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Monica Nedelcu

Bio: Monica Nedelcu is an academic researcher. The author has contributed to research in topics: Fourier transform infrared spectroscopy & Surface acoustic wave. The author has an hindex of 2, co-authored 2 publications receiving 14 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the structural changes in the molecular binding between ZnO and Ca, Fourier Transform Infrared spectroscopy (FTIR), Micro-Raman Spectroscopy and X-ray diffraction (XRD) were performed.
Abstract: ZnO thin films were synthesized using sol–gel method at 0.25 and 0.5 M molarity concentration. Moreover, the obtained thin films were Calcium-doped with 1 and 5 at% concentration. In order to investigate the structural changes in the molecular binding between ZnO and Ca, Fourier Transform Infrared spectroscopy (FTIR), Micro-Raman Spectroscopy and X-ray diffraction (XRD) were performed. The surface morphology and the chemical constituents distribution of the films were studied through Scanning Electron Microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and Atomic Force Microscopy (AFM), respectively. The optical and electrical properties were studied by UV–Vis spectroscopy, Spectral ellipsometry and electrical I–V measurements. The results show that the properties of prepared ZnO thin films were strongly influenced by the molarity concentration and Ca-dopant. The band shape obtained at FTIR is a band attributable to metal oxide bonds and can be attributed to the vibrational assignment of Zn–O bond. SEM-EDX and AFM investigations reveal an enlarged surface area due to the porous nature of the thin films and confirm the presence of Ca in the ZnO matrix. The XRD and Raman analyses indicate the achievement of the high crystalline quality and confirm the wurtzite phase of the synthesized thin films. The films transmittance spectra indicate values between 81 and 93% in the 350–800 nm wavelength region. We further performed I–V characteristics, resulting that Ca has a different impact of the electrical performances.

27 citations

Proceedings ArticleDOI
01 Oct 2013
TL;DR: In this paper, the authors presented experimental realization of shear horizontal surface acoustic wave (SH-SAW) sensor on Langasite (LGS) for mass detection in liquid media.
Abstract: This paper presents experimental realization of shear horizontal surface acoustic wave (SH-SAW) sensor on Langasite (LGS) for mass detection in liquid media. The presence of mycotoxins in food or pesticides in water supplies can produce grave implications on human health. Sensitive and selective sensors capable of quickly detecting the level of contamination with fungal toxins growing on grains in storage, are needed. Shear horizontal surface acoustic wave (SH-SAW) devices provide an attractive platform for the design of biosensors that operate in liquid media. The paper reports on a SH-SAW delay line designed and fabricated on langasite (LGS), Euler angles (0°, 22°, 90°). The SH-SAW devices have been fabricated using the microfabrication method by lift-off lithography process to define the patterns for the IDT structures. Frequency response of device was monitored using Anritsu vector network analyzer (VNA). A test setup was implemented for the characterization of LGS SH-SAW-based sensors.

4 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the effects of pH, Ca doping, light, ultrasound, and pH on the mineralization of tetracycline by Ca-doped ZnO nanopowders were systematically investigated.

45 citations

Journal ArticleDOI
TL;DR: In this article , the effects of pH, Ca doping, light, ultrasound, and pH on the mineralization of tetracycline by Ca-doped ZnO nanopowders were systematically investigated.

39 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of calcium on the structural, morphological, and optical properties of the resultant powders were investigated, and the XRD patterns showed that calcium has been incorporated into the ZnO lattice and the crystallites have nanometric size in the range of 50-nm.
Abstract: Ca-doped ZnO (CZO) nanopowders were synthesized via a simple sol–gel method. The effects of calcium on the structural, morphological, and optical properties of the resultant powders were investigated. The XRD patterns showed that calcium has been incorporated into the ZnO lattice and the crystallites have nanometric size in the range of 50 nm. TEM observations depicted that crystallites possess spherical shape and confirm the nanometric size. UV–Vis–NIR characterization revealed an absorption band in the UV range with a decrease in optical band gap from 3.24 to 3.2 eV with increasing Ca concentration. Pure ZnO- and Ca-doped ZnO nanoparticles were used as active layer and tested for their sensing performance to formaldehyde. The most performed prepared sensor exhibits good formaldehyde sensing properties, including a high response of 5.28 (5 ppm, 250 °C) and low detection limit (≤ 1 ppm).

23 citations

Journal ArticleDOI
TL;DR: In this paper, pure and doped ZnO thin films were prepared by sol-gel-based method and their electro-optical properties were investigated by using various techniques X-ray diffraction (XRD), EDS, and field emission scanning electron microscopy (FESEM).
Abstract: In this study, pure and doped ZnO thin films were prepared by sol–gel-based method and their electro-optical properties were investigated. For doping process, 1 at. % Al and Cu was incorporated in ZnO solution separately, and the thin films were prepared by dip coating method. The microstructure and morphology of calcined ZnO, Al-doped ZnO, and Cu-doped ZnO thin films were evaluated and compared by using various techniques X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and field emission scanning electron microscopy (FESEM). Results showed that nanostructured ZnO thin films with cross-linked nanoparticles (NPs) were formed, and the size of ZnO NPs increased with the Al and Cu doping. It was also found that the substitution and interstitial of Al and Cu dopants caused the instability of ZnO crystal structure and generation of extra point defects. Photoluminescence (PL) properties indicated that the dopants incorporation causes the decline of the PL intensity and the shift of the localized energy states of electrons and holes to lower energy levels. Evaluation of thin films in the UV–Vis range demonstrated that the transparency increased (>94%), and the band gap decreased to 3.08 and 3.06 eV with the incorporation of Al and Cu into ZnO thin films, respectively. The electrical conductivity also improved by Al and Cu doping of ZnO TFs.

21 citations

Journal ArticleDOI
01 Nov 2022-OpenNano
TL;DR: In this article , a thorough review of the use of selenium or silver doped ZnO NPs for photocatalytic and antibacterial objectives was conducted in this study.

10 citations