Mechanical strength and local structure of 'new' Hagi porcelain investigated by 57Fe-Mössbauer spectroscopy

A relationship between the local structure and mechanical strength of 'new' Hagi porcelain 'A' and 'B' prepared by sintering two types of iron containing aluminosilicate soils under oxidizing and reducing atmospheres were investigated by means of 57Fe-Mossbauer spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), as well as three point bending test. The largest mechanical strength (σ) value of 64.3±3.1 MPa was estimated from the three-point bending test of reductively sintered Hagi porcelain 'A'. The Mossbauer spectrum was composed of two paramagnetic doublets due to tetrahedral FeII FeIII with the isomer shift (δ) values of 1.13±0.02 and 0.31±0.01 mm s−1. On the other hand, a paramagnetic doublet and a magnetic sextet with the δ values of 0.30±0.01 and 0.35±0.02 mm s−1 were observed from the Mossbauer spectra of other samples. It can be concluded that the mechanically strengthened Hagi porcelain was successfully fabricated by choosing soil 'A' and by sintering under a reducing atmosphere.