Temperature-dependent Raman spectroscopic study of bismuth borate Bi2ZnOB2O6*
Zhang Jia), Zhang De-Mingb), Zhang Qing-Lib), Yin Shao-Tangb)
Anhui Xin Hua University, Hefei 230088, China
Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China

Corresponding author. E-mail: 18956063545@189.cn

Project supported by the National Natural Science Foundation of China (Grant Nos. 50932005 and 51102239).

Abstract

A temperature-dependent Raman spectroscopic study on Bi2ZnOB2O6 crystal was carried out to investigate the structure change of the crystal with the increase of temperature. Raman spectra of crystal Bi2ZnOB2O6 were recorded in the spectral range 10–1600 cm−1 at room temperature first. Compared with the vibrational spectra of the referred compounds, satisfactory assignment of most of the high-energy modes to vibrations of Bi–O, B–O, and Zn–O bonds was achieved. In particular, the Raman high-frequency peak located at 1344 cm–1 was attributed to the B–O vibration in the BO3 triangle. This temperature-dependent Raman spectroscopic study was carried out up to 600 °C. It was found that all the Raman lines exhibit decreases in frequency and the widths of the Raman peaks increase with increasing temperature. No phase transition was observed under 600 °C.

Keyword: 78.30.–j; 81.70.–q; 63.70.+h; Bi2ZnOB2O6crystal; high temperature Raman spectroscopy; vibrational mode
1. Introduction

The development of new crystals evokes a growing interest in synthesizing crystals with nonlinear optical (NLO) properties.[13] Binary bismuth borates, such as BiB3O6, [4, 5] have been of enhanced interest due to their promising nonlinear optical properties[69] and large nonlinear optical susceptibilities.[1015] A broad search for new NLO materials in the ternary ZnO– Bi2O3– B2O3 system leads to a new NLO crystal Bi2ZnOB2O6 (BZB). The bismuth borate Bi2ZnB2O7[16, 17] was synthesized first by Barbier et al. using the solid-state reaction method in the temperature range 650– 825 ° C at 1 atm. Its structure has been determined by powder x-ray diffraction (XRD) and refined by the Rietveld method using powder neutron diffraction data.[18, 19] In addition, a large single crystal of Bi2ZnOB2O6 has been grown by the top-seeded growth method.[20, 21] A high second harmonic generation (SHG) efficiency about 3– 4 times that of KH2PO4 (KDP) and a wide SHG phase matching range make the BZB crystal a promising NLO material. However, the structural stabilization at high temperature is important to the NLO crystal as an optical device. Temperature-dependent Raman scattering measurements are well suited to obtain the structural information of the sample at different temperatures because of the dependence of the phonon modes on the temperature.[22, 23]

Bi2ZnOB2O6 belongs to the space group with four formula units in the primitive cell. The zone-center optical phonons can be classified according to the following irreducible representations: Γ opt = 28A1 + 41A2 + 36B1 + 36B2. The A1, B1, B2 modes are both Raman and infrared active; and the A2 mode is Raman active only. Polarized Raman scattering of BZB has been measured by Zhang et al.[24] In this work, we present a study of the Raman spectra of BZB and their dependence on the temperature. The temperature dependence of the Raman bands is studied to investigate the structural change of the crystal at high temperature.

2. Experiment

The Bi2ZnOB2O6 polycrystalline powder was prepared by standard solid state reactions. ZnO, Bi2O3, and H3BO3 of analytic grade were mixed homogeneously with appropriate proportions in an agate mortar, and packed into a Pt crucible. The sample was heated slowly to 630 ° C and held at this temperature for 48 h with several intermediate grindings and mixings. The analysis of x-ray powder diffraction shows that the final product is Bi2ZnOB2O6.

The room- and high-temperature measurements were carried out using a home-made heating furnace. The temperature was monitored by a thermocouple attached to the metal sample holder and controlled by a temperature controller within 1 ° C. The Raman spectra were collected with Horiba Jobin Y’ von Raman spectrometer (LabRam800HR) with a backscattering configuration. The ultraviolet light pulse of 355 nm with a repetition frequency of 10 kHz from a Coherent Innova Ultra laser was focused onto the sample using a Raman microprobe with a 4× objective lens. An intensified charge coupled device (CCD) was used to collect the scattering light. The spectral acquisition, under the accumulated mode, was 10 s each for 10 times, the average power of the laser operation was fixed at 800 mW and the slit width was set at 300 nm for all the measurements under different temperatures.

3. Results and discussion

The structure of BZB is shown in Fig. 1. It has a three-dimensional network consisting of layers connected through O– Bi– O bands along the c axis. In this structure, through sharing the O atoms, two [BO3]3− triangles are condensed into a [B2O5]4− group and two [BO4]5− tetrahedra are condensed into a [B2O7]8− group. The [B2O5]4− and [B2O7]8− groups are bridged by tetrahedral Zn2+ centers through sharing three O vertices of each [ZnO4]6− tetrahedron to generate a 2D infinite [ZnB2O7]6+ layer parallel to the (001) plane. Figure 2 shows the crystal Raman spectra in the range from 100 cm− 1 to 1600 cm− 1 at room temperature.

Fig. 1. Structure of Bi2ZnOB2O6 viewed down the c axis.

Fig. 2. Raman spectrum of Bi2ZnOB2O6 crystal at room temperature.

In the structure of BZB, six-coordinated bismuth and the oxygens around form a distorted octahedron. Baia et al. assigned the Raman peaks located at 200– 550 cm− 1 and 880 cm− 1 in the Raman spectrum of B2O3– Bi2O3 glasses to the Bi– O vibration.[25] The Raman peak at 350 cm− 1 was observed in the Raman spectrum of B2O3– ZnO– Bi2O3 glasses due to the Bi– O– Bi vibration.[26] Therefore, the Raman peaks located at 350 cm− 1 and 873 cm− 1 are attributed to the Bi– O band of BiO6 octahedra.

A significant contribution to the Raman spectra of BZB comes from the vibration of the low-symmetric polyborate [B2O7] group with two BO4 tetrahedra and the [B2O5] group consisting of two BO3 triangles. A planar equilateral triangle molecule XY3 with symmetry D3h has four normal vibrational modes. For the [BO3] group with symmetry D3h, the ν s mode represents a non-degenerate symmetric B– O stretching vibration, the δ mode represents a non-degenerate out-of-plane B– O bending vibration, the ν as mode represents a doubly degenerate B– O stretching vibration, and the γ mode represents a doubly degenerate in-plane O– B– O bending vibration. It is known from the literature that the normal mode frequencies of the [BO3] group in the vibrational spectra of the bismuth borate crystals are typically situated as follows:[27, 28]ν s ∼ 950 cm− 1, δ ∼ 650– 800 cm− 1, ν as ∼ 1100– 1450 cm− 1, and γ ∼ 500– 650 cm− 1. In the Raman spectra of the BZB crystal, the peaks at 700 cm− 1 and 743 cm− 1 are assigned to the bending vibration of the B– O bands, while the peak at 1344 cm− 1 is assigned to the B– O stretching vibration. On the other hand, a tetrahedron molecule XY4 with symmetry Td has four normal vibrational modes: v1 (symmetric stretching mode), v2 (bending mode), v3 (asymmetric stretching mode), and v4 (bending mode). For the BO4 tetrahedron, v1 ∼ 800– 955 cm− 1, v2 ∼ 400– 600 cm− 1, v3 ∼ 1000 cm− 1, and v4 ∼ 600 cm− 1.[29, 30] Here the Raman peaks located at 637 cm− 1 and 968 cm− 1 are attributed to the B– O bond of the BO4 tetrahedron. The Zn atoms as a bridge connect the boron– oxygen groups with Zn– O bonds. The Raman peaks at 380 cm− 1 and 583 cm− 1 were observed in the Raman spectrum of the ZnO crystal.[31, 32] The Raman peaks at 328 cm− 1, 380 cm− 1, and 435 cm− 1 were present in the Raman spectra of the polycrystalline Zn1− xMgxO (x = 0– 0.15) powders, which were attributed to the Zn– O vibration.[33] Here, the Raman peaks located at 350 cm− 1, 391 cm− 1, and 582 cm− 1 are related to the Zn– O bond vibration in the BZB crystal.

The temperature dependent Raman spectra of a Bi2ZnOB2O6 crystal with the wavenumber range from 100 cm− 1 to 1600 cm− 1 were recorded with increasing temperature from room temperature to 600 ° C, as shown in Fig. 3. Nearly all the vibrational modes exhibit a decrease in wavenumber. Figures 4 and 5 illustrate the shifts of the Raman peaks with temperature. The Raman peaks located at 873 cm− 1 and 1344 cm− 1 have wavenumber shifts of 21 cm− 1 and 15 cm− 1, respectively. These phenomena also appear in the high-temperature Raman spectra of Bi12SiO20, KTa1− xNbxO3, Ba3 (PO4)2, and BiB3O6 crystals.[3437] With increasing temperature, all of the peaks decrease in frequency, which is ascribed to the increases in the inter-atomic distances in the BZB crystal when the crystal is heated.[38] In addition, the Raman peaks become wider during the heating process, the bending vibration of the B– O bands at 743 cm− 1 becomes a shoulder at 700 cm− 1 after the temperature increases to 400 ° C, as a consequence of larger distributions of the bonding angles and distances at higher temperature. Some of the adjacent peaks located below 300 cm− 1 become overlapped and merge together with increasing temperature. However, the spectra of the Bi2ZnOB2O6 crystal do not show any splitting or new bands, which indicates that no phase transition occurs in the present study.

Fig. 3. Temperature dependent Raman spectra of Bi2ZnOB2O6 crystal from room temperature to 600 ° C.

Fig. 4. The wavenumber shifts of Raman peaks at 1344 cm− 1, 873 cm− 1, 743 cm− 1, and 700 cm− 1 with increasing temperature.

Fig. 5. The wavenumber shifts of Raman peaks at 637 cm− 1, 582 cm− 1, 391 cm− 1, and 350 cm− 1 with increasing temperature.

4. Conclusion

A temperature-dependent Raman spectroscopic study on the Bi2ZnOB2O6 crystal was carried out up to 600 ° C. Raman spectra of single crystal Bi2ZnOB2O6 were recorded in the spectral range 10– 1600 cm− 1 at room temperature first. Compared with the vibrational spectra of the referred compounds, satisfactory assignment of most of the high-energy modes to vibrations of Bi– O, B– O, and Zn– O bonds was achieved. In particular, the Raman high-frequency peak located at 1344 cm− 1 was attributed to the B– O vibration in the [BO3] triangle. The changes of the Raman peaks and the crystal structure were investigated at high temperature. It was found that all the Raman peaks exhibit decreases in frequency and the widths of the Raman peaks increase with increasing temperature. No phase transition was observed under 600 ° C.

Acknowledgement

The authors thank the High Magnetic Field Laboratory of the Chinese Academy of Sciences for providing the Raman spectrometer.

Reference
1 Reshak A H, Chen X, Auluck S and Kityk I V 2008 J. Chem. Phys. 129 204111 DOI:10.1063/1.3021080 [Cited within:1] [JCR: 1.578]
2 Reshak A H and Auluck S 2007 Physica B 393 88 DOI:10.1016/j.physb.2006.12.065 [Cited within:1] [JCR: 1.327]
3 Reshak A H and Auluck S 2007 Physica B 388 34 DOI:10.1016/j.physb.2006.05.003 [Cited within:1] [JCR: 1.327]
4 Reshak A H, Kityk I V and Auluck S 2008 Appl. Phys. A 91 451 DOI:10.1007/s00339-008-4429-y [Cited within:1] [JCR: 1.545]
5 Reshak A H, Chen X and Auluck S 2009 Jpn. J. Appl. Phys. 48 011601 DOI:10.1143/JJAP.48.011601 [Cited within:1] [JCR: 1.067]
6 Becker P and Frohlich R Z 2004 Naturforsch B 59 256 [Cited within:1] [JCR: 0.899]
7 Filatov S, Shepelev Y, Bubnova R, Sennova N, Egorysheva A V and Kargin Y F 2004 J. Solid State Chem. 177 515 DOI:10.1016/j.jssc.2003.03.003 [Cited within:1] [JCR: 2.04]
8 Egorysheva A V, Kanishcheva A S, Kargin Y F, Gorbunova Y E and Mikhailov Y N 2002 Zh. Neorg. Khim. 47 1961 [Cited within:1]
9 Muehlberg M, Burianek M, Edongue H and Poetsch C 2002 J. Cryst. Growth 740 237 [Cited within:1] [JCR: 1.552]
10 Becker P, Liebertz J and Bohaty L 1999 J. Cryst. Growth 203 149 DOI:10.1016/S0022-0248(99)00078-0 [Cited within:1] [JCR: 1.552]
11 Kaminskii A, Becker P, Bohaty L, Ueda K, Takaichi K and Hanuza 2002 J. Opt. Commun. 206 179 DOI:10.1016/S0030-4018(02)01386-X [Cited within:1] [JCR: 1.433]
12 Hellwig H, Liebertz J and Bohaty L 1999 Solid State Commun. 109 249 [Cited within:1] [JCR: 1.534]
13 Lin Z, Wang Z, Chen C and Lee M H 2001 J. Appl. Phys. 90 5585 DOI:10.1063/1.1413711 [Cited within:1] [JCR: 0.71]
14 Teng B, Wang J, Wang Z, Hu X, Jiang H and Liu H 2001 J. Cryst. Growth 233 282 DOI:10.1016/S0022-0248(01)01526-3 [Cited within:1] [JCR: 1.552]
15 Teng B, Wang J, Wang Z, Jiang H and Hu X 2001 J. Cryst. Growth 224 280 DOI:10.1016/S0022-0248(01)00975-7 [Cited within:1] [JCR: 1.552]
16 Reshak A H, Chen X, Kityk I V and Auluck S 2007 Curr. Opin. Solid State Mater. Sci. 11 33 DOI:10.1016/j.cossms.2008.06.001 [Cited within:1]
17 Reshak A H, Chen X, Kityk I V, Auluck S, Iliopoulos K, Couris S and Khenata R 2009 Curr. Opin. Solid State Mater. Sci. 12 26 [Cited within:1]
18 Barbier J, Penin N and Cranswick L M 2005 Chem. Mater. 17 3130 DOI:10.1021/cm0503073 [Cited within:1] [JCR: 8.238]
19 Zhang Y, Wang W N and Wang G 2011 Chin. Phys. B 20 123301 DOI:10.1088/1674-1056/20/12/123301 [Cited within:1] [JCR: 1.148] [CJCR: 1.2429]
20 Li F, Pan S L, Hou X L and Yao 2009 J. Cryst. Growth 9 4091 DOI:10.1021/cg900336r [Cited within:1] [JCR: 1.552]
21 Li F, Hou X L, Pan S L and Wang X A 2009 Chem. Mater. 21 2846 DOI:10.1021/cm900560x [Cited within:1] [JCR: 8.238]
22 Pereira K, Silva D, Santos J, Maczka M, Paraguassu W, Freire P T, Mendes Filho J and Hanuza J 2013 J. Solid State Chem. 199 7 DOI:10.1016/j.jssc.2012.09.021 [Cited within:1] [JCR: 2.04]
23 Calizo I, Baland in A A, Bao W, Miao F and Lau C N 2007 Nano Lett. 7 2645 DOI:10.1021/nl071033g [Cited within:1] [JCR: 13.025]
24 Zhang J, Zhang D M, Wang D, Zhang Q L, Sun D L and Yin S T 2013 Acta Phys. Sin. 62 237802 DOI:10.7498/aps.62.237802(in Chinese) [Cited within:1] [JCR: 1.016] [CJCR: 1.691]
25 Baia L, Stefan R, Kiefer W and Simon S 2005 J. Raman Spectrosc. 36 262 DOI:10.1002/(ISSN)1097-4555 [Cited within:1] [JCR: 2.679]
26 Inoue T, Honmaa T, Dimitrov V and Komatsu T 2010 J. Solid State Chem. 183 3078 DOI:10.1016/j.jssc.2010.10.027 [Cited within:1] [JCR: 2.04]
27 Weir C E and Schroeder R A. 1964 J. Res. Sect. A 68 465 [Cited within:1]
28 Paul G L and Taylor W 1956 J. Phys. 25 1184 [Cited within:1] [JCR: 0.71]
29 Steele W C and Decius J C 1956 J. Chem. Phys. 25 1184 DOI:10.1063/1.1743175 [Cited within:1] [JCR: 1.578]
30 Zhang J, Wang D, Zhang D M, Zhang Q L, Wan S M, Sun D L and Yin S T 2013 Acta Phys. Sin. 62 037802 DOI:10.7498/aps.62.037802(in Chinese) [Cited within:1] [JCR: 1.016] [CJCR: 1.691]
31 Ma Y, Yang X H and Ye L J 2012 Acta Phys. Sin. 61 247701 DOI:10.7498/aps.61.247701(in Chinese) [Cited within:1] [JCR: 1.016] [CJCR: 1.691]
32 Xu J F, Cheng G X and Du Y W 1996 Chin. Phys. Lett. 13 765 [Cited within:1] [JCR: 0.811] [CJCR: 0.4541]
33 Young K, Katharine P, Andi M L, David R C and Ram S 2007 Phys. Rev. B 76 115204 DOI:10.1103/PhysRevB.76.115204 [Cited within:1]
34 Qiu H L, Wang A H, You J L, Liu X J, Chen H and Yin S T 2005 Spectroscopy and Spectral Analysis 25 222(in Chinese) [Cited within:1] [JCR: 0.293] [CJCR: 1.36]
35 Zhou W P, Wan S M, Yin S T Zhang Q L, You J L and Wang Y Y 2009 Acta Phys. Sin. 58 0570(in Chinese) [Cited within:1] [JCR: 1.016] [CJCR: 1.691]
36 Zhang J, Wang D, Zhang D M, Zhang Q L, Wan S M, Sun D L and Yin S T 2013 Acta Phys. Sin. 62 097802 DOI:10.7498/aps.62.097802(in Chinese) [Cited within:1] [JCR: 1.016] [CJCR: 1.691]
37 Wan S M, Teng B, Zhang X, You J L, Zhou W P, Zhang Q L and Yin S T 2010 CrystEngComm 12 211 DOI:10.1039/b913620g [Cited within:1] [JCR: 3.842]
38 Cerderira F, Melo F E A and Lemos V 1983 Phys. Rev. B 27 7716 DOI:10.1103/PhysRevB.27.7716 [Cited within:1]