Sodium Magnesium Fluoride Particles of Different Morphologies: Prepared by EDTA-assisted Hydrothermal Method

doi:10.15541/jim20180530

Abstract

Abstract:

Different morphologies of sodium magnesium fluoride particles were prepared by EDTA-assisted hydrothermal method using sodium fluoride, magnesium chloride hexahydrate as main materials and EDTA (ethylenediaminetetraacetic acid disodium salt) as auxiliary agent. Influence of solution pH, reaction temperature, time and complexing agent on the morphology and phase of the products was investigated, and the formation mechanism was discussed. Samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The results show that the EDTA not only provides sodium ions as raw material, but also forms complex with magnesium ions as a complexing agent in the reaction system. Reaction temperature, pH and complexing agent have great influences on the morphologies and phase of the products. The obtained products have microcube crystals with a smooth surface and micron-sized hollow spheres polymerized with nanoparticles. And the products have high crystallinity with crystal dimension ranging from 1 μm to 3 μm.

Key words: hydrothermal method, sodium magnesium fluoride, complexing agent, reaction mechanism

CLC Number:

O614

XU Yun-Qing,WANG Hai-Zeng. Sodium Magnesium Fluoride Particles of Different Morphologies: Prepared by EDTA-assisted Hydrothermal Method[J]. Journal of Inorganic Materials, 2019, 34(9): 933-937.

Figures/Tables 9

Fig. 1 XRD patterns of products prepared at different pH (120 ℃, 24 h)

Fig. 2 FT-IR spectra of products prepared at different pH (120 ℃, 24 h)

Fig. 3 SEM images of products prepared at different pH (120 ℃, 24 h) (a1, a2) pH=5; (b1, b2) pH=7; (c1, c2) pH=9

Table 1 lgKMgY, lgαY(H), lgK'MgY of Mg-EDTA complex at different pH

pH	lgK_MgY	lgα_Y(H)	lgK'_MgY
5		6.45	2.19
7	8.64	3.32	5.32
9		1.28	7.36

Fig. 4 SEM images of products prepared at different temperature (pH=9, 24 h) (a1, a2) 80 ℃; (b) 100 ℃; (c) 120 ℃; (d) 140 ℃; (e) 160 ℃

Fig. 5 SEM images of products prepared for different time (pH=9, 80 ℃) (a) 2 h; (b) 8 h; (c) 12 h; (d) 24 h

Fig. 6 (a) XRD patterns of samples prepared with or without EDTA (pH=9, 120 ℃, 24 h) (b) and SEM images without EDTA

Fig. 7 Schematic of EDTA and Mg2+ complexation structure

Fig. 8 Schematic diagram of the formation mechanism for hollow spherical sodium magnesium fluoride

References 16

[1]	何延青 . 钙钛矿KCaF₃, NaCaF₃及KMgF₃表面的第一性原理研究. 大连: 大连海事大学硕士学位论文, 2017.
[2]	TANG Q, SHEN J M, ZHOU W J ,et al. Fabrication, structure and magnetic properties of fluoroperovskite KMnF₃ nanostructures. Inorganic Chemistry Communications, 2004,2(7):283-285.
[3]	MEZIANI A, HECIRI D, BELKHIR H . Structural, electronic, elastic and optical properties of fluoro-perovskite KZnF₃. Physica B, 2011,406(19):3646-3653.
[4]	MARTIN C D, CRICHTON W A, LIU H Z , et al. Phase transitions and compressibility of NaMgF₃ (neighborite) in perovskite-and post-perovskite-related structures. Geophysical Research Letters, 2015,33(11):156-185.
[5]	LI Z L, AN X Y, CHEN X L ,et al. First-principles study of the electronic structure and optical properties of cubic perovskite NaMgF₃. Chinese Physics B, 2014,23(3):469-474.
[6]	LI Q Y, LI Z T, QI Y Y ,et al. Preparation and spectral properties of NaMgF₃: Ce³⁺ nanoparticles. Journal of Changchun University of Science and Technology (Natural Science Edition), 2008,31(2):69-71.
[7]	UMEMOTO K, WENTZCOVITCH R M, WEIDNER D J ,et al. NaMgF₃: a low-pressure analog of MgSiO₃. Geophysical Research Letters, 2006,33(15):483-507.
[8]	UMEMOTO K, WENTZCOVITCH R M . Two-stages dissociation of NaMgF₃ post-perovskite: a potential low-pressure analog of MgSiO₃ at multi-Mbar pressures. The Physical Society of Japan, 2015, 4: 011002-1-6.
[9]	KEVIN S , KNIGHT. A high-resolution powder neutron diffraction study of the crystal structure of neighborite (NaMgF₃) between 9 and 440 K. American Mineralogist, 2014,99(4):824-838.
[10]	李宁 . 钙钛矿型复合氟化物ABF₃的光催化活性研究. 天津: 天津大学硕士学位论文, 2008.
[11]	ZHAO Y S, WEIDNER D J, PARISE J B ,et al. Thermal expansion and structural distortion of perovskite-data for NaMgF₃ perovskite. Part I. Physics of the Earth and Planetary Interiors, 1993,76(1):1-16.
[12]	DING S, YANG X F, SONG E H ,et al. An efficient synthetic strategy for uniform perovskite core-shell nanocubes NaMgF₃: Mn ²⁺, Yb ³⁺@NaMgF₃: Yb ³⁺ with enhanced near infrared upconversion luminescence. Journal of Materials Chemistry C , 2018,6(9):2342-2350.
[13]	SEVONKAEV I, GOIA D V, MATIJEVIC E . Formation and structure of cubic particles of sodium magnesium fluoride (neigborite). Journal of Colloid and Interface Science, 2008,317(1):130-136.
[14]	沈海云 . 纳米钙钛矿型非氧化物的合成方法与机理研究. 天津: 天津大学硕士学位论文, 2008.
[15]	PENG Q, DONG Y J, LI Y D . ZnSe semicon ductor hollow spheres. Angew. Chem. Int. Ed., 2003,42(26):3027-3030.
[16]	WANG X, PENG Q, LI Y D . Interface-mediated growth of monodispersed nanostructures. Accounts of Chemical Research, 2007,40(8):635-643.