Munk Method Research Articles

Production of GeOx Films at Different Oxygen Flow Rates and Different Annealing Temperatures and Examination of Energy Band Gaps using Kubelka Munk Method

In this study, GeOx films were grown on silicon substrates using the Radio Frequency (RF) Magnetron Sputtering method at different oxygen flow rates and annealing temperatures. The films were produced at a substrate temperature of 250°C and a working pressure of 13 mTorr. Subsequently, the films were annealed at temperatures of 300°C, 500°C, 600°C, 700°C, 900°C, and 1000°C. Total and diffuse reflection measurements were performed to investigate the optical properties of the films. Energy band gaps were determined using diffuse reflection measurements and they were calculated using the Kubelka-Munk method. It was observed that the energy band gap increased with increasing oxygen ratio. Additionally, annealing temperatures were found to cause changes in the energy band gaps.

Optoelectronic properties of BiCuOSe p-type oxychalcogenides

BiCuOSe systems are proposed as candidates to develop transparent p-type semiconductors in the visible region. This work reports the characterization results obtained for the BiCuOSe powders, synthesized by the solid-state reaction (SSR) method through mechanical milling, and nanostructured thin films deposited from the same processed powders using the pulsed laser deposition (PLD) technique. Structural characterization through X-ray diffraction (XRD) showed that the material presents a tetragonal structure with an average crystallite size of 21 nm and a preferential orientation in the (1 0 2) plane. The morphological and particle size evolution of BiCuOSe powders is presented as a function of the milling time. Transmission and scanning electron microscopies confirmed the spherical geometry of the particles in the powders and nanosheets like structure for the films. Particle sizes were also estimated, ranging from 10 to 100 nm for powders and 60 to 70 nm for films. The bandgap values, EG, for BiCuOSe powders were estimated from diffuse reflectance spectra using the Kubelka–Munk method, yielding values close to 0.7 eV. For thin films, EG values were estimated using the Tauc method, obtaining values in the range of 0.8–3.5 eV, depending on the annealing treatment. Additionally, electrical properties were measured in all deposited thin films, confirming the p-type conductivity, a minimal resistivity of 0.0735 Ω cm, hole mobility on the order of 88 cm2/Vs, and carrier concentration of 9.7 × 1018 cm−3.

Structural, Optical, Electrical, and Magnetic Characterization of PC/PEO Blend Incorporated with ZnFe2O4 Nanoparticles

In this study, zinc ferrite nanoparticles (ZnFe2O4 NPs) were incorporated into a polycarbonate/polyethylene oxide (PC/PEO) blend using the casting method. The resulting blends were subjected to comprehensive analysis using various techniques. X‐ray diffraction (XRD) analysis revealed that the presence of ZnFe2O4 nanoparticles had a significant impact on the crystal structure of the PC/PEO blend, leading to a reduction in crystallinity. Fourier‐transform infrared (FT‐IR) measurements further confirmed the uniform distribution and compatibility of PC and PEO as polymer components, as well as their compatibility with the blend containing ZnFe2O4 NPs. The optical properties of the PC/PEO blend, including band gap and Urbach energy, were quantified using the Kubelka–Munk method. The incorporation of ZnFe2O4 NPs resulted in the formation of sub‐band states between the valence and conduction bands, leading to a decrease in the band gap values. Field emission scanning electron microscopy (FESEM) analysis revealed a noticeable modification in the surface roughness, with the addition of ZnFe2O4 NPs resulting in a smoother surface texture. The electrical properties of the blends, including dielectric constant, dielectric loss, and AC conductivity, were measured. The addition of ZnFe2O4 NPs increased the dielectric constant (ε′) at lower frequencies, while it remained relatively stable at higher frequencies due to the localized charge carriers within the polymer blend. The higher values of ε’ observed at lower frequencies can be attributed to the movement of ions, which contributes to enhanced ionic conductivity. The magnetic properties of the blends were evaluated, demonstrating an increase in magnetic saturation upon the addition of ZnFe2O4 NPs. These findings provide valuable insights into the structural, optical, electrical, and magnetic characteristics of PC/PEO blends incorporated with ZnFe2O4 nanoparticles, thereby highlighting their potential for a wide range of technological applications.

Green synthesis of emerging ZnO and Ca-doped ZnO nanoparticles towards optical, magnetic properties and its antibacterial application

A green synthesis method is adopted to prepare emerging low cost ZnO (ZNP) and Ca substitute ZnO nanoparticles (CZNP) using Psidium guajava fruit (PGF) extract as an effective reducing and capping agent. An X-ray diffraction study of the synthesized nanoparticles revealed that they have a hexagonal wurtzite structure. The elemental compositions and oxidation states of ZNP and CZNP surfaces are quantified. The HRSEM image shows the nano-flake like structure of the synthesized nanomaterials ZNP and CZNP samples. The elemental compositions were identified using EDAX spectra. From the Raman spectra, the low wavenumber region of 2nd order Raman modes at 341 and 346 cm-1 were ascribed to the difference E2 high-E2 low. Kubelka–Munk (K–M) method is used for estimating direct band gap and it is 3.3 eV and 3.04 eV for ZNP and CZNP respectively. Due to the zinc and oxygen vacancies, six different bands were observed in the photoluminescence spectra. The TG analysis was observed 5.6% of weight loss for ZNP and 5.8% of weight loss for CZNP sample. The Magnetization–Field (M–H) hysteresis curves revealed the appearance of diamagnetic behavior at room temperature. The asfabricated pure ZnO and Ca-doped ZnO nanoparticles were evaluated for the antibacterial activity. The Ca substituted ZnO sample showed higher antibacterial activity than pure ZnO sample.

Composite Fayalite with 5% Laterite Soil and Iron Sand: Structural Properties and Band Gap Calculation Based on Theoretical Kubelka–Munk, Taylor Expansion, and Self-Consistent Field Method

Composite Fayalite with 5% Laterite Soil and Iron Sand: Structural Properties and Band Gap Calculation Based on Theoretical Kubelka–Munk, Taylor Expansion, and Self-Consistent Field Method

Effect of the zinc substitution on the physical and optical properties of tellurium vanadate glasses

In this communication, we report the physical and optical properties of xZnO-(60-x)TeO2-40V2O5 (x = 20, 25, 30, 35, and 40 mol%) glass systems. The glasses were prepared using the melt-quenching method. The amorphous nature of the glass systems was confirmed using powder X-ray diffraction. We have elucidated the changes in the rigidity and elastic moduli of the glass system as a function of composition. These changes were measured in terms of changes in the physical parameters like density, molar volume, and packing density of the glasses. The elastic moduli of the glass systems, like Young's modulus, bulk modulus, shear modulus, longitudinal modulus, and Poisson's ratio, were estimated using Makishima-Mackenzie's theory. The changes in the elasticity of the present system were correlated with the structural changes occurring in the glasses by adding ZnO at the expense of TeO2. The optical properties of the glass system were found by means of diffuse reflectance spectroscopy. Using Kubelka Munk method, the corresponding band gap energy and Urbach energy of the glass system were estimated. The present investigation sheds light on understanding the concentration effect of ZnO in the glass network.

AlInN/AlN HEMT’in Detaylı Optik Özellikleri

In this study, the optical properties of AlInN/AlN high electron mobility transistor (HEMT) structure, grown on c-oriented sapphire with Metal-Organic Chemical Vapor Deposition (MOCVD) technique, being investigated. Optical characterization is made Kubelka- Munk method. Transmittance, absorbance, and reflectance are investigated in detail. Also, the Kubelka-Munk theory is employed to determine the forbidden energy band gap of InN by using special functions. The energy band gap obtained by this method was compared.

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

A comparative study on NiFe2O4 and ZnFe2O4 spinel nanoparticles: Structural, surface chemistry, optical, morphology and magnetic studies

A comparative investigation of the structural, optical, and magnetic properties of NiFe2O4 (NFO) and ZnFe2O4 (ZFO) spinel nanoparticles were synthesized by microwave combustion method. X-ray diffraction (XRD) showed that the ZFO spinel nanoparticles formed a cubic structure, but the NFO spinel nanoparticles formed with additional Fe2O3 in them. The average crystallite size was observed to be in the range 16–20 nm. X-ray photoelectron spectroscopy (XPS) peak areas are often used to quantify the elemental compositions and oxidizing states of NFO and ZFO spinel surfaces. The appearance of FT-IR bands at around 548, 514 and 649 cm−1 were correlated to the Fe–O and Zn/Ni–O stretching modes of cubic NFO and ZFO structure. The direct band gap estimated using Kubelka–Munk (K–M) method to obtain by the NFO is 3.35 eV and ZFO is 2.13 eV respectively. The surface morphology revealed nanosized crystalline grains with agglomerate separated particles that are like spherical/non-spherical forms and fused grain boundaries. Magnetic measurements of NFO and ZFO spinel nanoparticles showed ferromagnetic behavior at room temperature.

Thermal radiative properties of zirconium oxide films in the near‐infrared wavelengths

AbstractThermal barrier coatings (TBCs) using yttria‐stabilized zirconium dioxide (YSZ) are widely used in gas turbines to protect metal components against the high combustion product temperature. Increasing combustion temperature and pressure, radiative heat transfer becomes an essential portion of the overall heat transfer in TBCs. This necessitates a greater understanding of the thermal radiative properties of YSZ films, especially in the near‐infrared wavelength range. The commonly used Kubelka–Munk (KM) method in the radiative property reduction from the measured transmittance and reflectance spectra of YSZ films can incur inaccurate results when the coating optical thickness is not sufficiently large. The discrete ordinates method with the asymmetric spherical ring angular quadrature can solve the radiative transfer equation with good accuracy in optically thin media. Considering the solution accuracy and computational efficiency, a hybrid approach of combining the KM and discrete ordinate methods is used to invert radiative properties. The absorption and scattering coefficients of air plasma sprayed YSZ films are determined over the wavelength range from 1 to 2.6 μm at room temperature. Over this near‐infrared wavelength range, the scattering coefficient decreases with the increasing wavelength, and the absorption coefficient is very small overall.

Characterization and optical gas sensing properties of BaSnO3 synthesized by novel technique: flame spray pyrolysis

Barium stannate (BaSnO3) particles were synthesized using a one-step flame spray pyrolysis (FSP) method. The fabricated ceramic powders were investigated in terms of the structural, morphological, and optical properties by using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), zeta particle size analyzer, UV–Visible spectroscopy (UV–Vis) and photoluminescence spectroscopy (PL). The XRD results showed the structure of BaSnO3 crystals has been obtained when the powders were exposed at high temperatures, specifically at 1200 °C. The synthesized particles in the submicron size in a range of 70–980 nm were produced. The optical bandgap value of the synthesized crystals was calculated using reflectance spectra with the Kubelka–Munk method and found as 3.14 eV. When the powders were excited at 375 nm, they exhibited emission bands in the visible and near-infrared region (NIR) of the electromagnetic spectrum. In this study, the intensity- and decay time-based gas sensing properties of nanoscale BaSnO3 embedded in ethyl cellulose (EC) thin films when exposed to the vapors of different solvents were also measured. The optical sensitivities (I-I0/I0) of the sensing materials for the NH3, acetone, and EtOH solvent vapors were calculated as 0.835, 0.672, and 0.521, respectively.

Influence of Manganese and Copper Doping on Structural and Optical Properties of Chromium Oxide Nanoparticles

Mn and Cu-doped Cr2O3 nanoparticles were prepared by the co-precipitation method followed by calcination at 400 0 C for 3h. These synthesized nanoparticles were characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy, and UV/Visible spectroscopy. SEM images showed the irregular and nearly spherical structure of the Undoped and doped Cr2O3 nanoparticles respectively. The particle size of obtained nanoparticles exhibits in the range of 30-60 nm. X-ray diffraction study reveals at temperature 400 0 C, undoped and Cu-doped Cr2O3 nanoparticles exist in the crystalline phase and Mn-doped Cr2O3 nanoparticles exist in the amorphous phase. UV-Visible spectra have been used to determine the band gap of the synthesized nanoparticles. The optical band gap value has been calculated by using Tauc’s method and Kubelka Munk method. Results indicate band gap calculated by Kubelka-Munk method is higher (4.7, 4.5 and 4.32 eV) than Tauc’s method. (4.18, 4.0, 3.96 eV). It is also concluded the decrease in the band gap (in both Tauc’s and Kubelka Munk method) was observed by the addition of dopant.

Electrodeposition of Cu2O nanostructures with improved semiconductor properties

In the present research, nanocomposites based on copper (I) oxide poly(1-vinyl-2—pyrolidone-co-itaconic acid) nanostructures (Cu2O/p(NVP-co-AI)) were synthesized by the electrodeposition method using the copolymer p(NVP-co-AI) as a stabilizing agent in the reduction of Cu+2 to Cu+. The chemical and physical properties of the nanostructures were characterized by techniques such as scanning electron microscopy, infrared (IR) spectroscopy, Raman and ultraviolet-visible spectrophotometry. The obtained nanostructures are mainly a mixture of agglomerated nanospheres with a diameter of approximately 78 to 91 nm, with an alternation of nanolaminar structures, composed of copper (I) oxide species. In the case of the Cu2O/p(NVP-co-AI) nanocomposite, it was observed a decrease in the carbon-oxygen vibration links of the carbonyl groups in IR intensity for the polymer when it was dissolved in the electrolytic solution, which indicates that interactions are produced by the carbonyl groups with the Cu2O species. In addition, bandgap values of 1.80 and 1.63 eV were estimated by the Kubelka–Munk method for Cu2O and Cu2O/p(NVP-co-AI) samples, respectively.

Copper Oxides on a Cu Sheet Substrate Made by Laser Technique

This paper presents results from the production of copper oxide layers on a Cu sheet substrate using diode and Yb:YAG disc lasers operating in the wavelength ranges of 808–940 nm and 1030 nm. The parameters of these layers were compared with the layer obtained in the thermal process of copper oxidation at 300 °C in an infrared (IR) furnace in a natural atmosphere. Investigations into the layers mentioned above, concerning their topography, chemical composition and roughness, were made using scanning electron microscopy (SEM) and atomic force microscopy (AFM). A hot-point probe was used to determine and check the type of conductivity of the copper oxide layers formed. The optical band gap energy was estimated by applying the Kubelka–Munk method based on spectrophotometric data. Cross-sections and the element distribution maps were made using transmission electron microscopy (TEM). The phase analysis was investigated by the X-ray diffraction method (XRD). In sum, controlled laser oxidations of copper sheets allow for the formation of a mixture of Cu2O and CuO phases. The diode laser allows the production of a layer of copper oxides with a phase composition comparable to the oxides produced by the thermal oxidation method, while the distribution of high phase uniformity in the cross-section of the layer enables the process using a Yb:YAG disc laser.

Structural, optical and thermoluminescence properties of newly developed MnKB: Er3+ glass system

Erbium-doped manganese potassium borate glasses have been synthesized to study their physical, structural, optical and thermoluminescence properties. These glasses were prepared by melt quenching technique and characterized by using various techniques X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV-visible (UV) and thermoluminescence (TL). Through FTIR spectroscopy the presence of various structural units has been studied. From Kubelka- Munk method, the optical band gap energy (Eopt) corresponding to the allowed direct and indirect transitions and the Urbach energy (E) values of the prepared glasses were determined. The impact of different concentration of Er2O3 on the TL intensity of the glass samples has been analyzed. The recorded glow curves show a single prominent peak around 398–422 K and the trapping parameters exhibit the kinetics of second order. With a good linear correlation coefficient, the glass sample E5 is a suitable candidate for medical and personal radiation measurements purposes.

Dielectric relaxation and charge conduction mechanism in mechanochemically synthesized methylammonium bismuth iodide

In this work, methylammonium bismuth iodide [(CH3NH3)3Bi2I9] has been synthesized through the mechanochemical process. Indeed, (CH3NH3)3Bi2I9 emerges as promising alternative to lead-based inorganic–organic perovskite due to low toxicity and better stability. X-ray diffraction spectra reveal monoclinic structure of (CH3NH3)Bi2I9 with space group C2/c. Kubelka–Munk method is conducted to compute the bandgap (2.16 eV). The impedance and dielectric properties of (CH3NH3)3Bi2I9 have been investigated within frequency range of 4 Hz to 1 MHz for several temperatures in between 333 to 453 K. The complex impedance spectroscopy has analyzed by fitting the Cole–Cole plot with suitable grain and grain boundary contributions (rg, rgb). Conductivity and electric modulus spectra have been analyzed to enlight the shaded portion of transportation properties. The scaled coordination of modulus spectrum merges in a single master curve which signifies that the distribution of relaxation time is temperature independent. To compute the DC conductivity, AC conductivity data have fitted using Jonscher’s power law. The activation energy calculated from Arrhenius plot is 0.477 eV.

Vibrational and optical studies of Na0.45K1.55Cu3(MoO4)4

Sodium potassium copper(II) tetra-[molybdate(VI)], Na0.45K1.55Cu3(MoO4)4, was synthesized using solid-state reaction route, and its crystal structure (monoclinic P21/c) was solved using single-crystal X-ray diffraction method. Na0.45K1.55Cu3(MoO4)4 forms 3D framework with elongated cavities occupied by alkali ions. The factor group analysis of Na0.45K1.55Cu3(MoO4)4 was applied for determination of number and activity of internal and external modes. Infrared and Raman vibrational spectra were investigated, and assignment of observed IR and Raman modes was proposed. The three crystallographically independent Cu2+ cations of Na0.45K1.55Cu3(MoO4)4 adopt the [4 + 2] CuO6 Jahn–Teller distortion giving rise to an intense d–d transition observed in UV–Vis absorption spectra. The energies of indirect (3.01 eV) and direct (2.17 eV) band gaps were calculated using Kubelka–Munk method combined with the Tauc equation.

Structural, optical, and room temperature dielectric properties of La1-xAxFeO3 (A = Mg, Sr, and Ba) perovskite nanomaterials

This paper investigated the variation of structure, optical and electrical properties of LMFO, LSFO, and LBFO. All samples were synthesized by sol gel method. For this present research study, the structure of the material was investigated by X-Ray Diffraction (XRD). Nevertheless, the electrical properties of this materials were investigated by using RLC Meter. The optical band gap energy was obtained by using UV-Vis Spectroscopy. The optical gap energy evaluated by Kubelka Munk method are 1,58 eV, 1,32 eV and 1,38 eV for LMFO, LSFO and LBFO respectively. Therefore, this small gap energy impacted sensitivity of the material towards its optical properties. To sum up, this what makes all samples are the suitable candidates for alcohol gas sensor.

Band gap energy determination of TiO2 nanorod array by Kubelka - Munk method and investigation of the UV photodetection of Au/TiO2/Au

این مقاله به بررسی خواص ساختاری، اپتیکی و آشکارسازی نوری فرابنفش نانومیله‌های روتایل دی‌اکسید تیتانیوم می‌پردازد. آرایه منظم از نانومیله‌های نسبتا عمود دی‌اکسیدتیتانیوم طی یک مرحله به روش هیدروترمال بر سطح پوشش رسانای شفاف دی‌اکسید قلع آلاییده با فلوئور بر زیرلایه شیشه رشد داده شده‌است. بررسی ریخت‌شناسی و ساختار بلوری به ترتیب بوسیله میکروسکوپ الکترونی روبشی و پراش پرتو ایکس انجام شده است. اندازه‌گیری طیف نورتابی و طیف‌های عبور و انعکاس پخشی دو روش تجربی مورد استفاده برای تخمین انرژی نوار ممنوع نانوساختارها می‌باشند. طیف‌های نورتابی در دمای اتاق، با دو انرژی برانگیختگی 4/13 و 3/82 الکترون ولت اندازه‌گیری شده است. براین اساس انرژی نوار ممنوع نمونه تقریبا برابر 3/04 الکترون ولت می‌باشد و هنگامی مشاهده می‌شود که نمونه با انرژی 4/13 الکترون ولت برانگیخته می‌شود. مقایسه روش‌های موجود گزارش شده برای تعیین انرژی نوار ممنوع با استفاده از طیف‌های عبور و انعکاس پخشی به روش کوبلکا مونک نشان می‌دهد که بیشترین همخوانی با مقدار حاصل از طیف نورتابی هنگامی وجود دارد که از رابطه F(R)hv]= B(hv-Eg)n] استفاده می‌شود. در پایان عملکرد آشکارسازی نوری فرابنفش نانومیله‌های دی‌اکسید تیتانیوم در ساختار /Au2TiO Au/ تحت تابش nm365 با اندازه‌گیری کمیت‌های ضریب پاسخ، حساسیت، ثابت‌های زمانی افزایش و کاهش جریان ارزیابی و تحلیل شده است.

Impact of molarity on structural, optical, morphological and electrical properties of copper oxide thin films prepared by cost effective jet nebulizer spray pyrolysis technique

Copper oxide (CuO) thin films were prepared by simple and cost effective jet nebulizer spray pyrolysis method with different molar concentration 0.1, 0.2 and 0.3 M named as J1, J2 and J3 respectively. The impact of molarity on structural, optical, morphological and electrical of properties of CuO thin film was studied. The structural studies confirmed that the prepared CuO thin films are monoclinic crystal structure matching with standard JCPDS card No. 89-5899. The thickness of CuO thin films determined by surface profilometer found to be increasing while increasing molar concentration. The optical energy band gaps were determined using Kulbelka–Munk (K–M) method are found to be 2.1 eV, 1.9 eV and 1.8 eV for J1, J2 and J3 respectively. The morphological properties and chemical composition of CuO thin film were investigated via field-emission scanning electron microscope (FESEM) and energy dispersive analysis from X-ray spectroscopy (EDAX). According to FESEM all the prepared CuO thin films are well covered and adhered to the substrate with good homogeneity and EDAX spectra confirms the presence of copper (Cu) and oxygen (O). The adhesion strength has been determined in accordance with test method D3330 using scotch tape test. The electrical conductivity of CuO thin films were investigated. The maximum conductivity value of the CuO thin film is observed 2.75 × 10−8 S/cm.