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γ-Fe2O3 nanoparticles of ∼100 nm size were prepared through self-propagating combustion route using ferrous phthalate precursor employing polyethylene glycol as a fuel. As prepared γ-Fe2O3 was characterised by employing X-ray diffraction (XRD), scanning electron micrograph (SEM), Mossbauer spectroscopy, energy dispersive X-ray microanalysis (EDAX) and X-ray photoelectron spectroscopy (XPS). From XRD and XPS, we find that the surface of these nanoparticles is α-Fe2O3 and the core is γ-Fe2O3 . γ-Fe2O3 particles were spherical in shape showing a well-resolved 6 narrow bands in Mossbauer spectrum. No impurities were present, as indicated by EDAX and also no other phase than α and γ was present which substantiates suitability of the synthesis route for γ-Fe2O3 nanoparticles. The magnetic properties of the γ-Fe2O3 were also studied by using vibrating sample magnetometer (VSM). [ABSTRACT FROM AUTHOR]

In this work, the evolution of superparamagnetism (SPM) at room temperature is observed in the reactive magnetron sputter deposited amorphous Al-N-O alloy thin films after irradiation with oxygen ions (O−). Energy dispersive X-ray (EDX) analysis reveals the presence of notable Al-vacancy (V Al) in as-grown Al-N-O alloy thin film. X-ray photoelectron spectroscopy (XPS) confirms nitrogen trapping at V Al sites for thermodynamic stability, forming the Al(NO y) x phase. Upon the irradiation using O− at low fluence, i.e. 5 × 1013 ions/cm2, mainly V Al -O N complexes emerged. Here O N refers to nitrogen replaced by oxygen. Furthermore, an increase in oxygen fluence from 1 × 1015 to 2 × 1016 ions/cm2 yields the cross-over from V Al -O N complexes to mainly V Al , due to knocking off the trapped nitrogen atoms at V Al sites. From depth-resolved positron beam-based Doppler broadening measurements, the greater density of V Al sites is noticed in the film irradiated with the highest fluence of O− ion, i.e., 2 × 1016 ions/cm2. The correlation between the elevation of V Al sites with O− irradiation dose is in excellent agreement with the emergence of superparamagnetism (SPM) in the films. Hence, the emergence of SPM in the film after irradiation has been attributed to the creation of V Al sites, which leads to a localized magnetic moment. [ABSTRACT FROM AUTHOR]

The effect of thickness on the magnetic property of amorphous carbon thin film is reported. Three different carbon thin films are deposited by varying the deposition time keeping all the parameters fixed. Microstructural characterization carried out using Grazing Incidence X-ray Diffraction, and Raman spectroscopy indicates the films are amorphous with the presence of molecular units whose edges are bonded with sp3 hybridized atoms. The chemical characterization performed using X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge spectroscopy (XANES) indicates that the sp3 fraction and the conjugation between the sp2 hybridized atoms increases with increasing film thickness. The magnetic property studied using SQUID–VSM reveals the existence of weak ferromagnetic coupling between the unpaired spins present at sp2 sites. The saturation magnetization of the film decreases with increasing thickness. However, estimated magnetic moment/area reveals that there lies a threshold of thickness beyond which the insignificant enhancement in the magnetic moment of the film occurs. [Display omitted] [ABSTRACT FROM AUTHOR]

The crystalline aluminium nitride (AlN) thin films were isothermally annealed at 850 °C in a controlled oxygen environment. The oxidation process has led to significant enhancement in lattice parameters and degradation in the crystallinity of as-grown AlN film. The AlN bonding at the film's surface was systematically reduced and finally vanished when the film was annealed at 20% oxygen mixed with an argon environment. During annealing, nitrogen in AlN is replaced by oxygen, and a fraction of replaced nitrogen is trapped at the interstitial sites in AlN, which systematically enhances with an increment in oxygen content. Magnetic measurements exhibit dilute ferromagnetism induced in as-grown AlN film at 300 K after annealing. Density functional theory (DFT) calculation reveals interaction between N 2 p orbitals of interstitial nitrogen and first neighbouring nitrogen atoms contributing to observed magnetic properties. [Display omitted] • Annealing in O 2 environment elongates lattice and alleviates crystallinity of AlN. • O 2 ingress in AlN by replacing N along c-axis in AlN matrix. • N replaced by O gets trapped at interstitial site into the AlN matrix. • Annealing in O 2 environment instigates dilute FM and weak paramagnetism in AlN. • DFT calculation reveals that N at interstitial site in AlN has moments of 2 μ B. [ABSTRACT FROM AUTHOR]

Abstract: The effect of low energy argon plasma treatment on the surfaces of polyethylene terephthalate (PET) was investigated by means of contact angle measurement, X-ray photoelectron spectroscopy (XPS), Vickers’ microhardness indentation and atomic force microscopy (AFM). It was observed that the surface free energy (SFE) changes from 42.1mJ/m2 to 85.1mJ/m2 with the increase of plasma treatment time and the corresponding contact angle changes from 60o to 15o. The increase in SFE after plasma treatment is attributed to the functionalization of the polymer surface with hydrophilic groups. The XPS analysis shows the increase in C–O and Cafter plasma treatment of the polymer surface. The microhardness of the film increases with the treatment time. This may be attributed to the cross linking effect at the surface. Atomic force microscopy (AFM) reveals that average surface roughness increases from 5.8nm to 49.7nm as treatment time increases. [Copyright &y& Elsevier]