Influence of solution composition on sprayed ZnO nanorods properties and formation process: Thermoanalytical study of the precursors. Issue 2 (1st February 2019)

• Record Type: Journal Article
• Authors: Dedova, Tatjana; Acik, Ilona Oja; Polivtseva, Svetlana; Krunks, Malle; Gromyko, Inga; Tõnsuaadu, Kaia; Mere, Arvo
• Is Part Of: Ceramics international. Volume 45:Issue 2(2019)Part B
• Page Start: 2887
• Page End: 2892
• Publication Date: 2019-02-01
• Subjects: A. Films -- B. X-ray methods -- D. ZnO -- Simultaneous thermogravimetry (TG) and differential thermal analysis (DTA); Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2018.07.274
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: ZnO is an important inorganic material for numerous applications. Different physical and chemical methods have been applied to deposit ZnO. Spray pyrolysis method being simple, rapid and low-cost is amongst the many options and has been chosen for this study. Fabrication of ZnO nanorods crystals by chemical spray pyrolysis was performed using an acidic solution of ZnCl2 1 or a basic ammonia-containing solution of ZnCl2 2 . All layers were studied using X-ray diffractometry and Scanning Electron Microscopy. The formation of ZnO nanorods from 2 appeared at 450 °C, whereas spraying acidic solution 1 yielded ZnO nanorods like morphology at 550 °C. Thermal decomposition of precursors for ZnO layers prepared by de-watering of acidic aqueous solution of ZnCl2 with pH = 3 (1 ) and basic solution of ZnCl2 and NH4 OH with pH = 10 (2 ) was monitored by simultaneous thermogravimetric and differential thermal analysis (TG/DTA) in air coupled online with evolved gas analyses by Fourier transformed infrared spectroscopy (FTIR). The precursor (1 ) is ZnCl2 *nH2 O; the precursor (2 ) is a mixture of (NH4 )3 (ZnCl4 )Cl, Zn(NH3 )2 Cl2, NH4 Cl(NH3 )3 and Zn(OH)2 phases. The thermal decomposition of (1 ) and (2 ) in the temperature range of 30–700 °C consists of two steps with total mass losses of 86.2% and 93.8%, respectively. The main evolved gases from (1 ) are H2 O and HCl, whereas the main evolved gases from (2 ) are H2 O, NOx and NH3 . Degradation of (1 ) and (2 ) is completed by 670 and 620 °C, respectively. The final decomposition product of (1 ) and (2 ) at 700 °C is ZnO. This study shows that the use of basic solutions enables to decrease the temperature of ZnO formation and the deposition temperature of ZnO nanorods layers.