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The α-Ni(OH)2 coated with manganese (Mn) materials was synthesized by the chemical precipitation method, and the electrochemical properties were investigated. The results showed that the ingredient of the coating is a mixture of MnO2 and Mn2O3, and the coating can inhibit the intercalated anions escape and stabilize the α-Ni(OH)2 phase structure in KOH alkaline solution. The coated electrodes have higher discharge capacities and higher capacity retention rates than the uncoated α-Ni(OH)2 electrode, the discharge capacity of Mn-coated electrodes is over 350 mAh g−1, and the capacity retention rate exceeds 92%, separately. The reason may be that the Mn coatings can block or decelerate water molecule and the anion to escape from the interlayers, therefore prevent α phase structural collapse and maintain high discharge capacity during a long lifespan cycle. Therefore, the Mn coating α-Ni(OH)2 is a promising candidate for high-power Ni-MH batteries.

Effects of 0.5 wt% cerium (Ce) addition on microstructures and mechanical properties of a wrought Mg−8Gd−1.2Zn−0.5Zr alloy were thoroughly investigated in this work. The results indicate that 0.5 wt% Ce addition has slight refinement on the as-cast grains and results in a lattice expansion of the dominant intermetallic phase Mg3RE. After extrusion, 0.5 wt% Ce addition leads to higher level of recrystallization and finer dynamic recrystallization (DRX) grains and non-recrystallization stripes. In addition, there are much more dynamic precipitates on the DRX grain boundaries in the alloy with Ce addition, and the crystal structure (Mg12RE) is different from those (Mg5Gd) in the alloy with free Ce addition. Under peak-aging condition, 0.5 wt% Ce addition significantly changes the precipitates in the DRX grains from basal γ′ phase to prismatic β′ phase. As a result, the as-extruded Mg−8Gd−1.2Zn−0.5Zr alloy with 0.5 wt% Ce addition owns higher strength and more obvious precipitation hardening response than the alloy with free Ce addition.

Effects of samarium (Sm) addition on microstructures and tensile properties of Mg−6.0Zn−0.5Zr (ZK60) alloy under both as-cast and as-extruded states were thoroughly investigated. Similar to some other rare earth (RE) additions, the grains of the as-cast ZK60 alloy were refined and the dominant intermetallic phase was changed from MgZn 2 to Mg 3 Sm 2 Zn 3 (W) phase by Sm addition. After extrusion, the ZK60 sample with Sm addition owns much finer dynamic recrystallization (DRX) grains due to the widely spaced large particles and the fine particles on DRX grain boundaries. Furthermore, some other intermetallic phases were examined in the as-extruded samples such as Mg 4 Zn 7 and Mg 7 Zn 3 in ZK60 sample, Mg 22 Zn 64 Sm 14 (Z) and Mg 21 Zn 62 Sm 17 (W′) in ZK60+Sm sample. Thirdly, Sm addition results in much finer, much more and more stable spherical nano-scale precipitates in matrix. Finally, Sm addition further improves the strength of ZK60 alloy, with the dominant strengthening mechanisms being revealed as both fine grain strengthening and precipitation strengthening.

Microstructures and mechanical properties of a high-strength extruded Mg-3.5Sm-0.6Zn-0.5Zr alloy were thoroughly investigated. The results indicate that the dominant intermetallic phase in both as-cast and extruded samples is not the widely reported Mg 41 Sm 5 phase but Mg 3 Sm phase. After extrusion, the microstructures are composed of fine equiaxed dynamically recrystallized (DRXed) grains, coarse elongated unDRXed grains with ultrafine sub-grains, disintegrated intermetallic particles, and numerous small dynamically precipitated particles. Also, there are amounts of particularly dislocations in the Mg matrix after extrusion. Finally, numerous nano-scale plate β′ particles and lamellae β″ particles homogeneously precipitated in the matrix during artificial aging treatments. Therefore, the studied alloy exhibits very high ultimate tensile strength and yield strength, whose maximum values at room temperature are approximately 427 MPa and 416 MPa, respectively, much greater than most conventional Mg–RE based alloys with comparative or even much higher RE additions.

Microstructures and mechanical properties of a Mg−8Gd−3Yb−1.2Zn−0.5Zr (wt%) alloy have been investigated. The dominant intermetallic phases in the as-cast sample are Mg5RE (RE = Gd,Yb) phase, 14H-type long-period stacking ordered (LPSO) phase, and Mg2Zn2RE (W) phase and ordered Mg12RE phase. Furthermore, the ordered Mg12RE phase generally coexists with the W phase following an orientation relationship as [01¯1]w//[2¯30]Mg12RE, and (1¯11)w//(001)Mg12RE. After extrusion, the microstructure is consisted of un-recrystallized regions along with a small part of fine dynamically recrystallized (DRXed) regions. Simultaneously, the coarse Mg5RE, W and Mg12RE particles were disintegrated and mainly distribute at extrusion stringers while the fine LPSO plates mainly distribute in un-recrystallized regions. Moreover, amounts of nanoscale Mg5RE particles were dynamically precipitated in DXRed regions. Then, the as-extruded Mg−8Gd−3Yb−1.2Zn−0.5Zr alloy exhibits clearly higher strength than the classic rare-earth-containing magnesium alloys with comparative or even much higher rare earth content at both room temperature and high temperatures. The dominant strengthening mechanism was finally revealed as precipitation/dispersion strengthening.

In this work, granular Y 2 O 3 /Y 3 Al 5 O 12 (YAG) heterostructure thin films with 100–200 nm holes on surface were fabricated by depositing metal yttrium on c-plane sapphire and subsequent thermal anneal. Such Y 2 O 3 /YAG thin films are excellent matrix for luminescent materials based on rare earth. Based on this matrix, a Cr 3 + /(Pr 3 + /Yb 3 + ) broadband down-converter was fabricated for improving the photovoltaic conversion efficiency of crystalline silicon solar cell (c-Si SC). Cr 3 + was used to harvest the incident light and sensitize Pr 3 + /Yb 3 + quantum cutting (QC) couple. QC down-conversion to Yb 3 + infrared emission was realized in the region of 230 nm to 500 nm, which approaches the maximum bandwidth of QC down-conversion for c-Si SC.

A series of novel perovskites LaM0.25Mn0.75O3−δ (M = Fe, Co, Ni, Cu) are considered as promising cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Polycrystalline powders of LaM0.25Mn0.75O3−δ are synthesized by a modified Pechini method. Powder X-ray Rietveld refinements reveal that LaM0.25Mn0.75O3−δ series are in the orthorhombic perovskite structure within Pnma (no. 62) space group at room temperature. In situ high temperature X-ray diffractions indicate the existence of phase transformation from the orthorhombic Pnma phase to a higher symmetrical rhombohedral phase at elevated temperatures without any second phase formation for all these compounds. Multivalent states of M (Fe, Co, Ni and Cu) and Mn ions are testified by X-ray photoelectron spectroscopy measurement (XPS). The electrical conductivity are measured to be 39.6, 85.3 and 48.1, 99.4 S cm−1 for M = Fe, Co, Ni and Cu, respectively and the corresponding impedance are 0.131, 0.106, 0.107 and 0.0634 Ω cm2 at 850 °C. Among these compounds, LaCu0.25Mn0.75O3−δ exhibits the highest electrical conductivity and the lowest electrode polarization resistances, which is consistent with its calculated smallest band gap and lowest oxygen vacancy formation energy. Moreover, they all exhibit excellent chemical compatibility with prototypical electrolyte Ce0.8Sm0.2O2−δ (SDC). While the overall electrochemical properties of LaM0.25Mn0.75O3−δ (M = Fe, Co, Ni) are high enough to fulfill the practical applications. Thus, these LaM0.25Mn0.75O3−δ (M = Fe, Co, Ni, Cu) compounds are potential cathode materials for IT-SOFCs.

The microstructure and the mechanical properties of hot extruded Mg–Al–Zn alloy with the addition of Y and Gd were thoroughly investigated under two different conditions with and without aging treatments. The results showed that dynamic precipitation of Mg17Al12 phase occurred during hot deformation, and only Al2(Y,Gd) phase (no Al8Mn5 phase which was a common phase in Mg–Al–Zn alloy) was observed in the alloy. In addition, the basal texture intensity of Mg–Al–Zn alloy was weakened, which probably originates from both the promotion of nonbasal slip due to the addition of Y and Gd and the well-known particle-stimulated nucleation (PSN). Within the aged sample, there are less lamellar discontinuous precipitations (DPs), more globular DPs, and thinner continuous precipitation (CP) laths after Y and Gd addition. A new crystallographic orientation relationship (OR) between the β-Mg17Al12 precipitate and the α-Mg matrix was identified as (0001)m//(110)p and [01 1 ¯ 0]m//[ 1 ¯ 13]p. Finally, both tensile and compressive strengths are improved by the addition of Y and Gd, with the tension–compression yield asymmetry being reduced.

To date great efforts have been devoted to the development of solid oxide fuel cell (SOFC) devices that is able to run at intermediate temperature (IT) and to retain good electrochemical performance as in the high temperature regime. To this end, Tantalum (Ta) is doped into Sr 2 Fe 1.5 Mo 0.5− x Ta x O 6− δ (0.0 ≤ x ≤ 0.15) to further improve the electrochemical performance as the cathode materials for IT-SOFC. Pure orthorhombic Sr 2 Fe 1.5 Mo 0.5− x Ta x O 6− δ (0.0 ≤ x ≤ 0.15) samples, with space group Pnma (no. 62), are synthesized by a two-step method and identified via the powder X-ray Rietveld refinements. X-ray photoelectron spectroscopy and thermogravimetry results consistently show that the number of oxygen vacancy increases with the increasing of Ta content. The thermal expansion compatibility of the samples is found to match the electrolyte of La 0.9 Sr 0.4 Ga 0.1 Mg 0.2 O 3− δ (LSGM) better than that of cobalt-containing electrode compounds. Finally, the higher oxygen vacancy concentration leads to the enhanced ionic conductivity although electrical conductivity is slightly decreased due to the oxygen vacancy blocking. Therefore, Ta-doped Sr 2 Fe 1.5 Mo 0.5 O 6− δ is proved to be a promising candidate for future cathode materials of IT-SOFC.

Mg-1.5Y-1.2Zn-0.44Zr alloys were newly developed as degradable metallic biomaterials. A comprehensive investigation of the microstructure, mechanical properties, in vitro degradation assessments and in vitro cytotoxicity evaluations of the as-cast state, as-heat treated state and as-extruded state alloys was done. The microstructure observations show that the Mg-1.5Y-1.2Zn-0.44Zr alloys are mainly composed of the matrix α-Mg phases and the Mg12ZnY secondary phases (LPS structure). The hot extrusion method significantly refined the grains and eliminated the defects of both as-cast and heat treated alloys and thereby contributed to the better mechanical properties and biodegradation resistance. The values of tensile strength and tensile yield strength of the alloy in the as-extruded condition are about 236 and 178 MPa respectively, with an excellent elongation of 28%. Meanwhile, the value of compressive strength is about 471 MPa and the value of bending strength is about 501 MPa. The superior bending strength further demonstrates the excellent ductility of the hot extruded alloys. The results of immersion tests and electrochemical measurements in the SBF indicate that a protective film precipitated on the alloy's surface with the extension of degradation. The protective film contains Mg(OH)2 and hydroxyapatite (HA) which can reinforce osteoblast activity and promote good biocompatibility. No significant cytotoxicity towards L-929 cells was detected and the immersion extracts of alloy samples could enhance the cell proliferation with time in the cytotoxicity evaluations, implying that the Mg-1.5Y-1.2Zn-0.44Zr alloys have the potential to be used for biomedical applications.

In order to optimize the electrical properties of co-doped ceria electrolytes, Ce0.8Ca0.15Sm0.05O2-delta (CCS) sintered at different temperatures (1150 degrees C, 1200 degrees C, 1250 degrees C, 1300 degrees C and 1350 degrees C for 8 h) have been prepared and systematically investigated. It is found that among these samples sintered at different conditions, the electrical conductivity (sigma) measured at 800 degrees C can be ranked as: CCS1250 degrees C: sigma(800 degrees C)(CCS1250 degrees C) = 2.38 x 10(-2) S cm(-1) > CCS1200 degrees C: sigma(800 degrees C)(CCS1200 degrees C) = 1.81 x 10(-2) S cm(-1) > CCS1150 degrees C: sigma(800 degrees C)(CCS1150 degrees C) = 1.50 x 10(-2) S cm(-1) > CCS1300 degrees C: sigma(800 degrees C)(CCS1300 degrees C) = 1.26 x 10(-2) S cm(-1) > CCS1350 degrees C: sigma(800 degrees C)(CCS1350 degrees C) = 0.68 x 10(-2) S cm(-1). The electrical conductivity of CCS increases with the increase of sintering temperatures, and the 1250 degrees C-sintered sample presents the highest conductivity because of the best microstructures. However, the electrical conductivity of CCS decreases when the sintering temperatures goes beyond 1250 degrees C. We attribute this to the phase instability. It reveals that microstructures and the phase stability have important effects on the optimization of electrical properties for the co-doped ceria electrolytes. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Die cast AZ91– x Ymm ( x = 0–0.8 wt.%) magnesium alloys with excellent tensile properties and corrosion resistance behavior were successfully prepared by a simple addition of yttrium-rich misch metal (Ymm) to AZ91. Influences of Ymm on the microstructure, mechanical properties and corrosion behavior of AZ91 were investigated. The results showed that addition of Ymm to die cast AZ91 alloy could refine the microstructure including primary α-Mg and eutectic β-Mg 17 Al 12 . When the content of Ymm reached 0.8 wt.% a small quantity of Al 2 Y phase would form. The tensile properties were improved greatly with addition of Ymm to AZ91. The creep rate of the AZ91–Ymm alloys, tested at 150 °C/50 MPa, was one order of magnitude lower than that of AZ91. When addition of Ymm was more than 0.3 wt.%, the salt-spray corrosion resistance of AZ91–Ymm alloys could be 30–40 times of that of AZ91. The improvement of corrosion resistance with addition of Ymm was confirmed by the results of electrochemical polarization experiments. Mechanism of the improvement of mechanical properties and corrosion behavior caused by Ymm was also discussed.

Die-cast Mg–4Al–0.4Mn–xNd (x = 0, 1, 2, 4 and 6 wt.%) magnesium alloys were prepared successfully and influences of Nd on the microstructure, mechanical properties and corrosion behavior of the Mg–4Al–0.4Mn alloy have been investigated. The results showed that with the addition of Nd binary Al2Nd phase and Al11Nd3 phase, which mainly aggregated along the grain boundaries, were formed, and the relative ratio of above two phases was in correlation with the Nd content in the alloy. Meanwhile, the grain sizes were greatly reduced with the increasing Nd content. It was found that due to the addition of Nd both the tensile properties and corrosion resistance were improved substantially. The alloy E with 5.96 wt.% Nd content had the best tensile properties and corrosion resistance behavior in our research. While considering the cost of alloy, that with 1.13 wt.% Nd addition has already performed well enough for the improvement of properties. All the analyses demonstrated that the improvement of mechanical properties and corrosion resistance depended on the grain refinement, grain boundary strengthening as well as solid solution strengthening.

Single-component electrolyte-free fuel cells possess a similar function to the traditional fuel cells with a complex three-component structure. However, how to enhance their electrical properties for practical industrial applications remains a timely and important issue. Here, we report the manipulation of concentration ratios of ionic to electronic conductors in an electrolyte-free Ce0.8Sm0.2O2-δ–Li0.15Ni0.45Zn0.4 by adjusting the relative weight between its two inside compositions. Our systematic investigations reveal that the fuel cell with 30% in weight of Li0.15Ni0.45Zn0.4 exhibits an almost uniform distribution of the two compositions and has a total conductivity as high as 10 × 10−2 S cm−1 at 600 °C. Such an enhancement is found to be attributed to the established balance between the numbers of its inside ionic and electronic conductors. These findings are relevant for the technological improvement of this new species of electrolyte-free fuel cell and represent an important step toward commercialization of this single-component fuel cell.