M. Marczak

Bio: M. Marczak is an academic researcher from Mint.com. The author has contributed to research in topics: Crystal structure & Powder diffraction. The author has an hindex of 1, co-authored 1 publications receiving 9 citations.

Powder diffraction study of LiCu 2 O 2 crystals

Abstract: LiCu 2 O 2 crystals grown by spontaneous crystallization from the fluxed melt were studied by powder X-ray diffraction. The phase analysis shows that the applied growth conditions are suitable for preparation of a single-phase compound. The as-grown crystals contain only traces of foreign phases (Li 2 CuO 2 , CuO, Cu 2 O) typical for preparation of the LiCu 2 O 2 compound. Attempts to anneal or quench the as-grown crystals led to two-phase samples containing LiCu 2 O 2 and LiCu 3 O 3 . X-ray powder diffraction pattern of a LiCu 2 O 2 crystal is reported and compared with literature data. The crystal structure is orthorhombic, space group Pnma , in agreement with literature data. Lattice parameters of the studied sample are a =5.7286(2) A, b =2.8588(1) A, and c =12.4143(3) A. Time evolution of a diffraction pattern illustrates a slow increase of the secondary-phases contribution assumed to be due to interaction of the powdered crystal with humid air. A brief summary of compounds known in the Li–Cu–O system is included

Ab initio calculation of d-d excitations in quasi-one-dimensional Cu d(9) correlated materials

Abstract: With wave-function-based electronic-structure calculations we determine the Cu $d$-$d$ excitation energies in quasi-one-dimensional spin-chain and ladder copper oxides. A complete set of local excitations has been calculated for cuprates with corner-sharing (Sr${}_{2}$CuO${}_{3}$ and SrCuO${}_{2}$) and edge-sharing (LiVCuO${}_{4}$, CuGeO${}_{3}$, LiCu${}_{2}$O${}_{2}$, and Li${}_{2}$CuO${}_{2}$) CuO${}_{4}$ plaquettes, with corner-sharing CuF${}_{6}$ octahedra (KCuF${}_{3}$), for the ladder system CaCu${}_{2}$O${}_{3}$, and for multiferroic cupric oxide CuO. Our data compare well with available results of optical absorption measurements on KCuF${}_{3}$ and the excitation energies found by resonant inelastic x-ray scattering experiments for CuO. The ab initio results we report for the other materials should be helpful for the interpretation of future resonant inelastic x-ray scattering experiments on those highly anisotropic compounds.

Thermodynamic investigations of copper oxides used as conversion type electrodes in lithium ion batteries

Abstract: Copper oxides, which exhibit the conversion mechanism with lithium during electrochemical cycling, are promising electrode materials for next-generation lithium ion batteries. To better understand phase formations and equilibria in the Li–Cu–O system, the LiCu2O2 phase was synthesized using the solid-state method and characterized with X-ray powder diffraction technique and Rietveld analysis as well as inductively coupled plasma—optical emission spectrometry (ICP–OES). The phase stabilities in argon atmosphere and in a mixture of argon and oxygen were determined between 200 and 900 °C and between 200 and 950 °C, respectively. Based on this data as well as on other literature data, a thermodynamic description of the Li–Cu–O system valid in the battery relevant temperature regime was developed using the CALPHAD method. From this thermodynamic description, titration curves for CuO and Cu2O cathodes, which give the equilibrium cell voltage as a function of lithium content along a selected composition path, were calculated at different temperatures.

Growth and properties of LiCu2O2-NaCu2O2 crystals

Abstract: Platelike Li1 − xNaxCu2O2 single crystals up to 2 × 10 × 10 mm in dimensions have been grown by slowly cooling (1 − x)Li2CO3·xNa2O2·4CuO melts in alundum crucibles in air. Li1 − xNaxCu2O2 solid solutions in the LiCu2O2-NaCu2O2 system have been shown to exist in the composition range 0.78 < x < 1. The temperature stability ranges of NaCu2O2 and LiCu2O2 are 780–930 and 890–1050°C, respectively. The Mossbauer spectra and electrical conductivity of the crystals have been measured.

Kupfer- und Eisenoxide als Konversions-Elektrodenmaterialien für Lithium-Ionen-Batterien: Thermodynamische und Elektrochemische Untersuchungen

Abstract: Konversionselektroden sind vielversprechende Elektrodenmaterialien fur zukunftige Lithium-Ionen-Batterien, da sie sehr hohe spezifische Kapazitaten im Vergleich zu Interkalationselektroden aufweisen. In dieser Arbeit wird ein thermodynamischer Ansatz gewahlt, um den elektrochemischen Prozess von Konversions-Elektroden anhand der Modell-Systeme Li-Cu-O und Li-Fe-O zu beleuchten. Mit den konsistenten thermodynamischen Beschreibungen konnen elektrochemische Eigenschaften berechnet werden. Conversion-type electrodes are promising electrode materials for future lithium ion batteries since they exhibit high specific capacities compared to intercalation-type eclectrodes. In this work, a thermodynamic approach was used to elucidate the electrochemical behavior of conversion-type electrodes using Li-Cu-O and Li-Fe-O as model material systems. electrochemical properties can be calculated using self-sonstistent thermodynamic descriptions developed in this work. Umfang: XVI, 291 S. Preis: €48.00 | £44.00 | $84.00

Heat Capacities of LiCu2O2 and CuO in the Temperature Range 323-773 K and Cu2O in the Temperature Range 973-1273 K

Abstract: The Li-Cu-O system is a promising materials system for the development of new anode materials for lithium ion batteries based on copper oxides. The specific heat capacities of binary and ternary oxides in this system are required to generate thermodynamic descriptions using the CALPHAD method. Additionally, heat capacity data can be used to support development of thermal management systems for the lithium ion batteries based on these materials. In this study, differential scanning calorimetry was used to measure the heat capacities of the binary copper oxides and of the ternary LiCu2O2. The heat capacity of CuO was measured from 323 to 773 K and that of Cu2O was measured from 973 to 1273 K. The heat capacity of CuO is in good agreement with literature data. However, the heat capacity of Cu2O is slightly lower than that calculated using CALPHAD-based thermodynamic descriptions of the Cu-O system but higher than that determined using ab initio calculations. Although the synthesis of single phase LiCu2O2 is difficult because of the mixed oxidation states of Cu, our heat capacity measurements show that the constituent additivity method can be used to estimate the heat capacity of LiCu2O2.