UV Vis Transmission Spectra Research Articles

Ligand-assisted synthesis of novel π-SnS tetrahedrons for enhanced photocatalytic H2 evolution from water

Tin sulfide (SnS) is a potentially promising chalcogenide material for efficient solar energy conversion. In this study, pure π-SnS particles with a novel cubic phase were successfully synthesized by a simple one-pot solvothermal reaction method. The effects of solvothermal reaction time and amount of the ligand, hexamethyldisilazane (HMDS), on physical and photocatalytic properties were investigated. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction revealed that the obtained π-SnS consisted of tetrahedral particles with a high degree of crystallinity and exhibited a cubic phase. UV-Vis transmission spectra and photoluminescence (PL) revealed that the bandgap of π-SnS particles was about 1.62 eV. Importantly, the H2 evolution capacity of π-SnS particles prepared with Tin-HMDS complexes was dramatically improved. About 12-fold and 23-fold larger amounts of H2 were produced than the amounts produced by π-SnS particles prepared without HMDS and α-SnS particles with similar size, respectively. Post-annealing treatment further confirmed the existence of surface ligands and their importance for the photocatalytic activity of particles. X-ray photoelectron spectroscopy (XPS) revealed HMDS ligands instead of oleylamine molecules interacted with π-SnS particles.

Structural, optical, and morphological properties of PVC-BaTiO3 nanocomposite films

This work aims to fabricate barium titanate (BaTiO3) nanoparticles and study the effect of adding different contents of BaTiO3 nanoparticles on the structural, optical, and electrical properties of PVC polymer matrices. The PVC/BaTiO3 nanocomposite films were characterized by X-ray diffraction, FT-IR spectroscopy, and SEM. In addition, dielectric properties were studied within the frequency range of 0.1 KHz–6 MHZ. The XRD analysis reveals an amorphous nature of pure PVC with two characteristic peaks at 2θ = 17.09° and 2θ = 23.25°, and it reveals that BaTiO3 has sharp and narrow peaks. In PVC/BaTiO3 nanocomposite films, all XRD peaks of BaTiO3 appeared in all the samples with an increase in the average particle size from ∼46 nm to 55 nm. There is no shift of IR position in PVC bands, but the decreased intensity of some bands suggests complexation between PVC and BaTiO3. The UV–visible absorption spectrum of pure PVC has a band at λ = 278 nm. This band was shifted to 252 nm after adding BaTiO3 content. UV–visible transmission spectra demonstrate a decrease in the transmittance as an increase of BaTiO3 content from 89.23 % for pure PVC to 5.23 % for 0.1 wt% of BaTiO3. The values of the optical bandgap decrease with increasing BaTiO3 contents due to defect formation in PVC matrices. The optical parameters of the prepared nanocomposite films were also enhanced. The AC conductivity shows an increase with both frequency and BaTiO3 concentration, leading to enhanced movement of charge carriers and relaxation of interface polarization.

P-type nickel cobalt oxide synthetized by chemical bath deposition to applications on thin film transistors

This work studies nickel-cobalt oxide (NiCo2O4) thin films synthesized via chemical bath deposition for potential application as p-type active layers in electronic devices. X-ray photoemission electron spectroscopy (XPS) confirms the synthesis of a ternary compound with a stoichiometry of Ni1.04Co1.96O4. The thin film sample exhibiting the closest stoichiometry to the ternary compound has a thickness of approximately 50 nm. Scanning Electron Microscopy (SEM) micrographs indicate an increase in surface porous size corresponding to higher nickel concentrations in the ternary compound. All synthesized NiCo2O4 thin films demonstrate p-type behavior. The lowest resistivity film had a majority carrier concentration of 1×1020 1/cm3, a mobility value of 0.1 cm2/V·s, and a resistivity of 0.1 Ω cm. X-ray diffraction (XRD) studies reveal that the thin films have a type of spinel cubic structure for the phase NiCo2O4. Characteristic spinel bands are observed in the UV–Vis transmittance spectra, and the energy bandgaps of the Ni1.04Co1.96O4 film are estimated to be approximately 3.41 and 2.19 eV using the Tauc method. The thin film with the lowest resistivity was used as an active layer to fabricate a thin-film transistor, displaying typical output curves of a p-channel transistor.

Feasibility study of coffee husk char-derived carbon dots to enhance solar photovoltaic-thermal applications

Coffee is one of the most traded commodities in the world. Coffee husk makes up the majority of the solid debris generated during the dry processing of coffee, which is between 30% and 50%. Pyrolysis is a reliable and feasible technology to valorise the coffee husk. The present study proposes and investigates a novel method for producing carbon dots from coffee husk char through pyrolysis. Nanomaterials are becoming more popular to improve the thermal and optical properties of working fluids used in solar photovoltaic and thermal conversion systems. The coffee husk-char derived carbon dot (CHC-CD) nanofluids are prepared with different char concentrations (1%, 2%, 3% and 4%). The chemical and optical properties of the nanofluid produced from coffee husk char (CHC-CD nanofluid) are investigated. The morphology, size and particle size distribution of the CHC-CD particles were studied using field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). The particles were found to have an average size of 5.38 nm. The CHC-CD nanofluid had a basic pH and negative zeta potential, which was found to decrease with an increase in the char concentration and pH. The nanofluid prepared with 2% char was found to have a zeta potential of −61.4 mV. It was evident from the UV–vis transmittance spectra that the CHC-CD nanofluid prepared with a char concentration of 2% had very limited transmittance in the UV region and good transmittance above 735 nm. This transmittance range is found to be favourable for the smooth and efficient operation of silicon-based solar PV cells. The CHC-CD nanofluid also showed a maximum intensity emission wavelength of 522 nm at an excitation wavelength of 450 nm. Characterisation of the carbon phase, surface functional groups, and surface defects was also done using XRD, FTIR, and Raman spectroscopy, respectively. The optical and chemical properties indicate that the developed CHC-CD nanofluid can find application not only in solar photovoltaic and thermal systems but also in applications in biomedical and chemical sensor applications.

Crystal growth, structural, optical, mechanical characterization and quantum chemical analysis by DFT of an organic nonlinear optical single crystal 4-Hydroxy pyridinium succinate for photonic and optoelectronic devices

A new organic nonlinear optical single crystal 4-Hydroxypyridinium Succinate was synthesized and grown successfully by slow evaporation method using methanol as solvent at ambient temperature. Single crystal X –ray diffraction studies on the grown crystal reveals that 4HPS crystallizes into orthorhombic structure with the non-centrosymmetric space group (Pna21). In structural point of view, the 4-Hydroxypyridinium cation is bonded to the hydrogen succinate anion by direct electron conjugation through nitrogen atom. In addition, the UV visible transmittance spectrum implies that the crystal has high transparency domain in the entire UV visible region with a lower cut-off wavelength of 286 nm. The various functional groups present in the crystal and their frequency assignments are derived from FTIR spectral analysis. The Photoluminescence spectrum brings forth that the grown crystal has violet emission property. The microhardness measurements testify that the crystal belongs to soft material category with reasonable hardness parameters. The compound was found to be thermally stable up to 188 °C without any weight loss from the TGA and DTG traces. The detailed quantum chemical calculation done by density functional theory (DFT) indicates the Homo –Lumo energy gap of the molecule is 3. 956 eV and 4. 289 eV for α and β wave functions respectively. The Laser induced damage threshold of the crystal investigated using Nd: YAG laser of 1064 nm radiation was found to be 21. 93 Gw/cm2. The second harmonic generation efficiency of the 4HPS crystal was confirmed by the emission of green light under Kurtz and Perry powder test.

Novel red emitting Phosphor-in-Glass (PiG) based on Na6CaP2O9: Eu3+ phosphor as an inorganic colour converter for w-LED applications

A set of transparent, red-emitting, nUV excitable phosphor-in-glass (PiG) of different phosphor concentrations was fabricated via low temperature co-sintering process by incorporating Na6CaP2O9:Eu3+ phosphor into the multicomponent borosilicate glass. Structural and morphological properties were estimated through XRD, FTIR, HR-TEM and FE-SEM. The electron microscope images confirm the successful incorporation of phosphor into the amorphous glass with negligible glass-phosphor interaction. The luminescent characteristics of the prepared samples were investigated via UV–Vis transmittance spectra, photoluminescence spectra, JO theory, decay analysis and quantum yield measurement. The transmittance spectra reveal exceptional transparency of the samples in the visible region. The PiGs emit prominently at 614 nm under 393 nm excitation with a lifetime in the millisecond range. Chromaticity coordinates corresponding to red emission under 393 nm excitation are (0.634, 0.366). These results contemplate the fabricated PiGs as a potential red emissive inorganic colour converter in lighting and display devices.

Optimization of visible photoluminescence emission from Ni-Zn ferrite thin films

Ni-Zn ferrite films with different thicknesses were prepared by the spray method, aiming to study the relationship between the annealing effect in an oxygen rich environment and the structural, optical properties and photoluminescence emission. X-ray diffraction (XRD) analysis used with Rietveld refinement showed that all prepared samples had a single spinel phase structure. Likewise, the Fourier transform infrared (FTIR) spectra confirmed the phase formation of Ni-Zn ferrites by appearing in both of the two characteristic absorption bands which are related to the tetrahedral and octahedral sites. For annealed thin film samples of Ni-Zn ferrite, the atomic force microscope (AFM) surface morphology exhibits pinning structure on the surface in nanoscale height, whereas for un-annealed samples, there are hills and valleys cover a broad region. The different electronic transitions were estimated from the UV-visible transmission spectrum. Strong photoluminescence (PL) intensity in the visible range was observed under the excitation of UV radiation. The intensity of the PL signal was strongest at a film thickness of 750 nm then decreased for higher thicknesses. This could be interpreted by using proposed energy level structures based on the transmission spectrum of the investigated samples. The strong PL intensity introduces the samples as a direct optical detector for UV radiation.

Single crystal growth and characterization of pyroelectric L-arginine dihydrobromide monohydrate (LADB)

The formation and the crystal growth conditions of all compounds from the L-Arg + HBr + H2O system were studied and described. IR spectroscopy method was used to identify the obtained crystals. Solubility was determined by the sequential dissolution of decreasing amounts method at a given temperature. The main difficulty of L-Arginine dihydrobromide monohydrate (LADB) crystal growth is its very high solubility in water. This study however demonstrates that a high-quality single crystal was grown by the SERS method, developed by the authors. The achieved high quality of grown LADB crystal makes it possible to count on its wide application as a pyroelectric crystal. These grown crystals were subjected to a microhardness study. Thermal properties and UV–Vis transmittance spectrum were also investigated. The efficiency of the second harmonic generation of L-arginine halide crystals was measured and compared with that of KDP.

Effect of film thickness on the electrical and the photocatalytic properties of ZnO nanorods grown by SILAR technique

In this work, Zinc oxide (ZnO) thin films were synthesised by the successive ionic layer adsorption and reaction (SILAR) technique at various number of cycles (10–50 cycles). The effect of film thickness on the structural properties, surface morphology, optical and electrical properties, and sunlight assisted photocatalytic activities through photocatalytic degradation of Methylene Blue (MB) dye of ZnO thin films were studied. The energy dispersive x-rays (EDX) analysis confirmed the presence Zn and O elements. The x-rays diffraction (XRD) pattern showed the polycrystalline nature of ZnO thin films and the crystallite size increases with film thickness. The SEM images showed that a greater film thickness resulted in the growth of hexagonal nanorods arrays. Atomic force microscopy (AFM) images revealed that the surface roughness increases with film thickness yielding in an enhanced specific surface area. The UV—visible transmission spectra showed that increasing film thickness results in band gap expansion from 3.15 eV to 3.31 eV together with a reduction in optical transmittance. The estimated sheet resistance and resistivity were found to be in the range of 1.34–7.1 Ω sq−1 and 0.09–2.12 ×10–1 Ω.cm. The photocatalytic studies reveal that increasing film thickness leads to an improved photocatalytic efficiency of ZnO films. The enhanced photocatalytic activity of ZnO films is due to the increased surface area and low recombination rate of carriers charges (e−/h+), resulting from band gap expansion.

Synergic versus Antagonist Effects of Rutin on Gallic Acid or Coumarin Incorporated into Chitosan Active Films: Impacts on Their Release Kinetics and Antioxidant Activity.

This work deals with the study of the release and antioxidant activity kinetics of three natural antioxidants associated as binary mixture (coumarin, and/or gallic acid and rutin) from chitosan films. Antioxidants were incorporated into film alone or in binary mixture. The aim was to determine the influence of rutin on the phenolic acid and benzopyrone. The UV-visible light transmission spectra of the films were also investigated. Neat chitosan films and chitosan incorporated coumarin exhibited high transmittance in the UV-visible light range, while GA-added chitosan films showed excellent UV light barrier properties. The molecular interactions between chitosan network and antioxidants were confirmed by FTIR where spectra displayed a shift of the amide-III peak. Rutin has a complex structure that can undergo ionization. The chitosan network structure induced change was found to influence the release behavior. The film containing rutin showed the highest antioxidant activity (65.58 ± 0.26%), followed by gallic acid (44.82 ± 3.73%), while coumarin displayed the lowest activity (27.27 ± 4.04%). The kinetic rate against DPPH-free radical of rutin is three times higher than coumarin. The kinetic rates were influenced by the structure and interactions of the antioxidants with chitosan. Rutin exhibited a slow release due to its molecular interactions with chitosan, while coumarin and gallic acid showed faster release. The diffusion coefficient of coumarin is 900 times higher than that of rutin. The rutin presence significantly delayed the release of the gallic acid and coumarin, suggesting an antagonistic effect. However, their presence weakly affects the release behavior of rutin.

Tunable luminescence of Bi3+/Eu3+-doped SiO2–Al2O3-MCO3 (M = Ca, Sr, Ba) glasses for WLED

In this work, a group of Bi3+/Eu3+-doped SiO2–Al2O3-MCO3 (M = Ca, Sr, Ba) glasses were fabricated through melt-quenching method. Their structure and photoluminescence characters were studied via X-ray diffraction (XRD), UV–Vis transmission spectra (TRS), excitation spectra, emission spectra and decay lifetimes. The XRD results show that no nano-crystal phase forms in glass matrix with different doping concentrations of Bi3+ and Eu3+ ions. Through regulating optical alkalinity value, the intensity of Bi3+ ions increases and the peak position shifts to red wavelength. The Bi3+/Eu3+ co-doped glasses show a blue-white-yellow-red luminescence by changing concentration of Eu3+ ions. Energy transfer efficiency from Bi3+ to Eu3+ can reach as high as 10.54%. At 423 K, the emission intensity of 55SiO2–10Al2O3–35BaO-0.25Bi2O3 (GBE0.5) is 31.1% of that at 308 K. Meanwhile, the activation energy of the glass matrix is 0.251 eV. All results suggest that these Bi3+/Eu3+ co-doped glass samples possess potential application in LED field.

Band Alignment of β-Ga2O3 with BaTiO3, SrTiO3, and Related Composites

Integrating perovskite oxides BaTiO3 (BTO), SrTiO3(STO) with β-Ga2O3 is of great interest for developing β-Ga2O3 power devices due to its promotion for improving uniformity in the electric field profile and breakdown characteristics. In this work, β-Ga2O3/BaTiO3 (BTO), β-Ga2O3/SrTiO3 (STO), β-Ga2O3/Ba0.5Sr0.5TiO3 (BSTO) heterojunction were epitaxially grown on sapphire substrates by low-pressure chemical vapor deposition (LPCVD) and radio frequency physical vapor deposition (RF PVD). The energy band alignment of β-Ga2O3/BaTiO3, β-Ga2O3/SrTiO3, β-Ga2O3/Ba0.5Sr0.5TiO3 (BSTO) heterojunction have been analyzed by X-ray photoemission spectroscopy and UV–visible transmittance spectrum. The conduction band offsets (∆E c ) of β-Ga2O3/BTO, β-Ga2O3/STO, β-Ga2O3/BSTO is found to be 0.32 ± 0.05, 1.15 ± 0.05, 0.78 ± 0.05 eV, respectively; and the valence band offsets (∆E v ) of these heterojunction is 0.76 ± 0.05 eV, 0.55 ± 0.05 eV, and 0.73 ± 0.05 eV, respectively. Our results indicate that type-I band alignment respectively form at these heterojunction, in which the valence and conduction bands of β-Ga2O3 are concomitantly higher than those of BTO, STO, and BSTO. The accurate determination of ∆E c and ∆E v is important for the design of β-Ga2O3/ferroelectric heterojunction multifunctional devices.

Optical characteristics of Mg-based (Mg/Co & Mg/Mn) TF for hydrogen storage applications

This study has proposed and analyzed the role of hydrogen gas on optical characteristics of Mg-based Mg/Co and Mg/Mn bilayer structures. Thermal evaporation at a pressure of 10-5 torr was used to prepare these Thin Films (TF), which were then effectively deposited onto glass substrates. To obtain homogenous structure, prepared TF were vacuum annealed at 573 K. Hydrogen gas was injected into the chamber at various pressures (10, 20 & 30 psi) to observe how hydrogenation influenced TF. Using a Hitachi-330 spectrophotometer, the UV–Vis transmission spectra were recorded in visible range of wavelength (300–800 nm). TF' optical transmission was reduced, and it was revealed that the energy band gap increased as hydrogen pressure increased. It implies that hydrogen absorption in TF can be used to tailor the energy band gap. An optical micrograph of a hydrogenated TF that has been annealed reveals a dark black state. The variation in energy band gap due to hydrogen and increasing value of the film resistance are evidence for the phase shifts caused on by hydrogenation from metal to semiconductor.

A Method of Evaluating NV centers Concentration by UV–Vis Transmittance Spectra

The ultraviolet-visible (UV-Vis) spectrum was not generally considered an available method for measuring the concentration of negatively charged nitrogen-vacancy (NV-, NV center). In this study, we propose the idea of evaluating the concentration of NV center by the slope of the UV-Vis spectrum. To establish this new method we synthesized diamonds with different NV center concentrations by the chemical vapor deposition (CVD) method. We then measured the zero-phonon line (ZPL) intensity of PL spectra at 637 nm and estimated the concentration of the NV centers as a baseline for comparison to our new UV-Vis method. The UV-Vis transmission spectra were then measured and transformed to relative absorption coefficient spectra. Slopes of the transformed UV-Vis spectra between 400 nm and 800 nm were calculated and compared with the ZPL intensities. The results show a strong positive correlation between the slopes of the absorption spectra and the ZPL intensities of PL spectra at 637 nm. Therefore, this paper demonstrates the feasibility of estimating the concentration of the NV centers from measuring the transmission UV-Vis spectrum.

Spectroscopic, Magnetic and Morphological studies of MgFe2O4 Nanopowder

Spinel type nano ferrite compound MgFe2O4 was synthesized through sol gel technique using metal nitrates as precursors. The phase composition, morphology and elemental analysis of magnesium ferrite (MgFe2O4) were performed by X-ray diffraction, fourier transform infrared, atomic force microscopy, energy dispersive x-ray and scanning electron microscopy, analyses. 
 The sample's X-ray diffraction pattern verifies the existence of single phase material, with the size of its crystallites estimated to be 39.9 nm. Fourier transform infrared examination supported metal-oxygen vibrations corresponding to tetrahedral and octahedral sites, respectively. From scanning electron microscopy image, grain size obtained about 97.7 nm. Raman spectra of the sample shows five Raman active modes (A1g + Eg + 3F2g), which is compatible with the spinel structure. Magnetic measurement study at room temperature shows a hysteresis loop behaviour with a low saturation magnetization value, 27.192 emu g-1 and a small coercivity value. The optical band gap determined using UV-visible transmittance spectra. Additionally, X-ray photoelectron spectroscopy are used to confirm oxidation states and explore the chemical composition of the sample.

Investigation of Physiochemical Impact of Organic Molecule L-Lysine on Ammonium Dihydrogen Phosphate Single Crystal for Optoelectronics Applications

Ammonium dihydrogen phosphate (ADP) single crystals along with the incorporated 0.5 and 1% L-lysine, an organic molecule which possesses a good nonlinear response, were grown with the vision to meet the requirements of the optoelectronic industry. The inclusion of the L-lysine molecule in the crystal was confirmed by the XRD and EDX. The experiment not only confirms the inclusion level of the impurity but also the capability of the amino acid molecule to bond hydrogen within the crystal facet. A minor decrease in lattice parameters was reported for all ADP: L-lysine crystals compared with pure ADP. The structures of the grown crystals were identified as tetragonal with the space group I42d by the single-crystal XRD analysis. Vibrational signatures and functional groups were confirmed using FTIR spectroscopy. The thermal stability and decomposition temperatures of 0.5 and 1% L-lysine-added crystals were measured by TG/DTA and found to be 203 °C and 207 °C, respectively. The UV–visible transmission spectra prove a higher transparency for doped crystals as compared to pure crystals; therefore, these doped crystals can be considered the best option for the frequency doubling process in a broad range of visible and near-IR spectra. The improved hardness of the doped crystals was confirmed by the Vickers hardness data. The nonlinear optical (NLO) behaviour investigated using a second-harmonic generation (SHG) technique, indicating an efficient quadratic nonlinear coefficient of ADP: Lysine crystals at a 1064 nm initial wavelength, shows about 1.5-fold higher efficiency compared with undoped ADP.

Gel growth and characterization of Cs3Bi2Br9 perovskite single crystals for radiation detection

Metal halide perovskites have been sought for ionizing radiation detection due to their tunable bandgap, high quantum yield, high absorption coefficient, excellent charge transport properties, flexible chemistry synthesis and cost-effective manufacturing. Among the family of perovskites, bismuth-based halide perovskites have attracted a rapidly growing interest as possible alternatives to lead-based halide perovskites in the development of nontoxic perovskites for opto-electronic devices. Herein, bismuth-based inorganic perovskite Cs3Bi2Br9 single crystals were successfully grown using an innovative dual-diffusion gel growth technique for the first time. Silica gel has been developed as an enabling medium for gel growth of single crystals due to its transparency and easy control of nucleation sites. The UV-vis transmission spectrum was recorded using a light source of deuterium and halogen lamps and a Tauc plot was obtained, which gave an estimate of the bandgap energy, 2.54 eV. Silver electrodes were used on the top surface and the bottom surface of Cs3Bi2Br9 single crystals for material characterization and detector tests. Current-voltage (I-V) measurements gave a room-temperature resistivity of 1.79×1011 Ω•cm. The Cs3Bi2Br9 single crystals were then tested for X-ray response using ON\OFF testing which revealed attractive responsiveness for X-ray photons (rise and fall time: ≈0.3 s ). Using the net current (IXray−Idark), which can be extracted from the X-ray response measurements at varied applied voltages, a modified Hecht fitting was applied to estimate the mobility-lifetime product of electrons, μτ=5.12×10−4 ±6.70×10−5 cm2/V for a Ag/Cs3Bi2Br9/Ag device. This study shows that our innovative crystal growth method, enabled by the unique gel growth process, can be used as an appealing technique to grow functional crystals for opto-electronic devices. Meanwhile, Cs3Bi2Br9 has shown great potential as a promising candidate for X-ray detection applications. The efforts in this work will serve as a metric for growing halide perovskites in the gel for opto-electronic devices.

Structural, morphological & optical studies of Hydroxyapatite microplates synthesized using hydrothermal technique

Hydroxyapatite or Penta-calcium hydroxide triphosphate (Ca10(PO4)6(OH)2 - HA) is biologically as well as naturally occurring mineral of Calcium. It has a vast range of applications in curing bone and teeth related issues as well as in solving environmental problems. In the present study, an attempt was made to synthesize HA using the conventional hydrothermal technique. Calcium and Phosphate precursors (namely Calcium nitrate tetrahydrate and Di-potassium Hydrogen Phosphate) were mixed in a certain proportion via drop wise addition with a stoichiometric Ca/P molar ratio of 1.67. Around 1 ml solution of Potassium Hydroxide (KOH) was used to set the pH of the solution to 4.0 – 5.0 (acidic medium). The resultant solution was given hydrothermal treatment at 160 ˚C for 24 h. Obtained precipitates were air-dried and calcinated at 600 ˚C for 2 h. X-ray Diffraction (XRD) analysis was carried out for the structural study of the synthesized sample. XRD analysis shows that HA is present as a major phase (JCPDS Card no. – 09–0432) along with secondary phases, namely Calcium Hydrogen Phosphate, Calcium Phosphate and Calcium Carbonate. Sharp peaks attributed to HA having (h k l) plane (002), (102), (210), (211) and (112) can be observed that confirm the formation of HA. Average Crystallite size was about 40 nm calculated using Debey-Scherrer’s equation. A morphological study was carried out using Scanning Electron Microscopy (SEM). SEM micrographs show well-defined plate-like particles (similar to bone apatite) with non-similar size distribution. At higher magnification, agglomerated smaller size particles can be observed. UV–vis spectroscopy was utilized to study the optical property. UV–vis transmittance spectrum was taken in the range of 200 nm to 1000 nm. It was found that HA exhibits strong absorption in the UV region and the approximate optical band gap of as-synthesized material was about 4.5 eV.

Synthesis and characterization of strontium tartrate tetrahydrate crystal using silica gel method

In the present study, strontium tartrate tetrahydrate crystals were grown using the silica gel method. Optimum growth parameters were obtained by varying molar concentration, volume of upper reactant solution, and pH of gel mixture at ambient temperature (31 °C). Large size crystal (9 × 8 × 4 mm3) of strontium tartrate tetrahydrate were obtained when the pH of the gel mixture was 4.2 and upper reactant had a molar concentration of 1.5 M and volume of 20 ml. As grown crystal was characterized using different techniques viz. Powder X-ray Diffraction (PXRD), Fourier Transform Infrared spectroscopy (FTIR), Energy Dispersive Analysis of X-ray (EDAX), and UV–vis spectral analysis. Analysis of Powder X-ray diffraction data carried out in the 2θ range 10°–60° revealed that as grown crystal had an orthorhombic structure with space group P2 2 2 and unit cell parameters a = 9.8865 Å, b = 10.0448 Å, c = 9.5186 Å, α = β = γ = 90°. Various vibrational peaks of hydroxyl group (OH) at wavenumber 3170.42, 3384.44, 3536.72 cm−1, carbonyl (CO) group at 1601.88 cm−1 were observed in FTIR spectroscopy. One peculiar peak at 478.2 cm−1 where one O− and was replaced by Sr2+ was also obtained in FTIR spectroscopy suggesting formation of strontium tartrate crystal. Energy dispersive analysis of X-ray confirms the presence of expected major elements like strontium, carbon, and oxygen in the crystal. UV–vis transmission spectrum of strontium tartrate tetrahydrate crystals was recorded in the wavelength range of 190 to 1100 nm. The energy bandgap estimated from transmission data is 5.64 eV. Non-linear Optical (NLO) competence of STT crystal is observed at 532 nm. The electrical property of pelletized samples was studied by dielectric measurement in the frequency range of 20 Hz–2 MHz at room temperature. It is observed that dielectric loss is very low at higher frequency.

The effect of deposition cycles on structural, morphological, optical and gas detection properties of Mg doped ZnO thin films

In this study, Mg doped ZnO thin films were successfully prepared using the modified SILAR approach throughout various numbers of deposition cycles. XRD data shows the prepared films have a ZnO wurtzite hexagonal structure. The crystalline size and crystallinity were found to be increased by increasing the number of deposition cycles. FESEM showed there are nanoparticles and nanorods on the surface, with random distribution in the case of the sample synthesized with 30 cycles, while the agglomeration of nanoparticles to form a maize-like structure and flower-like morphology was predominant in the case of the sample with 40 cycles. The UV-VIS transmittance spectra showed a decrease in transmittance by increasing the number of deposition cycles, and the increment of energy band gap by increasing the number of deposition cycles was found. The response of the samples towards NO2 gas at 200 °C operating temperature was found to be enhanced in the case of the sample prepared at 40 cycles as compared to the sample prepared at 30 cycles.