Double Potassium Research Articles

In-Band Pumped Continuous-Wave Lasers Based on Ho:KY(WO<sub>4</sub>)<sub>2</sub> Crystal and Ho:KGdYbY(WO<sub>4</sub>)<sub>2</sub> Epitaxial Layer

2 μm lasers are in demand for a number of practical applications, such as environmental monitoring, remote sensing, medicine, material processing, and are also used as a pump sources for optical parametric generators. Crystals of double potassium tungstates doped with ions of rare-earth elements were shown to be promising materials both for the creation of classical solid-state lasers and waveguide lasers. The aim of this work was to develop a tunable pump laser in the spectral region of 1.9 µm based on double tungstate crystals doped with thulium ions and to study the lasing characteristics of a Ho:KY(WO4)2 crystal and a Ho:KGdYbY(WO4)2 single-crystal epitaxial layer under in-band pumping.With a Ho(1at.%):KY(WO4)2 crystal, continuous wave low-threshold lasing with an output power of 85 mW with a slope efficiency of 54 % at 2074 nm was achieved. For the first time to our knowledge, continuous wave laser generation in a waveguide configuration is realized in a single-crystal layer of potassium tungstate doped with holmium ions grown by liquid-phase epitaxy. The maximum output power at a wavelength of 2055 nm was 16.5 mW.

Fontes de fertilizantes potássicos na qualidade dos tubérculos de batata

A resposta da batateira à adição de nutrientes ao solo proporciona relevante atenção, especialmente a adubação com potássio (K), por ser um elemento que interfere na composição dos tubérculos, consequentemente em sua qualidade. O cloro, presente na principal fonte de K para as plantas (KCl), pode gerar efeito negativo em atributos relacionados a qualidade dos tubérculos. Neste sentido, objetivou-se avaliar a influência de duas fontes de fertilizante potássico (KCl e K2SO4.2MgSO4) e combinações entre elas na composição dos tubérculos de batata, cv. Asterix. A quantidade de N, P e K utilizada foi determinada mediante análise de solo e necessidade da cultura. A determinação dos glicídios redutores foi realizada segundo o método espectrofotométrico (Somogyi-Nelson), já os Glicídios totais e o amido, pelo método de Lane Eyno (titulométrico). A maior massa seca e amido na cultivar Asterix está relacionada à aplicação de 26.3% de KCl e 73.7% de K2SO4.2MgSO4 e 41.9% de KCl e 58.1% de K2SO4.2MgSO4, respectivamente. Assim, a combinação das fontes é indicada para promover maior teor dessas qualidades nos tubérculos. Por outro lado, fontes e proporções, de fertilizantes potássicos não interferem na composição dos açúcares. A taxa usada neste estudo (180 kg ha-1) provavelmente não foi suficiente para refletir o efeito deletério do cloro nos constituintes de açúcares dos tubérculos.
 Palavras-chave: Solanum tuberosum L., cultivar Asterix, cloreto de potássio, sulfato duplo de potássio e magnésio.

Электрохимические свойства композитных электродов, содержащих наночастицы солей меди

The energetic properties of the new composite electrode materials suitable for electrochemical capacitors were investigated. Composite electrodes were made using Norit A activated carbon and synthesized sparingly soluble copper salts such as copper iodide(I) and hexacyanoferrates (II), etc. (III). The composition of the salts was confirmed by elemental analysis and the particle size was determined by the Scherrer equation using the data of X ­ray phase analysis. The electrochemical characteristics of the electrodes were determined with the help of cyclic voltammetry, charge discharge galvanostatic curves, and impedance spectroscopy. It was found that the composite materials containing 5–30 wt.% of copper iodide and copper hexacyanoferrate (II) had lower capacitive characteristics compared with the pure carbon electrode. The introduction of double hexacyanoferrates (II), copper (III) and potassium into the electrode material led to the increase in the specific capacitance by 30 and 20% respectively, compared with a carbon electrode.

Physicochemical properties of manganese oxides obtained via the sol–gel method: The reduction of potassium permanganate by polyvinyl alcohol

Experimental data on the sol–gel synthesis of manganese oxides formed during the reduction of potassium permanganate by polyvinyl alcohol in an aqueous medium are presented. The physicochemical properties of the obtained manganese oxide systems that depend on the conditions of the synthesis are studied by means of DTA, XRD, SEM, and the low temperature adsorption–desorption of nitrogen. It is found that the obtained samples have a mesoporous structure and predominantly consist of double potassium–manganese oxide K2Mn4O8 with a tunnel structure and impurities of oxides such as α-MnO2, MnO, α-Mn2O3, and Mn5O8. It is shown that the proposed method of synthesis allows us to regulate the size and volume of mesopores and, to a lesser extent, the texture of the obtained oxides, which can be considered promising sorbents for the selective extraction of strontium and cesium ions from multicomponent aqueous solutions.

Specific directions of ultrasound propagation in double potassium tungstates for light modulation

Acousto-optical characteristics of double potassium tungstates are analyzed and specific directions for light modulation are found. First, an important subgroup of elasto-optic coefficients of KYb(WO4)2 and KLu(WO4)2 crystals are calculated with use of experimental data. It is revealed that with proper choice of ultrasound direction the acousto-optical figure-of-merit approximately 2 times exceeds the maximum value detected in previous experiments. Another unique direction is determined, which permits modulation of randomly polarized light. The elasto-optic characteristics of KYb(WO4)2 and KLu(WO4)2 crystals are compared to those of previously investigated materials of the same crystal group: KY(WO4)2, KGd(WO4)2.

Spectroscopic studies and density functional theory investigations of a cobalt phthalocyanine derivative

Colloidal solutions at room temperature were used to obtain various polymorphic forms of a [PcCoCN]n and double potassium salt from 1,8 dihydroxyanthraquinone derivative. Nanocrystals in the form α and β were characterized using IR and UV–Vis spectroscopy techniques. Likewise in this context, an energy doublet in the absorption spectra of the monoclinic form at 1.8 and 2eV was observed. The complex structure inherent to the spectra of the CoPc derivative is attributed to the simultaneous presence of both crystalline and molecular phases in the samples. The optical absorption of the compound was also investigated in order to evaluate changes in the electronic structure of these metal organic nanostructures. The absorption spectra of the CoPc derivative recorded in the UV–Vis region manifested two absorption bands, namely the Q- and B- bands. DFT calculations of this structure help to establish the source of the spectroscopic behavior and also lead to a particular phenomenon not known previously in this kind of complex, because the optimized structure of the cobalt complex manifests a very strange deformation of the bond between the anthraquinone derivative and the cobalt atom; the origin of this deformation is also discussed.

Efficient laser oscillation of disks and composite structures

The spectral and lasing characteristics of active disk elements made of double potassium – lutetium tungstates 5 %Tm : KLuW and 5 %Tm : KLuW/KLuW composite structures are comparatively studied. Laser power of about in the cw regime at a wavelength of was achieved in a composite sample with the active layer thickness of . Under quasi-cw pumping, the slope efficiency of all the studied samples exceeded 50 %. It is experimentally shown that the internal stresses in the composite structures strongly affect the spectral characteristics of the laser radiation.

Water-soluble double potassium and ammonium salts of iron(III) and manganese(II) with (hydroxyethylidene)diphosphonic acid

A method to multifold increase the water solubility of diiron(III) tris[(hydroxyethylidene)-diphosphonate) tetrahydrate Fe2(H2L)3·4H2O and manganese(II) (hydroxyethylidene)diphosphonate dihydrate MnH2L·2H2O, prepared by the reaction of 1-hydroxyethylidene-1,1-diphosphonic acid with iron(III)hydroxide and basic manganese carbonate. The method involves conversion of the phosphonates into their double salts Fe2K6L3·4H2O [Fe2(NH4)6L3·4H2O] and MnK1.3H0.7L·2H2O [Mn(NH4)2L·2H2O] by treatment of their aqueous suspensions with potassium or ammonium hydroxides. The solubility of the iron salt increases from 0.2 to 4.0 g per 100 mL solution (20 times) and that of the manganese salt increases from 0.1 to 4.8 g per 100 mL solution (45 times).

Screening of Microorganisms Capable of Producing Ethanol by Direct Fermentation of D-Xylose

A total of 120 D-xylose fermenting yeast strains were isolated from composition soil samples. 6 strains capable of fermenting D-xylose to produce ethanol were obtained by TTC double medium agar method screening and potassium dichromate oxidation method re-screening. All the 6 strains belong to the genera Candida or Pichia by morphology and physiology identification. Candida spp. strains showed rather high efficiency to produce ethanol from D-xylose than the Pichia spp. strains, of which, strain M-105 exhibited a D-xylose consumption rate of 98.28% and the highest ethanol yield (0.465 g/g), with concentration up to 18.58 g/L under the condition of fermenting 40 g/L of this sugar at 28°C and 100 r/min for 72 hours. An average ethanol concentration of 18.35±0.07 g/L was reached from three batches fermentation of M-105 in shaking flask.

Dielectric relaxation and electronic spectroscopy of double potassium yttrium tetraoxophosphate(V) K3Y(PO4)2 doped by neodymium and europium ions

The paper presents the results of our investigation on electric properties of double potassium yttrium tetraoxophosphate(V) doped by lanthanide ions K3Y(1−x)Lnx(PO4)2 (x = 0.01, 0.05, Ln = Eu3+, Nd3+). Electric permittivity and dielectric loss measurements have been performed on polycrystalline samples in the temperature range −50 °C to +120 °C and frequency range 1 kHz–1 MHz by means of HP 4282A impedance meter. The frequency and temperature dependence of electric properties were analyzed by theoretical models of dielectric relaxation in order to obtain information abut molecular dynamic of our solids in external electric field.

Dielectric relaxation in double potassium yttrium orthophosphate K3Y(PO4)2 doped by praseodymium and dysprosium ions

We report the paper presents the results of electric properties of double potassium yttrium orthophosphates doped by lanthanide ions K 3 Y( 1− x ) Ln x (PO 4 ) 2 ( x = 0.01, 0.05, Ln = Pr 3+ , Dy 3+ ). Electric permittivity and dielectric loss measurements have been performed on polycrystalline samples in the temperature range −50–120 °C and frequency range 1 kHz–1 MHz by means of HP 4282A impedance meter. The frequency and temperature dependence of electric properties were analyzed by theoretical models of dielectric relaxation in order to obtain information abut molecular dynamic of our solids in external electric field.

Synthesis and photoluminescence study of Ce 3+ /Dy 3+ -activated KLa(WO 4 ) 2 phosphors

In this study, the authors report the synthesis of Ce3+- and Dy3+-activated double potassium lanthanum tungstates [KLa(WO4)2], prepared by solid-state diffusion method. The prepared phosphors were characterised by X-ray diffraction, scanning electron microscopy and photoluminescence (PL) techniques. The PL spectra of KLa(WO4)2:Dy3+ shows the emission peaks at 569 and 476 nm. KLa(WO4)2:Ce3+ showed the emission peaks at 388 nm. Excitation wavelengths of these Ce3+- and Dy3+-activated tungstates are in near-UV region, that is, Hg-free excitation. Accordingly, Ce3+- and Dy3+-activated KLa(WO4)2 may be the promising materials for solid-state lighting applications.

Dielectric relaxation in double potassium yttrium orthophosphate K 3Y(PO 4) 2 doped by ytterbium ions

Electric properties were examined in double potassium yttrium orthophosphates K 3Y( 1− x )Yb x (PO 4) 2 ( x = 0.01, 0.05). Electric permittivity and dielectric loss measurements have been performed on polycrystalline samples in the temperature range −50 °C to 120 °C and frequency range 1 kHz–1 MHz by means of HP 4282A impedance meter. The frequency and temperature dependence of electric properties were analyzed by theoretical models of dielectric relaxation in order to obtain information about molecular dynamic of our solids in external electric field.

Matrix Interference-Free Method for the Analysis of Small Molecules by Using Negative Ion Laser Desorption/Ionization on Graphene Flakes

This work presents a new approach for the analysis of small molecules with direct negative ion laser desorption/ionization (LDI) on graphene flakes. A series of matrix interference-free mass spectra were obtained for the analysis of a wide range of small molecules including peptides, amino acids, fatty acids, as well as nucleosides and nucleotides. The mixture of analytes and graphene flakes suspension were directly pipetted onto a sample plate for LDI-time-of-flight mass spectrometry (TOFMS) analysis. Deprotonated monomeric species [M-H](-) ions were homogeneously obtained on uniform graphene flakes film when negative ion mode was applied. In positive ion mode, the analytes were detected in form of multiple adduct ions such as sodium adduct [M+Na](+), potassium adduct [M+K](+), double sodium adduct [M+2Na-H](+), double potassium adduct [M+2K-H](+), as well as sodium and potassium mixed adduct [M+Na+K-H](+). Better sensitivity and reproducibility were achieved in negative ion mode compared to positive ion mode. It is believed that the new method of matrix interference-free negative ion LDI on graphene flakes may be expanded for LDI-MS analysis of various small molecules.

Intense Visible Photoluminescence from C<sub>46</sub>H<sub>22</sub>N<sub>8</sub>O<sub>4</sub>KM (M = Co, Fe, Pb) Derivatives Thin Films

Strong visible photoluminescence (PL) at room temperature is obtained from thermal-evaporated thin solid films of Metallophthalocyanine (M = Co, Fe, Pb) and double potassium salt from 1,8 dihydroxyan-thraquinone. The PL of all the investigated samples is observed with the naked eye in a bright background. The deconvolution of the normalized PL spectra shows that each PL spectrum is composed of four emission bands which peak at approximately the same energies of 2.1, 2.2 and 2.4 eV and whose intensities and widths depend upon the structure of the complexes. FTIR and ellipsometry are employed to investigate the structural differences among the films. The optical absorption of the films is also investigated to evaluate the changes in the electronic structure of these metal organic compounds, with respect to other metalphtalocya-nines thin films. Our results suggest that the visible PL comes from radiative transitions between energy lev-els associated to the double potassium salt coordination to the metallic ion in the phthalocyanine.

Electrical and optical properties of (PPh 4) 2[Fe(CN) 5NO] non-crystalline thin films prepared with the vacuum thermal evaporation technique

Molecular-material thin films of (PPh 4) 2[Fe(CN) 5NO] and a double potassium salt from 1,8-dihydroxyanthraquinone have been prepared by vacuum thermal evaporation on Corning glass substrates and crystalline silicon wafers. The surface morphology, thickness and structure of the deposited films were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), ellipsometric measurements, ultraviolet–visible (UV–vis) and Fourier-transform infrared (FT-IR) spectroscopies. The amorphous films show the same intra-molecular bonds as the IR spectroscopic studies, which suggests that the thermal evaporation process did not alter the initial chemical structures. The conductivity and the electrical-conduction mechanism in the thin films were also investigated. Finally, the optical band gap ( E g) of these molecular complexes was evaluated from optical absorption measurements.

SODIUM AND POTASSIUM SENSORS BASED ON SEPARATED EXTENDED GATE FIELD EFFECT TRANSISTOR

A double potassium and sodium ions sensor based on separated extended gate field effect transistor (SEGFET) and a new entrapment method are proposed in this study. Having high sensitivity, reproducibility, and a simple manufacturing process, the sensors are quickly able to supply information and detect human blood within an abnormal range. The sensing membranes were fabricated using a Poly(vinyl chloride) carboxylated (PVC-COOH) matrix; sodium ionophore (B12C4) or potassium ionophore (valinomycin). The sensitivity of ion-selective biosensors is 42.55 mV/decade for Na+ between 1 M and 10-7 M, 42.75 mV/decade for K+ between 1 M and 10-6 M.

Optically stimulated luminescence at room temperature of hydrothermal K2YF5:Pr3+ crystals

AbstractIn this paper optically stimulated luminescence (OSL) properties of Pr3+‐doped double potassium yttrium fluoride (K2YF5) under green light stimulation at room temperature as a function of the doping concentration are reported. Besides, some characteristics concerning the possible application of this composition as a new OSL dosimeter are presented, namely, the dose–response and fading of the OSL signal. The residual thermoluminescence (TL) response of K2YF5:Pr3+ after the OSL experiment has been investigated in order to establish whether the traps responsible for OSL are also involved in the TL process. Spectral analysis of the OSL emission has been carried out to determine the role played by Pr3+ ions in the radiative relaxation process. Finally, the total OSL output of K2YF5:Pr3+ is compared to that of commercial Al2O3:C.

Preparation and optical and electrical evaluation of bulk SiO 2 sonogel hybrid composites and vacuum thermal evaporated thin films prepared from molecular materials derived from (Fe, Co) metallic phthalocyanines and 1,8 dihydroxiantraquinone compounds

Semiconducting molecular material of PcFe(CN)L1 and PcCo(CN)L1 (L1 = 1,8 dihydroxianthraquinone), PcFe(CN)L2 and PcCo(CN)L2 (L2 = double potassium salt of 1,8 dihydroxianthraquinone) have been successfully used to prepare thin film and bulk sol–gel hybrid optical materials. These samples were developed according to the vacuum thermal evaporation technique and the catalyst-free sonogel route, respectively. Thin films samples were deposited on Corning glass substrates and crystalline silicon wafers and were characterized by infrared (FTIR), Raman and ultraviolet-visible (UV–vis) spectroscopies. IR-spectroscopy and Raman studies unambiguously confirmed that the molecular material thin films exhibit the same intra-molecular bonds, which suggests that the thermal evaporation process does not alter these bonds significantly. These results show that it is possible to deposit molecular materials of PcFe(CN)L2 and PcCo(CN)L2 on Corning glass substrates and silicon wafers. From the UV–vis studies the optical band gap ( E g) was evaluated. The effect of temperature on conductivity was also evaluated in these samples. Finally, the studied molecular systems dissolved at different concentrations in tetrahydrofuran (THF) were successfully embedded into a highly pure SiO 2 sonogel network generated via sonochemical reactions to form several solid state, optically active sol–gel hybrid glasses. By this method, homogeneous and stable hybrid monoliths suitable for optical characterization can be produced. The linear optical properties of these amorphous bulk structures were determined by the Brewster angle method and by absorption-, Raman- and photoluminescent (PL)-spectroscopies, respectively.

Determination of the trapping parameters of thermoluminescent glow peaks of K 2YF 5:Ce by three points method

The three points analysis method was applied to determine the number of peaks and kinetic parameters. These are the order of kinetics b, the activation energy E (eV), the frequency factor S (s −1) or the pre-exponential factor S″ (s −1) and the relative value of the initial concentration of trapped electrons n 0 (cm −3) associated with the thermoluminescence (TL) glow peaks in double potassium yttrium fluoride (K 2YF 5) doped with cerium ions (Ce 3+) in response to β-irradiation. The three points analysis method indicated that the glow curve of this material is the superposition of five general-order components, which was referred to as P1–P5, in the temperature range between room temperature and 500 °C.