Microstructure and Morphology Control of Potassium Magnesium Titanates and Sodium Iron Titanates by Molten Salt Synthesis

Abstract

Titanates materials have attracted considerable interest due to their unusual functional and structural properties for many applications such as high-performance composites, devices, etc. Thus, the development of a large-scale synthesis method for preparing high-quality titanates at a low cost is desired. In this study, a series of quaternary titanates including K0.8Mg0.4Ti1.6O4, Na0.9Mg0.45Ti1.55O4, Na0.75Fe0.75Ti0.25O2, NaFeTiO4, and K2.3Fe2.3Ti5.7O16 are synthesized by a simple molten salt method using inexpensive salts of KCl and NaCl. The starting materials, intermediate products, final products, and their transformations were studied by using TG-DSC, XRD, SEM, and EDS. The results show that the grain size, morphology, and chemical composition of the synthesized quaternary titanates can be controlled simply by varying the experimental conditions. The molar ratio of mixed molten salts is critical to the morphology of products. When KCl:NaCl = 3:1, the morphology of K0.8Mg0.4Ti1.6O4 changes from platelet to board and then bar-like by increasing the molar ratio of molten salt (KCl–NaCl) to raw materials from 0.7 to 2.5. NaFeTiO4 needles and Na0.75Fe0.75Ti0.25O2 platelets are obtained when the molar ratio of molten salt (NaCl) to raw materials is 4. Pure phase of Na0.9Mg0.45Ti1.55O4 and K2.3Fe2.3Ti5.7O16 are also observed. The formation and growth mechanisms of both potassium magnesium titanates and sodium iron titanates are discussed based on the characterization results.

Solar-driven CO2 reduction using modified earth-abundant ilmenite catalysts

“…A similar comportment was observed from 500 °C, related to the oxidation of iron oxide. However, the crystallization of the NaFeTiO 4 compound was observed around 850 °C, which is agreement with previous reports [ 29 , 30 ].

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Assessment of Titanate Nanolayers in Terms of Their Physicochemical and Biological Properties

“…The further heat treatment leads to dehydration and compaction of the hydrogel layer, which leads to the formation of the stable amorphous or crystalline titanate layer [ 28 , 29 , 30 ]. Various kinds of sodium titanates have been synthesized, which consist of negatively charged sheets made from TiO 6 8− octahedra, sharing corners and edges with each other [ 31 , 32 , 33 ]. Depending on the sodium ion content, the titanates form different structures (cage, tunnel, or layered), resulting in differences in their properties.…”

Influence of the Aspect Ratio of Sodium Iron Titanate Whiskers on the Mechanical and Tribological Performances of Fluorocarbon Composite Coatings

“…It is noteworthy that the (112) crystal face of the three samples is slightly different in peak intensity from that in the standard pattern, which can be attributed to the preferential growth of NFTO whiskers. In addition, the characteristic signals of unreacted reactants (Na 2 CO 3 ) or intermediate phase (Fe 2 O 3 ) have not appeared, indicating the complete conversion of raw materials [20].…”

“…The Whisker M (NFTO whiskers with a medium aspect ratio) was prepared with the same procedure, but the iron source was replaced by Fe 2 O 3 . To prepare the Whisker S (NFTO whiskers with a small aspect ratio), FeTiO 3 was still the iron source, but KCl-NaCl (1:1) was used, and the sintering temperature was increased to 1000 • C. Other preparation conditions, such as the molar ratio of raw materials and the sintering duration, were consistent with the preparation procedure of Whisker L and Whisker M. The standard X-ray diffraction (XRD) characteristic pattern of NFTO whiskers (NaFeTiO 4 ) is PDF#33-1255 [20].…”