Electrochemical synthesis, characterization and thermal properties of niobium ethoxide

Abstract

Niobium(V) ethoxide (Nb(OEt)₅) was synthesized by electrochemical reaction of ethanol with niobium plate as the sacrificial anode, stainless steel as the cathode and tetraethylammonium chloride (TEAC) as the conductive additive. The condensates were isolated by vacuum distillation under 5 kPa. The product was characterized by Fourier transform infrared (FT-IR) spectra, Raman spectra and nuclear magnetic resonance (NMR) spectra. The results indicate that the product is niobium ethoxide. Thermal properties of niobium ethoxide were analysed by TG/DTG. Vapour pressure was calculated from the Langmuir equation and the enthalpy of vaporization was calculated from the vapour pressure-temperature data using the Clausius-Clapeyron equation. The concentrations of impurity metallic elements in the sample were detected by ICP-MS. It is shown that the purity can reach 99.997%. The volatility and purity of the niobium ethoxide ensure that it could be a good precursor for chemical vapor deposition and atomic layer deposition of niobium oxide layers.

Keywords

electrochemical synthesis / niobium ethoxide / characterization / thermal analysis

References

[1] MasseJ. P., SzymanowskiH., ZabeidaO., AmassianA., Klemberg-SapiehaJ. E., MartinuL.. Stability and effect of annealing on the optical properties of plasma-deposited Ta₂O₅ and Nb₂O₅ films [J]. Thin Solid Films, 2006, 515(4): 1674-1682

[2] TanakaA., MiyashitaK., TashiroT., KimuraM., SukegawaT.. Preparation of lithium niobate films by metalorganic chemical vapor deposition with a lithium alkoxide source [J]. Journal of Crystal Growth, 1995, 148(3): 324-326

[3] MaruyamaT., KanagawaT.. Electrochromic properties of niobium oxide thin films prepared by chemical vapor deposition [J]. Journal of the Electrochemical Society, 1994, 141(10): 2868-2871

[4] WERNBERG A A, GYSLING H J. Chemical vapor deposition of niobium and tantalum oxide films: US, 5271957 [P]. 1993-12-21.

[5] BradleyD. C.. Metal alkoxides as precursors for electronic and ceramic materials [J]. Chemical Reviews, 2002, 89(6): 1317-1322

[6] WoodB. D., MocanuV., GatesB. D.. Solution-phase synthesis of crystalline lithium niobate nanostructures [J]. Advanced Materials, 2008, 20(23): 4552-4556

[7] MacekM., OrelB.. Electrochromism of sol-gel derived niobium oxide films [J]. Solar Energy Materials and Solar Cells, 1998, 54(1): 121-130

[8] PignoletA., RaoG. M., KrupanidhiS. B.. Rapid thermal processed thin films of niobium pentoxide (Nb2O5) deposited by reactive magnetron sputtering [J]. Thin Solid Films, 1995, 261(1/2): 18-24

[9] AkiyamaY., ShitanakaK., MurakamiH., ShinY. S., YoshidaM., ImaishiN.. Epitaxial growth of lithium niobate film using metalorganic chemical vapor deposition [J]. Thin Solid Films, 2007, 515(12): 4975-4979

[10] TongH.-x., ChenQ.-y., HuH.-p., YinZ.-l., LiJ., ZhouJ.-liang.. Preparation, characterization and photocatalytic behavior of WO₃-TiO₂/Nb₂O₅ catalysts [J]. Journal of Central South University of Technology, 2007, 14(6): 788-792

[11] ZhangJ.-c., ZhouH.-l., ChenY.-l., ShenY., ZhangY.-hua.. Analysis of synthetical conditions, hydrolytic process and their characteristics for niobium alkoxides [J]. Journal of Shanghai University, 1998, 4(1): 38-44

[12] YangS.-h., ChenY.-m., YangH.-p., LiuY.-y., TangM.-t., QiuG.-zhou.. Preparation of high-purity tantalum ethoxide by vacuum distillation [J]. Transactions of Nonferrous Metals Society of China, 2008, 18(1): 196-201

[13] YangS.-h., CaiY.-n., YangH.-p., JinS.-ming.. Electrochemical synthesis and characterization of tantalum alkoxides [J]. Transactions of Nonferrous Metals Society of China, 2009, 19(6): 1504-1508

[14] ShreiderV. A., TurevskayaE. P., KoslovaN. I., TurovaN. Y.. Direct electrochemical synthesis of metal alkoxides [J]. Inorganica Chimica Acta, 1981, 53: L73-L76

[15] BerezkinM. Y., ChernykhI. N., PolyakovE. G., TomilovA. P.. Electrochemical synthesis of niobium(V) ethylate [J]. Applied Electrochemistry and Corrosion Protection of Metals, 2006, 79(5): 752-756

[16] SilversteinR. M., WebsterF. X., KiemleD.Spectrometric identification of organic compounds [M], 2005, New York, John Wiley & Sons: 82-101

[17] DollishF. R., FateleyW. G., BentleyF. F.Characteristic Raman frequencies of organic compounds [M], 1974, New York, Wiley: 218

[18] RushworthS., DaviesH., KingsleyA., LeeseT., OdedraR.. Volatility and vapourisation characterisation of new precursors [J]. Microelectronics Reliability, 2007, 47: 718-721

[19] LangmuirI.. The vapor pressure of metallic tungsten [J]. Physical Review, 1913, 2: 329-342

[20] KunteG. V., ShivashankarS. A., UmarjiA. M.. Thermogravimetric evaluation of the suitability of precursors for MOCVD [J]. Measurement Science and Technology, 2008, 19(2): 1-7

[21] WrightS. F., DollimorelD., DunnJ. G., AlexanderK.. Determination of the vapor pressure curves of adipic acid and triethanolamine using thermogravimetric analysis [J]. Thermochimica Acta, 2004, 421: 25-30

[22] HOCHIDO Y, KADOKURA H, TANABE S, KOBAYASHI R. Process for purifying niobium alkoxides and tantalum alkoxides: US, 5919963 [P]. 1999-07-06.