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Zn_1-xCr_xO(x = 0, 0.03, 0.09) films were prepared by the radio frequency (RF) magnetron sputtering technique on Si(111) and quartz glass substrates. The effects of Cr-doping on the structural and optical properties of ZnO films have been discussed. The structural properties were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) while optical properties using UV-Visible spectrophotometer (UV-VIS). XRD measurement revealed that the films were single phase and wurtzite structure with c-axis orientation. With the increase of Cr concentration, the intensity of the (002) peak and the grain size of the Zn_1-xCr_xO(x = 0, 0.03, 0.09) films decreased, and the Full Width at Half Maximum (FWHM) of (002) peak, the crystal lattice parameter c of Zn_1-xCr_xO(x = 0, 0.03, 0.09) films and the width of optical band gap increased, respectively. In the transmittance spectra of the Zn_1-x Cr_xO(x = 0, 0.03, 0.09) films, the movement of the absorption edge of the ultraviolet region is the Burstein–Moss shift with the increase of Cr concentration.

Three samples of boro-germanate glass system (GeO₂–B₂O₃) were prepared by cooling the melt from 1473°K in the compositional series containing 40, 35 and 30 mol% B₂O₃. For these glasses the optical absorbance, % transmission, optical band gap, relative permittivity (ε_r), index of refraction (n) and index of dispersion (Abbe No., V_d) have been determined. The position of the absorption edge and hence the optical band gap (E_opt) was found to depend on glass composition. The absorption edge was attributed to indirect transitions. The values of E_opt and n_d were observed to decrease with increasing B₂O₃ content while ε_r and V_d increased with increasing B₂O₃ content.

Zinc manganese phosphate glasses (ZnO-MnO-P₂O₅) of different compositions are synthesized. The optical band gaps are measured in the UV-VIS region. Photoconduction measurements are also made in the spectral energy range 1.5–6.2 eV. At various applied electric fields, the values of the energy band gaps have been deduced from the spectral dependence curves. Furthermore, the band gaps at zero applied voltage were also obtained for different compositions. The charge transport mechanism in these glasses is studied under the Mott's model.

Optical transmittance of Ba_1-xCa_xTi₂O₅ (x=0, 0.01, 0.03) bulk glasses of ferroelectric BaTi₂O₅ is measured at room temperature in the wavelength range 190–800 nm. The fundamental absorption edge located in the ultraviolet (UV) region tends to shift toward the longer wavelength region on increasing x. The optical band gap of 3.31 eV estimated for x=0 decreases on increasing x. The decrease in the optical band gap energy is related to the creation of non-bridging oxygen ions, which increase on Ca substitution. The observed increase in the Urbach energy with increasing x is associated with the possible increase of structural disorder in the ferroelectric BaTi₂O₅-based bulk glass occurred by substituting Ca for Ba.

The glasses of compositions xFe₂O₃⋅ (40 - x)Bi₂O₃⋅60B₂O₃⋅2V₂O₅ have been prepared by the standard melt-quenching technique. Amorphous nature of these samples is ascertained by XRD patterns. The presence of BO₃ and BO₄ units is identified by IR spectra of glass samples. The absorption edge (λ_cut-off) shifts toward longer wavelengths with an increase in Fe₂O₃ content in the glass matrix. The values of optical band gap energy for indirect allowed and forbidden transitions have been determined and it is found to decrease with increase in transition metal ions. The Urbach's energy is used to characterize the degree of disorder in amorphous solids.

Orange-red emitting Sm${}^{3+}$-doped MgGeO₃ phosphors were synthesized by traditional high temperature solid state method. The powders were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), UV-Vis spectrometer and photoluminescence (PL) spectra. XRD, SEM and EDS analysis results revealed that MGO:Sm phosphor samples were successfully synthesized. and the optimum MGO:0.1% mol Sm${}^{3+}$ phosphor exhibited good photoluminescence emission intensity, thermal stability, life time and color purity. The diffuse reflectance spectra give the results of sample absorption, reflectance, transmittance and optical band gap. The larger optical band gap is 5.25 eV and the stronger photoluminescence intensity $I_{\mathrm{\text{PL}}}=3\times 10^6$ when the doping concentration is 0.1$\%$ mol. The dipole–dipole interaction is the main mechanism of the concentration quenching phenomenon. The thermal activation energy of the sample is 0.176 eV, and the life time of the prepared sample can reach 14.76 $\mu$s, due to the correlated color temperature (CCT) of less than 2000 K, the potential application value in warm white light emitting device.

The new class of Tricarboxylate-Bismuth (TB)-based Metal Organic Frameworks (MOFs) was attempted, using the impressive capability of alkaline earth metal Bismuth (Bi), to realize more massive complex structures for real-world applications including supercapacitors, energy storage devices, biomedical imaging, drug delivery, fluorescence sensing and far-UVC applications. The grown structure and band gap of the TB-based MOFs samples were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and Ultraviolet-Visible Absorption Spectroscopy (UV-Vis spectra), respectively. The SEM observation identifies the TB-based MOFs nanosheet layered with orthorhombic structure, which shows strong agglomeration with a grain size of 668 nm. The EDS analysis indicates the presence of Bi-peaks as well as carbon peaks (organic linkers) in the grown samples. Furthermore, the peak of TB-based MOFs structure during the Raman spectroscopy was also confirmed. The optical band gap of the newly synthesized TB-based MOFs was estimated and the optical band gap ($E_g)$ approximately $\sim 5.45$eV was confirmed. These findings open the possibility of Bi-based MOFs for the applications in far-UVC emission range.

This paper reports the band gap shifting due to nitrogen (N₂) doping, microwave power and composition gas pressure of nitrogenated amorphous carbon (a-C:N) thin films deposited by newly-developed surface wave microwave plasma chemical vapor deposition (SWMP-CVD). Results show that the optical band gap decreased from 4.1 eV to 2.4 eV corresponding to the increase of N₂ doping from 0 to 5% in the gas ratio. However, further increase of N₂ doping beyond 5% did not decrease the band gap. It was found that composition gas pressure and launched MW power during film deposition also largely control the optical band gap. Investigation of annealing effects on optical band gap and film thickness of the N₂ doped films revealed that both band gap and film thickness decrease significantly with increase of annealing temperature. The optical band gap decreased from 2.4 eV to 1.1 eV, while film thickness decreases from 320 nm to 50 nm corresponding to 200 to 400°C annealing temperature. The results revealed that the properties of a-C:N can be tuned by changing the annealing temperature, composition gas pressure and microwave power of the SWMP-CVD system.

Nitrogen-doped amorphous carbon (a-C:N) thin-films have been deposited on novel heat tolerant flexible plastic substrates by a newly developed microwave surface wave plasma chemical vapor deposition (MWSWP-CVD) method. Methane gas and also camphor dissolved with ethyl alcohol gas composition have been used as plasma source. Nitrogen gas has been used as a dopant material for a-C:N films. In this paper, the optical characteristics of absorption coefficients and band gaps for a-C:N are discussed. The optical band gap of a-C:N films was found to be approximately 1.7 eV, which is close to the suitable band gap for solar cell. The optical band gap of a-C:N was found to be dependent on the composition gas source pressures.

Nitrogen doped amorphous carbon (a-C:N) thin films were deposited on silicon and quartz substrates by microwave surface-wave plasma chemical vapor deposition (SWMP-CVD) technique at low temperatures (<100°C). We used argon (Ar), camphor dissolved in alcohol, and nitrogen (N) as carrier, source, and dopant gases, respectively. Optical band gap (E_g) decreased from 4.1 to 2.4 eV when the N gas concentration increased from 0% to 4.5%. The films were annealed at different temperatures ranging from 150°C to 450°C in Ar gas environment to investigate the optical and electrical properties of the films before and after annealing. Both E_g and electrical resistivity (ρ) decreased dramatically up to 0.95 eV and 57×10³ Ω cm at 450°C annealing. The structural modifications of the films leading them to become more graphitized as a function of the annealing temperature were confirmed by the characterization of Raman spectra.

This paper reports catalytic effects of ferrocene on bonding, optical and structural properties of diamond-like carbon (DLC) thin films grown on silicon and quartz substrates by microwave surface-wave plasma chemical vapor deposition. For film deposition, helium and methane gases were used as plasma source. Bonding, optical and structural properties of the DLC films were measured both with and without using ferrocene as a catalyst. The ferrocene content in the DLC was confirmed by X-ray spectroscopy (XPS) measurement. The optical band gap decreased from 2.7 eV (without ferrocene) to 1.6 eV (with ferrocene). Raman spectra of the ferrocene content film shows that the G-peak was more pronounced compared to the film without ferrocene. Results suggest that appropriate concentration of ferrocene in DLC film helps to reduce the optical band gap because of ferrocene-induced graphitization.

The Editor has retracted the above article from its publication in Surface Review and Letters due to duplicate publication

Effects of buffer salt concentration on the rate of deposition, dominated deposition mechanism and subsequently the structural, morphological, and optical properties of cadmium sulfide (CdS) thin films deposited by chemical bath deposition (CBD) on glass substrate were investigated. The precursors were chosen to be cadmium chloride (CdCl₂) as the cadmium source, thiourea (CS(NH${}_2{)}_2$) as the sulfur source, ammonium nitrate (NH₄NO₃) as the buffer salt and ammonia as the complexing agent and the pH controller. The influence of the NH₄NO₃ concentration on the structure, morphology, film uniformity, stoichiometry and optical properties of CdS thin films was also studied by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX) spectroscope, uv–visible and photoluminescence (PL) spectroscopes. The XRD studies revealed that all the deposited films exhibited a (002)h/(111)c preferred orientation. The crystallite size was increased from 20nm to 30nm by the increase of concentration of NH₄NO₃ from 0.5M to 2.5M. The morphology of CdS thin films were agglomerated spherical particles consisted of smaller particles. The surface of thin films deposited at the NH₄NO₃ concentration of 0.5M was compact and smooth. The increase of the concentration of NH₄NO₃ decreased the packing density of the films. The optical band gap was in the range of 2.25–2.4eV, which was decreased by the decrement of packing density. The PL spectra showed two peaks centered at 400nm and 500nm which are attributed to violet and band-to-band emissions, respectively.

Europium-doped (0.01–0.04) Al${}_{0.8}$La${}_{0.2}$TiO₃ (AELTO) nanoparticles (NPs) series were synthesized using a hydrothermal method. These NPs were investigated for structural, and morphological studies through XRD, FTIR, FESEM and TEM analysis. Scherrer’s formula and Williamson–Hall (W–H) analysis were employed to determine crystallite size and lattice strain. The crystallite size was decreased with an increase in Eu content up to 0.03 wt.%. The surface morphology and percentage of elementals of AELTO NPs were investigated using FESEM with EDX as well as TEM analysis. The vibrational modes of AELTO NPs were attained by employing FTIR spectra. These modes are deferred mainly on chemical composition, crystallinity, morphology and strain of the AELTO NPs. Optical bandgaps of AELTO NPs were calculated and found to be in the range of 3.40–3.37eV with the increase of Eu content. These NPs could find potential applications for solid state lighting and down-shifter for solar energy harvesting.

Nanostructured zinc sulfide (ZnS) thin films were synthesized in polyvinyl alcohol matrix by chemical bath deposition and self-assembly techniques. ZnS nanostructured thin films show second harmonic generation (SHG) under irradiation with a pico-second Nd:YAG laser system and the second harmonic intensity is higher for self-assembled nanotree like structured ZnS thin film in comparison with that from chemical bath deposited thin film. Under nanosecond laser pulses, thin films possess good saturable absorption behavior. The optical bandgap and visible luminescence also get enhanced.

Optically good quality Diglycine Perchlorate (DGPCL) single crystals were grown by the solution growth slow evaporation method. Single crystal X-ray diffraction of DGPCL was analyzed in this paper. From the FTIR study, the functional groups of crystal were identified and confirmed. UV–Vis absorption spectrum was examined, which shows that large transmittance in the entire visible and NIR region and the value of optical band gap were determined. The Second Harmonic Generation efficiency of the crystal was determined by the Kurtz–Perry powder method, which authenticates nonlinear optical property of the title material. Thermal study with kinetic parameter calculations was analyzed. Laser Induced Damage threshold of the sample crystal was determined. The dielectric study was carried out by determining dielectric constant, dielectric loss and ac conductivity using LCR meter and the variations of these parameters with frequency and temperature were analyzed.

The optical and electrical studies on ZnO thin film are reported. Thin film of ZnO is deposited on glass substrate by physical vapor deposition method. In this method, Zn powder is evaporated at a temperature of 400°C in the presence of oxygen and argon gases, and the resulting ZnO is deposited on the glass substrate which is kept at liquid nitrogen temperature. The crystallinity of this ZnO film is studied using XRD technique. The XRD pattern suggests that the nature of this film is polycrystalline. The prominent peaks observed at 31.78, 34.34, 36.18, and 56.32 correspond to the (100), (002), (101), and (110) planes, confirming the formation of hexagonal zinc oxide phase (JCPD 36-1451 for wurtzite zinc oxide). The XRD spectrum very clearly demonstrates that the film deposited in oxygen atmosphere has a dominant (101) orientation. The d_hkl values are estimated for this as-deposited ZnO thin-film. It is observed that these calculated values in close agreement with the reported d_hkl values for ZnO. Debye–Scherrer equation is used to estimate the size of these nanoparticles. It is found that size estimated by Debye–Scherrer equation agrees well with the size observed by TEM images. It is clear from the transmission electron microscope (TEM) images that the film contains nanoparticles of ZnO and the diameter of these nanoparticles varies from 5–20 nm. In optical properties, the UV visible spectrum of these nanoparticles is recorded in the wavelength range (300–900 nm). The absorption coefficient increases exponentially with the increase in photon energy. The direct optical band gap is calculated which comes out to be 3.54 eV. The value of Urbach energy (E_U) is also calculated using the slope of the plot ln α versus photon energy and it comes out to be 805.8 meV. For electrical properties, the DC conductivity of ZnO film deposited on glass substrate is measured in the temperature range of 450–300 K. On the basis of temperature dependence of DC conductivity of ZnO film, it is suggested that the conduction takes place via thermally activated process.

In the present work, Zinc–Tin–Oxide (ZTO) thin films were deposited on glass substrate with varying concentration (ZnO:SnO₂-100:0, 90:10, 70:30 and 50:50 wt.%) at room temperature by flash evaporation technique. These deposited ZTO film were annealed in vacuum to study the thermal stability and to see the effects on the structural and optical properties. The XRF spectra revealed the presence of Zinc and Tin with varying concentration in ZTO thin films. XRD results show the crystallinity of the ZTO films was improved with increasing the concentration of SnO₂ and post annealing. The surface composition and oxidation state were analyzed by X-ray photoelectron spectroscopy. The variation of % composition shows as the concentration of SnO₂ increases from 0 to 50%, the atomic ratio of Sn/Zn and O/Zn increases for both types of ZTO films and deficiency of oxygen has been appeared after annealing. The optical band gap was also found to be decreased for both types of films with increasing concentration of SnO₂.

With a view to understand the influence of nanometric size on various properties of nanocrystalline Zn_0.9Ni_0.1O diluted magnetic semiconductors, a systematic investigation has been undertaken. Samples were prepared for the first time by hydrazine assisted polyol method and are post annealed in air at different temperatures to vary the crystallite size. From the Rietveld refinement of XRD data, the isotropic crystallite size values are found to be in the range, 15–42 nm. Further, the phase analysis of Rietveld refined XRD data, FT-IR and optical absorbance spectral studies revealed that all the samples are having hexagonal wurzite structure without any detectable impurity phases. From AFM topography studies, it has been found that the surface condition of the grains and their distributions clearly depend on the nano size of the materials. From the PL measurements, the local defects of the materials were explored. From magnetization studies which were carried out by using VSM and MFM techniques, it has been found that all the samples are found to exhibit a clear ferromagnetic hysteresis behavior at room temperature without any magnetic clusters. Finally, electrical properties were also undertaken at room temperature to understand the variation of magnetic behavior as a function of nanometric size of these materials.

Iron-doped lead sulfide thin films were deposited on glass substrates using successive ionic layer adsorption and reaction method (SILAR) at room temperature. The X-ray diffraction pattern of the film shows a well formed crystalline thin film with face-centered cubic structure along the preferential orientation (1 1 1). The lattice constant is determined using Nelson Riley plots. Using X-ray broadening, the crystallite size is determined by Scherrer formula. Morphology of the thin film was studied using a scanning electron microscope. The optical properties of the film were investigated using a UV–vis spectrophotometer. We observed an increase in the optical band gap from 2.45 to 3.03eV after doping iron in the lead sulfide thin film. The cutoff wavelength lies in the visible region, and hence the grown thin films can be used for optoelectronic and sensor applications. The results from the photoluminescence study show the emission at 500–720nm. The vibrating sample magnetometer measurements confirmed that the lead sulfide thin film becomes weakly ferromagnetic material after doping with iron.