Molten salt synthesis of complex perovskite-related dielectric oxides

Effects of molten salt content and reaction temperature on molten salt preparation of CaNaBi2Nb3O12 powder

“…When the temperature is higher than the molten temperature of the salt, the salt becomes liquid-phase. The fluid molten salt runs through and around the powder grains, preventing the conglutinations of grains, so the powder prepared by molten salt method cannot agglomerate or can agglomerate weakly [10][11][12][13]. In contrast, the grains of CNBNO powder prepared by molten salt method are flake-like, with almost no agglomeration.…”

Effects of molten salt synthesis (MSS) parameters on the morphology of Sr3Ti2O7 and SrTiO3 seed crystals

“…It is a well-established fact that the reaction rates and diffusion kinetics are sluggish in low-temperature processes because of limited thermal activation. A typical countermeasure to overcome such barriers is to increase the processing temperature so as to increase reaction and mass transport rates, thereby reducing the time scales involved in a given process [1]. A good example to such an approach is the so-called mixed oxide route-a process based on solidstate diffusion.…”

“…A good example to such an approach is the so-called mixed oxide route-a process based on solidstate diffusion. MSS, on the other hand, takes advantage of the much higher mass transport rates attainable in a melt, thereby enabling one to carry out the synthesis at modest temperatures at a reasonable rate [1]. The three main stages of MSS include: (i) mechanical mixing of the salt and oxides, (ii) melting of the salt and homogenization of the constituents in the melt, and (iii) heat treatment to effect the nucleation and growth of the desired phase [2].…”

“…The two fundamental requirements for MSS are: (i) the judicious choice of proper oxides that will ultimately form the desired solid solution in the end, and (ii) the use of suitable lower melting temperature fluxes, which will promote the reactions to occur at a low temperature. The choice of the fluxes is critical since the salts should not react with what is being synthesized (negligible solid solubility in the oxides), should be easy to remove after the process is completed, and should have low melting temperatures relative to the formation temperatures of the products [1]. Of utmost importance are MSS processing parameters such as the ratio of salt-to-oxide powder, the type of salt or salt mixture, the initial particle size of the starting materials, and the synthesis temperature and dwell time of the heat treatment as they dictate the final particle size, morphology and aspect ratio of the product(s) (hereafter seeds) [2].…”

Characterization of BaMg1/3(Ta1−xNbx)2/3O3 ceramics obtained by a modified Pechini method

“…Li [3] suggested that pure phase BaMg 1/3 Ta 2/3 O 3 ceramics can be synthesized in a two step process at a relatively lower temperature. Thirumal et al [4] reported that barium-based 1:2 ordered complex perovskite could be prepared at a sufficiently lower temperature using molten salts. However, despite the advantage of simplicity, the solid-state reaction method is less preferred for the synthesis of complex oxides because of their reported compromise in phase purity and high processing temperatures.…”