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In order to explore the difference of CMAS corrosion resistance in high temperature and rainwater environment of single-layer and double-layer thermal barrier coatings (TBCs), and further reveal the mechanism of CMAS corrosion resistance in above environment of double-layer TBCs modified by rare earth, two TBCs were prepared by air plasma spraying, whose ceramic coating were single-layer ZrO2–Y2O3 (YSZ) and double-layer La2Zr2O7(LZ)/YSZ, respectively. Subsequently, CMAS corrosion resistance tests at 1200 °C and rainwater environment of two TBCs were carried out. Results demonstrate that after high temperature CMAS corrosion for the same time, due to phase transformation, the volume of YSZ ceramic coating in single-layer TBCs shrank and surface cracks formed, which would lead to coating failure. When LZ ceramic coating of double-layer TBCs reacted with CMAS, compact apatite phases and fluorite phases formed, the penetration of CMAS into ceramic coating was inhibited effectively. Raman analysis and calculation results show that both of the surface residual stress of ceramic coating in two TBCs were compressive stress, and the residual stress of ceramic coating in double-layer TBCs were smaller than that of single-layer TBCs. Atomic force microscopy of TBCs after CMAS corrosion show that surface of double-layer TBCs was more uniform and compact than that of single-layer TBCs. The electrochemical properties in simulated rainwater of two TBCs after high temperature CMAS corrosion showed that double-layer TBCs possessed higher free corrosion potential, lower corrosion current and higher polarization resistance than those of single-layer TBCs. Consequently, the presence of LZ ceramic coating effectively improved CMAS corrosion resistance in high temperature and rainwater environment of double-layer TBCs.

In order to reveal the mechanism of high temperature oxidation resistance improvement of double-layer thermal barrier coatings (TBCs) by La, two kinds of TBCs were prepared by atmospheric plasma spraying, whose ceramic coating were single-layer ZrO2 Y2O3 (YSZ) and double-layer La2Zr2O7(LZ)/YSZ, respectively. Subsequently, the two TBCs were oxidized at 1100 °C. The experimental results show that the presence of LZ prevented the rapid oxidation of bonding coating and the rapid growth of thermal growth oxide (TGO), which led to the decrease in frequency of TGO bulges and the number of spinel oxides in TGO. La3+ can control the phase transformation of TGO, i.e. reduce the transition rate from metastable phase θ-Al2O3 to stable phase α-Al2O3, thereby reduce the residual stress. La3+ made the diffusion of cations in bonding coating to be obstructed, thus the formation of spinel phase was inhibited further, which was beneficial to the adhesion between TGO and coating. Therefore, double-layer LZ/YSZ TBCs exhibited superior high temperature oxidation resistance to single-layer YSZ due to the presence of LZ ceramic coating.

A series of Sr2+-doped Li3×La2/3-x□1/3–2×TiO3 (LLT), i.e., Li0.33SrxLa0.56–2/3×□0.11–1/3×TiO3 (LSLT, □ represents vacancy), materials were synthesized and investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurement methods. Sr2+-doped LLT materials exhibited an increase in electrical conductivity when the doping content was ca. 0.25 mol% in our investigation. It was found that the doped elements were uniformly distributed, and no impurity phase was detected in the bulk materials. In addition, the improved electrical conductivity was probably caused by the proper enlargement of the Li+ migration path when Sr2+ ions, with a larger ionic radius, replaced La3+ ions and changed the Li+-La3+ bond after doping. The solid-state ionic supercapacitor, using-doped LSLT as an electrolyte, showed a capacitance of 0.48 mF g−1 for a 0.25 mol% Sr2+-doped sample.

LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) cathode has been modified by incorporating ZrO 2 nanoparticles to improve its electrochemical performance. Compared to the pristine electrode, the cycling stability and rate capability of 0.5 wt% ZrO 2 modified-NCM622 have been improved significantly. The 0.5 wt% ZrO 2 modified-NCM622 cathode shows a capacity retention of 83.8% after 100 cycles at 0.1 C between 2.8 and 4.3 V, while that of the pristine NCM622 electrode is only 75.6%. When the current rate is set as 5C, the capacity retention of the 0.5 wt% ZrO 2 -modified NCM622 is 10% higher than that of the pristine NCM622. Also, the rate capability of 0.5 wt% ZrO 2 -modified NCM622 is better than that of the pristine NCM622 at various C-rates in a voltage range of 2.8–4.3 V. The enhanced electrochemical performances of the ZrO 2 -modified NCM622 cathodes can be attributed to their high Li-ion conductivity and structural stability.

Relaxor ferroelectrics demonstrate great potential in achieving large electrocaloric effect (ECE) which could be used as cooling devices in microelectronics industry as well as in daily life. The electrical field dependence of ECE, however, remains unclear, especially for relaxor ferroelectrics. The electrical field dependence of ECE can help to predict the ECE characteristics of cooling devices, and facilitate the design of highly efficient refrigerators. In this work, relaxor ferroelectric 0.71Pb(Mg 1/3 Nb 2/3 )O 3 –0.29PbTiO 3 (PMN–PT) (011) single crystals, (PbLa)(ZrTi)O 3 ceramic thin films, and poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF–TrFE–CFE))/poly(vinylidene fluoride–trifluoroethylene) (P(VDF–TrFE)) terpolymer/copolymer blends were used to investigate the electrical field dependence of ECE. Direct method was used to measure the ECE adiabatic temperature change as a function of electrical field. Results indicate that, the ECE temperature change tends to show quadratic relationship, i.e., Δ T – E 2 , at lower electrical fields. At higher fields, however, the temperature change has a tendency towards saturation in terms of the relationship, i.e., Δ T – E 2/3 . In the intermediate electrical fields, the temperature change shows a roughly linear relationship with electrical field. The above phenomena could be illustrated in the frame of approximately continuous phase transition derived Belov–Goryaga equation, which can be modified for ferroelectrics.