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Physica
North-Holland
Physica

North-Holland

0921-4526

Physica/Journal Physica
正式出版
收录年代

    Study of the influence of synthesis method in BaFeO3-delta perovskite on structural, optical, magnetic and antibacterial properties

    Abdel-Khalek, E. K.Askar, Ahmed. A.Motawea, M. A.Aboelnasr, Mohamed A....
    11页
    查看更多>>摘要：In this study, the BaFeO3-delta perovskite nanomaterials sample has been synthesized by co-precipitation (Cop) and sol-gel (Sol) methods respectively. Rietveld refinements of X-ray diffraction (XRD) patterns showed that these samples crystallized in rhombohedral structure with space group R3c. Scanning electron microscope (SEM) showed that these samples have different surface morphologies. Mo center dot ssbauer results revealed that the iron exists in different oxidation states (Fe3+, Fe3.5+, and Fe4+ ions) with oxygen vacancies in these samples. X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of Fe3+, Fe4+ ions, and oxygen vacancies at the surface of these samples. The thermal, optical, and magnetic properties of these samples depend on the amount of oxygen deficiency (delta) and the valence states of Fe ions. BaFeO3-delta perovskite samples exhibited antibacterial and antibiofilm activity which can be controlled by the synthesis method. Accordingly, to the present results, the obtained BaFeO3-delta perovskite could be considered as a potential antibacterial and antibiofilm agent.
      原文链接:
    • NSTL
    • Elsevier

    Controlling local relaxation in small clusters of magnetic nanoparticles

    Anand, Manish
    10页
    查看更多>>摘要：We investigate the local (particle level) and averaged magnetic relaxation characteristics in linear chain-like agglomerates of k magnetic nanoparticles (MNPs) or k-mers using computer simulations. The local relaxation behaviour is dictated by the corresponding dipolar field acting on the nanoparticle, irrespective of k-mer size. There is a wide variation in local relaxation characteristics as a function of nanoparticle position in a small nanocluster. On the other hand, there is more uniformity in the local relaxation response with a larger kmer, except for MNPs at the boundary. Interestingly, there is a smooth decay of magnetization with small h(d), independent of cluster size. In contrast, the magnetization ceases to relax in the presence of substantial dipolar interaction strength. Remarkably, the local Neel relaxation time tau(')(N) is directly proportional to the corresponding dipolar field. Likewise, the averaged Neel relaxation time tau(N) also depends strongly on the k-mer size and h(d).
      原文链接:
    • NSTL
    • Elsevier

    The influences of hydrogen-like impurities and magnetic field on magnetopolaron in asymmetric semi-exponential and parabolic potential quantum wells

    Miao, Xiu-JuanSun, YongDing, Zhao-HuaXiao, Jing-Lin...
    5页
    查看更多>>摘要：In the current research, the impacts of anisotropic parabolic confinement potential (APCP) on strong-coupled impurity bound magnetopolaron (SCIMP) in asymmetrical semi-exponential quantum wells (ASEQWs) containing hydrogen-like impurities (HLIs) at their center under uniform magnetic fields applied along the direction of z axis have been theoretically investigated. Lee-Low-Pine unitary transformation and linear combination operation methods were applied for the derivation of formulations for ground state energy (GSE) and the mean number of LO phonons (MNLOP) of SCIMPs. Also, GSE and MNLOP as functions of magnetic field cyclotron frequency, Coulombic impurity potential (CIP) strength, APCP effective confinement strengths along x and y directions, and two positive parameters of asymmetrical semi-exponential confinement potential (ASECP) were acquired. Numerical results were expressed for a typical CsI. It was found that when considering magnetic field, APCP, CIP, ASECP, GSE and MNLOP were increased.
      原文链接:
    • NSTL
    • Elsevier

    UV sensitivity enhancement in ZnO:Cu films through simple post-annealing treatment

    Nurfani, EkaAntika, LutfiAnrokhi, M. SamsulSipahutar, Wahyu S....
    7页
    查看更多>>摘要：Influence of post-annealing temperature on structural, morphological, optical, and electrical properties of ZnO:Cu films was investigated. The films were deposited using the ultrafast spray pyrolysis technique for 10 s. Post-annealing treatment was then conducted at a temperature range of 400-600 degrees C under ambient pressures. Structural, morphological, electrical, and optical properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), current-voltage (I-V) curve, and UV-Vis spectroscopy, respectively. By increasing the annealing temperature, SEM images show morphology modification from rods to spherical grain due to atomic rearrangement. XRD patterns show significant improvement in crystallinity. From I-V curves, the sensitivity of UV detection is also increased. The increase of annealing temperature provokes both the dark current and photocurrent enhancement. UV-Vis spectroscopy analysis shows the decrease of bandgap by increasing the annealing temperature. Our study is essential to improve the functionality of ZnO:Cu film and realizes mass-scale fabrication with low cost.
      原文链接:
    • NSTL
    • Elsevier

    Tm3+,Yb3+: Y2SiO5 up-conversion phosphors: Exploration of temperature sensing performance by monitoring the luminescence emission

    Rakov, Nikifor
    7页
    查看更多>>摘要：Tm3+,Yb3+:Y2SiO5 ceramic powders synthesized via combustion route exhibited up-conversion (UC) fluorescence when were submitted to CW-laser radiation at 980 nm. Four emission bands at 478 nm, 650 nm 690 nm and 798 nm, corresponding to transitions (1)G(4)-> H-3(6), (1)G(4)-> F-3(4), F-3(2,3) -> H-3(6) and H-3(4)-> H-3(6) were observed. The properties of the UC emission bands are influenced by temperature. Thermal coupling levels (TCL) cause a noticeable change in the relative intensities between the excited states F-3(2,3) -> H-3(6) and H-3(4)-> H-3(6) in the temperature range of 298-473 K. The maximum absolute sensitivity (1.25 x 10(-3) K-1, 473 K) and relative sensitivity (1.83% K-1, 298 K) were obtained using the fluorescence intensity ratio (FIR) technique. Thermal sensing performance has been explored by utilizing the FIR technique between non-thermally coupled levels (NTCL). Through the calculation of FIR of NTCL (1)G(4)-> H-3(6) and H-3(4)-> H-3(6), the value of the relative sensitivity was acquired (1.5% K-1, 298 K). The comparison of TCL and NTCL FIR-method performances shows that this ceramic powder has the potential to be used as a ratiometric thermal sensor for remote temperature measurements.
      原文链接:
    • NSTL
    • Elsevier

    RIXS, XES and XAS studies for electronic structure of rare earth and alkaline earth modified manganite

    Abu-Samak, MahmoudKumar, UpendraQuraishi, A. M.Kumar, Rajneesh...
    7页
    查看更多>>摘要：This article reports on the RIXS (Resonant inelastic X-ray scattering), XES (X-ray emission spectroscopy), and XAS (X-ray absorption spectroscopy) of the LaSr2Mn2O7, La0.95Ba0.05MnO3, and La-1.2(BaCa)(1.8)Mn2O7 at 40 K, 100 K and 300 K. The RIXS spectra of these samples show the presence of Mn in different valence states (Mn2+, Mn3+, and Mn4+) which is associated with the Jahn-Teller distortion due to overlapping between O-2(-) and the unpaired electrons of transition metal Mn. It has also been noticed that the distortion observed in different valence states of Mn with O(2)(-& nbsp;)is found to be suppressed with dropping and the temperature. So, based on aforementioned studies, the Manganites have been considered as a strongly correlated magnetic system which would be useful in magnetic device applications.
      原文链接:
    • NSTL
    • Elsevier

    An investigation on the role of low temperature annealing on the structural, morphological, optical, and electrical properties of DC magnetron sputtered Zn(1-x)Sn(x)O thin films

    Bhat, PrashantSalunkhe, ParashuramaMurari, M. S.Kekuda, Dhananjaya...
    12页
    查看更多>>摘要：This study reveals the effect of low-temperature air annealing on various physical properties of Zn(1-x) Sn (x)O (x = 0.14) (TZO) thin films. The thin films were grown on glass substrates by co-sputtering techniques and the grown films were subjected to low temperature air -annealing. X-ray diffraction studies on the grown samples reveal a polycrystalline nature with a hexagonal wurtzite structure. A Change in orientation from (002) to (100) followed by an increase in crystallinity was observed in 100 degrees C annealed samples. A variation in the optical band gap from 3.17 to 3.44 eV after annealing was noticed. Changes in the defect density of Zn interstitials and Oxygen vacancies are clearly noticeable from PL analysis. X-ray Photoelectron Spectroscopy (XPS) elucidate an enhanced oxygen vacancies after doping. The van der Pauw resistivity measurement revealed a decrement in the resistivity after doping and annealing.
      原文链接:
    • NSTL
    • Elsevier