scholarly journals Optical Detection of VOC Vapors Using Nb2O5 Bragg Stack in Transmission Mode

Photonics ◽  
2021 ◽  
Vol 8 (9) ◽  
pp. 399
Author(s):  
Rosen Georgiev ◽  
Yoana Chorbadzhiyska ◽  
Venelin Pavlov ◽  
Biliana Georgieva ◽  
Tsvetanka Babeva

In this study, an emphasis is put on vapor-sensitive Bragg stacks as an important class of optical sensors. All-niobia Bragg stacks were deposited by spin-coating of sol-gel Nb2O5 thin films alternated with mesoporous layers after proper design through optimization of operating wavelength and number of layers in the stack. Mesoporous Nb2O5 films with different morphology and identical structure were obtained using organic templates (Pluronics PE6200 and PE6800) and subsequent annealing. Transmittance measurements were performed as a detection method that offers technological simplicity and accuracy. It was demonstrated that stacks including PE6200 templated films exhibit higher sensitivity than stacks templated with PE6800. It was assumed and verified by computer-aided modelling of experimental data that mesoporous films prepared with addition of PE6200, although less porous, were more stable compared to those templated with PE6800, and did not collapse during the thermal treatment of the stacks. Furthermore, the reproducibility of optical response was studied by sorption and desorption cycles of acetone vapors. The suitability of all-niobia Bragg stacks for optical sensing of VOCs was discussed.


2015 ◽  
Vol 815 ◽  
pp. 136-140
Author(s):  
S.H. Najamudin ◽  
H.Mohd Yusof ◽  
Ala’eddin A. Saif ◽  
R.A. Osman ◽  
P. Poopalan

— Barium titanate (BaTiO3) thin films are suitable for many application especially photonics. BaTiO3thin films are deposited using spin coating with an optimum spin speed of 4500rpm. The samples are then characterized using XRD, AFM and SEM. The results of the XRD analysis showed that both the 5-and 10-coated layers are polycrystalline BaTiO3with differences in terms of diffraction intensity, due to the number of layers. As for optical application, the surface roughness is the most crucial part. The number of layers of 5 and 10 have thickness of 2.927nm and 4.456nm RMS.



2016 ◽  
Vol 694 ◽  
pp. 120-124 ◽  
Author(s):  
Nurul Azuwa Azmi ◽  
Umar Al Amani Azlan ◽  
Maziati Akmal Mohd Hatta ◽  
Mohd Asyadi' Azam Mohd Abid ◽  
Mohd Warikh Ab Rashid

(K, Na)NbO3 (KNN) thin films were prepared by sol-gel technique. Spin coating deposition and rapid thermal annealing (RTP) process were applied to produce the KNN thin films. The films obtained demonstrated that highly crystallographic orientation was produced at five layer deposition with increase (preferred orientation) peak at (1 1 1). The thickness of five layers thin films observed by field emission scanning electron microscopy (FE-SEM) was determined to be ~200nm. However, the inhomogeneous distribution of KNN particles was detected in KNN thin films. The distribution of KNN elements was confirmed by energy-dispersive X-ray (EDX) spectra. Improvement was observed in resistivity (2.71-7.81x106 Ω.cm) and dielectric loss (0.35%-0.21%) following the increasing number of layers.



2020 ◽  
Vol 6 (2) ◽  
pp. 152
Author(s):  
Haris Munandar ◽  
Aris Doyan ◽  
Susilawati Susilawati

This research succeeded in creating a thin layer of SnO2 and SnO2: In+Al through a synthesis process with the sol-gel spin-coating technique on a glass substrate. The manufacture of this thin layer uses the basic material SnCl2.2H2O, and the doping material InCl3.4H2O and AlCl3. This thin layer is made with variations in doping concentration, number of layers, and heating temperature. The results of the synthesis of SnO2: In+Al films show that the thin film formed is more transparent when the doping concentration and the number of layers is increased. Meanwhile, the thin layer that forms is increasingly not transparent when heated at higher temperatures



2019 ◽  
Vol 5 (2) ◽  
pp. 175 ◽  
Author(s):  
Lalu Muliyadi ◽  
Aris Doyan ◽  
Susilawati Susilawati ◽  
Syamsul Hakim

A thin layer of tin oxide with doping Fluorine was synthesized using the sol-gel spin coating method. The synthesis aims to determine the quality of thin layers formed based on temperature variations and the number of layers. The basic material used is SnCl2.2H2O, while the doping material used is NH4F with variations in concentrations of dopants 0, 5, 10, 15, 20 and 25%. The substrate used is glass with a size of 10 x 10 x 3 mm. The synthesis of the thin layer includes substrate preparation, sol-gel making, thin film making, and heating process. At this stage SnO2:F is deposited on a glass substrate with sol-gel spin coating technique at the concentration of sol 1 M with doping levels of Fluorine 0, 5, 10, 15, 20 and 25%, and treated with maturation for 24 hours. Making a thin layer using a spin coater at a speed of 2000 rpm for 3 minutes. The layer made consists of one layer, two layers, three layers and four layers. The resulting layer shows that the higher the doping percentage, the higher the transparency of the layer. In addition, the more the number of layers, the lower the transparency level. Keywords: Thin Film, Tin Oxide, Fluorine, Sol-gel, Spin Coating



Author(s):  
Ayu Uswatu Lissa Sapta Setyadi ◽  
Yofentina Iriani ◽  
Fahru Nurosyid

<p class="AbstractEnglish"><strong>Abstra</strong><strong>ct</strong><strong>:</strong><strong> </strong>Preparation of Barium Titanate thin film (BaTiO3) has been done on Quartz substrate using sol gel method with spin coating technique. A thin film BaTiO3 wase made with a mole variation of 0.4 mol and 0.8 mol at a rotation speed of 3000 rpm. The samples were annealed at 400 ° C with 30 minutes stand-up time and at 900 ° C with 2 hours stand-up time and a heating rate of 5 ° C per minute. Characterization of optical properties samples was performed using UV-Vis spectrometers and characterization of microstructure samples using X-Ray Diffraction (XRD). The particle size was calculated by Scherer's formula. Based on the results of the analysis it was found that mole variation of the solution influenced the absorbance value, intensity, crystality level and BaTiO3 thin film particle size. The greater mole of BaTiO<sub>3</sub> solution the higher then absorbance value. The fewer then number of layers the greater then diffraction peak intensity. More number of layers the greater the level of crystallinity and particle size.</p><p class="KeywordsEngish"> </p><p class="AbstrakIndonesia"><strong>Abstra</strong><strong>k: </strong>Pembuatan lapisan tipis Barium Titanat (BaTiO<sub>3</sub>) telah dilakukan  diatas substrat Quartz menggunakan metode sol gel dengan teknik spin coating. Lapisan tipis BaTiO<sub>3 </sub>dibuat dengan variasi mol  0.4 mol dan  0.8 mol pada kecepatan putar 3000 rpm. Sampel diannealing  pada suhu 400<sup>o</sup>C dengan waktu tahan 30 menit  dan pada suhu 900<sup>o</sup>C dengan waktu tahan 2 jam dan kenaikan suhunya 5<sup>o</sup>C per menit. Karakterisasi sifat optik sampel dilakukan  menggunakan spektrometer UV-Vis dan karakterisasi struktrur mikro sampel menggunakan X-Ray Diffraction (XRD).Ukuran partikel dihitung dengan formula Scherer. Berdasarkan hasil analisis didapat bahwa variasi mol larutan mempengaruhi  mempengaruhi nilai absorbansi, intensitas, tingkat kekristalan dan ukuran partikel lapisan tipis BaTiO<sub>3</sub>. Semakin besar mol larutan BaTiO<sub>3 </sub>maka semakin tinggi nilai absorbansinya. Semakin sedikit jumlah lapisan maka intensitas puncak difraksi semakin besar. Semakin banyak jumlah lapisan maka semakin besar pula tingkat kekristalan dan ukuran partikel<em>. </em></p>



2021 ◽  
Vol 18 (2) ◽  
pp. 147-160
Author(s):  
Rohanieza Abdul Rahman ◽  
◽  
Muhammad AlHadi Zulkefle ◽  
Sukreen Hana Herman ◽  
Rosalena Irma Alip ◽  
...  

This paper presents the investigation of the thickness of the ZnO thin films by varying the number of deposition layers during the spin coating deposition process. ZnO thin films were deposited with a different number of layers (ranging from 1, 3, and 5), and the main purpose of this study is to explore the effect of the thickness on the properties of ZnO thin films. The deposited thin films were characterised using field emission scanning electron microscope, surface profilometer, and X-ray diffraction. From the characterisation results, the morphology of the ZnO thin films changed significantly with the number of layers and their thickness value. As expected, the thickness increased as the number of layers increased. The crystalline quality of the deposited film improved as the thickness increased. A change in crystallographic orientation was also observed in which the thicker, thin films showed crystal growth in the (102) direction, whereas the thinner one was in the (101) direction. A slight increase in crystallite size for dominant orientation also was observed with the increase of film thickness.



2000 ◽  
Vol 628 ◽  
Author(s):  
Mark A. Clarner ◽  
Michael J. Lochhead

ABSTRACTOrganically modified silica gels and dye-doped silica gels have been patterned into micrometer-scale structures on a substrate using micro molding in capillaries (MIMIC). This approach is from a class of elastomeric stamping and molding techniques collectively known as soft lithography. Soft lithography and sol-gel processing share attractive features in that they are relatively benign processes performed at ambient conditions, which makes both techniques compatible with a wide variety of organic molecules, molecular assemblies, and biomolecules. The combination of sol-gel and soft lithography, therefore, holds enormous promise as a tool for microfabrication of materials with optical, chemical, or biological functionality that are not readily patterned with conventional methods. This paper describes our investigation of micro-patterned organic-inorganic hybrid materials containing indicator dyes for microfluidic sensor applications. Reversible colorimetric pH sensing via entrapped reagents is demonstrated in a prototype microfluidic sensor element. Patterned structures range from one to tens of micrometers in cross-section and are up to centimeters in length. Fundamental chemical processing issues associated with mold filling, cracking and sensor stability are discussed.



2019 ◽  
Vol 7 (1) ◽  
pp. 28
Author(s):  
KOMARAIAH DURGAM ◽  
RADHA EPPA ◽  
REDDY M. V. RAMANA ◽  
KUMAR J. SIVA ◽  
R. SAYANNA ◽  
...  


Author(s):  
Atefeh Nazari Setayesh ◽  
Hassan Sedghi

Background: In this work, CdS thin films were synthesized by sol-gel method (spin coating technique) on glass substrates to investigate the optical behavior of the film. Methods: Different substrate spin coating speeds of 2400, 3000, 3600 rpm and different Ni dopant concentrations of 0 wt.%, 2.5 wt.%, 5 wt.%) were investigated. The optical properties of thin films such as refraction index, extinction coefficient, dielectric constant and optical band gap energy of the layers were discussed using spectroscopic ellipsometry method in the wavelength range of 300 to 900 nm. Results: It can be deduced that substrate rotation speed and dopant concentration has influenced the optical properties of thin films. By decreasing rotation speed of the substrate which results in films with more thicknesses, more optical interferences were appeared in the results. Conclusion: The samples doped with Ni comparing to pure ones have had more optical band gap energy.



2017 ◽  
Vol 623 ◽  
pp. 14-18 ◽  
Author(s):  
Fenglin Tang ◽  
Chao Mei ◽  
Peiyu Chuang ◽  
Tingting Song ◽  
Hailin Su ◽  
...  


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