The templated grain growth (TGG) method has gained significant attention for its ability to produce highly textured piezoelectric ceramics with significantly enhanced performance, making it a promising method for transducer and actuator applications. However, the texturing process using the TGG method requires the optimization of multiple steps, which can be challenging for beginners in this field. Therefore, in this tutorial, we provide an overview of the TGG method mainly based on our previous published works, including its various processing steps such as synthesizing anisotropic-shaped templates with size and size distribution control using the molten salt synthesis technique, tape casting, and identifying key factors for proper alignment of the templates in the target matrix system. Our goal is to provide a resource that can serve as a basic reference for researchers and engineers looking to improve their understanding and utilization of the TGG method for producing textured piezoelectric ceramics.
Thermal batteries are primary power sources for military applications requiring high reliability, robustness and long storage life. Conventional electrodes for thermal batteries are prepared by compacting powder mixtures into pellets. Separator is composed of halide mixture, such as LiCl-KC1 eutectic salt, blended with MgO to immobilize the molten salt. In order to increase the power density and energy density, the resistance of electrolyte should be reduced because the resistance of electrolyte is predominant in thermal batteries. In this study, wetting behaviors and impregnation weight of molten salts as well as the micro structures of ceramic felt were investigated to be applicable to thin electrolyte. Discharge performances of single cell with the ceramic separator impregnated by molten salt were evaluated also. Zirconia felt with high porosity and large pore outperformed alumina felt in wetting characteristics and molten salt impregnation as well as discharge performances. Based on the results of this study, ceramic felt separator impregnated with molten salt have revealed as an alternative of conventional thick MgO based separator with no conspicuous sign of thermal runaway by short circuit.
Thermal batteries are primary reserve batteries that use inorganic salt as electrolytes which areinactive at room temperature. The two principal heat sources that have been used in thermal batteries areheat paper and heat pellets. As soon as the heat paper, which is ignited by the initiator, in turn ignites theheat pellets, all the solid electrolytes are melted into excellent ionic conductors. However, the highcombustion temperature by heat papers in thermal batteries causes thermal decomposition at the cathode,eventually leading to a thermal runaway. In this paper, we have attempted to prepare Zr/BaCrO4 heatpapers coated with KCl molten salt. We have also investigated the effect of a molten salt coating on theheat papers through the thermal characteristics such as calorimetric value, combustion temperature andburning rate. The calorimetric value and combustion temperature of heat papers were reduced with anincrease in the molten salt coating. As a result, the molten salt coating on heat papers greatly reducedrisk of a thermal runaway and improved the stability of thermal batteries.
Nano-structured one-dimensional Na2Ti6O13 particles were synthesized by a molten salt process. Effects of processing parameters on the microstructure and band gap energy of the Na2Ti6O13 powder were studied in this paper. For the synthesis of the Na2Ti6O13 particles, two different raw materials of tubular shaped Na-titanate (Na-TiNT) and spherical shaped TiO2 were utilized. Synthesizing with the raw material of Na-TiNT, around 70nm thick 1D-Na2Ti6O13 with the bandgap energy of 3.5 eV was obtained at 810℃. Below 810℃ or without the presence of NaCl, 1D-Na2Ti6O13 was in a relatively short in length and agglomerated state. With the processing temperature increased, the thickness of the 1D-Na2Ti6O13 was also observed to be increased. On the other hand, when TiO2 was employed as a raw material, the mixed amount of Na2CO3 played an important role in transforming the morphology and phase of the raw material, affecting the bandgap energy of the synthesized product. Specific surface area of the synthesized 1D-Na2Ti6O13 was significantly affected by the raw and mixed materials as well as processing temperature. When Na-TiNT was processed at 810℃ with NaCl, the specific surface area of the 1D-Na2Ti6O13 showed the best value of 30.63 m2/g.