Solid gas and electrochemical hydrogenation properties of the selected R,R’MgNi4-xMx (R,R’ = La, Pr, Nd; M = Fe, Mn; x = 0.5, 1) alloys

New R,R’MgNi4-xMx (R,R’ = La, Pr, Nd; M = Fe, Mn; x = 0.5, 1) phases with cubic structure have been synthesized by powder sintering method. By the hydrogenation of the parent alloys seven hydrides with cubic (LaMgNi3.5Fe0.5H6.0, PrMgNi3.5Mn0.5H~6 and NdMgNi3.5Mn0.5H~5) and orthorhombic (PrMgNi3.5Fe0.5H4.5, NdMgNi3.5Fe0.5H4.3, La0.5Pr0.5MgNi3.5Fe0.5H4.6 and La0.5Nd0.5MgNi3.5Fe0.5H4.4) structures were obtained.  The relationship between the structure, hydrogen content and the relative increase of the lattice volume of the new and early known hydrides is shown. Electrochemical parameters of the electrodes based on new materials are compared with already known ones. Highest discharge capacity is observed for PrMgNi3.5Mn0.5 (271 mAh/g) and NdMgNi3.5Mn0.5 (263 mAh/g). The best cyclic stability was seen for the electrode based on NdMgNi3.5Fe0.5 (S50 = 74%)

Analysis of heat capacity and Mössbauer data for LuZnSn_{2} compound

New analysis of heat capacity data is presented for LuZnSn_[2} compound that takes into account anharmonic effects together with the existence of Einstein modes. ^{119m} Mössbauer spectroscopy was used to monitor the hyperfine parameters at the two crystallographically inequivalent Sn sites in the studied compound. The problem of non-unique mathematical resonance spectrum description and the problem how to choose physically meaningful set of hyperfine parameters will be thoroughly discussed. Measured quadrupole interaction constants by ^{199m} Sn Mössbauer spectroscopy give estimations for V_{zz} component of electric field gradient tensor at both Sn sites in LuZnSn_{2}

Mössbauer and heat capacity studies of ErZnSn_{2}

Heat capacity results obtained for the intermetallic compound ErZnSn_{2} were re-analysed to also consider, apart from the classical Debye model, the anharmonicity of the crystal lattice and the proper set of Einstein modes. The 119mSn Mössbauer technique was applied to derive the hyperfine interaction parameters characteristic of the two inequivalent crystallographic Sn sites in the compound studied. Quadrupole interaction constants, as measured by 119mSn Mössbauer spectroscopy, allowed for estimations of Vzz components of the electric field gradient tensor that exist at both Sn sites in the discussed compound

Solid gas and electrochemical hydrogenation of the selected alloys (R’,R’’)2-Mg Ni4-Co (R’, R’’ = Pr, Nd; x = 0.8–1.2; y = 0–2)

International audienceA number of alloys with the (R’, R’’)2-xMgxNi4-yCoy (R’, R’’ = Pr, Nd; x = 0.8–1.2; y = 0–2) compositions were synthesized by the sintering method and characterized by X-ray powder diffraction method. They are all with cubic MgCu4Sn structure and belong to the continuous solid solution. Gas hydrogenation was performed for the selected alloys and 15 new hydrides belonging to cubic or orthorhombic structures were obtained. PCT diagrams are constructed for the Nd1.2Mg0.8Ni3Co - H2 and Nd0.8Mg1.2Ni3Co - H2 systems. The influence of R/Mg and Ni/Co substitution on the discharge characteristics of the (R’, R’’)2-xMgxNi4-yCoy electrodes was studied. It was established that cobalt-doped alloys with high magnesium content show the highest discharge capacities

Analysis of heat capacity and Mössbauer data for LuZnSn2 compound

New analysis of heat capacity data is presented for LuZnSn2 compound that takes into account anharmonic effects together with the existence of Einstein modes. 119mSn Mössbauer spectroscopy was used to monitor the hyperfine parameters at the two crystallographically inequivalent Sn sites in the studied compound. The problem of non-unique mathematical resonance spectrum description and the problem how to choose physically meaningful set of hyperfine parameters will be thoroughly discussed. Measured quadrupole interaction constants by 119mSn Mössbauer spectroscopy give estimations for Vzz component of electric field gradient tensor at both Sn sites in LuZnSn2

Mössbauer and heat capacity studies of ErZnSn2

Heat capacity results obtained for the intermetallic compound ErZnSn2 were re-analysed to also consider, apart from the classical Debye model, the anharmonicity of the crystal lattice and the proper set of Einstein modes. The 119mSn Mössbauer technique was applied to derive the hyperfine interaction parameters characteristic of the two inequivalent crystallographic Sn sites in the compound studied. Quadrupole interaction constants, as measured by 119mSn Mössbauer spectroscopy, allowed for estimations of Vzz components of the electric field gradient tensor that exist at both Sn sites in the discussed compound