Back-scattered electron (BSE) image

Back-scattered electron (BSE) images of polished surfaces for cold-sintered CTO-xKMO are shown in Fig. 2(a–c). Microstructures appear dense in all studied ceramic composites (also observed in fracture surface of CTO-BMO, Fig. 2d), in agreement with data given in Table 1. Image contrast indicates that the microstructure is composed of two chemically discrete and distinct phases which are identified by EDS mapping (Fig. 2e-j) as KMO (light contrast) and CTO (dark contrast), respectively, consistent with XRD patterns and Raman spectra (Fig. 1). To check the compatibility of CTO-xKMO composite ceramics with Ag electrodes, Ag paste was introduced in the cold-sintered CTO-0.92KMO composite ceramics, with BSE images shown in Fig. 2(k,l). The bright regions correspond to Ag due to its greater weight averaged atomic number than CTO-0.92KMO with no evidence of reaction at the ceramic/electrode interface, indicating good compatibility.