Nanoscale materials are of great interest due to their unique optical, electrical, and magnetic properties compared with bulk materials [1–6]. These properties are strongly dependent on the size and the shape of the particle, and therefore it is very important to be able to finely control the morphology of the nanomaterials. In recent years, the synthesis of one-dimensional nanomaterials such as nanowires, nanorods, or nanofibers has became the focus of research work because the morphological anisotropy results in many very complex physical properties and selfassembly behaviors compared with those of spherical nanoparticles [7–9]. Lanthanum hydroxide (La(OH)3) has been used in many fields, such as ceramic, superconductive materials, hydrogen storage materials, electrode materials, etc., especially catalyst and sorbent materials [10, 11]. For all these applications, the particle size, the agglomerated state, the porosity, and the specific surface area are of major importance. Generally, these features are strongly dependent on the preparation process and the used thermal treatment method. The study of one-dimensional La(OH)3 has also been of growing interest owing to the promising application in nanoscale optoelectronic devices. Ma et al. [12] synthesized poly-crystalline La(OH)3 nanorods via a hydrothermal method and Deng et al. [13] also obtained La(OH)3 nanorods under the similar conditions. Herein, we report a simple solvothermal route to the synthesis of La(OH)3 nanorods, whose crystal growth habit is different from that via the hydrothermal method reported by Ma et al. [12]. From this synthesis method, the single crystalline La(OH)3 nanorods can be synthesized with longer length and larger diameter. In a typical synthesis, 2 g of lanthanum nitrate (La(NO3)3) was dissolved into 40 ml of distilled water to form a clear solution. Then 20 ml of absolute ethanol and 20 ml of ethylene glycol monomethyl ether (HO (CH2)OCH3) were added into the solution. After that, 5 g of NaOH was added into the above-mentioned solution to form white slurry. At last, the white slurry was stirred for 10 min and transferred into a 100 ml Teflon-lined autoclave for a solvotherml process at 240 C for 24 h. After the solvotherml process, the gained white precipitation was filtrated, washed with distilled water, and then dried in oven at 110 C for 12 h. The as-obtained product was denominated as A. In addition, one sample prepared with 1 g of (La(NO3)3) in initial reactant was denominated as B and another sample prepared using pure water without ethylene glycol monomethyl ether and absolute ethanol as solvent with 1 g of (La(NO3)3) in initial reactant was denominated as C (Table 1). The phase purity of the as-prepared products was evidenced using D/max2500 X-ray diffractometer (XRD) with monochromatized CuKa radiation (k = 1.5406 A). The diffraction peaks of the samples in Fig. 1 can be indexed to the hexagonal La(OH)3, whose calculated cell constants were numerically close to the reported values of the bulk materials in the standard card (a = 6.529 A and c = 3.859 A, JCPDS File No. 36-1481). No other phase was detected in the final products. From the XRD patterns, it is observed that the peaks of the sample C were consistent with that in the standard card; the strongest peak is B. Hou (&) AE Y. Xu AE D. Wu AE Y. Sun State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P.R. China e-mail: sxtyhoubo@yahoo.com.cn
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Jul 14, 2023
Jingwei Zhao + 3
Open Access