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β-tricalcium phosphate is a promising bone graft substitute material with biocompatibility and high osteoinductivity. However, research on the ideal degradation and absorption for better clinical application remains a challenge. Now, we focus on modifying physicochemical properties and improving biological properties through essential ion co-substitution (Fe and Sr) in β-TCPs. Fe- and Sr-substituted and Fe/Sr co-substituted β-TCP were synthesized by aqueous co-precipitation with substitution levels ranging from 0.2 to 1.0 mol%. The β-TCP phase was detected by X-ray diffraction and Fourier transform infrared spectroscopy. Changes in Ca–O and P–O bond lengths of the co-substituted samples were observed through X-ray photoelectron spectroscopy. The results of VSM represent the M-H graph having a combination of diamagnetic and ferromagnetic properties. A TRIS–HCl solution immersion test showed that the degradation and resorption functions act synergistically on the surface of the co-substituted sample. Cell adhesion tests demonstrated that Fe enhances the initial adhesion and proliferation behavior of hDPSCs. The present work suggests that Fe and Sr co-substitution in β-TCP can be a candidate for promising bone graft materials in tissue engineering fields. In addition, the possibility of application of hyperthermia for cancer treatment can be expected.

Aluminum silicate powder was prepared using two different syntheses: (1) co-precipitation and (2) two-step sol-gel method. All synthesized powders were characterized by various techniques including XRD, FE-SEM, FT-IR, BET, porosimeter, and zetasizer. The particle morphology of the synthesized aluminum silicate powder was greatly different depending on the synthesis. The synthesized aluminum silicate powder by co-precipitation had a low specific surface area (158 m2/g) and the particle appeared to have a sharp edge, as though in a glassy state. On the other hand, synthesized aluminum silicate powder by the two-step sol-gel method had a mesoporous structure and a large specific surface area (430 m2/g). The aluminum silicate powders as adsorbents were characterized for their adsorption behavior towards Pb (II) ions and methylene blue in an aqueous solution performed in a batch adsorption experiment. The maximum adsorption capacities of Pb (II) ions and methylene blue onto the two-step sol-gel method powder were over four-times- and seven-times higher than that of the co-precipitation powder, respectively. These results show that the aluminum silicate powder synthesized with a two-step sol-gel method using ammonia can be a potential adsorbent for removing heavy metal ions and organic dyes from an aqueous solution.

Recently, a Li-ion solid electrolyte material LiTa 2 PO 8 (LTPO) which exhibits a high bulk ionic conductivity of 1.6 × 10 −3 S/cm and a total ionic conductivity of 2.5 × 10 −4 S/ cm was developed. In a previous study, we sintered the LTPO pellet, which has a high relative density of 82% and a total ionic conductivity of 1.05 × 10 −5 S/cm at room temperature via a cold sintering process (CSP). In this study, to achieve the ionic conductivity comparable to LTPO ceramic electrolytes obtained via high-temperature sintering, a Li 2 O−B 2 O 3 −Li 2 SO 4 amorphous layer was formed at the interface between LTPO particles via the CSP, and the microstructure and electrochemical properties of LTPO with the Li 2 O−B 2 O 3 −Li 2 SO 4 amorphous layer were investigated. Moreover, humidity acceleration tests were conducted to confirm the chemical stability of the pellet under ambient humidity conditions. It was found that pellets of LTPO prepared via the CSP exhibited a relative density of 85−87%, which is comparable to the density of high-temperature sintered pellets, and high adhesion between LTPO particles was observed due to the Li 2 O−B 2 O 3 −Li 2 SO 4 amorphous layer forming a particle interface. LTPO pellets with the Li 2 O−B 2 O 3 −Li 2 SO 4 amorphous boundary layer exhibited a high grain boundary ionic conductivity of 7.47 × 10 −5 S/cm, a total ionic conductivity of 1.07 × 10 −4 S/cm, and an extremely low activation energy of 0.215 eV. After humidity acceleration testing, the pellets showed good chemical stability against humidity, and the grain boundary and total ionic conductivities were increased by approximately 1.3 times to 9.21 × 10 −5 and 1.38 × 10 −4 S/cm, respectively. These results provide evidence that introducing an amorphous layer at the particle interface is a solution to the issues associated with low grain boundary ionic conductivity in ceramic-based solid electrolytes.