UV Vis NIR Spectroscopy Research Articles

Facile synthesis, structure, AFM, thermal, and optical analysis of BiI3/PVAL nanocomposite films for laser CUT-OFF optical devices

In the progress work, the facile microwave method has been used to synthesize BiI3 nanoparticles at low temperatures, while nanocomposite films based on polyvinyl alcohol (PVAL) filled with selective content of BiI3 nanoparticles (from 0 to 18.51 wt %) have been prepared by casting technique. The structural analysis has been analyzed by X-ray diffraction, EDX (energy dispersive analysis spectroscopy of X-rays), HR-TEM (High-resolution transmission electron microscope), and atomic force microscope (AFM) measurements. The thermal behavior such as DTG (derivative thermogravimetric) and TGA (thermogravimetric analysis) of BiI3/PVAL nanocomposite was also studied. At the same time, the optical performance of these films was measured using UV–Vis–NIR spectroscopy. The structure study shows significant incorporation between the two phases of PVAL and BiI3 in all films. The AFM images show an increase in surface roughness with the nanoparticle content. The BiI3 level has influenced optical parameters like the energy of the band tail, the energy gap, the absorption coefficient, and the dielectric loss of the PVAL matrix. 18.51 wt % BiI3/PVAL film has a direct transition with the lowest energy gap, while its higher absorbance is due to the increase of the influence of the crystalline phases of BiI3 in the polymeric matrix. The strong competence of the films to reduce the power of the two laser beams (632.8 nm & 533 nm) has been detected. Therefore, the results support that this nanocomposite is a fruitful material for commercial laser cut-off and optoelectronics.

Effects of element ratio on robustness of CZTS films: Variations in sulfurization temperature

In this study, Cu2ZnSnS4 (CZTS) thin films are fabricated through radio frequency magnetron sputtering followed with sulfurization process under different annealing temperatures. Scanning electron microscopy, X-ray diffraction, energy dispersive X-rays, Raman spectroscopy, UV–vis–NIR spectroscopy, and Hall effect measurement system are used to characterize the fabricated CZTS films. Elemental ratio variations during the sulfurization process under different temperatures are examined from the perspective of the following decomposition process: Cu2ZnSnS4 (s) ⇋ Cu2S (s) + ZnS (s) + SnS (s) +1/2 S2 (s). Furthermore, the lattice parameters, grain size, full-width at half-maximum (FWHM), dislocation density, and micro-stress are calculated and analyzed in light of the elemental ratio variations. Meanwhile, the Raman spectra and a joint analysis with the energy band gaps validate the presence of secondary phases including orthorhombic Cu3SnS4, cubic Cu2SnS3 and tetragonal Cu2SnS3. The results indicate that the energy band gap can be adjusted by controlling the amount of S, loss of Sn through annealing temperature, and temperature of 500 °C is a appropriate sulfurization temperature for preventing the decomposition of CZTS during the annealing process. This study is an important reference for experimental works that seek to improve quality of CZTS thin films in solar cells with high conversion efficiency.

$$\hbox {Bi}_{(1-y)}\hbox {Sm}_{{y}}\hbox {FeO}_{{3}}$$ as prospective photovoltaic materials

The bandgap energy ( $${E}_{\mathrm {g}}$$ ) of silicon-based photovoltaic (PV) cells is 1.1 eV, which limits its efficiency to 33.33%. Thus, the quest for alternative materials with maximum theoretical power conversion efficiencies (PCE) is growing in full swing within scientific community. Bismuth ferrite (BFO) is one of the promising candidates due to its tunable $${{E}}_{\mathrm {g}}$$ . For visible light with wavelength from 380 to 750 nm, $${{E}}_{\mathrm {g}}$$ falls within the range of 1.65–3.1 eV. The photons with wavelengths of higher than 464 nm ( $${{E}}_{\mathrm {g }}= 2.67$$ eV) constitute 80% of the solar spectrum, which cannot be absorbed by un-doped BFO. Thus, lowering the $${{E}}_{\mathrm {g}}$$ of BFO is a promising way to obtain higher PCE of PV cells to harvest a wide range of visible light spectrum. In this context, we have synthesized samarium (Sm)-doped $$\hbox {Bi}_{{(1-y)}}{\mathrm {Sm}}_{y} {\mathrm {FeO}}_{{3}}$$ ( $${y} = 0.05$$ , 0.1 and 0.15) multiferroic nanoparticles using sol–gel method. The evolution of phase from xerogel was thoroughly investigated by differential scanning calorimetry and a noticeable peak shift of $$7^{\circ }\hbox {C}$$ was observed due to Sm doping compared to un-doped counterpart. For crystallinity, xerogel powder was annealed at $$600^{\circ }\hbox {C}$$ . Rietveld refinement of X-ray diffraction data have confirmed rhombohedral crystal structure (R3c) of annealed samples and a substantial reduction of crystal size from 57.4 to 16 nm. For the first time, a total suppression of secondary phase was obtained in $$\hbox {Bi}_{{99.05}}{\mathrm {Sm}}_{{0.05}} {\mathrm {FeO}}_{{3}}$$ with only 5 (at.)% Sm addition. Fe–O–Fe bond angle was found to change significantly from 154.77 to $$158.84^\circ $$ and Fe–O bond length was found to be decreased along long axis and increased along short axis in Sm-doped samples. Field emission scanning electron microscopy demonstrated a reduction in particle size from 164 to 88 nm with increasing Sm-dopant concentration. The bandgap energy of un-doped and Sm-doped $$\hbox {BiFeO}_{{3}}$$ was calculated from measured diffused reflectance data using UV–Vis–NIR spectroscopy, the result has shown a reduction of bandgap in Sm-doped $$\hbox {BiFeO}_{{3}}$$ to 1.9 eV.

Defects and oxygen vacancies tailored structural, optical and electronic structure properties of Co-doped ZnO nanoparticle samples probed using soft X-ray absorption spectroscopy

The structural, optical and electronic structure properties of all the Zn1-xCoxO nanoparticles [x = 0.01, 0.03, and 0.05], synthesized using co-precipitation method have been studied using X-ray diffraction (XRD), Surface Enhanced Raman Spectroscopy (SERS), UV–Vis–NIR spectroscopy and X-ray Absorption Spectroscopy measurements. The XRD and SERS analysis have confirmed the formation of hexagonal wurtzite structure (space group C46v). UV–Vis–NIR spectra indicate the blue shifting of the absorbance edge and the band gap is found to decrease with doping. The electronic structure of undoped and Co-doped ZnO nanoparticles have been investigated using site selective and element sensitive X-ray absorption spectroscopy. From the XAS spectra at Zn L3,2, Co L3,2 and O K-edges we have found that Zn ions are in +2 valence state in undoped and Co-doped ZnO nanoparticles. From the XAS analysis it can be seen that proper incorporation of Co-ion in the host lattice take place in t2geg state Co+2 (d7) under tetrahedral symmetry and maintain the crystal symmetry with lattice distortion. The Co-ion doping in the ZnO nano-matrix leads to creation of various defects & oxygen vacancies, which results in the blue shift in band-gap energy makes them useful for various applications e.g. photocatalytic water splitting, hydrogen generation, spintronics and optoelectronics.

Understanding of K and Mg co-promoter effect in ethylene oxychlorination by operando UV–vis-NIR spectroscopy

The comprehensive kinetic study for CuCl2/γ-Al2O3-based catalysts was performed to elucidate the co-promoter effect in the ethylene oxychlorination, one of the most significant industrial processes to produce vinyl chloride monomer. Kinetic analysis was performed separately by transient kinetic studies, taking account of the reduction and oxidation steps in the catalytic cycle. The promoter effects on ethylene oxychlorination were ascribed to their influence on the Cu2+ reduction or Cu+ oxidation in the catalytic cycle. The reaction rate-diagram was gained and used to predict the steady-state reaction rate and Cu oxidation state by an operando setup combing MS and UV–vis-NIR spectroscopy. The results indicated that the K-doped catalyst could greatly increase the reaction rate of the oxidation step, which gave rise to higher Cu2+ concentration on the catalyst. Mg-doped catalyst had a great effect on enhancing the reaction rate for the reduction step. K and Mg co-doped catalyst had the dual effect, both the reaction rate and Cu oxidation state were located between K and Mg mono-doped catalyst. The results of steady-state reactions indicated that the reaction rates were quite close with that predicated by the rate-diagram. Byproduct analysis during the steady-state was also performed, the results demonstrated that the co-promoted catalysts can also reduce the byproduct formation. The current study is expected to provide one way for exploring the potential benefits of co-promotion on CuCl2/γ-Al2O3-based industrial oxychlorination catalysts to improve the catalytic performance and understand the reaction further.

Structural and optical properties of copper oxide (CuO) nanocoatings as selective solar absorber

Selective solar absorber thin films of copper oxide (CuO) on copper substrates were synthesised through chemical oxidation using alkaline solution and additives at 60 °C for different oxidation reaction. The surface morphology, elemental composition, structural and optical properties of the CuO coatings were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and UV–VIS-NIR Spectroscopy and emissometer respectively. From XRD peaks cupric oxide (CuO) phases were confirmed from all the films. EDS spectrum confirms that all the synthesized nanocoatings is mainly Cu & O, which was free from contamination. Nanoflake-like structure and nano-pillar like surface are observed from SEM and AFM morphology, respectively. The surface roughness of the CuO films was ranged from 13.8 to 15.7 nm. The solar absorptance (α) and thermal emittance (ε) of the CuO nanostructured thin films were ranged between 91.84 and 89.06%, and 9–13%, respectively. A high solar absorptance of 0.92 and low thermal emittance of 0.13 was achieved for 2.0 hr oxidation time.

Tribological characterization of graphene nanoplatelets/alumina particles filled epoxy hybrid nanocomposites

AbstractIn this work, graphene nanoplatelets have been synthesized using liquid phase exfoliation of graphite flake powder. The exfoliated graphene nanoplatelets were identified and characterized by using UV–Visible–NIR spectroscopy, High resolution transmission electron microscopy, electron diffraction, scanning electron microscopy and X‐ray diffraction. The obtained graphene nanoplatelets and nano alumina at various weight ratios were dispersed in an epoxy matrix to enhance the surface roughness (Ra), micro hardness (Hv) and coefficient of friction (CoF) of epoxy hybrid nanocomposites. The results showed that the Ra and CoF value for the combined loading of 0.2 wt% of graphene nanoplatelets and 0.8 wt% of alumina into the epoxy was decreased to 41.02 and 20.01% whereas, the Hv value was increased to 10.04% when compared with the neat epoxy. The improved mechanical and tribological behaviors are suitable for the applications bearing and coating.

Optimization of Al-doped ZnO films by RF magnetron sputtering at room temperature for Cu (In, Ga) Se2 solar cells

In this work, Al-doped zinc oxide (AZO) thin films were deposited by RF magnetron sputtering with various RF power at room temperature. The effect of RF power on the structural, electrical, and optical properties of AZO thin films were investigated by XRD, SEM, UV–Vis–NIR spectroscopy and Hall measurements. The lowest resistivity of 1.8×10−3 Ω·cm was obtained at the highest RF power of 450 W. The average optical transmittance is about 90% in the visible range and above 80% in the range of 300-2000 nm. CIGS thin-film solar cells were prepared using the AZO films as the windows layer and an efficiency of 15.36% in CIGS solar cell has been achieved.

Effect of RF sputtering power and vacuum annealing on the properties of AZO thin films prepared from ceramic target in confocal configuration

Aluminum-doped zinc oxide (AZO) thin films are deposited on glass substrate by radio frequency (RF) magnetron sputtering method in confocal configuration at room temperature (RT). Several techniques are used to investigate the effects of sputtering power, from 50 to 300 W, on structural, optical and electrical properties. It is found, from Grazing Incidence X-Ray Diffraction (GIXRD) analysis, that the sputtering power has a great influence on the crystalline quality of AZO films. A preferential orientation along the c-axis is obtained at lower sputtering power of 50 W. XPS analysis confirms the existence of only Zn and Al in the oxidized state in accordance with the XRD results. SEM and AFM observations of AZO films reveal dense and homogenous distribution of small grains on the surface. Analysis by UV–Vis–NIR spectroscopy at RT reveals that the average optical transmittance in the visible range (400–800 nm) of the AZO thin films is higher than 75%. Hall-effect measurements put into evidence that the electrical resistivity of the films increases with the increase of the sputtering power. A low resistivity of 1.65 × 10−3 Ω cm is obtained for the lowest sputtering power (50W). Moreover, AZO thin film deposited at 50 W and annealed for 1h at 400 °C under vacuum shows a lower resistivity of 5.75 × 10−4 Ω cm, an average optical transmission above 86% and a high figure of merit (ФTC) value of 3.4 × 10−3 Ω−1sq which suggests that the fabricated AZO thin films are promising for optoelectronic devices in the UV region.

Eco-friendly dye sensitized solar cell using natural dye with solid polymer electrolyte as hole transport material

Dye sensitized solar cells (DSSC) are placed in third generation of solar cells. DSSC have more benefits over silicon solar cells such as low fabrication cost and eco-friendliness. In the existing research work dye-sensitized solar cells were fabricated using natural dye extracted from some fruits as ‘sensitizer’. The TiO2 thin films were prepared on FTO coated glass substrate using doctor blade technique as photoanode. The fruits and plants dye extracted in ethanol was used as sensitizes. The standard polymer electrolyte with counter electrode of platinum was used and natural DSSCs were fabricated. The optical properties of FTO coated thin film and extracted dyes were studied using UV–VIS-NIR spectroscopy. The extracted fruits and plants dye showed absorption up to 500 nm wavelength of incident light. The fabricated solar cells were characterized for electrical properties through Keithley source meter which are current, fill factor, open circuit voltage was achieved. Results showed that fruits and plants dyes using in DSSCs can be the promising source as light harvester.

Effect of OH content in the quartz crucible on the growth and quality of CsI single crystals and remedies

We have investigated the effect of hydroxyl (OH) content in fused silica crucible on the scintillation and optical properties of the CsI single crystal, but not limited to, grown by Bridgman technique. For the purpose, 0.1 mol% Tl doped CsI single crystals were grown in crucibles made from fused silica of different grades with OH content varying from 20 ppm to 200 ppm. Silica glass of crucibles was characterized by FTIR and UV–VIS-NIR spectroscopy for the estimation of OH content. Grown crystals were tested for their scintillation performance and a correlation between OH content in silica glass and crystal quality is established. The possibility of ‘OH’ out-diffusion from silica crucible into the melt at higher temperature was further established by temperature dependent study of outgassing from silica crucible by residual gas analyzer (RGA). Further, an optimized process for silica crucible annealing to remove OH (<20 ppm) is proposed to achieve excellent crystal quality of a 5.6% energy resolution at 662 keV without any co-doping in Tl doped CsI.

Effect of substrate temperature on the properties of RF sputtered CdS thin films for solar cell applications

We report the effect of substrate temperature (25–300 °C) on the structural, optical and electrical properties of Cadmium Sulphide (CdS) thin films deposited onto glass substrate by Radio Frequency (RF) magnetron sputtering. The structural, morphological, optical and electrical properties of the films were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), UV–VIS-NIR spectroscopy and Hall Effect measurement respectively. The XRD studies showed that the films were polycrystalline with hexagonal wurtzite structure preferentially oriented along the (0 0 2) plane parallel to the substrate surface. The XRD data analysis further revealed the crystallite size of the nanocrystalline films i.e. 22–24 nm exhibiting the fact that crystallite size increased with increasing the substrate temperature. The FE-SEM images along with energy dispersive spectroscopy (EDS) studies confirmed the homogeneous, compact and pin-hole free surface morphology. The UV–VIS-NIR studies unveiled the optical transmittance in the range of 75–90% after 540 nm of the wavelength of light. The optical band gaps were found to be decreasing from 2.34 eV to 2.26 eV with increasing the substrate temperature. The films were characterized as n-type as evidenced by the Hall Effect measurement. The carrier mobility was found to be increasing gradually from 5.53 to 12.57 cm2/V·s by increasing the substrate temperature from room temperature to 300 °C due to the improvement of crystalline quality and grain size of the films. The results showed good optical and electrical properties of the films deposited at 300 °C which are suitable to use as window layer in thin film based solar cells.

FTIR, UV–Vis–NIR spectroscopy, and gamma rays shielding competence of novel ZnO-doped vanadium borophosphate glasses

Structural, optical, and gamma radiation safety properties of 46V2O5·46P2O5·(8–x)B2O3·xZnO (x = 0,2,4,6, and 8 mol%) abbreviated as VPB/Zn glasses were investigated. The structure of the synthesized glasses has been examined via FTIR spectra within the range of 400–1500 cm−1 at room temperature. UV–Vis–NIR measurements of the proposed glasses were performed within the range of 200–3300 nm. The optical characteristics such as optical energy bandgap ($$E_{{{\text{Optical}}}}$$), refractive index (nLinear), and Urbach’s energy (EU) have been determined. In addition, the mass attenuation coefficients (MAC) for VPB/Zn glasses were performed utilizing MCNP-5 simulation code and XCOM program for various gamma ray energy varied in range 0.015–15 MeV. Based on MAC values, the equivalent atomic number (Zeq) and buildup factors (EABF and EBF) were evaluated. Results reveal that the direct $$E_{{{\text{Optical}}}}^{{{\text{Tauc}}^{\prime } {\text{s}}}}$$ of the VPB/Zn glasses ranged from 0.688 to 0.710 eV, while from 0.560 to 0.647 eV for the indirect transition. The admission of the ZnO improves the MAC of the VPB/Zn glasses. Thus, one can conclude that the proposed glasses can be applied for optical devices as semiconductor glasses and considered as good materials for γ-rays shielding.

Lanthanide complexes with N-(2,6-dimethylphenyl)oxamate: Synthesis, characterisation and cytotoxicity

The complexation reactions of Ce(III), Nd(III), Gd(III) and Er(III) ions with the chelating/ bridging monoanionic ligand N-(2,6-dimethylphenyl)oxamate (Hpma−) in basic media were performed in view of the potential applications of oxamate derivatives as cytotoxic agents. The coordination compounds were characterised by different physico-chemical techniques: elemental analysis, conductivity measurements, IR, 1H NMR and UV–Vis-NIR spectroscopy, and X-ray crystallography. The anionic Hpma− ligand was obtained through conversion of the proligand ethyl (2,6-dimethylphenylcarbamoyl)formate (Hdmp). The reactions afforded lanthanide(III)–oxamate coordination polymers of the formulae: {[Ln(Hpma)3(MeOH)(H2O)]∙2MeOH}n (Ln = Ce (1) and Nd (2)), {[Gd2(Hpma)6(MeOH)4]∙6MeOH}n (3), {[Er2(Hpma)6(MeOH)(H2O)3]∙2MeOH}n (4) and [Ln2Na2(Hpma)8(EtOH)(H2O)6]n (Ln = Nd (5) and Gd (6)). The polymeric complexes feature Ln-Hpma moieties bridged by μ2-η1:η1:η1 Hpma− ligands, giving one-dimensional zig-zag chains of the LnOCOLn type. Atomic charge analysis and the MEP map of the Hpma− moiety using the DFT/B3LYP method were consistent with the chelating and bridging modes of the anionic ligand through all the oxygen atoms. An evaluation of the cytotoxic activities of the metal salts, the proligand and the novel lanthanide complexes on MCF-7, HEC-1A and THP-1 cells revealed that only the rare-earth metal salts [Ce(NO3)3·6H2O] and [Nd(NO3)3·6H2O] showed moderate cytotoxicity against MCF-7 and HEC-1A cells, respectively.

Synthesis, plasmonic properties, and CWA simulant decontamination activity of first row early transition metal nitride powders and nanomaterials

The complexes MCl3(THF)3 (M = Ti, V, Cr) were used as precursors to form early transition metal nitrides, and solid solutions of these isomorphous complexes MxM’1−xCl3(THF)3 were prepared by co-crystallization. Heating the precursor under NH3 flow from 800 to 950 °C produced powders of the nitride MN, and solid solutions of these precursors produced alloys of the nitrides. Nanomaterials were synthesized by two methods: (1) reaction of a MCl3(THF)3 solution with 3 eq of KNH2 in THF in the presence (or absence) of oleylamine, followed by nitridation under NH3 flow at 650–950 °C and (2) loading a porous catalyst support such as pelletized Al2O3 with the MCl3(THF)3 complex, followed by similar heat treatment. The materials were characterized by powder X-ray diffraction, elemental analysis, SEM, and optical spectroscopy. Diffuse reflectance and UV–Vis-NIR spectroscopy showed the local surface plasmonic resonances (LSPRs). Although diffuse reflectance and UV–Vis-NIR spectroscopy showed LSPRs whose position was sensitive to surface functionalization and conditions of preparation, preliminary results show TiN nanoparticles have some activity in the degradation of the Chemical Warfare Agent (CWA) simulant DEMETON-S, but light plays no role in the mechanism.

Microscopic Analysis of Heterogeneous Nucleation of Nanoparticle Superstructures.

Nucleation phenomena play an important role in our world, and understanding them is of major interest. However, we lack analytical methods with the sufficient temporal and spatial resolution to analyze nucleation processes. In this work we used CTAB-stabilized gold nanocubes as a model system for nucleation, meaning the nanoparticles act like ions or atoms and built up larger superstructures comparable to normal nucleation phenomena. Thereby we analyzed the heterogeneous nucleation of the gold nanocubes on hydrophobized and negatively charged mica surfaces with a combination of UV-vis-NIR spectroscopy and light microscopy. With the plasmon resonance of the gold nanocubes we gained valuable information about the early nucleation of the particles and their concentration in solution via UV-vis-NIR spectroscopy. The combination with a light microscope enabled the simultaneous detection of nucleated species on the surfaces and opened the possibility to analyze the kinetics of the heterogeneous nucleation process. With this, we were able to determine the nucleation rates. While the hydrophobized surfaces did not influence the nucleation of the gold nanocubes, the negatively charged surfaces greatly promoted the nucleation. Thereby, we could demonstrate that the combination of simple and commonly available light microscopy and optical spectroscopies in general is a suitable and easy strategy to analyze heterogeneous nucleation processes directly in solution on a relevant statistical basis.

Discovery of mono(u-oxo)dicopper and bis(u-oxo)dicopper in ordered Cu incorporated in SBA-15 via sol-gel process from silatrane at room temperature: An in situ XAS investigation

Abstract We proposed a synthesis pathway to obtain high-yielding SBA-15 containing copper (Cu-SBA-15) via a sol-gel process from silatrane and discovered that the active copper species had a large pore size and narrow size distribution, where the pore sizes increased with increasing copper content. In addition, the results from UV–Vis–NIR spectroscopy revealed that the active copper species were mono(u-oxo)dicopper [Cu2(μ-OH)2]2+ (21 740 cm−1) and bis(μ- η2: η2 peroxo)dicopper [Cu2(μ- η2: η2-O2]2+ bent (17 850–18 691 cm−1) and planar (24 690 cm−1). Furthermore, the microscopic techniques (scanning (SEM) and transmission (TEM) electron microscopy) showed the characteristic of a long length channel and retained SBA-15 structure after incorporation of Cu, even at high copper loadings, and had a higher copper content loading with a longer length of Cu-SBA-15. In addition, the 9% Cu-SBA-15 was characterized by broad X-ray powder diffraction (XRD) which was used to inspect the aggregation and formation of CuO and no peak was observed. All evidence suggested that the Cu-SBA-15 successfully prepared and discovered the active copper species. In-situ XAS showed that to produce active copper species in Cu-SBA-15, heating under a helium atmosphere at 350 °C for 30 min was sufficient for the formation of bridge oxygen (Cu-Ox-Cu) with the characteristics of mono(u-oxo)dicopper and bis(u-oxo)dicopper.

Investigation of energy band-gap of the composite of hexaferrites and polyaniline

The Bi–Al doped M-type hexaferrite (BaFe11.8Bi0.1Al0.1O19) was prepared by the use of sol gel auto combustion process. The prepared sample was sintered at 1000 °C for 5 h. Polyaniline was synthesized by oxidative polymerization. Mechanical blending was used to synthesize BaFe11.8Bi0.1Al0.1O19-PANI composite. X-ray diffraction (XRD), Fourier Transform Infra-red spectroscopy (FTIR), Field Emission Scanning Electron Microscope, Energy Dispersive X-ray spectroscopy and UV–vis-NIR spectroscopy were used for structural and optical analysis. XRD spectra show pure single phase of M-type hexagonal ferrites. The presence of bands in FTIR spectra in the range of 400–600 cm−1 and 800–1600 cm−1 indicate possible formation of hexaferrite and PANI. The band gaps were found nearly 2.24, 2.36 and 2.21 eV for HP1, HP2 and HP3 respectively.

Dy(9.33-x)Lax(SiO4)6O2 crystals with improved magneto-optical performances prepared by Czochralski growth method

In this account, Dy(9.33-x)Lax(SiO4)6O2 crystals were grown by the Czochralski technique, and their magneto-optical properties were examined. Rietveld structural refinement of XRD patterns illustrated Dy(9.33-x)Lax(SiO4)6O2 possess hexagonal system P63/m with oxyapatite structure. UV–Vis–NIR spectroscopy revealed higher transparency in the 420–700 nm spectral region when compared to PSO and TGG crystals. The magneto-optical properties and temperature dependence of magnetic susceptibility demonstrate that Dy8.36La0.97(SiO4)6O2 crystals show paramagnetic behavior within the temperature range of 2–300 K and yield a Faraday rotation angle which is approximately 1.16-fold larger than that of Tb3Ga5O12 crystals. Overall, Dy8.36La0.97(SiO4)6O2 crystals look promising for applications in magneto-optical devices in the visible wavelength range.

Dopant Occupancy and UV–Vis–NIR Spectroscopy of Sc:Yb:Tm:LiNbO3 in the 300–3000 nm Wavelength Range

AbstractA series of Sc:Yb:Tm:LiNbO3 crystals with variable Sc3+ (0, 1, 2, and 3 mol%) concentration are grown by the Czochralski method. The effective distribution coefficients of Sc3+, Yb3+, and Tm3+ ions in the Sc:Yb:Tm:LiNbO3 crystals are determined by inductively coupled plasma atomic emission spectrometer. Sc3+ ions distribute uniformly in crystals when Sc3+ concentration reaches up to 3 mol%. The influence of Sc3+ concentration on the dopant occupancy and defect structure of Sc:Yb:Tm:LiNbO3 crystals is investigated by IR transmission spectra. Threshold concentration of Sc3+ ions in Sc:Yb:Tm:LiNbO3 crystals is nearly 3 mol%. By analyzing UV–vis–NIR absorption spectra, absorption property of Sc:Yb:Tm:LiNbO3 crystals is improved by doping Sc3+ ions. Additionally, the Sc:Yb:Tm:LiNbO3 crystals can be pumped by commercially available high power AlGaAs LDs.