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Hydrothermal synthesis and crystal structure of a new lithium copper bismuth oxide, LiCuBiO4
Journal of Solid State Chemistry 245 (2017) 30–33
Contents lists available at ScienceDirect
Journal of Solid State Chemistry journal homepage: www.elsevier.com/locate/jssc
Hydrothermal synthesis and crystal structure of a new lithium copper bismuth oxide, LiCuBiO4
crossmark
⁎
Nobuhiro Kumadaa, , Ayumi Nakamuraa, Akira Miuraa,b, Takahiro Takeia, Masaki Azumac, Hajime Yamamotoc, Eisuke Magomed, Chikako Moriyoshid, Yoshihiro Kuroiwad a
Center for Crystal Science and Technology, University of Yamanashi, Miyamae-cho 7-32, Kofu 400-8511, Japan Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo 060-8628, Japan c Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku Yokohama, Kanagawa 226-8503, Japan d Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8526, Japan b
A R T I C L E I N F O
A BS T RAC T
Keywords: Bismuth oxide Hydrothermal reaction, Crystal structure, Magnetic property
A new lithium copper bismuth oxide, LiCuBiO4 was prepared by hydrothermal reaction using NaBiO3·1.4H2O. The crystal structural model of this compound was refined by using synchrotron X-ray powder diffraction data. This bismuthate has the LiCuSbO4 related structure with the orthorhombic cell (Space group: Pnma) of a=10.9096(9), b=5.8113(5) and c=5.0073(4) Å, and the final R-factors were Rwp=4.84 and Rp=3.58%. This compound is the first example of a lithium copper bismuthate containing Bi5+. An antiferromagnetic ordering of Cu2+ moment was observed at 6 K.
1. Introduction A variety of new bismuthates have been prepared by low temperature hydrothermal reactions using a hydrate of sodium bismuthate, NaBiO3·1.4H2O [1]. These hydrothermal reactions can yield bismuthates with Bi5+, which could not be synthesized by high temperature solid state reaction, for example, ABi5+2O6-type (A: Mg, Ca, Sr, Ba, Cd, Pb) compounds have been crystallized for the first time by this method [2–6]. Some of bismuthates with Bi5+ exhibited an interesting photocatalytic property under visible light irradiation [7–9]. Also there have been some publications on such hydrothermal reactions using a hydrate of sodium bismuthate, NaBiO3·1.4H2O [10–13]. Recently, we reported that this hydrothermal reaction could be produced new superconductive perovskite-type bismutahes [14–17]. In the course of pursuing a new bismuthate, a lithium copper bismuth oxide, LiCuBiO4 was found and its crystal structure refinement was successful by using synchrotron X-ray powder diffraction data. The crystal structure was related to that of LiCuSbO4 [18]. In this paper we will describe the preparation, crystal structure and magnetic property of a new compound, LiCuBiO4. 2. Experimental
0.2, 1.0 with molar ratio) and H2O (30 ml) were put into a Teflon-lined autoclave (70 ml), and stirred for 1 h. All starting reagents were served by Kanto Chemical Co., Ltd. The autoclave was heated at 180 °C for 7 d. The solid products were separated by filtration, washed with distilled water, and dried at 50 °C. The products were identified by X-ray powder diffraction using monochromated CuKα radiation. The thermal stability was investigated by TG-DTA with a heating rate of 10 °C/ min in a flow of air from room temperature to 650 °C and the gas evolution during the TG-DTA measurement in a flow of He gas was checked by mass spectroscopy. Synchrotron X-ray powder diffraction (PXRD) measurements were made using beamline BL02B2 at the SPring-8 facility. The data were collected with a constant wavelength (λ=0.413653(2) Å) at room temperature. EXPO-2004 [19] was used for crystal structure solution, and RIETAN-FP [20] was used for refinement of the structure. Crystal structure was drawn by a computer software VESTA [21]. The temperature dependence of the DC magnetic susceptibility was measured on cooling in a magnetic field of 1000 Oe from 300 to 2 K using a superconducting quantum interference device magnetometer, Quantum Design, MPMS-5S. The specific heat capacity of a pellet sample which was solidified at 6 GPa in a cubic-anvil-type high pressure apparatus, was measured in the temperature range from 2 to 100 K by a relaxation method with a Quantum Design, PPMS DYNACOOL.
The sample was prepared by hydrothermal reaction as follows; LiOH·H2O (5 g) NaBiO3·1.4H2O, CuO (Li: Bi: Cu=1: 0.1: 0, 0.04, 0.1,
⁎
Corresponding author. E-mail address: [email protected] (N. Kumada).
http://dx.doi.org/10.1016/j.jssc.2016.10.003 Received 4 August 2016; Received in revised form 28 September 2016; Accepted 3 October 2016 Available online 05 October 2016 0022-4596/ © 2016 Elsevier Inc. All rights reserved.
Journal of Solid State Chemistry 245 (2017) 30–33
N. Kumada et al. 111
Intensity (a.u.)
Table 1 Crystal data for LiCuBiO4. Chemical formula Crystal System Space group Lattice parameters (Å)
311
LiCuBiO4 Orthorhombic Pnma, No.62, Z=4 a=10.9096(9) b=5.8113(5) c=5.0073(5) 317.46(5) 343.46 7.19 4.84% 3.58% 5.40% 3.05% 1.61
220 400
200 011
211
101
301 020
002 121
210
10
20
321 221411212 501420
30 CuKα 2θ / degree
Volume (Å3) Formula weight (g/ mol) Calculated density (g/ cm3) RWP RP RB RF S
022 122 421
40
50
Fig. 1. X-ray powder diffraction pattern for LiCuBiO4. The definition of R factors is referred in the reference [23]. Table 2 Structural parameters for LiCuBiO4. Atom
Site
x
y
z
B (Å2)
BVS
Li Cu Bi O1 O2 O3
4b 4a 4c 4c 4c 8d
0 1/2 0.7663(1) 0.936(2) 0.588(2) 0.177(1)
1/2 0 1/4 1/4 1/4 0.489(3)
1/2 1/2 0.5569(3) 0.772(4) 0.359(4) 0.693(3)
1.0a 1.3(1) 0.50(5) 1.0a 1.0a 1.0a
0.78 2.28 5.28 2.04 2.01 2.27
a
1μm
denotes the fixed parameter.
Table 3 Selected interatomic distances (Å) for LiCuBiO4. Li
Fig. 2. SEM image of LiCuBiO4.
Exo.
mean Bi
Mass loss
Endo.
DTA mean
Intensity (a.u.)
4.21 mass%
m/z = 32 200
300
400
500
O1 O2 O3
– – – –
O1 O2 O3 O3
2.11(1)×2 2.50(2)×2 2.16(2)×2 2.26 2.14(2) 2.18(2) 2.06(2)×2 2.11(2)×2 2.11
Cu
mean
– – –
O1 O2 O3
1.98(1)×2 1.88(2)×2 2.47(2)×2 2.11
unreacted CuO coexisted with a new phase. The X-ray powder diffraction pattern of a new compound was indexed with orthorhombic cell of a=10.91, b=5.81 and c=5.01 Å (Fig. 1). The Li: Cu:Bi molar ratio in the new phase was 1:1:1 from ICP chemical analysis. The morphology of this compound is irregular shape with submicron size as shown in Fig. 2. Fig. 3 shows the TG-DTA curves and gas evolution during TGDTA measurement. Above 300 °C this compound decomposed, being accompanied by release of O2 gas suggesting the reduction of Bi5+ to Bi3+. The calculated value of the mass loss was 4.66% with assumption of complete reduction of Bi5+ to Bi3+, and this value agreed with the observed one (4.21%). The X-ray powder diffraction pattern of the product heated at 650 °C in air indicated the mixture of Bi2CuO4 [15], LiBiO2 [16] and a small amount of an unknown phase. The major phases of the decomposition product at high temperature have trivalent bismuth. These results suggests that the chemical composition of a new phase is LiCuBiO4.... The X-ray powder diffraction pattern of LiCuBiO4 could be indexed with the orthorhombic cell as mentioned above, and this indexing indicated size possible space groups; P212121, Pna21, Pnc2, Pncm, Pccn and Pnma. The crystal structure analysis was attempting using EXPO-2000 in assumption with the lattice parameters (a=10.91, b=5.81 and c=5.01 Å) and these space groups, and then reasonable atomic positions of copper and bismuth atoms were determined only in the case of the space group, Pnma. The crystal structure refinement using PXRD was carried out with this initial model and the reasonable
TG
100
– – –
600
Temperature / ºC Fig. 3. TG-DTA curves and gas evolution during TG-DTA measurement for LiCuBiO4.
3. Results and discussion The products synthesized by hydrothermal reaction using NaBiO3· 1.4H2O, CuO and LiOH·H2O depended on the molar ratio of the starting compounds at 180 °C. When the molar ratio of Li: Bi:Cu in the starting compound was 1:0.1:0.1, the title compound was obtained as an almost single phase and the color of the sample was dark brown. At lower CuO content Bi2CuO4 [22] appeared and at higher CuO content 31
Journal of Solid State Chemistry 245 (2017) 30–33
N. Kumada et al.
Fig. 4. The Rietveld refinement pattern of the synchrotron X-ray powder diffraction data for LiCuBiO4. In the upper portion observed and calculated intensities are drawn by dots and lines, respectively. In the middle portion the short vertical lines denotes the position of possible Bragg reflections. In the lower portion the difference between the observed and calculated intensities is shown.
LiO6 BiO6
CuO6 a
a
c
b Fig. 5. Crystal structure of LiCuBiO4. The solid lines represent the unit cell.
LiO6
LiO4
CuO6
CuO6 SbO6
BiO6 a
b
c
c
LiCuBiO4
LiCuSbO4
Fig. 6. Crystal structure comparison between LiCuBiO4 and LiCuSbO4. The solid lines represent the unit cell.
and the other Cu-O distances are 1.88 and 1.98 Å. This elongation of the CuO6 octahedron comes from a Jahn-Teller effect of d9 Cu2+ ions. The Bi-O distances in the BiO6 octahedron ranges from 2.06 to 2.18 Å and the mean value (2.11 Å) is in agreement with those in other pentavalent bismuthates; 2.101 Å in Bi2O4 [25], 2.11 Å in LiBiO3 [26] and 2.10 Å in MgBi2O6 [2] and 2.12 Å in AgBiO3 [27].. This crystal structure is related to that of LiCuSbO4, the crystal data of which are the space group (Cmc21 (#36)) and the lattice parameters (a=5.74260(4), b=10.86925(7), c=9.73048(6) Å) [18]. The relationship of the lattice parameters between LiCuBiO4 and LiCuSbO4 is observed as follows; aBi≈bSb, bBi≈aSb and cBi≈2×cSb as shown in Fig. 5. The common feature between two types of crystal structures is the one dimensional chain formed by edge-sharing elongated CuO6 octahedra and edge-sharing of CuO6 octahedra and BiO6 or SbO6 octahedra. The way of ordering of CuO6 and BiO6 octahedra in LiCuBiO4 is different from that of CuO6 and SbO6 octahedra in LiCuSbO4. In LiCuBiO4 CuO6
R-factors (Rwp=4.84 and Rp=3.58%) were obtained. The details of structure refinement and the structure parameters are summarized in Tables 1 and 2, respectively. The bond valence sum [24] was calculated and listed in Table 2 and the value for each atom was a reasonable value. Selected interatomic distances are listed in Table 3. The Rietveld refinement patterns of PXRD for LiCuBiO4 are shown in Fig. 3. Fig. 4 shows the crystal structure of LiCuBiO4. In this crystal structure all metal atoms are coordinated octahedrally by six O atoms and LiO6 and CuO6 octahedra form one-dimensional chains by edge-sharing along the b-axis. The LiO6 and CuO6 chains form the layer by face-sharing in the bc plane. The Bi atoms are placed in that interlayer and BiO6 octahedra are edge-sharing with LiO6 and CuO6 octahedra. Both of LiO6 and CuO6 octahedra are elongated to the direction of the apex of the octahedron; in the LiO6 octahedron the LiOapex distances are 2.50 Å and the other Li-O distances are 2.11 and 2.16 Å, and in the CuO6 octahedron the Cu-Oapex distances are 2.47 Å 32
Journal of Solid State Chemistry 245 (2017) 30–33
N. Kumada et al.
4. Conclusions A new lithium copper bismuth oxide, LiCuBiO4 was prepared by hydrothermal reaction and its crystal structure was refined by using synchrotron X-ray powder diffraction data. The crystal structure of LiCuBiO4 is closely related with that of LiCuSbO4. We are attempting to prepare the other bismuthates, LiM2+BiO4 (M2+; Co, Ni, Zn) by hydrothermal reaction. Acknowledgments This work was supported by JSPS KAKENHI Grant Number 26420678. The experiments at SPring-8 were performed with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2014B1003). References [1] N. Kumada, J. Ceram. Soc. Jpn. 106 (1993) 476–484. [2] N. Kumada, N. Kinomura, N. Takahashi, A.W. Sleight, Mater. Res. Bull. 32 (1997) 1003–1008. [3] N. Kumada, N. Kinomura, A.W. Sleight, Solid State Ion. 122 (1999) 183–189. [4] N. Kumada, A. Miura, T. Takei, M. Yashima, J. Asian Ceram. Soc. 2 (2014) 150–153. [5] N. Kumada, N. Xu, A. Miura, T. Takei, J. Ceram. Soc. Jpn. 122 (2014) 509–512. [6] N. Kumada, A. Miura, T. Takei, S. Nishimoto, Y. Kameshima, M. Michihiro, Y. Kuroiwa, C. Moriyoshi, J. Asian Ceram. Soc. 3 (2015) 251–254. [7] R. Ramachandran, Rajalakshmi, M. Sathiya, K. Ramesha, A.S. Prakash, G. Madras, A.K. Shukla, J. Chem. Sci. 123 (2011) 517–524. [8] T. Kako, Z. Zou, M. Katagiri, J. Ye, Chem. Mater. 19 (2007) 198–202. [9] T. Takei, R. Haramoto, Q. Dong, N. Kumada, Y. Yonesaki, N. Kinomura, J. Solid State Chem. 184 (2011) 2017–2022. [10] K. Sardar, R.I. Walton, J. Solid State Chem. 189 (2012) 32–37. [11] K. Sardar, S.C. Ball, J.D.B. Sharman, D. Thompsett, J.M. Fisher, R.A.P. Smith, P.K. Biswas, M.R. Less, R.J. Kashtiban, J. Sloan, R.I. Walton, Chem. Mater. 24 (2012) 4192–4200. [12] P. Kanhere, Y. Tang, J. Zheng, Z. Chen, J. Phys. Chem. Solids 74 (2013) 1708–1713. [13] M.H. Harunsani, D.I. Woddward, P.A. Thomas, R.I. Walton, Dalton Trans. 44 (2015) 10714–10720. [14] M.H.K. Rubel, A. Miura, T. Takei, N. Kumada, M. Mozahar Ali, M. Nagao, S. Watauchi, I. Tanaka, K. Oka, M. Azuma, E. Magone, C. Moriyoshi, Y. Kuroiwa, A.K.M. Azharul Islam, Angew. Chem. Int. Ed. 147 (2014) 3599–3603. [15] M.H.K. Rubel, A. Miura, T. Takei, N. Kumada, M.M. Ali, K. Oka, M. Azuma, E. Magome, C. Moriyoshi, Y. Kuroiwa, J. Alloy. Compd. 634 (2015) 208–214. [16] M.H.K. Rubel, T. Takei, N. Kumada, M.M. Ali, A. Miura, K. Tadanaga, K. Oka, M. Azuma, M. Yashima, K. Fujii, E. Magome, C. Moriyoshi, Y. Kuroiwa, J.R. Hester, M. Avdeev, Chem. Mater. 28 (2016) 459–465. [17] M.H.K.RubelT.TakeiN.KumadaM.M.AliA.MiuraK.TadanagaK.OkaM.AzumaE. MagomeC.MoriyoshiY.Kuroiwa, Inorg. Chem. in submission. [18] S.E. Dutton, M. Kumar, M. Mourigal, Z.G. Soos, J.-J. Wen, C.L. Broholm, N.H. Andersen, Q. Huang, M. Zbiri, R. Toft-Petersen, R.J. Cava, Phys. Rev. Lett. 108 (2012) (187206-1-187206-5). [19] A. Altomare, R. Caliandro, M. Camalli, C. Cuocci, C. Giacovazzo, A.G.G. Moliterni, R. Rizzi, J. Appl. Crystallogr. 37 (2004) 1025–1028. [20] F. Izumi, T. Ikeda, Solid State Phenom. 130 (2007) 15–20. [21] K. Momma, F. Izumi, J. Appl. Crystallogr. 41 (2008) 653–658. [22] K. Yamada, K.I. Takada, S. Hosoya, Y. Watanabe, Y. Endoh, N. Tomonaga, T. Suzuki, T. Ishigaki, T. Kamiyama, H. Asano, J. Phys. Soc. Jpn. 60 (1991) 2406–2414. [23] R.A. Young, R.A. Young (Ed.)The Rietveld Method, Chap. 1, Oxford University Press, 1995. [24] N.E. Brese, M. O’Keeffe, Acta Crystallogr. B47 (1991) 192–197. [25] N. Kumada, N. Kinomura, P.M. Woodward, A.W. Sleight, J. Solid State Chem. 116 (1995) 281–285. [26] N. Kumada, N. Kinomura, N. Takahashi, A.W. Sleight, J. Solid State Chem. 126 (1996) 121–126. [27] N. Kumada, N. Kinomura, A.W. Sleight, Mater. Res. Bull. 35 (2000) 2397–2402.
Fig. 7. Temperature dependence of the magnetic susceptibility and the inverse susceptibility of LiCuBiO4. Inset shows the low temperature region of the inverse susceptibility.
Fig. 8. Total specific heat divided by temperature of LiCuBiO4. Inset shows the low temperature region of the total specific heat divided by temperature.
and BiO6 octahedra are stacked alternatively along the a-axis, however, alternative stacking of CuO6 and SbO6 octahedra are not observed in LiCuSbO4. The coordination environment for Li atoms is different each other; Li atoms are placed at the octahedral site in LiCuBiO4 and Li atoms are disordered in the tetrahedral site in LiCuSbO4.. Fig. 6 shows the temperature dependence of the magnetic susceptibility for LiCuBiO4. The data above 200 K were fitted to the CurieWeiss law (χ=χ0+C/(T-θ) where χ0: temperature independent susceptibility, C: Curie constant and θ: Weiss temperature) with χ0=4.8255×10−7 emu mol−1, C=0.428 emu K−1 mol−1 and θ=−73.8 K. This Curie constant corresponds to S=1/2 with g=2.13, indicating that Cu2+ carries S=1/2 interacting antiferromagnetically. An inflection is observed at around 50 K. This should be attributed to the magnetic ordering of small amount of impurity, Bi2CuO4 [22], since a slight kink is observed in the specific heat divided by temperature shown in Fig. 7. The antiferromagnetic ordering of Cu2+ spin of LiCuBiO4 was observed at 6 K as a kink in the susceptibility data and also as a lambda-type anomaly in the specific heat data Fig. 8....
33
Contents lists available at ScienceDirect
Journal of Solid State Chemistry journal homepage: www.elsevier.com/locate/jssc
Hydrothermal synthesis and crystal structure of a new lithium copper bismuth oxide, LiCuBiO4
crossmark
⁎
Nobuhiro Kumadaa, , Ayumi Nakamuraa, Akira Miuraa,b, Takahiro Takeia, Masaki Azumac, Hajime Yamamotoc, Eisuke Magomed, Chikako Moriyoshid, Yoshihiro Kuroiwad a
Center for Crystal Science and Technology, University of Yamanashi, Miyamae-cho 7-32, Kofu 400-8511, Japan Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo 060-8628, Japan c Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku Yokohama, Kanagawa 226-8503, Japan d Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8526, Japan b
A R T I C L E I N F O
A BS T RAC T
Keywords: Bismuth oxide Hydrothermal reaction, Crystal structure, Magnetic property
A new lithium copper bismuth oxide, LiCuBiO4 was prepared by hydrothermal reaction using NaBiO3·1.4H2O. The crystal structural model of this compound was refined by using synchrotron X-ray powder diffraction data. This bismuthate has the LiCuSbO4 related structure with the orthorhombic cell (Space group: Pnma) of a=10.9096(9), b=5.8113(5) and c=5.0073(4) Å, and the final R-factors were Rwp=4.84 and Rp=3.58%. This compound is the first example of a lithium copper bismuthate containing Bi5+. An antiferromagnetic ordering of Cu2+ moment was observed at 6 K.
1. Introduction A variety of new bismuthates have been prepared by low temperature hydrothermal reactions using a hydrate of sodium bismuthate, NaBiO3·1.4H2O [1]. These hydrothermal reactions can yield bismuthates with Bi5+, which could not be synthesized by high temperature solid state reaction, for example, ABi5+2O6-type (A: Mg, Ca, Sr, Ba, Cd, Pb) compounds have been crystallized for the first time by this method [2–6]. Some of bismuthates with Bi5+ exhibited an interesting photocatalytic property under visible light irradiation [7–9]. Also there have been some publications on such hydrothermal reactions using a hydrate of sodium bismuthate, NaBiO3·1.4H2O [10–13]. Recently, we reported that this hydrothermal reaction could be produced new superconductive perovskite-type bismutahes [14–17]. In the course of pursuing a new bismuthate, a lithium copper bismuth oxide, LiCuBiO4 was found and its crystal structure refinement was successful by using synchrotron X-ray powder diffraction data. The crystal structure was related to that of LiCuSbO4 [18]. In this paper we will describe the preparation, crystal structure and magnetic property of a new compound, LiCuBiO4. 2. Experimental
0.2, 1.0 with molar ratio) and H2O (30 ml) were put into a Teflon-lined autoclave (70 ml), and stirred for 1 h. All starting reagents were served by Kanto Chemical Co., Ltd. The autoclave was heated at 180 °C for 7 d. The solid products were separated by filtration, washed with distilled water, and dried at 50 °C. The products were identified by X-ray powder diffraction using monochromated CuKα radiation. The thermal stability was investigated by TG-DTA with a heating rate of 10 °C/ min in a flow of air from room temperature to 650 °C and the gas evolution during the TG-DTA measurement in a flow of He gas was checked by mass spectroscopy. Synchrotron X-ray powder diffraction (PXRD) measurements were made using beamline BL02B2 at the SPring-8 facility. The data were collected with a constant wavelength (λ=0.413653(2) Å) at room temperature. EXPO-2004 [19] was used for crystal structure solution, and RIETAN-FP [20] was used for refinement of the structure. Crystal structure was drawn by a computer software VESTA [21]. The temperature dependence of the DC magnetic susceptibility was measured on cooling in a magnetic field of 1000 Oe from 300 to 2 K using a superconducting quantum interference device magnetometer, Quantum Design, MPMS-5S. The specific heat capacity of a pellet sample which was solidified at 6 GPa in a cubic-anvil-type high pressure apparatus, was measured in the temperature range from 2 to 100 K by a relaxation method with a Quantum Design, PPMS DYNACOOL.
The sample was prepared by hydrothermal reaction as follows; LiOH·H2O (5 g) NaBiO3·1.4H2O, CuO (Li: Bi: Cu=1: 0.1: 0, 0.04, 0.1,
⁎
Corresponding author. E-mail address: [email protected] (N. Kumada).
http://dx.doi.org/10.1016/j.jssc.2016.10.003 Received 4 August 2016; Received in revised form 28 September 2016; Accepted 3 October 2016 Available online 05 October 2016 0022-4596/ © 2016 Elsevier Inc. All rights reserved.
Journal of Solid State Chemistry 245 (2017) 30–33
N. Kumada et al. 111
Intensity (a.u.)
Table 1 Crystal data for LiCuBiO4. Chemical formula Crystal System Space group Lattice parameters (Å)
311
LiCuBiO4 Orthorhombic Pnma, No.62, Z=4 a=10.9096(9) b=5.8113(5) c=5.0073(5) 317.46(5) 343.46 7.19 4.84% 3.58% 5.40% 3.05% 1.61
220 400
200 011
211
101
301 020
002 121
210
10
20
321 221411212 501420
30 CuKα 2θ / degree
Volume (Å3) Formula weight (g/ mol) Calculated density (g/ cm3) RWP RP RB RF S
022 122 421
40
50
Fig. 1. X-ray powder diffraction pattern for LiCuBiO4. The definition of R factors is referred in the reference [23]. Table 2 Structural parameters for LiCuBiO4. Atom
Site
x
y
z
B (Å2)
BVS
Li Cu Bi O1 O2 O3
4b 4a 4c 4c 4c 8d
0 1/2 0.7663(1) 0.936(2) 0.588(2) 0.177(1)
1/2 0 1/4 1/4 1/4 0.489(3)
1/2 1/2 0.5569(3) 0.772(4) 0.359(4) 0.693(3)
1.0a 1.3(1) 0.50(5) 1.0a 1.0a 1.0a
0.78 2.28 5.28 2.04 2.01 2.27
a
1μm
denotes the fixed parameter.
Table 3 Selected interatomic distances (Å) for LiCuBiO4. Li
Fig. 2. SEM image of LiCuBiO4.
Exo.
mean Bi
Mass loss
Endo.
DTA mean
Intensity (a.u.)
4.21 mass%
m/z = 32 200
300
400
500
O1 O2 O3
– – – –
O1 O2 O3 O3
2.11(1)×2 2.50(2)×2 2.16(2)×2 2.26 2.14(2) 2.18(2) 2.06(2)×2 2.11(2)×2 2.11
Cu
mean
– – –
O1 O2 O3
1.98(1)×2 1.88(2)×2 2.47(2)×2 2.11
unreacted CuO coexisted with a new phase. The X-ray powder diffraction pattern of a new compound was indexed with orthorhombic cell of a=10.91, b=5.81 and c=5.01 Å (Fig. 1). The Li: Cu:Bi molar ratio in the new phase was 1:1:1 from ICP chemical analysis. The morphology of this compound is irregular shape with submicron size as shown in Fig. 2. Fig. 3 shows the TG-DTA curves and gas evolution during TGDTA measurement. Above 300 °C this compound decomposed, being accompanied by release of O2 gas suggesting the reduction of Bi5+ to Bi3+. The calculated value of the mass loss was 4.66% with assumption of complete reduction of Bi5+ to Bi3+, and this value agreed with the observed one (4.21%). The X-ray powder diffraction pattern of the product heated at 650 °C in air indicated the mixture of Bi2CuO4 [15], LiBiO2 [16] and a small amount of an unknown phase. The major phases of the decomposition product at high temperature have trivalent bismuth. These results suggests that the chemical composition of a new phase is LiCuBiO4.... The X-ray powder diffraction pattern of LiCuBiO4 could be indexed with the orthorhombic cell as mentioned above, and this indexing indicated size possible space groups; P212121, Pna21, Pnc2, Pncm, Pccn and Pnma. The crystal structure analysis was attempting using EXPO-2000 in assumption with the lattice parameters (a=10.91, b=5.81 and c=5.01 Å) and these space groups, and then reasonable atomic positions of copper and bismuth atoms were determined only in the case of the space group, Pnma. The crystal structure refinement using PXRD was carried out with this initial model and the reasonable
TG
100
– – –
600
Temperature / ºC Fig. 3. TG-DTA curves and gas evolution during TG-DTA measurement for LiCuBiO4.
3. Results and discussion The products synthesized by hydrothermal reaction using NaBiO3· 1.4H2O, CuO and LiOH·H2O depended on the molar ratio of the starting compounds at 180 °C. When the molar ratio of Li: Bi:Cu in the starting compound was 1:0.1:0.1, the title compound was obtained as an almost single phase and the color of the sample was dark brown. At lower CuO content Bi2CuO4 [22] appeared and at higher CuO content 31
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Fig. 4. The Rietveld refinement pattern of the synchrotron X-ray powder diffraction data for LiCuBiO4. In the upper portion observed and calculated intensities are drawn by dots and lines, respectively. In the middle portion the short vertical lines denotes the position of possible Bragg reflections. In the lower portion the difference between the observed and calculated intensities is shown.
LiO6 BiO6
CuO6 a
a
c
b Fig. 5. Crystal structure of LiCuBiO4. The solid lines represent the unit cell.
LiO6
LiO4
CuO6
CuO6 SbO6
BiO6 a
b
c
c
LiCuBiO4
LiCuSbO4
Fig. 6. Crystal structure comparison between LiCuBiO4 and LiCuSbO4. The solid lines represent the unit cell.
and the other Cu-O distances are 1.88 and 1.98 Å. This elongation of the CuO6 octahedron comes from a Jahn-Teller effect of d9 Cu2+ ions. The Bi-O distances in the BiO6 octahedron ranges from 2.06 to 2.18 Å and the mean value (2.11 Å) is in agreement with those in other pentavalent bismuthates; 2.101 Å in Bi2O4 [25], 2.11 Å in LiBiO3 [26] and 2.10 Å in MgBi2O6 [2] and 2.12 Å in AgBiO3 [27].. This crystal structure is related to that of LiCuSbO4, the crystal data of which are the space group (Cmc21 (#36)) and the lattice parameters (a=5.74260(4), b=10.86925(7), c=9.73048(6) Å) [18]. The relationship of the lattice parameters between LiCuBiO4 and LiCuSbO4 is observed as follows; aBi≈bSb, bBi≈aSb and cBi≈2×cSb as shown in Fig. 5. The common feature between two types of crystal structures is the one dimensional chain formed by edge-sharing elongated CuO6 octahedra and edge-sharing of CuO6 octahedra and BiO6 or SbO6 octahedra. The way of ordering of CuO6 and BiO6 octahedra in LiCuBiO4 is different from that of CuO6 and SbO6 octahedra in LiCuSbO4. In LiCuBiO4 CuO6
R-factors (Rwp=4.84 and Rp=3.58%) were obtained. The details of structure refinement and the structure parameters are summarized in Tables 1 and 2, respectively. The bond valence sum [24] was calculated and listed in Table 2 and the value for each atom was a reasonable value. Selected interatomic distances are listed in Table 3. The Rietveld refinement patterns of PXRD for LiCuBiO4 are shown in Fig. 3. Fig. 4 shows the crystal structure of LiCuBiO4. In this crystal structure all metal atoms are coordinated octahedrally by six O atoms and LiO6 and CuO6 octahedra form one-dimensional chains by edge-sharing along the b-axis. The LiO6 and CuO6 chains form the layer by face-sharing in the bc plane. The Bi atoms are placed in that interlayer and BiO6 octahedra are edge-sharing with LiO6 and CuO6 octahedra. Both of LiO6 and CuO6 octahedra are elongated to the direction of the apex of the octahedron; in the LiO6 octahedron the LiOapex distances are 2.50 Å and the other Li-O distances are 2.11 and 2.16 Å, and in the CuO6 octahedron the Cu-Oapex distances are 2.47 Å 32
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4. Conclusions A new lithium copper bismuth oxide, LiCuBiO4 was prepared by hydrothermal reaction and its crystal structure was refined by using synchrotron X-ray powder diffraction data. The crystal structure of LiCuBiO4 is closely related with that of LiCuSbO4. We are attempting to prepare the other bismuthates, LiM2+BiO4 (M2+; Co, Ni, Zn) by hydrothermal reaction. Acknowledgments This work was supported by JSPS KAKENHI Grant Number 26420678. The experiments at SPring-8 were performed with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2014B1003). References [1] N. Kumada, J. Ceram. Soc. Jpn. 106 (1993) 476–484. [2] N. Kumada, N. Kinomura, N. Takahashi, A.W. Sleight, Mater. Res. Bull. 32 (1997) 1003–1008. [3] N. Kumada, N. Kinomura, A.W. Sleight, Solid State Ion. 122 (1999) 183–189. [4] N. Kumada, A. Miura, T. Takei, M. Yashima, J. Asian Ceram. Soc. 2 (2014) 150–153. [5] N. Kumada, N. Xu, A. Miura, T. Takei, J. Ceram. Soc. Jpn. 122 (2014) 509–512. [6] N. Kumada, A. Miura, T. Takei, S. Nishimoto, Y. Kameshima, M. Michihiro, Y. Kuroiwa, C. Moriyoshi, J. Asian Ceram. Soc. 3 (2015) 251–254. [7] R. Ramachandran, Rajalakshmi, M. Sathiya, K. Ramesha, A.S. Prakash, G. Madras, A.K. Shukla, J. Chem. Sci. 123 (2011) 517–524. [8] T. Kako, Z. Zou, M. Katagiri, J. Ye, Chem. Mater. 19 (2007) 198–202. [9] T. Takei, R. Haramoto, Q. Dong, N. Kumada, Y. Yonesaki, N. Kinomura, J. Solid State Chem. 184 (2011) 2017–2022. [10] K. Sardar, R.I. Walton, J. Solid State Chem. 189 (2012) 32–37. [11] K. Sardar, S.C. Ball, J.D.B. Sharman, D. Thompsett, J.M. Fisher, R.A.P. Smith, P.K. Biswas, M.R. Less, R.J. Kashtiban, J. Sloan, R.I. Walton, Chem. Mater. 24 (2012) 4192–4200. [12] P. Kanhere, Y. Tang, J. Zheng, Z. Chen, J. Phys. Chem. Solids 74 (2013) 1708–1713. [13] M.H. Harunsani, D.I. Woddward, P.A. Thomas, R.I. Walton, Dalton Trans. 44 (2015) 10714–10720. [14] M.H.K. Rubel, A. Miura, T. Takei, N. Kumada, M. Mozahar Ali, M. Nagao, S. Watauchi, I. Tanaka, K. Oka, M. Azuma, E. Magone, C. Moriyoshi, Y. Kuroiwa, A.K.M. Azharul Islam, Angew. Chem. Int. Ed. 147 (2014) 3599–3603. [15] M.H.K. Rubel, A. Miura, T. Takei, N. Kumada, M.M. Ali, K. Oka, M. Azuma, E. Magome, C. Moriyoshi, Y. Kuroiwa, J. Alloy. Compd. 634 (2015) 208–214. [16] M.H.K. Rubel, T. Takei, N. Kumada, M.M. Ali, A. Miura, K. Tadanaga, K. Oka, M. Azuma, M. Yashima, K. Fujii, E. Magome, C. Moriyoshi, Y. Kuroiwa, J.R. Hester, M. Avdeev, Chem. Mater. 28 (2016) 459–465. [17] M.H.K.RubelT.TakeiN.KumadaM.M.AliA.MiuraK.TadanagaK.OkaM.AzumaE. MagomeC.MoriyoshiY.Kuroiwa, Inorg. Chem. in submission. [18] S.E. Dutton, M. Kumar, M. Mourigal, Z.G. Soos, J.-J. Wen, C.L. Broholm, N.H. Andersen, Q. Huang, M. Zbiri, R. Toft-Petersen, R.J. Cava, Phys. Rev. Lett. 108 (2012) (187206-1-187206-5). [19] A. Altomare, R. Caliandro, M. Camalli, C. Cuocci, C. Giacovazzo, A.G.G. Moliterni, R. Rizzi, J. Appl. Crystallogr. 37 (2004) 1025–1028. [20] F. Izumi, T. Ikeda, Solid State Phenom. 130 (2007) 15–20. [21] K. Momma, F. Izumi, J. Appl. Crystallogr. 41 (2008) 653–658. [22] K. Yamada, K.I. Takada, S. Hosoya, Y. Watanabe, Y. Endoh, N. Tomonaga, T. Suzuki, T. Ishigaki, T. Kamiyama, H. Asano, J. Phys. Soc. Jpn. 60 (1991) 2406–2414. [23] R.A. Young, R.A. Young (Ed.)The Rietveld Method, Chap. 1, Oxford University Press, 1995. [24] N.E. Brese, M. O’Keeffe, Acta Crystallogr. B47 (1991) 192–197. [25] N. Kumada, N. Kinomura, P.M. Woodward, A.W. Sleight, J. Solid State Chem. 116 (1995) 281–285. [26] N. Kumada, N. Kinomura, N. Takahashi, A.W. Sleight, J. Solid State Chem. 126 (1996) 121–126. [27] N. Kumada, N. Kinomura, A.W. Sleight, Mater. Res. Bull. 35 (2000) 2397–2402.
Fig. 7. Temperature dependence of the magnetic susceptibility and the inverse susceptibility of LiCuBiO4. Inset shows the low temperature region of the inverse susceptibility.
Fig. 8. Total specific heat divided by temperature of LiCuBiO4. Inset shows the low temperature region of the total specific heat divided by temperature.
and BiO6 octahedra are stacked alternatively along the a-axis, however, alternative stacking of CuO6 and SbO6 octahedra are not observed in LiCuSbO4. The coordination environment for Li atoms is different each other; Li atoms are placed at the octahedral site in LiCuBiO4 and Li atoms are disordered in the tetrahedral site in LiCuSbO4.. Fig. 6 shows the temperature dependence of the magnetic susceptibility for LiCuBiO4. The data above 200 K were fitted to the CurieWeiss law (χ=χ0+C/(T-θ) where χ0: temperature independent susceptibility, C: Curie constant and θ: Weiss temperature) with χ0=4.8255×10−7 emu mol−1, C=0.428 emu K−1 mol−1 and θ=−73.8 K. This Curie constant corresponds to S=1/2 with g=2.13, indicating that Cu2+ carries S=1/2 interacting antiferromagnetically. An inflection is observed at around 50 K. This should be attributed to the magnetic ordering of small amount of impurity, Bi2CuO4 [22], since a slight kink is observed in the specific heat divided by temperature shown in Fig. 7. The antiferromagnetic ordering of Cu2+ spin of LiCuBiO4 was observed at 6 K as a kink in the susceptibility data and also as a lambda-type anomaly in the specific heat data Fig. 8....
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