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Öğe Annealing time effect on the optical properties of Zn(O,OH,S) films onto ZnO seed layer under un-vacuum ambient(2018) Özütok, Fatma; Yakar, EminIn this study, Zn (O,OH,S) films were synthesized onto ZnO seed layers by chemical bath deposition, which wereannealed at 500 °C. The differences of structural, morphological and detailed optical properties of the films wereinvestigated depending on the annealing time (between 30 min. and 90 min.). While samples of 30.min and 90 min.showed decomposed structures, sample of 60 min. showed different dimensions of nano-flower structures. Althoughall films had ZnO-hexzagonal crystal structure, the most obvious ZnS-related peaks were observed in the sample of90 min. Optical absorption edge was shifted at 362 nm from Uv-Vis spectroscopy. Although ZnO, Zn(OH)2 vibrationrelated peaks were so sharp, ZnS vibration peaks were so weak for all samples from FTIR. The PL intensities weredifferential depending on the annealing time but defect state-corresponding peaks were similar for each films.Öğe Determination of Structural and Optical Properties of Zn1-xCuxO Nanoparticles by Chemical Bath Deposition Waste Recovery Technique(2023) Yakar, EminThe present study was conducted to obtain Cu:ZnO nanoparticles by precipitation technique from chemical bath deposition wastes and to characterize the samples by various techniques to determine their size, morphology, band gap and defect energy states. In this work, Zn1-xCuxO nanoparticles (x= 0.025, x=0.050, and x=0.075) were synthesized by co-precipitation technique using chemical bath deposition wastes of Cu:ZnO thin films. The XRD evaluation showed that the well-crystalline hexagonal wurtzite ZnO indexed peaks. Average crystallite sizes were found to be around 35.6-42.9 nm range by using the Debye-Scherrer equation. Surface mor- phology results showed that dense layer of nano-roses and less nanorods formations in low Cu-concentrated (x=0.025 and x=0.050) samples. The optical absorption edge shifted slightly to the higher wavelength from 350 nm to 375 nm with decreasing copper concentration, as mentioned the blue shift. Blue shift might be caused an increase in optical band gap from 3.14 eV to 3.28 eV due to the decrease in Cu concentration. In this study, the preferred co- precipitation technique was performed by using the wastes of chemical bath deposition. This work aims to produce high quality Cu:ZnO nanoparticles and investigate their optical properties by using “Chemical Bath Deposition” wastes of Cu:ZnO films. In this way, the recovery of chemical bath deposition waste and the production of thin films and nanoparticles from a single solution might be possible.Öğe Developing Novel Materials to Increase Opacity Performance of the CaOAl2O3-SiO2 System in Ceramic Coatings(2019) Çırpın, Arife; Yakar, EminThe era we live in is the age of rapid changes. Turkey is a developing country with increasingneeds. As in other countries, the main axis of development inevitably constitutes theconstruction sector. This motivation is a common for the ceramic industry; however it shouldbe focused on the whitening agents used on ceramic tiles with the view of their contributionon the cost including imported ingredients. In this study, a novel whitening agent isformulated by introducing native raw material compositions to reduce costs in ceramic tilesproduction. To characterize the whitening agent, chemical structures of the raw materialswere firstly carried out with particle size, X-ray diffraction (XRD), and X-ray fluorescence(XRF) analyses. Zircon, aluminum and silicon oxide were obtained based on the regardingchemical analyzes in the content of introduced raw materials. In addition, the XRD analysisreveals that grain sizes of zircon, corundum, spinel (Li, Ti), baddeleyite and gibbsite are inbetween 1.50-2.00 µm.Öğe Development and characterisation of olive oil based spreads containing different seasonings(Innovhub Ssi-Area Ssog, 2023) Ogutcu, Mustafa; Albayrak, Elif (Dincer); Cokay, Hatice; Yakar, EminThe main objective of the present study was to produce olive oil-based table spreads enriched with different spices by using the organogel technique and to investigate the effect of spices on the oleogel network formed by the self-assembly of natural waxes. For that reason, the oleogels were prepared with sunflower wax, beeswax and shellac wax, and enriched with poppy seeds, thyme, lemon peel, mint, and their physico-chemical, thermal, textural and structural properties were determined. In order to determine the storage stability, peroxide, acid and colour values were monitored during 90 days of storage at +4 degrees C. The sunflower oleogels with and without additives had higher oil binding capacity, firmness and stickiness values than the beeswax and shellac wax oleogels. The sunflower and shellac wax oleogels had peaks around 3.70 and 4.10 A that indicated presence of beta prime polymorphic form. Both enriched and plain oleogels prepared with sunflower wax remained stable even at the end of the storage period at 5% wax addition level. Similar results were observed in the beeswax and shellac wax oleogels without spices. Particularly, the oil-binding capacity, stability, firmness and stickiness values of the oleogels were influenced by spice addition. In conclusion, sunflower wax was found to be more suitable than beeswax and shellac wax for the formation of oleogels with additives, such as spices, at 5% wax addition level.Öğe Effectiveness of different packaging films and trays on mushrooms (Agaricus bisporus) subjected to simulated transportation conditions at different vibration frequencies(Wiley Periodicals LLC., 2021) Özturk, Mehmet; Yakar, Emin; Temizkan, Rıza; Aday, Mehmet SeçkinThis study aimed to determine the different vibration frequencies (4, 8, 12, and 16 Hz) and packaging trays and films (Polypropylene trays + microperforated films (MP) and Polystyrene foam trays + polyvinyl chloride stretch films (PVC)) effects on mushroom quality. The quality of the mushrooms in MP was reduced with the increment in the frequency, whereas the effect of the frequency was only detrimental in the mushrooms packaged with PVC at 16 Hz. Oxygen concentration reached the equilibrium state at the level of 15% in PVC and 9% in MP groups. The whiteness index of mushrooms in MP was between 25 and 40, whereas it was around 20-30 in PVC films. However, changes in electrolyte leakage, pH, and hardness were minimal in the mushrooms packaged with PVC. As a result, PVC stretch films reduced the effect of transport frequencies, however, the optimal gas concentrations for mushrooms were only achieved using MP films. Practical applications In this study, effects of different packaging films, and trays were studied on mushrooms (Agaricus bisporus) which were subjected to simulated transportation conditions at different vibration frequencies. Foam trays with PVC films reduced the effect of transportation damage. Transportation damage in MP packages observed to be increased with the rise in the frequency. MP films helped to achieve the desired gas composition inside the packages.Öğe Facile synthesis and electrochemical properties of Prussian Blue/MWCNT and PB/WO3 films(Bulgarska Akademiya na Naukite, 2021) Yakar, EminIn this study, Prussian Blue (PB)/MWCNTs and PB/WO3 nanocomposite films were deposited onto In-SnO2 (ITO) substrates by a simple chemical bath deposition method. The structural, morphological, and electrochemical properties of PB/MWCNTs films were systematically investigated in detail. Removing influence of ITO, it was evident that both of the patterns could be indexed in the cubic PB phase, from X-ray diffraction analysis. While intense tubular carbon and agglomerative formations were detected in PB/MWCNTs films, cubic PB and spherical WO3 forms were depicted in PB/WO3 films. Average particle sizes (D) of MWCNTs (5.8 nm) were smaller than WO3 (10.5 nm) due to improved particle growth process as shown in this work. Raman analysis proved the production of PB structures. Typical Prussian Blue ν(CN) and stretching vibration of Fe-C at 2159 cm-1 and 507 cm-1 were observed, respectively. Improved electrochemical performance of PB/MWCNTs electrodes was indicated compared to PB/WO3 electrodes.Öğe Identification of intrinsic deep level defects responsible for electret behavior in T1GaSe2 layered semiconductor(Elsevier, 2016) Seyidov, MirHasan Yu; Mikailzade, Faik A.; Uzun, Talip; Odrinsky, Andrei P.; Yakar, Emin; Aliyeva, Vafa B.; Babayev, Sardar S.Unusual behavior of pyroelectric current signal polarity near the Curie point ( T-c) was observed for TIGaSe2 a ferroelectric-semiconductor. It has been revealed that the polarity of the spontaneous polarization near T-c depends on the sample poling prehistory. In particular, applying an external electric field only in the temperature range of the paraelectric state during cooling regime in darkness brought to the depolarization current at I with the sign opposite to the external field polarity. Otherwise, if the sample was poled in the temperature interval of the incommensurate phase, pyroelectric current exhibits a peak at T-c with the polarity that is the same as for the external poling electric field. These observations indicate that internal electric field is present in the bulk and near-surface layer regions of the electrically poled single crystal TIGaSe2. Possible mechanisms and origins responsible for the internal electric fields in TIGaSe2 are discussed. It is shown that the formation of internal electric fields in TIGaSe2 is due to charging of intrinsic native defects during the poling process. Characteristics of electrically active intrinsic defects in TIGaSe2 were investigated by using of Photo-Induced Current Transient Spectroscopy (PICTS) technique. Six deep defect levels in the band gap of TIGaSe2 were determined, which were localized both in the bulk and on the surface of the sample and could be electrically charged. The correlation between polarization effects and PICTS results has been established. It was shown that native deep defects (A3-A6) localized in the bulk of crystal are responsible for hetero-charge formation and negative sign of the pyroelectric current peak observed around the Curie temperature after poling the sample in the temperature intervals well above I. It was also shown that the positive sign pyrocurrent observed near the Curie point is attributed to the homo-charge formed by native A2-trapping centers which are localized near the surface region of TIGaSe2. Native deep level trap having an activation energy of 0.26 eV and the capture cross section of 2.8 x 10(-13) cm(2) were established for A2 from PICTS measurements. (C) 2015 Elsevier B.V. All rights reserved.Öğe Investigation of Ferromagnetism and Growth Correlation ofTransition Metal Doped ZnO(2021) Sarf, Fatma; Aşıkuzun, Elif; Yakar, EminIn this study, a series of 3d transition metal (TM) (Co, Ni and Fe) doped ZnO particles synthesized by simple co-precipitation method. Structural, morphological and magnetic properties were investigated to determine correlation between growth process and ferromagnetism of metal doped ZnO samples. All samples had ZnO hexzagonal würtzite structure and slightly shift of ZnO indexed peaks was observed by TM incorporation in ZnO. Although ZnO samples had granular forms, agglomerative forms had emerged in TM:ZnO samples due to the fast growth process. The pure ZnO sample transformed paramagnetic to ferromagnetic by TM incorporation due to carrier mediated exchange interaction between TM ions. The results demonstatedthat doping with Fe3+ ions in ZnO structure had enhanced ferromagnetism although fast growth and high particle agglomeration.Öğe Investigation of H2S gas sensing performance of Ni:WO3 films at room temperature: nickel precursor effect(Springer, 2022) Er, Irmak Karaduman; Sarf, Fatma; Yakar, EminIn this work, pure and nickel-doped WO3 films were produced by chemical bath deposition on In-doped SnO2 (ITO) substrates without annealing process. To synthesize the Ni:WO3 films, two different types of nickel precursors were used as NiSO4 and NiCl2. The influence of Ni doping using different Ni precursors on the structural, morphological, optical, and gas sensing properties of WO3 films toward H2S gas was investigated in detail. All samples have monoclinic WO3 polycrystallization where a substitution of Ni2+ ions with W6+ mi olmali ions is detected from the slight shift in x-ray diffraction patterns with the Ni doping process. With nickel chloride source, the synthesized Ni:WO3 samples exhibit nano-ball shapes with different dimensions on the film surfaces. Optical band gap energy severely decreases with nickel doping due to increasing oxygen vacancies, especially when nickel chloride is used as a precursor source in Ni:WO3 samples. Ni2+ ions introduction in WO3 host lattice has improved H2S gas detection capability; however, the biggest positive effect came from the NiSO4 precursor with increasing solubility and improved growth process. The response to 50 ppb H2S gas at room temperature was calculated as 7%, 11%, and 23% for pure WO3, NiCl2-based Ni:WO3, and NiSO4-based Ni:WO3 sensors, respectively. When the gas selectivity property was studied for NiSO4-based Ni:WO3 sensors, they showed more selectivity against H2S gas compared to H-2, benzene, methanol, etc. It is found that precursor type has an incredible impact on the H2S, reducing gas sensing properties in doped metal oxide gas sensor applications.Öğe Kompleks Etken Madde Oranına Bağlı Olarak ZnFe2O4 Filmlerin İncelenmesi(2018) Sarf, Fatma; Yakar, EminSon yıllarda spinel ferrit malzemeler (MFe2O4; M= Fe,Ni,Co,Mg vb.) oldukça farklıalanlarda, örneğin indüktörler, manyetik sensörler, magneto-optik depolama ve kayıt cihazlarıvb., kullanımı ile dikkat çekmektedir. Spinel ferrit malzeme grubu içerisinde yer alanZnFe2O4 (çinko-ferrit) yüksek direnci, mekanik stabilitesi ve düşük dielektrik kayıpları ileözellikle yüksek frekans uygulamalarında karşımıza çıkmaktadır. Basit sentezlenme sürecineve düşük üretim/güç maliyetine sahip ZnFe2O4 malzemelerine olan ihtiyaç bu yöndekiaraştırma ve geliştirme çalışmalarını arttırmaktadır.Bu çalışmada çinko-ferrit filmleri kimyasal banyo depolama ile ITO alttaşlar üstüne farklıoranlarda kompleks etken madde kullanılarak sentezlenmiştir. Kompleks etken madde olarakamonyak tercih edilmiştir. Filmlerin amonyak oranına ve dolayısıyla çözeltinin pH’ına bağlıolarak değişen yapısal, yüzeysel ve optik özellikleri sırasıyla XRD, SEM ve Uv-Vis/Ramanspektroskopisi ile incelenmiştir. XRD spektrumlarından elde edilen veriler ışığında, kristalleşmenin amonyak oranı artışı ile birlikte arttığı tespit edilmiştir. SEM-yüzey morfoloji görüntüleri ile amonyak oranı değişiminin farklı biçimlerde nanoparçacıklar oluşumuna sebepolduğu gözlenmiştir. Ayrıca filmlerin optik özelliklerinin amonyak oranı artışı ile iyileştiğitespit edilmiştir.Öğe Optical and Electrical Characterization of Crystallized M:$WO_3$ (Cu, Fe, Ni) Films in Acidic Medium(2024) Yakar, Emin; Er, Irmak Karaduman; Sarf, FatmaPure and metal (M) doped [copper (Cu), nickel (Ni) and iron (Fe)] $WO_3$ films have been produced on In:$SnO_2$ (ITO) slides by using facile chemical bath deposition and then annealed at 500 oC for 2 h. Structural, morphological, electrical and optical properties of the produced $WO_3$-based films were examined. Monoclinic $WO_3$ phase were observed in all the samples, and the peak intensities were decreased by metal inclusion with heterogeneous film growth on ITO substrate. Slight shifts from defect related emission peaks (blue and green) were observed in metal-substituted $WO_3$ samples from PL study. An optical band gap was observed to decrease in M:$WO_3$ samples. The surface resistance values were significantly reduced by metal additives compared to its pure counterpart, especially by the inclusion of nickel ions in $WO_3$. The results indicated that nucleus growth and thereby impurity/defect-related surfaces had a serious effect on the optical and electrical properties of M:$WO_3$ films.Öğe Optical and Electrochemical Properties of PB-ZnO and PB-ZnO/MWCNT Nanocomposite Films Deposited by Chemical Bath(Int Information & Engineering Technology Assoc, 2018) Ozutok, Fatma; Yakar, EminThe first aim of this study was to investigate the ZnO modification effect on the prussian blue (PB) films. A second aim of the study was to determine the decoration effect of multi walled carbon nanotube (MWCNT) on the PB-ZnO nanocomposite films which could be deposited by chemical bath. The electrochemical behaviour of PB films was systematically studied using ZnO-orZnO/MWCNT modification. Additionally, detailed optical properties of nanocomposite films were determined by UV-VIS, FTIR and Raman spectroscopy. Optical transparency was severely decreased by ZnO modification onto PB film but the decoration of MWCNTs did not change the optical transparency of film compared to PB film. PB, ZnO and MWCNT presence in the nanocomposite films were proven by FTIR spectrum. Stretching vibration peak of C=N shifted to short-wavelength for PB-ZnO nanocomposite films and same peak disappeared with MWCNT coating due to the structural distortion. ZnO modification and MWCNT coating affected the electrochemical properties due to the different factors such as OH-group effect in film growth process, Zn2+ substitution with Fe2+ site and interaction between ferricyanide ions and oxygen.Öğe Potasyum Katkılamanın Ag:ZnO Filmlerinin Yapısal Özellikleri Üzerine Etkisinin İncelenmesi(2022) Sarf, Fatma; Yakar, EminBu çalışmada, Ag:ZnO ve Ag-K:ZnO filmleri basit ve efektif bir üretim tekniği olan kimyasal banyolama tekniği ile ZnO gövde tabakalar üzerine sentezlenmiştir.Filmlerin yapısal özelliklerinin detaylı şekilde incelenmesinin yanı sıra yüzey pürüzlülük değerleri hesaplanmış ve örneklerin Raman spektrumu incelenmiştir. Tüm filmler hekzagonal würtzite ZnO kristal yapısına sahiptir. Ag katkılaması ile tane büyüklüğü µm mertebesinden 36 nm’ye azalmış ve ZnO kristalleşmesi iyileşmiştir. Buna karşın, K+ iyonlarının yapıya girmesiyle tane büyüklüğü nispeten azalmasına karşın (32 nm) ZnO kristalleşmesi ciddi biçimde bozunmuştur. Yüzeyde nanoparçacıkların oluşumuna ve yüzey pürüzlülük değerlerinde azalmaya potasyum katkılamanın etkisi olduğu gözlenmiştir. Numunelerde gözlenen farklı şiddette tüm zirveler, ZnO würtzite yapısının Raman modlarından bazıları ile eşleşme göstermiştir. Elde edilen sonuçlardan, gerek tekil (Ag) gerek ise ikili (Ag-K) katkılamayla beraber, ZnO yapısındaki kusur yoğunluklarının artması ve değişmesi nedeniyle, kristal yapı ve yüzey dağılımında bozulma meydana geldiği düşünülmektedir. Ancak potasyum atomlarının Ag:ZnO yapısına girmesi ile fiziksel ve kimyasal özellikler üzerinde iyileştirici etkisi saptanmıştır.Öğe Production and Characterization of ZrO2-Al2O3-K2O Based Ceramic Whitening Agents(Springer, 2022) Cirpin, Arife; Yakar, EminZircon-containing whitening agents are indispensable components increasing the cost of ceramic tiles. In the ceramic industry, the developing of unique and low-cost whitening agents with comparable final product quality is an essential motivation. In this study, a unique ZrO2-Al2O3-K2O-based whitening agent was developed by mixing zircon silicate, Al2O3, K-feldspar, and marble with various weight concentrations to reduce costs and give a valid alternative to the commercially available R6-coded ZrO2-Al2O3-Na2O whitening agent. To test the innovative ZrO2-Al2O3-K2O-based whitening agent's efficiency, a systematic characterization procedure was utilized to reveal factors affecting the tile opacity, including size, shape, and distribution of opacifier particles and the incident light wavelength. First, x-ray diffraction and x-ray fluorescence analyses examined the initial grain sizes and structural properties of the whitening agent constituents. Second, a wet milling process in industrial mills was utilized to produce a homogenized ZrO2-Al2O3-K2O-based composite whitening agent. Structural, mineralogical, and morphological properties of the final product were determined after the drying process. The efficiency of the wet milling process was proved according to scanning microscopy analysis revealing homogenous particle size distribution of constituents with mainly composed of ZrO2, Al2O3, and SiO2 phases. Energy dispersive x-ray analysis reveals that Si-Al-O-Zr and Ca were major elements whereas Na was obtained as minor element.Öğe Substrate critical effect on the structural and H-2 Gas sensing characteristics of solution-processed Zn0.075Cu0.025O films(IOP Publishing, 2021) Sarf, Fatma; Er, Irmak Karaduman; Yakar, Emin; Acar, Selim; Yakar, EminIn this study, we report the synthesis of Zn0.075Cu0.025O films by chemical bath deposition to determine the effect of substrate (glass slide or ZnO seed layer) on the structural and H2 gas sensing properties of the produced films. The crystal phase, structural topography, surface morphology, and functional groups of the as-synthesized films as well as H2 gas sensing properties were investigated. Although both films have a hexagonal wurtzite structure, ZnO seed layer-based Zn0.075Cu0.025O film is more crystalline than glass slide-based Zn0.075Cu0.025O films. ZnO seed layer-based Zn0.075Cu0.025O films exhibited much more nanorod and fewer nanosphere forms compared to glass slide-based Zn0.075Cu0.025O films. EDX analysis and Raman spectra of both samples confirmed the presence of defects in Cu: ZnO samples. ZnO seed layer-based sensors showed higher response (140%) and lower operating temperature (80 °C) compared to glass slide-based sensors(87% response and 140 °C operating temperature). The most important thing to note here is that the fabricated sensors exhibited a high response at room temperature. The responses at room temperature were found as 46% and 23% for the ZnO seed layer-based and glass slide-based sensors, respectively. Sensors operating at room temperature are especially important for commercial applications.Öğe Surface dynamics and electrochemical examination of Co3O4 films by iron doping(Iop Publishing Ltd, 2024) Yakar, Emin; Sarf, Fatma; Bayirli, Mehmet; Ilgaz, AykutThis study focused on Co3O4 films, which were prepared by cost-effective chemical bath deposition on In:SnO2 (ITO) substrates with iron doping concentrations ranging from 2 to 6 mol %. Structural properties were investigated by XRD as well as nanotexture of Fe: Co3O4 films was captured via SEM and detailed fractal analysis was analyzed in each prepared film. Effective using of prepared Fe: Co3O4 electrodes for electrochemical charge storage applications has been examined by using CV and EIS. From x-ray patterns, spinel cubic structure of Co3O4 was observed in all samples, while peaks with Co(2)O(3 )and substrate indexed peaks were also shown. Pure and iron doped Co3O4 surfaces have spherical agglomerative forms while porous structures were observed in 4% Co3O4 samples. Redox peaks induced by Faradaic reactions in the CV plots present pseudo- capacitive nature for all electrodes and improves charge transfer process in 4% Co3O4 and 6% Co3O4 from EIS measurements. Additionally, using scaling theory, the coverage ratio, fractal dimensions, cluster sizes and interface critical exponent values of the superficial hetero morphology of the samples are calculated. While the coating rate decreases according to the iron concentration, fractal dimensions increase. However, as the number of clusters increases, the average cluster size decreases. The interface critical exponent value shows an irregular change.Öğe The role of rare-earth metal (Y, Ru and Cs)-doped ZnO thin films in NH3 gas sensing performances at room temperature(Springer, 2020) Sarf, Fatma; Er, Irmak Karaduman; Yakar, Emin; Acar, SelimPure and rare-earth metal [Yttrium (Y), Ruthenium (Ru) and Caesium (Cs)]-doped ZnO thin films were deposited onto In-doped SnO2 substrates by chemical bath deposition. The present study detailed investigated the effect of rare-earth metal-doped ZnO on NH3 gas sensing. X-ray diffraction analysis indicated that the incorporated rare-earth metal ions substitute Zn sites in the ZnO lattice. Dimension of ZnO films decreased with rare-earth metal doping which detected from surface morphology images. The response of 100 ppb NH3 gas was calculated to be 0.80 (200 degrees C), 14.00 (90 degrees C), 17.00 (50 degrees C), and 10.00 (120 degrees C) for the pure, Y-, Ru-, and Cs-doped ZnO films, respectively. In addition, the response of 15 ppm NH3 gas at room temperature was calculated to be 0.20, 27.00, 57.00, and 18.00 for undoped Y-, Ru-, and Cs-doped ZnO films, respectively.Öğe Varying electrical and dielectric properties of Ni:SnO2 films by MWCNTs and GNPs coating(Iop Publishing Ltd, 2022) Sarf, Fatma; Er, Irmak Karaduman; Ajjaq, Ahmad; Cagirtekin, Ali Orkun; Yakar, Emin; Acar, SelimIn this research, pure SnO2 and Ni-doped SnO2 (Ni:SnO2) nanocomposite films were produced by chemical bath deposition method and the latter were coated with multi-walled carbon nanotubes (Ni:SnO2/MWCNTs) or graphene nanoplatelets (Ni:SnO2/GNPs) by spin coating. All samples have tetragonal rutile SnO2 structure with the presence of carbon (002) peak in MWCNTs- or GNPs-coated films. Crystallite size of SnO2 films decreased remarkably with Ni doping followed by a slight decrease with MWCNTs coating and slight increase with GNPs coating. Scanning electron microscope images manifested a dispersed agglomerative nature of SnO2 nanoparticles which reduced especially with MWCNTs coating due to the porous surface provided by carbon nanotubes. From the photoluminescence measurements, oxygen defects-related peaks were spotted in the SnO2-based structures with different luminescence intensities. The most significant decrease in resistance was observed with the addition of GNPs into Ni-doped SnO2 nanocomposites compared to the other produced films mainly due to the synergetic effect that promotes excellent charge transfer between surfaces of Ni:SnO2 and graphene nanosheet. The huge increase in conductivity of GNPs-coated films led to a huge increase in dielectric losses and this followed by a drop down of dielectric constant of the GNPs-coated films.
