fig4

Figure 4. (A) XANES spectra of the Ca K-edge in BC4T and BTC4 ceramics; (B) XPS spectra of Ca 2p in BC4T and BTC4 ceramics, which were obtained by subtracting the XPS intensity of BT from those of BC4T and BTC4, respectively; (C) Fourier transform (FT) of k-space EXAFS spectra for Ba in BT ceramic, and Ca in BC4T and BTC4 ceramics; FT of k-space EXAFS spectra for the Ba element in (D) BTC ceramics and (E) BCT ceramics. XANES: X-ray absorption near-edge structure; XPS: X-ray photoelectron spectroscopy; BT: BaTiO₃; EXAFS: extended X-ray absorption fine structure; BTC: BaTi_100-xCa_xO₃; BCT: Ba_100-xCa_xTiO₃.