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The present work reports the synthesis of nanostructured thin films on glass substrate by dip coating. The thickness of thin film was varied by varying the no. of dips of glass substrate in the aqueous solution of Ca(NO3)2⋅4H2O and NaOH. Deposited films were studied by the X‐Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), and Ultraviolet‐visible (UV‐Vis) spectroscopy techniques. The thickness of film was increased almost linearly with number of dips. Accordingly, the nanocrystalline size and band gap was varied. Interestingly the nanoflower like structure of calcite thin films was observed in FESEM and that varied with the thickness of film. The calcite thin film formation was discussed in terms of reactivity due to nanostructure and surface structure was discussed in terms of nucleation and growth of film on the substrate. Finally, the implications of these results in terms of microstructurally tuned nano calcite thin films development for prospective futuristic industrial applications are highlighted. [ABSTRACT FROM AUTHOR]

CuAlO2 thin films were grown on single crystalline sapphire substrates with c-axis orientation by rf sputtering method. The x-ray diffraction data indicate the formation of delafossite structure and tend to be oriented along (001). Temperature dependent Raman spectra of CuAlO2 thin films were measured from 80 to 1273 K, and we observed two optical modes at Eg (∼418 cm-1) and A1g(∼767 cm-1) showing anomalous frequency and linewidth shifts with temperature, which were interpreted as an experimental evidence of combined effect of lattice expansion and anharmonic phonon-phonon interaction in CuAlO2. At high temperature, polaronic state and change in effective mass due to lattice expansion also affect the frequency shift and the linewidth of the observed Raman modes. [ABSTRACT FROM AUTHOR]

Bismuth zinc niobate (Bi1.5Zn1.0Nb1.5O7) thin films were deposited on fused silica substrates by pulsed laser deposition. Its phase composition and microstructure were characterized by x-ray diffraction and atomic force microscopy. The as deposited films were amorphous and all of them were crystallized after a postdeposition annealing at 600 °C for 30 min in air. The crystallite size of the films was found to be varying between 31 and 60 nm with respect to the oxygen pressure in the deposition chamber. The films were found to be less oriented with the decreasing crystallite size. The films deposited under different oxygen pressures showed a microwave dielectric permittivity in between 98–124 and a loss tangent in between 0.005 and 0.007 over the X-band frequency range. From the Raman scattering data of the bulk and thin films, it was found that the Raman modes in thin films are relatively more intense and additional Raman modes were appearing in the films in the low frequency range, which reveal that the local symmetry in the films is different from that of the bulk. The variations in the microwave dielectric properties due to processing can be attributed to the change in the local symmetry of the film. [ABSTRACT FROM AUTHOR]

The magnetic properties of BiFeO3(BFO) - CoFe2O4(CFO) heterostructure thin films, grown on (100), (110) and (111) SrTiO3 (STO) substrates by employing pulsed laser deposition (PLD) method, have been studied. The XRD patterns of BFO-CFO multilayer thin films compared with the pure CFO and BFO thin films grown using under identical conditions evidenced that all peaks present correspond to CFO and BFO structure in two separate phases. Micro-Raman spectra analysis also reveals the presence of BFO and CFO in two separate phases in the heterostructures thin films. The anomalous enhancement in magnetization has been observed for BFO-CFO multilayer thin films, relative to pure BFO thin films in all three different orientations. The saturation magnetization for (100), (111) and (110) oriented BFO-CFO thin films are 44, 62 and 80 emu/cc suggesting that (110) is most preferable direction to achieve the magneto electric (ME) coupling effect. [ABSTRACT FROM AUTHOR]

Abstract: Monoclinic Bi2Zn2/3Nb4/3O7 (m-BZN) thin films were deposited by pulsed laser deposition on fused silica substrates at different oxygen pressures. Microwave dielectric and Raman scattering studies were systematically carried out on films that had been annealed at 600 °C after deposition. The dielectric constant of films changes in the range 56–71 due to varying the oxygen pressure during deposition. X-ray diffraction measurements indicate that the BZN thin films deposited at the oxygen pressure of 10 Pa have the best crystalline quality. Atomic force microscopy results show that the surface roughness of the m-BZN film increases with the increase of oxygen pressure. The anomalous change in two higher-frequency Ag modes appearing at 774 and with varying oxygen pressure also suggests a nonequivalent change in the oxygen octahedra around the Nb and Zn and is closely related to the microwave dielectric properties of the thin films. [Copyright &y& Elsevier]

Highly (111)-oriented rhombohedral BiFeO3 (BFO) thin films were grown on (111) SrTiO3 substrates by pulsed laser deposition. Polarized Raman-scattering study of the (111)-oriented epitaxial BFO thin film with rhombohedral R3c symmetry was carried out by employing two distinct backscattering geometries. The A1-symmetry transverse-optical [A1(TO)] phonons were selectively isolated from the E-symmetry transverse-optical [E(TO)] phonons by employing Y′(ZZ)Y′ polarization configuration in a novel side-view backscattering. By comparing the Y′(ZZ)Y′ spectrum with the Z(X′X′)Z polarization spectrum in a normal backscattering, we were able to assign most of A1 and E-symmetry normal modes of R3c BFO. In addition, we found that there was a negligible LO-TO splitting in the A1-symmetry normal modes. [ABSTRACT FROM AUTHOR]

Raman spectra of epitaxal BiFeO3 thin films, grown on (111) SrTiO3 substrates, have been studied in temperature range 300-800 K. All four prominent A1-symmetry (81, 138, 170, and 214 cm-1) Raman modes show evolution with the temperature near the Néel temperature (TN), which is interpreted due to spin lattice coupling and it could be also linked with the structural instability originated by octahedral tilting near TN as reported by A. Palewicz et al., Acta Cryst B 63, 537 (2007). As another evidence of spin-phonon coupling, softening of the 214 cm-1 stretching mode is observed near and below the magnetic ordering temperature. [ABSTRACT FROM AUTHOR]