scholarly journals Solid gas and electrochemical hydrogenation properties of the R1-xR’xMgNi4-yCoy (R, R’ = Y, La, Ce) alloys

2020 ◽  
Vol 21 (3) ◽  
pp. 503-509
Author(s):  
Yu. V. Verbovytskyy ◽  
I. Yu. Zavaliy ◽  
V. V. Berezovets ◽  
P. Ya. Lyutyy
Keyword(s):  
Room Temperature ◽  
Electrode Materials ◽  
High Rate ◽  
X Ray Diffraction ◽  
Hydrogen Storage Properties ◽  
X Ray ◽  
Powder Sintering ◽  
Related Compounds ◽  
Sintering Method ◽  
Storage Properties

New R1-xR’xMgNi4-yCoy (R, R’ = Y, La, Ce; x = 0.5; y = 0, 1, 2) alloys have been synthesized by powder sintering method, and their crystal structure and hydrogen storage properties have been studied. X-ray diffraction analysis showed that R1-xR’xMgNi4-yCo alloys belong to the MgCu4Sn-type structure. The synthesized alloys absorb hydrogen at room temperature and hydrogen pressure 0.1-10 bar. For some of the studied compounds, the formation of hydrides with cubic and orthorhombic structures was found. Highest hydrogen content is found for the Co-rich compounds: La0.5Y0.5MgNi2Co2H5.18 and La0.5Ce0.5MgNi2Co2H6.48. Electrochemical studies showed that Y-based electrode materials exhibit better electrochemical performance comparing with Ce-doped ones. Highest discharge capacity of 292 mА∙h/g was observed for La0.5Y0.5MgNi3Co, but the best cyclic stability after 50th cycle of 92% was seen for La0.5Y0.5MgNi2Co2. Additionally, obtained results of the electrochemical properties were compared with related compounds. High rate dischargeability of Co-free alloys at I = 1 A/g were twice higher than ones containing cobalt.

PHASE STRUCTURE, PIEZOELECTRIC AND MULTIFERRIOC BEHAVIOR OF (K0.48Na0.52)NbO3-Co2O3 PIEZOELECTRIC CERAMICS

2011 ◽  
Vol 04 (03) ◽  
pp. 225-229 ◽  
Author(s):  
WENJUAN WU ◽  
DINGQUAN XIAO ◽  
JIAGANG WU ◽  
JING LI ◽  
JIANGUO ZHU
Keyword(s):  
Room Temperature ◽  
Sintering Temperature ◽  
Magnetic Behavior ◽  
Orthorhombic Phase ◽  
Piezoelectric Ceramics ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Solid State Sintering ◽  
Sintering Method

( K 0.48 Na 0.52) NbO 3-x% Co 2 O 3 (x = 0, 0.03 and 0.05) (KNN-x% Co2O3 ) lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. An orthorhombic phase was observed for all KNN-x% Co2O3 ceramics at room temperature, and two phase transitions were confirmed by the high temperature X-ray diffraction and the temperature dependence of the dielectric constant. The Co2O3 greatly improves the density and decreases the sintering temperature of KNN ceramics. The KNN-0.05 mol%Co2O3 ceramic exhibits good properties (d33 = 120 pC/N , k p = 0.41, Q m = 213 and T c = 407°C) and a good age stability. The multiferroic behavior was also observed at room temperature for the KNN-0.05 mol%Co2O3 ceramic, as confirmed by P–E loops and magnetic behavior.

scholarly journals Dehydrogenation/rehydrogenation mechanism in aluminum destabilized lithium borohydride

2009 ◽  
Vol 24 (8) ◽  
pp. 2720-2727 ◽  
Author(s):  
Xuebin Yu ◽  
Guanglin Xia ◽  
Zaiping Guo ◽  
Huakun Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hydrogen Desorption ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Lithium Borohydride ◽  
Hydrogen Storage Properties ◽  
X Ray ◽  
Before And After ◽  
Storage Properties ◽  
Desorption Cycle

LiBH4/Al mixtures with various mol ratios were prepared by ball milling. The hydrogen storage properties of the mixtures were evaluated by differential scanning calorimetry/thermogravimetry analyses coupled with mass spectrometry measurements. The phase compositions and chemical state of elements for the LiBH4/Al mixtures before and after hydrogen desorption and absorption reactions were assessed via powder x-ray diffraction, infrared spectroscopy, and x-ray photoelectron spectroscopy. Dehydrogenation results revealed that LiBH4 could react with Al to form AlB2 and AlLi compounds with a two-step decomposition, resulting in improved dehydrogenation. The rehydrogenation experiments were investigated at 600 °C with various H2 pressure. It was found that intermediate hydride was formed firstly at a low H2 pressure of 30 atm, while LiBH4 could be reformed completely after increasing the pressure to 100 atm. Absorption/desorption cycle results showed that the dehydrogenation temperature increased and the hydrogen capacity degraded with the increase of cycle numbers.

The synthesis and hydrogen storage properties of Mg2Ni substituted with Cu, Co

2009 ◽  
Vol 24 (4) ◽  
pp. 1311-1316 ◽  
Author(s):  
Yu’an Chen ◽  
Hua Huang ◽  
Jie Fu ◽  
Qing Guo ◽  
Fusheng Pan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Hydrogen Absorption ◽  
Energy Dispersive Spectrometry ◽  
Induction Melting ◽  
X Ray Diffraction ◽  
Hydrogen Storage Properties ◽  
X Ray ◽  
Storage Properties ◽  
Scanning Electron

Mg2Ni1-xCux (x = 0, 0.2, 0.4) and Mg2Ni1-yCoy (y = 0, 0.2, 0.4) were successfully synthesized via two steps: induction melting and then ball milling. The component and microstructure of the alloys were determined with x-ray diffraction (XRD) and scanning electron microscopy/x-ray energy-dispersive spectrometry (SEM/XEDS). Mg2Ni phase was observed in all 5 alloys. When the amount of Cu was increased, it led to the formation of phase from Mg2Cu to Cu11Mg10Ni9. Co2Mg was detected in the Co-containing alloys. The hydrogen absorption/desorption properties were tested with p-C-T measurement apparatus, and the results showed that the gaseous storage properties of the alloys were improved by the addition of Cu or Co.

Effect of Substrate Temperature on High Rate Deposited ZnO:Al Films by Magnetron Sputtering

2012 ◽  
Vol 430-432 ◽  
pp. 480-483
Author(s):  
Wei Min Li ◽  
Hui Ying Hao
Keyword(s):  
Magnetron Sputtering ◽  
Substrate Temperature ◽  
Room Temperature ◽  
Optical Transmittance ◽  
High Rate ◽  
X Ray Diffraction ◽  
Electrical And Optical Properties ◽  
X Ray ◽  
Atomic Force ◽  
High Optical Transmittance

A series of ZnO:Al (AZO) thin films was prepared on quartz at different substrate temperature using magnetron sputtering with high deposited rate of 67 nm/min. The structural, electrical and optical properties of these films were investigated as a function of substrate deposition temperature ranging from room temperature to 500 °C. The surface micrograph of AZO film deposited at room temperature was measured by a scanning electron microscope (SEM) and an atomic force microscope (AFM). The results of X-ray diffraction (XRD) test show that all the films have a (002) preferential orientation. The best electrical property was obtained at 500 °C, the resistivity was 9.044×10-4 ohm•cm, and the corresponding carrier concentration and mobility were 3.379×1020 /cm3 and 20.45 m2/Ns, respectively. What's more, all the films show a high optical transmittance.

Sintering, Microstructure and Electrical Properties of MnO2 and CuO-Doped [Na0.515K0.485]0.94Li0.06(Nb0.99Ta0.01)O3 Ceramics

2013 ◽  
Vol 770 ◽  
pp. 258-261
Author(s):  
Pornsuda Bomlai
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Room Temperature ◽  
Secondary Recrystallization ◽  
Lead Free ◽  
Reaction Sintering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Doping ◽  
Sintering Method

Ceramics with formula (1-x-y)[Na0.515K0.485]0.94Li0.06(Nb0.99Ta0.01)O3 (NKLNT) xMnO2yCuO (when x, y = 0, 0.005 and 0.01) were prepared by a reaction sintering method. The effects of doping level on sinterability and properties of NKLNT ceramics were studied. The results indicated that the co-doping of MnO2 and CuO was effective in promoting the densification of ceramics. Grain growth during secondary recrystallization was also affected, leading to larger grain size with x, y = 0.01 sample. X-ray diffraction data showed that the orthorhombic tetragonal morphotropic phase boundary existed in all the samples. At room temperature, the dielectric properties of NKLNT ceramics were improved by doping of appropriate MnO2 and CuO content. The temperature dependence of dielectric constant showed a decrease slightly in Curie temperature (TC) with increasing MnO2 and CuO content. The composition with x = 0.005, y = 0 exhibited favorable properties for the promising lead-free piezoelectric candidate material.

Hydrogen storage properties of mechanically alloyedMg–8 mol% LaNi0.5 composite

2004 ◽  
Vol 19 (10) ◽  
pp. 2871-2876 ◽  
Author(s):  
Qian Li ◽  
Qin Lin ◽  
Kuo-Chih Chou ◽  
Li-Jun Jiang ◽  
Feng Zhan
Keyword(s):  
Hydrogen Storage ◽  
Mechanical Alloying ◽  
X Ray Diffraction ◽  
Equilibrium Pressure ◽  
Hydrogen Storage Properties ◽  
X Ray ◽  
Transmission Electron ◽  
Lower Temperature ◽  
Material Preparation ◽  
Storage Properties

A new nano-ternary Mg–8 mol% LaNi0.5 was prepared by melted and subsequent mechanical alloying technique for hydrogen storage. It was found from our experiments that, this kind of alloy had superior hydriding/dehydriding characteristics in comparison with conventional materials for hydrogen storage. It possessed large hydrogen capacity at a lower temperature, which could absorb 4.55–7.01 mass% H under 3 MPa hydrogen pressure and desorb 4.40–6.90 mass% H under 0.0133 MPa in 600 s above 423 K without any activation requirement drawn from our pressure-composition isotherm and kinetic experiments. Through the x-ray diffraction and transmission electron microscopy experiments, we further found that these superior characteristics could be attributed to the multiphase structure and a catalytic effect of LaH3 and Mg2Ni that were formed in the material preparation of mechanical alloying process. Finally, based on these data the relationships between equilibrium pressure of hydrogen and temperature were obtained, they were lgp(0.1 MPa) = −3985/T + 7.188(553 K ⩽ T ⩽ 573K) for hydriding and lgp(0.1 MPa) = −3804/T + 6.770 (553 K ⩽ T ⩽ 573 K) for dehydriding.

Crystal Structure and Hydrogen Storage Properties of novel Mg-Zr-(Li, Na, K) Hydrides Prepared by Gigapascal Hydrogen Pressure Method

2011 ◽  
Vol 1334 ◽  
Author(s):  
Nobuhiko Takeichi ◽  
Kenji Shida ◽  
Xiao Yang ◽  
Tetsuo Sakai
Keyword(s):  
Crystal Structure ◽  
Hydrogen Pressure ◽  
Hydrogen Desorption ◽  
X Ray Diffraction ◽  
Hydrogen Storage Properties ◽  
X Ray ◽  
Pressure Method ◽  
Xrd Patterns ◽  
Storage Properties ◽  
Fcc Structure

ABSTRACTNovel Mg-Zr-A (A=Na, Li and K) hydrides have been synthesized by the gigapascal hydrogen pressure method. Their crystal structures were analyzed based on synchrotron X-ray diffraction (XRD) patterns. In the Mg-Zr-H system, the Mg-Zr hydride with FCC structure was formed under 8 GPa and 873 K. In the case of Mg-Zr-Li and Mg-Zr-K systems, the quaternary hydrides were formed and these retained the same crystal structure, FCC structure, up to x = 1.0 While in the Mg-Zr-Na system, the quaternary hydrides were formed and these retained the FCC structure, up to x = 0.3. With the addition of 0.5 NaH, a hydride with the Ca7Ge type structure was formed instead of the FCC structure. The Mg-Zr-(Li, Na, K) hydrides can reversibly absorb and desorb hydrogen. The hydrogen desorption temperatures of those hydrides decrease with the increasing ionic radius of the alkali metal.

Hydrogen Storage Properties of Mg76Ti12Ni12-xCrX(x=0,3,6,9) Alloys by Mechanical Alloying

2010 ◽  
Vol 156-157 ◽  
pp. 1146-1150
Author(s):  
Zhi Qiang Lan ◽  
Shu Bo Li ◽  
Zhao Lu ◽  
Jin Guo
Keyword(s):  
Hydrogen Storage ◽  
Mechanical Alloying ◽  
Storage Capacity ◽  
X Ray Diffraction ◽  
Hydrogen Storage Capacity ◽  
Hydrogen Storage Properties ◽  
X Ray ◽  
Cr Content ◽  
Ti2ni Phase ◽  
Storage Properties

Mg76Ti12Ni12-xCrx(x=0,3,6,9) alloys were synthesized by mechanical alloying(MA) approach and hydrogen storage properties of the alloys were investigated by X-ray diffraction, thermal analysis and pressure-composition isotherm measurement. It is found that Ti2Ni phase and Mg2Ni phase exist as the main phases in Mg76Ti12Ni12-xCrx(x=0,3,6,9) alloys. The Mg76Ti12Ni12-xCrx(x=0,3,6,9) alloys exhibit the hydrogen storage capacity of 4.61,4.30,4.21 and 4.12wt%, and the decomposition enthalpies of the alloy hydrides are 928.4, 898.3, 831.2 and 851.4J/g H2, respectively. Mg76Ti12Ni6Cr6 alloy shows small hysteresis and fast hydrogen absorption rate. Proper Cr content can improve the performance of the Mg76Ti12Ni12-xCrx(x =0,3,6,9) alloys.

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