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  1. Article ; Online: Pr

    Oumezzine, Ma / Sales, Herbet Bezerra / Selmi, Ahmed / Hlil, E K

    RSC advances

    2019  Volume 9, Issue 44, Page(s) 25627–25637

    Abstract: Bulk nanocrystalline samples of ( ... ...

    Abstract Bulk nanocrystalline samples of (La
    Language English
    Publishing date 2019-08-15
    Publishing country England
    Document type Journal Article
    ISSN 2046-2069
    ISSN (online) 2046-2069
    DOI 10.1039/c9ra03494c
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Pr3+ doping at the A-site of La0.67Ba0.33MnO3 nanocrystalline material: assessment of the relationship between structural and physical properties and Bean–Rodbell model simulation of disorder effects

    Oumezzine, Ma / Sales, Herbet Bezerra / Selmi, Ahmed / Hlil, E. K

    RSC advances. 2019 Aug. 15, v. 9, no. 44

    2019  

    Abstract: Bulk nanocrystalline samples of (La1−xPrx)0.67Ba0.33MnO3 (0.075 ≤ x ≤ 0.30) manganites with a fixed carrier concentration are prepared by the sol–gel based Pechini method. Rietveld refinement of the X-ray diffraction patterns, shows the formation of ... ...

    Abstract Bulk nanocrystalline samples of (La1−xPrx)0.67Ba0.33MnO3 (0.075 ≤ x ≤ 0.30) manganites with a fixed carrier concentration are prepared by the sol–gel based Pechini method. Rietveld refinement of the X-ray diffraction patterns, shows the formation of single-phase compositions with rhombohedral symmetry. Upon Pr3+ doping at the A-site, the unit cell volume and the B–O–B bond angles are reduced. FTIR spectra present a prominent absorption peak of the in-phase stretching mode (B2g mode) rising from the vibration of the Mn–O bond. Raman spectra at room temperature reveal a gradual shift toward lower frequencies in (Eg) phonon mode with increasing Pr3+ concentration. The M(T) measurements shows a clear ferromagnetic (FM)–paramagnetic (PM) phase transition with increasing temperature. An increase in resistivity and activation energy and a decrease in the metal–semiconductor transition (TM–SC) and Curie temperatures (TC) was observed as a consequence of Pr3+ doping. The results are discussed according to the change of A-site-disorder effect caused by the systematic variations of the A-site average ionic radius 〈rA〉 and A-site-cation mismatch σ2, resulting in the narrowing of the bandwidth and the decrease of the mobility of eg electrons. The magneto-transport behavior in the whole measured temperature and a magnetic field can be described by a percolation model, which is in agreement with the limited experimental data of the samples for x = 0.075, 0.15 and 0.30. The experimental results confirm that A-site substitution with Pr3+ destroys the Mn3+–O2−–Mn4+ bridges and weakens the double exchange (DE) interaction between the Mn3+ (t32ge1g, S = 2) and Mn4+ (t32ge0g, S = 3/2) ions. On the other hand, the Bean and Rodbell model has been successfully used to simulate the magnetization data of the samples with x = 0.15 and x = 0.22. The random replacement of La3+ by Pr3+ is shown to induce more disorder in the system, which is reflected in the increase of the fitted disorder parameter and spin value fluctuation. At a temperature close to room temperature, the maximum magnetic entropy change (ΔSMax) and the relative cooling power (RCP) of La0.52Pr0.15Ba0.33MnO2.98 are found to be, respectively, 1.34 J kg−1 K−1 and 71 J kg−1 for a 1.5 T field change.
    Keywords Fourier transform infrared spectroscopy ; Raman spectroscopy ; X-ray diffraction ; activation energy ; ambient temperature ; chemical bonding ; cooling ; electrons ; entropy ; ferromagnetism ; ions ; lanthanum ; magnetic fields ; manganese ; nanocrystals ; phase transition ; praseodymium ; simulation models
    Language English
    Dates of publication 2019-0815
    Size p. 25627-25637.
    Publishing place The Royal Society of Chemistry
    Document type Article
    ISSN 2046-2069
    DOI 10.1039/c9ra03494c
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Copper-doped lanthanum manganite La

    Chebaane, M / Bellouz, R / Oumezzine, Ma / Hlil, E K / Fouzri, A

    RSC advances

    2018  Volume 8, Issue 13, Page(s) 7186–7195

    Abstract: Bulk nanocrystalline samples of ... ...

    Abstract Bulk nanocrystalline samples of La
    Language English
    Publishing date 2018-02-13
    Publishing country England
    Document type Journal Article
    ISSN 2046-2069
    ISSN (online) 2046-2069
    DOI 10.1039/c7ra13244a
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

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