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Flash sintering is considered a promising energy-saving and efficient technology for preparing high-temperature ceramics. The effects of limited current on flash sintering parameters, microstructure, and electrical properties of (La1/2, Ta1/2)0.02Ti0.98O2 ceramic were investigated by the XRD, SEM, XPS, and precision impedance analyzer. With limiting current increase, the grain size of flash sintering sample increases gradually, and the relative density increases first and then decreases. The average grain size is about 1 μm, and the highest relative density is 96.9%. Joule heating runaway and oxygen vacancy defect lead to rapid densification of flash sintering La and Ta co-doped TiO2 ceramics. According to the EPDD model, doped La3+ and Ta5+ ions increase the concentration of oxygen vacancies and free electrons, lead to local polarization of carriers, and obtain a giant dielectric constant of ε' = 7.6 × 104 and low dielectric loss of tanδ = 0.11. At high temperature, electrons break free from the constraints of defect clusters and accumulate at the interface, leading to interface polarization due to the IBLC model. The giant dielectric properties originate from the combined effect of EPDD and IBLC model. [ABSTRACT FROM AUTHOR]

Soil productivity is a primary determinant of vegetation restoration and land resources utilization in debris flow deposits. However, little is known on the soil productivity change process of debris flow deposits behind check dams during rehabilitation. To investigate the change process of soil productivity at debris flow deposits behind check dams, soil physicochemical properties were measured in different time of rehabilitation (0, 2, 4, 5, 16, 23, 28, 33, 39, 45 years) in Hunshui gully (HSG). Modified Productivity Index (MPI) model was used to evaluate soil productivity. The results showed that soil organic matter (OM), total nitrogen, total phosphorus, available potassium and clay increased with rehabilitation time, while total potassium, pH and bulk density decreased. OM and MPI exponentially increased with the increase of rehabilitation time from 0.1% to 1.7% and 0.0006 to 0.1423, respectively. The rehabilitation time of 23 years was most likely a threshold time for the restoration of soil productivity at debris flow deposits. The trend of MPI indicated that soil productivity increased slowly in the early stage of ecosystem restoration, followed by a rapid with the increase of vegetation and OM. Our results can provide scientific bases for the effective utilization and restoration of debris flow deposits. [ABSTRACT FROM AUTHOR]