Growth of Cu2+ and Mg2+ doped nonlinear optical LATF crystals and their characterization

Single crystals of pure, Cu²⁺ and Mg²⁺ doped l-arginine trifluoroacetate (LATF) have been grown by the temperature lowering method. The presence of Cu²⁺ and Mg²⁺ was determined by atomic absorption spectroscopy (AAS). Single crystal X-ray diffraction studies were performed to calculate the lattice parameters of the pure and doped crystals. Absorption of these crystals was analyzed and the result confirms that they possess low absorption in the range 230–1100 nm. Thermal analysis (TGA, DTA) and Fourier transform infrared (FTIR) spectroscopy were carried out to investigate the thermal behavior and molecular vibrations of these crystals, respectively. The second harmonic generation (SHG) measurement reveals the NLO properties of pure and doped crystal. Surface morphologies of these crystals were also observed and studied in detail by atomic force microscopy.     

Microhardness,FTIR and transmission spectral studies of Mg2+ and Zn2+ doped nonlinear optical BTCC single crystals

Pure, Mg²⁺ and Zn²⁺ doped BTCC single crystals are grown from their aqueous solutions at 301 K. The grown crystals are characterized by single crystal XRD, FTIR and UV–Vis-NIR spectral studies. The preliminary investigations of the UV–Vis-NIR spectra on the doped samples suggest an increased percentage of transmission in comparison to pure BTCC crystals. The SHG efficiency of the metal doped BTCC crystals is found better than the pure ones. It is estimated from the microhardness studies that the mechanical strength of the BTCC crystals are improved due to the metallic (Mg²⁺ and Zn²⁺) substitutions.     

Growth and characterization of metal ions and dyes doped KDP single crystals for laser applications

The organic dyes (Amaranth, Rhodamine B and Methyl Orange) are doped in Potassium Dihydrogen Phosphate crystals. Influences of supersaturation and dye concentration in the solution, on the color and crystal habit of Potassium Dihydrogen Phosphate, were observed. Amaranth in the solution at low super saturation and high dye concentration colored the pyramidal section (1 0 1) of the crystals. The highly super saturated solutions produce entirely colored crystals. Dyes doped Potassium Dihydrogen Phosphate crystals were also grown by solution growth technique. The concentration of dopants in the mother solution was varied from 0.1 to 10 mol%. The studies on pure and doped Potassium Dihydrogen Phosphate crystals clearly indicate the effect of dopants on the crystal structure, in the absorption of IR frequencies and the non-linear optical property. The frequencies with their relative intensities are obtained in Fourier Transform-Infrared spectra of pure and doped Potassium Dihydrogen Phosphate. The very weak bands for dopants indicate its presence in low concentration. The absence of even such a weak band in the case of Potassium Dihydrogen Phosphate doped with Amaranth indicates the strong interaction with O-H groups. The calculated IR frequency 3333 cm⁻¹ for O-H stretching was in close agreement with the experimentally obtained one for pure Potassium Dihydrogen Phosphate at 3340 cm⁻¹.The doped crystals show good second harmonic generation efficiency. The dopants increase the hardness value of the material, which also depends on the concentration of the dopants. Dye doping improves the Nonlinear Optical properties of the grown crystals. Results of the growth kinetics of Potassium Dihydrogen Phosphate crystals in the presence of impurities are also discussed.     

Effect of cobalt (Co<Superscript>2+</Superscript>) concentration on structural,optical, thermal and mechanical properties of potassium acid phthalate (KAP) crystals

Single crystals of pure and Co²⁺ (0.2, 0.4 and 0.6 mol%) doped KAP crystals were grown by low temperature slow evaporation method. The grown crystals were subjected to various characterization techniques such as X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), UV–visible spectroscopy and Second Harmonic Generation studies. The XRD profile confirms that Co²⁺ ions incorporated into the KAP crystal lattice. The existence of functional groups in the grown crystals have been studied by FTIR analysis. Optical transmission is decreased when doping Co²⁺ concentration increase. After melting point, no decomposition is found in the pure crystal. Vickers micro hardness studies revealed that the doped crystals possess very high hardness values. The dielectric constant, dielectric loss and thermal stability values have been measured as a function of frequency and temperature respectively for the doped crystals.     

Thermal, dielectric studies on pure and amino acid (l-glutamic acid, l-histidine, l-valine) doped KDP single crystals

Amino acids (l-glutamic acid, l-histidine, l-valine) doped potassium dihydrogen phospate crystals are grown by solution growth technique. Slow cooling as well as slow evaporation methods were employed to grow these crystals. The concentration of dopants in the mother solution was varied from 0.1 mol% to 10 mol%. The solubility data for all dopants concentration were determined. There is variation in pH value and hence, there is habit modification of the grown crystals were characterized with UV–VIS, FT-IR studies, SHG trace elements and dielectric studies reveal slight distortion of lattice parameter for the heavily doped KDP crystals. UV–Visible spectra confirm the improvement in the transparency of these crystals on doping metal ions. FT-IR spectra reveal strong absorption band between 1400 and 1600 cm⁻¹ for metal ion doped crystals. TGA–DTA studies reveal good thermal stability. The dopants increase the hardness value of the material and it also depends on the concentration of the dopants. Amino acids doping improved the NLO properties. The detailed results on the spectral parameters, habit modifications and constant values will be presented.     

Exciting Dilute Magnetic Semiconductor: Copper-Doped ZnO

The present study is focused on the copper-doped ZnO system. Bulk copper-doped ZnO pellets were synthesized by a solid-state reaction technique and used as target material in pulsed laser deposition. Thin films were grown for different Cu doped pellets on sapphire substrates in vacuum (5×10^?5 mbar). Thin films having (002) plane of ZnO showed different oxidation states of dopants. M–H curves exhibited weak ferromagnetic signal for 1–3 % Cu doping but for 5 % Cu doped thin film sample showed the diamagnetic behavior. For deeper information, thin films were grown for 5 % Cu doped ZnO bulk pellet in different oxygen ambient pressures and analyzed. PL measurement at low temperature showed the emission peak in thin films samples due to acceptor-related transitions. XPS results show that copper exists in Cu²⁺ and Cu⁺¹ valence states in thin films and with increasing O₂ ambient pressure the valence-band maximum in films shifts towards higher binding energy. Furthermore, in lower oxygen ambient pressure (1×10^?2 mbar) thin films showed magnetic behavior but this vanished for the film grown at higher ambient pressures of oxygen (6×10^?2 mbar), which hints towards the decrease in donor defects.     

Growth and properties of benzil doped benzimidazole (BMZ) single crystals

In the present work, we have made an attempt to study the effect of benzil doping on the properties of benzimidazole single crystals. For this purpose we have grown pure and benzil doped benzimidazole single crystals by vertical Bridgman technique. The grown crystals were characterized by various characterization techniques. The presence of dopants confirmed by powder X-ray diffraction (XRD). Crystalline perfection of the grown crystals has been analysed by high-resolution X-ray diffraction (HRXRD). The transmittance, electrical property and mechanical strength have been analysed using UV-vis-NIR spectroscopic, dielectric and Vicker's hardness studies. The relative second harmonic generation efficiency of pure and doped benzimidazole crystals measured using Kurtz powder test.     

Microhardness studies in ammonium halide crystals

Microhardness studies of NH₄Cl (pure and doped), NH₄Br and alkali halide crystals are presented. The hardness of ammonium halides is found to be less as compared to alkali halide crystals. Doping NH₄Cl crystals with copper (Cu²⁺) is found to increase the hardness enormously and the results obtained with various concentrations of copper are presented. The results have been analysed and the various factors contributing to the increase in hardness at lower loads have been discussed.     

Crystal structure,magnetic susceptibility and electrical conductivity of pure and NiO-doped MoO2 and WO2

Single crystals of MoO₂ and WO₂, pure and doped with NiO, were grown by chemical transport in Vycor ampoules using iodine as the transporting agent. From X-ray diffraction analyses it was found that all the crystals were monoclinic, and that doping up to 5% does not change the unit cell constants. The pure dioxide crystals are weakly paramagnetic χ_M < 100×10^?6 emu, but doping raises the magnetic susceptibility markedly: ～ 2500×10^?6 emu. Resistance studies show that these materials are metallic conductors, the room temperature specific resistivity being of the order of 10^?4 – 10^?3 Ωcm, decreasing by one order of magnitude at liquid nitrogen temperature. Doping also substantially lowers the conductivity.     

Cu ion in-diffusion in congruent LiNbO3 single crystals

Congruent LiNbO₃ (LN) crystals were grown by Czochralski technique. Thermal in-diffusion of transition metal ion Cu²⁺ into crystal wafers was performed at various temperatures. The absorption peaks in transmission spectra indicates the Cu²⁺ ion diffusion in LN crystal wafer. A broad absorption band centered at 948 nm was observed in the absorption spectra due to the vibronic transition associated with Cu²⁺ centers. The significant red shift in absorption edges indicates the decrease in Li/Nb ratio in Cu in-diffused crystal wafers. Powder XRD of pure and Cu in-diffused LN samples show no structural change during thermal diffusion.     

Growth and stability of pure and amino doped TGS crystals

Pure and amino (L-alanine and L-valine) doped TGS crystals were grown by the slow cooling method. The rates of nucleation as indicated by the induction period were measured. Effects of dopants on the solubility, stability and induction periods were investigated in stirred solutions. The interfacial energy for pure and doped solutions at 30°C was calculated. High quality single crystals of dimension 9×5×4 cm³ were grown.     

Morphology and luminescent properties of Al<Superscript>3+</Superscript>/Mg<Superscript>2+</Superscript>-doped Y<Subscript>2</Subscript>O<Subscript>3</Subscript>:Eu<Superscript>3+</Superscript> phosphor

Al³⁺/Mg²⁺ doped Y₂O₃:Eu phosphor was synthesized by the glycine-nitrate solution combustion method. In contrast to Y₂O₃:Eu which showed an irregular shape of agglomerated particles (the mean particle size >10 μm), the morphology of Al³⁺/Mg²⁺ doped Y₂O₃:Eu crystals was quite regular. Al³⁺/Mg²⁺ substituting Y³⁺ in Y₂O₃:Eu resulted in an obvious decrease of the particle size. Meanwhile, higher the Al³⁺/Mg²⁺ concentration, smaller the particle size. In particular, the introduction of Al³⁺ ion into Y₂O₃ lattice induced a remarkable increase of PL and CL intensity. While, for Mg²⁺ doped Y₂O₃:Eu samples, their PL and CL intensities decreased. The reason that causes the variation of PL and CL properties for Al³⁺ and Mg²⁺ doped Y₂O₃:Eu crystals was concluded to be related to sites of Al³⁺ and Mg²⁺ ions inclined to take and the difference of ion charge.     

Up-conversion emission in KGd(WO4)2 single crystals triply-doped with Er/Yb/Tm, Tb/Yb/Tm and Pr/Yb/Tm ions

Triply-doped single crystals KGd(WO₄)₂:Er³⁺/Yb³⁺/Tm³⁺, KGd(WO₄)₂:Tb³⁺/Yb³⁺/Tm³⁺ and KGd(WO₄)₂:Pr³⁺/Yb³⁺/Tm³⁺ were grown by the Top Seeded Solution Growth (TSSG) method, with an aim of getting efficient up-converted multicolored luminescence, which subsequently can be used for generation of white light. Such an aim determined the choice of the triply doped compounds: excitation of the Yb³⁺ ions in the infrared spectral region is followed by red, green and blue emission from other dopants. It was shown that all these systems exhibit multicolor up-conversion fluorescence under 980 nm laser irradiation. Detailed spectroscopic studies of their absorption and luminescence spectra were performed. From the analysis of the dependence of the intensity of fluorescence on the excitation power the conclusion was made about significant role played by the host’s conduction band and other possible defects of the KGd(WO₄)₂ crystal lattice in the up-conversion processes.     

Antibacterial efficacy,corrosion resistance,and cytotoxicity studies of copper-substituted carbonated hydroxyapatite coating on titanium substrate

This work elucidated the antibacterial efficacy, corrosion resistance, and cytotoxicity of electroplated copper-substituted hydroxyapatite (CuHAP) coating on titanium (Ti). The fabricated CuHAP coatings were characterized by scanning electron microscopy, energy-dispersive X-ray analysis spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction studies. The CuHAP coating had needle-like apatite crystals, the doping of Cu²⁺ into HAP reduced porosity, and the coating became denser. The CuHAP crystals were carbonated with a few of Cu²⁺ incorporation (about 0.80 wt%). The Cu²⁺ ions were homogenously deposited into HAP films. Potentiodynamic polarisation test revealed that the CuHAP coating provided good barrier characteristics and achieved superior corrosion protection for Ti substrates. The in vitro antibacterial activity of as-prepared CuHAP coating was evaluated against Escherichia coli and was found to be effectively high against bacterial colonization. Bioactivity test conducted by soaking the coatings in simulated body fluid demonstrated that CuHAP coating can quickly induce bone-like apatite nucleation and growth. In vitro biocompatibility tests, MTT, were employed to assess the cytotoxicity of CuHAP coating with osteoblast-like MC3T3-E1 cells. The obtained HAP coating doped with a low content of Cu²⁺ exhibited good cytocompatibility and had no toxicity toward MC3T3-E1.     

Effect of Zn<Superscript>2+</Superscript>, Ti<Superscript>2+</Superscript> dopants on structural,optical and electrochemical properties of V<Subscript>2</Subscript>O<Subscript>5</Subscript> nanoparticles synthesized via non-aqueous sol–gel route

Transition divalent metal cations (Zn²⁺, Ti²⁺) doped V₂O₅ nanoparticles were synthesized via non-aqueous sol–gel route. The influence of dopant materials on the characteristics of V₂O₅ nanoparticles was studied. XRD studies ensure that all the prepared samples possess phase pure orthorhombic structure. From the FESEM images, it was noted that the products possess uniform particle size around 20–30 nm. The presence of functional groups and dopants was confirmed by FTIR, Raman, and elemental analysis respectively. From UV–Vis spectra, the significant blue shift was observed for doped samples compared to pure V₂O₅ nanoparticles, which is attributed to the quantum confinement effect. The high capacity retention of the intercalation compound was measured by using C–V study and implies that the prepared samples are very promising electrode materials for supercapacitor.     

Physical properties of Bi2Te2.85Se0.15 single crystals doped with Cu, Cd, In, Ge, S, or Se

Bi₂Te_2.85Se_0.15 crystals doped with Cu, Cd, In, Ge, S, or Se were grown by the floating-crucible technique. The effective segregation coefficients for the dopants were determined. The thermoelectric power, electrical conductivity, and thermal conductivity of the samples were measured in the temperature range from 77 to 350 K. The effects of the dopants studied on the temperature dependences of the electrical properties and thermoelectric figure of merit were examined. The bending strength of the doped crystals was measured.     

Green synthesis of ZnO and Mg doped ZnO nanoparticles,and its optical properties

The Zinc oxide nanoparticles (ZnO NPs) and Magnesium doped ZnO nanoparticles (Mg doped ZnO NPs) are synthesized by Psidium guajava leaf extract. X-ray diffraction studies confirmed that, synthesized nanoparticles were retained the wurtzite hexagonal structure. In FESEM and HRTEM image analysis, ZnO and Mg doped ZnO NPs morphology were trigonal and spherical shape. Elemental compositions were identified by EDAX analysis. From FTIR result, the Zn–O stretching was observed at 453 and 448 cm^?1 for both ZnO samples. In Raman spectra, the high intensive E₂ ^high mode observed for 438 cm^?1 for ZnO NPs. But Mg doped ZnO NPs intensity of E₂ ^high mode decreased as compared to the pure ZnO NPs, it is due to the Mg²⁺ ion in to ZnO lattice site. The photoluminescence measurements revealed that the broad emission was composed of seven different bands due to zinc vacancies, oxygen vacancies and surface defects.     

Optical, structural and electrical properties of pure and urea doped KDP crystals

Single crystals of good optical quality, made of potassium dihydrogen phosphate (KDP) doped with urea were grown by slow evaporation solution growth technique at a constant temperature of 35 °C. Optical absorption and dielectric properties were studied for pure and urea doped KDP crystals. Using powder XRD studies, crystalline nature of pure and urea doped KDP crystals was confirmed. AC conductivity was measured for the grown crystals. DC electrical conductivity and photoconductivity studies were carried out for pure and urea doped KDP crystals and the differences caused by the dopant were also discussed.     

Synthesis,characterization and optical properties of bismuth germanate doped with trivalent europium

Bismuth germanate single crystals doped with trivalent europium were grown by the Czochralski method. Procedures and results of synthesis experiments are reported. Microprobe analysis reveals the segregation of doped rare-earth elements. Spectroscopic studies of Eu³⁺ ions suggests C_3v point symmetry for the cationic site. Oscillator strengths and τ_λ parameters for Eu³⁺ were calculated.     

Synthesis and photochemical properties of Cu2+ doped layered hydrogen titanate

Cu²⁺ doped layered hydrogen titanate was prepared by the calcination of K₂CO₃, TiO₂ and CuO mixtures with the K₂CO₃:TiO₂:CuO molar ratio of 1:2.5(1−x):2.5x at 1200°C for 5 h followed by an ion-exchange reaction in 1 M HCl solution. The crystalline phase changed from monoclinic hydrogen tetratitanate to an orthorhombic lepidocrocite-type hydrogen titanate by increasing the amount of Cu²⁺ doped. Both compounds could be excited by visible light irradiation (λ>400 nm) and were capable of hydrogen gas evolution from an aqueous methanol solution, where the photocatalytic activity of Cu²⁺ doped hydrogen tetratitanate was slightly greater than that of Cu²⁺ doped lepidocrocite-type hydrogen titanate. The photocatalytic activity of Cu²⁺ doped hydrogen tetratitanate was enhanced by constructing Pt and TiO₂ pillars in the interlayer, and the incorporation of Pt in Cu²⁺ doped hydrogen tetratitanate enabled the cleavage of water into hydrogen and oxygen by irradiating visible light (λ>400 nm) without a sacrificial hole acceptor.