Papers by Author: Thomas C.K. Yang

Abstract: In this study, nanostructured Ce- and Sm-substituted Ca10(PO4)6(OH)2 samples have been synthesized using an aqueous sol-gel chemistry route. For the characterization of obtained specimens, the XRD, SEM, UV-visible reflection and IR spectroscopy and luminescence measurements were recorded. It was shown that phase purity of the end products highly depends on the amount of lanthanide element. The reflectance of lanthanide-substituted calcium hydroxyapatite samples is wavelength independent in the wavelength range of 450-800 nm and equal almost 100%. The cerium-substituted samples show a significant decrease of transmission at ~300 nm. The characteristic samarium absorption line (~430 nm) is evident in the UV-vis reflection spectra of samarium-substituted hydroxyapatites.

Abstract: In this study, the feasibility for use of multiphase BaTiO3 ceramics as microwave dielectric resonators was evaluated through the substitution of metal ions in B sites, such as ions of Mn, Co, Mg, In, Fe, Zn, and Ni. The effects of metal ions substitution and sintering conditions on the densification, microstructural evolution and microwave properties of the BaTiO3 ceramics containing cubic and hexagonal phase were examined.