and TpolyN3 ~ 4 K (6.5 K) respectively, which are consistent with the report and are considered as possible signature of a spin reorientation.12 Considering the different coupling exchange interactions between the honeycomb layers and within the honeycomb layers, we measured the magnetization of the single crystal with the applied magnetic field along the honeycomb plane and perpendicular to the honeycomb plane. For the case of magnetic field parallel case as shown in figure 3(d), three phase transitions were observed in FC (ZFC) mode at the temperature T//N1 ~ 26.9 K (27 K), T//N2 ~ 14.7 K (20 K), T//N3 ~ 4.7 K (9.5 K) respectively. For the magnetic field perpendicular case as shown in figure (3), only two phase transitions were observed in FC (ZFC) mode at the temperatures of T⊥N1 ~ 7



27 K (26 K), T ⊥ N2’ ~ 16 K (4 K) respectively. Compared the results of single crystal with the polycrystalline sample, the obvious anisotropic magnetization behaviors were observed in single sample, which suggest the different exchange interactions interand intra- the honeycomb layers are exist in the single crystal. In addition, considering the absolute value of magnetization, the case of magnetic field parallel to the honeycomb plane is larger than that of the magnetic field perpendicular case, which indicates that the honeycomb plane is the easy magnetization plane.

Figure 4 Temperature dependence of the susceptibility measured at 0.05 T and Curie-Weiss fitting (marked with solid lines), the temperature region of the fitting ranges from 100 K to 300 K.

Figure 4 shows the temperature dependence of DC susceptibility of Na2Co2TeO6 measured at a magnetic field of 0.05 T. Above 100 K, the samples show paramagnetic behavior and the susceptibility can be fitted well with Curie-Weiss law (χ = C/(T-Θ)). For polycrystalline sample, the Curie-Weiss temperatures Θ is -8.3 K, and the effective magnetic moment B =5.34 μ B/Co2+, which is consistent with previous report. 11 For single sample, the Curie-Weiss temperatures Θ = -139 K (Θ// = -9 K), and the effective magnetic moment B = 5.98 μ B/Co2+ (// = 5.99 μ B/Co2+). The effective moment of Co2+ is within the range of calculated values for Co2+ ions in a spin polarization of 3d7 configuration with a nonzero orbital contribution. The negative Curie-Weiss temperatures suggest that the AFM coupling is dominant and the different Curie-Weiss temperatures show that the AFM couplings of inter- and intra- layers are different, which lead to the observed anisotropic magnetization behaviors. 8


Page 8 of 17

Page 9 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 5 Magnetic field dependence of magnetization at 4.2 K of polycrystalline and single crystal sample with magnetic field parallel and perpendicular to ab-planes. The dotted arrows point to the magnetic field direction, the solid arrows point to critical field of the phase transition. Inset is the temperature dependence of differential of the magnetization over the magnetic field.

Magnetic field dependence of magnetization of Na2Co2TeO6 are measured at 4.2 K, both the field-increasing and field-decreasing branches are shown in figure 5, the critical fields of phase transitions were determined with the magnetization differential over the magnetic field as shown in the inset. For polycrystalline sample, an obvious spin flop phase transition was observed at BC1poly = 5.7 T in the magnetic field increasing branch, which is consistent with the previous study12. Similar magnetization behavior was observed in the field decreasing branch, and a slightly magnetic hysteresis loop was observed around the magnetic field 5.5 T. For single crystal sample, when magnetic field perpendicular to honeycomb plane, no obvious magnetic phase transition was observed in the measured magnetic field region. But when magnetic field parallel to honeycomb plane, an obvious spin flop transition at BC1// = 5.7 T was observed in the field increasing branch, and the spin flop became gentle in the field-decreasing one and the phase transition field was shifted to around B’C1// = 5 T. Accompanying the phase transition an obvious hysteresis was also observed, which indicates the first-order transition characteristic. The results show that the single crystal sample has obvious anisotropic magnetization, which may result from the quasi-2D honeycomb magnetic coupling. Because the easy magnetization is in the honeycomb plane, that is the spin of Co ion is in the plane and easy rotation 9



within the plane and hard out-off-plane. On the other hand, the obvious difference between the lattice constant a (=b) and c leads to the sensitive to the magnetic interaction inter- and intrahoneycomb layers different. The detail experimental measurements on the inter- and intrahoneycomb layers will be done in the future with pulsed high magnetic field, and the high quality single sample brings convenience for future study on the complex magnetic transition and anisotropic magnetic properties. CONCLUSION We have succeeded in synthesizing the Na2Co2TeO6 single crystal, which has honeycomb hexagonal structure. Magnetic susceptibility measurements indicate that Na2Co2TeO6 single crystal has distinct magnetic anisotropic behavior. In lower temperature region, a series of temperature and magnetic field induced phase transitions were observed, in which the phase temperatures and critical magnetic field are also anisotropy. The distinct spin flop is usually considered as a spin reorientation behavior, however, the detail explanation on the magnetic anisotropy of the quasi-two-dimensional honeycomb lattice will be help to explore the long-range antiferromagnetic ordering, short-range magnetic correlations, the role of Na ion between the honeycomb planes, spin fluctuations in the ordered state, multiferroic and/or magnetoelectric properties etc. Thus, the high quality honeycomb structure Na2Co2TeO6 single crystal provides great convenience for the further exploration. ACKNOWLEDGMENTS This work was supported in part by the National Key R&D Program of China (Grant No. 2016YFA0401003), the National Natural Science Foundation of China (Grant No. 11674115 and 51861135104), and the Fundamental Research Funds for the Central Universities (Grant No.2018KFYXKJC010).

10


Page 10 of 17

Page 11 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


REFERENCE (1) Karna, S. K.; Zhao, Y.; Sankar, R.; Avdeev, M.; Tseng, P. C.; Wang, C. W.; Shu, G. J.; Matan, K.; Guo, G. Y.; Chou, F. C., Sodium layer chiral distribution and spin structure of Na2Ni2TeO6 with a Ni honeycomb lattice. Phys. Rev. B 2017, 95, 104408. (2) Janssen, L.; Andrade, E. C.; Vojta, M., Magnetization processes of zigzag states on the honeycomb lattice: Identifying spin models for α−RuCl3 and Na2IrO3. Phys. Rev. B 2017, 96,064430. (3) Wong, C.; Avdeev, M.; Ling, C. D., Zig-zag magnetic ordering in honeycomb-layered Na3Co2SbO6. J.Solid State Chem. 2016, 243, 18-22. (4) Kadari, R.; Velchuri, R.; Sreenu, K.; Ravi, G.; Munirathnam, N. R.; Vithal, M., Synthesis, characterization and tin/copper–nitrogen substitutional effect on photocatalytic activity of honeycomb ordered P2-Na2Ni2TeO6. Mater. Res. Express 2016, 3, 115902. (5) Roudebush, J. H.; Andersen, N. H.; Ramlau, R.; Garlea, V. O.; Toft-Petersen, R.; Norby, P.; Schneider, R.; Hay, J. N.; Cava, R. J., Structure and magnetic properties of Cu3Ni2SbO6 and Cu3Co2SbO6 Delafossites with honeycomb lattices. Inorg Chem 2013, 52, 6083-95. (6) Schmidt, W.; Berthelot, R.; Sleight, A. W.; Subramanian, M. A., Solid solution studies of layered honeycomb-ordered phases O3–Na3M2SbO6 (M = Cu, Mg, Ni, Zn). J. Solid State Chem. 2013, 201, 178-185. (7) Kim, S. W.; Deng, Z.; Fischer, Z.; Lapidus, S. H.; Stephens, P. W.; Li, M. R.; Greenblatt, M., Structure and Magnetic Behavior of Layered Honeycomb Tellurates, BiM(III)TeO6 (M = Cr, Mn, Fe). Inorg Chem 2016, 55, 10229-10237. (8) Zvereva, E. A.; Stratan, M. I.; Ovchenkov, Y. A.; Nalbandyan, V. B.; Lin, J. Y.; Vavilova, E. L.; Iakovleva, M. F.; Abdel-Hafiez, M.; Silhanek, A. V.; Chen, X. J.; Stroppa, A.; Picozzi, S.; Jeschke, H. O.; Valentí, R.; Vasiliev, A. N., Zigzag antiferromagnetic quantum ground state in monoclinic honeycomb lattice antimonates A3Ni2SbO6 (A = Li,Na). Phys. Rev. B 2015, 92, 144401. (9) Viciu, L.; Huang, Q.; Morosan, E.; Zandbergen, H. W.; Greenbaum, N. I.; McQueen, T.; Cava, R. J., Structure and basic magnetic properties of the honeycomb lattice compounds Na2Co2TeO6 and Na3Co2SbO6. J. Solid State Chem. 2007, 180, 1060-1067. (10)Chaudhary, S.; Srivastava, P.; Patnaik, S., Evidence of magnetodielectric effect in honeycomb oxide Na2Co2TeO6. AIP. Conf. Proc. 2018, 1942, 130045. (11)Bera, A. K.; Yusuf, S. M.; Kumar, A.; Ritter, C., Zigzag antiferromagnetic ground state with anisotropic correlation lengths in the quasi-two-dimensional honeycomb lattice compound Na2Co2TeO6. Phys. Rev. B 2017, 95,094424. (12)Lefrançois, E.; Songvilay, M.; Robert, J.; Nataf, G.; Jordan, E.; Chaix, L.; Colin, C. V.; Lejay, P.; Hadj-Azzem, A.; Ballou, R.; Simonet, V., Magnetic properties of the honeycomb oxide Na2Co2TeO6. Phys. Rev. B 2016, 94, 214416. (13)Berthelot, R.; Schmidt, W.; Sleight, A. W.; Subramanian, M. A., Studies on solid solutions based on layered honeycomb-ordered phases P2-Na2M2TeO6 (M=Co, Ni, Zn). J. Solid State Chem. 2012, 196, 225-231. 11



Page 12 of 17

For Table of Contents Use Only cg-2018-01770c.R1: “ Crystal

growth

and

the

magnetic

properties

of

Na2Co2TeO6

with

quasi-two-dimensional honeycomb lattice”, by Guiling Xiao, Zhengcai Xia, Wanwan Zhang, Xiaoyu Yue, Sha Huang, Xiaoxing Zhang, Feng Yang, Yujie Song, Meng Wei, Han Deng, Dequan Jiang.

The single crystal Na2Co2TeO6 has been successfully grown by self-flux method and its lattice structure and basic magnetic properties were characterized. Magnetic susceptibility measurements indicate that single crystal sample displays a distinct anisotropic behavior and the easy axis parallels to the honeycomb plane (ab-plane).

12


Page 13 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

Figure1 (a) crystal structure of Na2Co2TeO6, (b) view perpendicular to the honeycomb layers, in which the layers of honeycomb formed by CoO6 octahedral and the non-magnetic TeO6 octahedral.



Figure 2 (a) room temperature X-ray diffraction patterns and the refinement results of the polycrystalline sample (crushed single sample) with General Structure Analysis System. (b) X-ray diffraction pattern of the single crystal sample, inset is the morphology of the measured single crystal sample.


Page 14 of 17

Page 15 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3(a) Temperature dependence of magnetization measured at 0.01 T with temperature from 2 K to 300 K for polycrystalline and single crystal (magnetic field perpendicular to and parallel to ab-planes). (b), (c) and (d) show the zoom in of temperature range from 2 to 30 K, the AFM transition are marked with blue arrow. The curves of ZFC and FC are marked by solid symbols and open symbols respectively.



Figure 4 Temperature dependence of the susceptibility measured at 0.05 T and Curie-Weiss fitting (marked with solid lines), the temperature region of the fitting is the range from 100 K to 300 K.


Page 16 of 17

Page 17 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 5 Magnetic field dependence of magnetization at 4.2 K of Na2Co2TeO6 polycrystalline and single crystal sample with magnetic field parallel and perpendicular to ab-planes. The dotted arrows point to the magnetic field direction, the arrow point to critical field of magnetic phase transition. The inset is the temperature dependence of differential of magnetization over temperature.


Crystal Growth and the Magnetic Properties of Na2Co2TeO6 with

Recommend Documents