Addition Of H3BO3 Research Articles

Microwave dielectric properties of Li2TiO3 ceramics sintered at low temperatures

Li2TiO3 ceramics were prepared at the sintering temperatures from 1050 to 1250 °C. The optimal microwave dielectric properties were ɛr = 23.29, Q × f = 15,525 GHz (5.9 GHz), and τf = 35.05 ppm/ °C for the sample sintered at 1200 °C. The microwave dielectric properties were improved obviously when the Li2TiO3 ceramics were sintered at low temperatures with small additions of H3BO3 (B2O3 in the form of H3BO3). Only monoclinic Li2TiO3 was found in the pure or H3BO3-doped Li2TiO3 ceramics. About 1.0 wt.% H3BO3 addition aided the sintering of Li2TiO3 ceramics effectively while excessive H3BO3 (≥2.5 wt.%) was not favorable. Typically the best microwave dielectric properties were ɛr = 23.28, Q × f = 37,110 GHz (6.3 GHz), and τf = 30.43 ppm/ °C for the 1.0 wt.% H3BO3-doped Li2TiO3 ceramic sintered at 920 for 3 h, which is promising for LTCC applications.

Effectively Leveraging Solar Energy through Persistent Dual Red Phosphorescence: Preparation, Characterization, and Density Functional Theory Study of Ca2Zn4Ti16O38:Pr3+

To effectively leverage and convert cheap, abundant, and environmentally friendly solar energy is still an unaccomplished endeavor. In this work, we prepare and characterize the long-lasting red-light-emitting, single-phase Ca2Zn4Ti16O38 phosphor by the sol−gel method with nonstoichiometry or addition of H3BO3 as flux. Excitation and emission mechanisms are proposed and supported by the computational results from density functional theory. Phase identification of powders was performed by X-ray powder diffraction analysis, confirming the existence of single-phase Ca2Zn4Ti16O38 crystals in samples of every series. Unit cell parameters of the crystal were subsequently determined, together with its excitation spectra in the blue-green region with the maximum peak at 474 nm monitored by 644 nm light. The corresponding emission spectra showed a wide emission range with two narrow bands at 614 nm (1D2 → 3H4) and 644 nm (3P0 → 3F2) after the addition of H3BO3. If excited at 474 nm, the phosphor displays a superlong afterglow with the emission peak at 614 nm, enabling it to be a novel persistent red long phosphor for visible-light conversion. Luminescent properties of the phosphor were thoroughly examined. The mechanism of the dual persistence phosphorescence originated at 614 and 644 nm wavelengths induced by two separate kinds of doping defects was proposed. Density functional theory calculations under the periodic boundary condition provide insights about their excitation, emission, and long-lasting phosphorescence mechanisms.

H3BO3-Induced Formation of Metal Oxide Hollow Spheres in Flowing Aerosols

We report that hollow spheres of transition metal oxides (TiO2, ZrO2, SnO2, Fe2O3, and Co3O4) could be formed in flowing aerosols. The formation of hollow structures was attributed to the in situ emission of gas phase HBO2 from the inner part of the metal oxide microspheres during the pyrolysis of flowing aerosols. We interestingly found that the addition of H3BO3 could not only result in the formation of hollow spheres but also tailor the property of the metal oxides. The resulting TiO2 and Co3O4 hollow spheres exhibited enhanced photocatalytic and magnetic properties compared to the counterpart solid spheres, respectively. We believe this study provides a simple and convenient method for industrial production of transition metal oxide hollow spheres with enhanced properties.

Low-Temperature Sintering of Ba<sub>5</sub>(Nb<sub>1-x</sub>V<sub>x</sub>)<sub>4</sub>O<sub>15</sub> Ceramics with H<sub>3</sub>BO<sub>3</sub>

Ba5(Nb1-xVx)4O15 (0≤x≤0.1) ceramics doped with H3BO3 were prepared by solid-state reaction. The effects of H3BO3 additives on the sinterability and microwave dielectric properties of the ceramics were investigated. The formation of a single phase was identified with the X-ray powder diffraction patterns of Ba5(Nb1-xVx)4O15 ceramics in the composition x from 0 to 0.025. Minor phases including Ba3(VO4)2 were formed as the secondary phase for the compositions with x>0.025. The dielectric constants (εr) of the ceramics increased firstly from 38.7 to 39.69 with x increasing from 0 to 0.01, and, then decreased to 36.91 with x=0.1, meanwhile, the unloaded quality factor and temperature coefficient of resonance frequency (τf) decreased as the x value increased from 0 to 0.1. Microwave dielectric properties, εr=36.91, Q×f =16,167GHz and τf =35ppm/°C, were obtained for Ba5(Nb0.9V0.1)4O15 ceramics with 1wt% H3BO3 sintered at 900°C for 2h.

Electrodeposition of Rh and CoFeRh from CoFe Plating Solution and Characterization of Thin Films

This paper describes electrodeposition of Rh and CoFeRh alloys from CoFe solution containing RhCl3, CoSO4, FeSO4, H3BO3, NH4Cl, saccharin, and NaLS. The electrochemistry of Rh+3 species is influenced by each of the compounds present in CoFe plating solution but especially by addition of saccharin and H3BO3. The co-electrodeposition of Co and Fe occurs in the range of more positive potentials (-0.6 to -0.8 V vs. SCE) in the presence of Rh+3 species. This phenomenon is possibly driven by the negative enthalpy associated with CoFeRh alloy formation. It was demonstrated that CoFeRh alloys with 1-3 wt% Rh have a high corrosion resistance and high magnetic moment in the range of 2.3-2.4 Tesla. It is also demonstrated that the decrease of magnetic moment is linked to the increase of nonmagnetic elements in CoFeRh deposit.

Characteristic Evaluation of High Corrosion Resistant Ti/ (Pt + B<sub>2</sub>O<sub>3</sub>) Electrode with New Microstructure of Coat

In order to improve the durability of Pt coated Ti electrodes as an anode of the sulfuric acid system electrolysis, tantalum oxide (Ta2O5) additions have been used widely. However that is not enough for uses under severe conditions. In this study,boric acid (H3BO3) was added into the Pt coating during manufacturing process of Ti/Pt-coated electrodes, and the (Pt + B2O3)/Ti electrodes were obtained. The effect of H3BO3 addition on the microstructure, surface area, and lifetime of (Pt + B2O3)/Ti electrodes was also investigated in detail. Commercially available titanium plates (10 100.5mm) were employed for prepare Ti/ (Pt + B2O3) electrodes, where it was confirmed by XRD that B2O3 formed by heating the boric acid was amorphous in the temperature range of 250 to 550. The coating solution of 2 μl of H2PtCl66H2O (Pt:50 g/l) dissolved in butanol and 5~20 mass% H3BO3 mixture was spread over the etched Ti plates. After drying at 70 for 30 min, the substances were heated at 250 to 550 for 10 min. The lifetime of the electrodes was examined by a direct current of 1 A using Pt plate as the counter electrode in 1 M H2SO4 solution at 40. The end of life was determined as the time when the cell voltage changed 2 times of the beginning.

ＢａＴｉＯ３セラミックスのマイクロ波焼成とその焼結体の電気的特性―液相の影響

Effects of liquid phase on microwave sintering with a frequency of 2.45 GHz of BaTiO3 ceramics were investigated. The additives to form the liquid were BaCO3, H3BO3 and BaB2O4. Addition of the liquid phase in microwave sintering promotes densification of BaTiO3 ceramics significantly, and densified ceramics were obtained by lower applied power and shorter processing time. Furthermore, electric resistivity of dense ceramics with BaCO3+2H3BO3 addition was different by sintering techniques, and a sample obtained by microwave sintering showed the dielectric, while one obtained by conventional sintering showed the semiconducting properties. Such different result is considered to be relating to presence of liquid phase with strong microwave absorption.

Hydration Behavior of Calcium Sulfoaluminate and Tricalcium Aluminate Mineral Phases in H3BO3 Solution

ABSTRACT The influence of H3BO3 on the hydration of calcium sulfoaluminate and calcium aluminate phases was investigated. The addition of H3BO3 affected the solubility and the dissolution rate of calcium sulfoaluminate and calcium aluminate particles. In particular, the Al ion concentration was shown to be very low in the H3BO3 solution. The gelatinous products were also observed when the solution of calcium aluminate was reacted with H3BO3 solution. These gelatinous products were constituted by the basic Al ions with incorporated B ions and great quantity of water. Overall, these gelatinous products form the impermeable layer on the surface of the particles of calcium sulfoaluminate and calcium aluminate particles, and interrurrt the diffusion process of the other ions, e.g. Ca2+ and SO4 2-.

In vitro pollen tube growth and penetration of female gametophyte in Douglas fir ( Pseudotsuga menziesii )

Pollen tube and female gametophyte interactions in Douglas fir (Pseudotsuga menziesii) were examined in vitro. Formation of pollen tubes in Douglas fir occurred on a modified Murashige and Skoog medium in which concentrations of H3BO3 and Ca(NO3)2 were altered and supplemented with sucrose and polyethylene glycol. Addition of 100 μg/ml H3BO3 and 300 μg/ml Ca(NO3)2 resulted in optimum pollen viability. Lack of H3BO3 inhibited pollen tube formation. Addition of H3BO3 and Ca(NO3)2 significantly increased pollen tube formation within one week in culture. Using a medium supplemented with mannitol, viability of Douglas fir pollen can be sustained for 7 weeks in culture, about the same length of time as in vivo. However, pollen tubes are not formed. This suggests that the factors responsible for tube formation reside in the external environment of the pollen. Culture of female gametophytes to examine egg viability and longevity had not been done previously. We found that egg viability in culture is short-lived, and therefore the window to study and manipulate events of fertilization in Douglas fir is very limited. In spite of this, about 7% of the female gametophytes that were co-cultured became penetrated by pollen tubes. In vitro archegonial penetration has been repeatedly achieved, but pollen tubes also penetrated other parts of the female gametophytes. Pollen tubes also penetrated non-viable eggs. Most female gametophytes were not penetrated because of pollen tube branching and swelling, failure of tubes to orient towards the female gametophytes, or premature pollen tube death due to plasmolysis. This report outlines the first attempt towards in vitro fertilization in conifers.

Assessment of Closed Vessel Digestion Methods for Elemental Determination of Airborne Particulate Matter by ICP-AES

Closed vessel acid digestion methods, especially the microwave digestion, have been investigated for elemental analysis of airborne particulates collected by glass fiber filter and analyzed by ICP-AES. A two-step digestion procedure was examined; it included the digestion of airborne particulates with HNO3+HClO4 in the first step and the addition of HF after removal from the intact filter membrane in the second step. Both the NIST Standard Reference Material 1648 urban particulate matter and real samples were employed to assess the capabilities of the suggested methods throughout the QA/QC programs. It was found that the two-step method is an appropriate pretreatment procedure for multi-element analysis by ICP-AES. The importance of evaporation after the digestion and of the substitution of H3BO3 addition for evaporation process are discussed. Both evaporation and H3BO3 addition processes after the digestion may effectively reduce the matrix effect on the suppression of the analyte elements. A comparison between the conventional pressure bomb and microwave digestion methods was performed using real samples.

Addition of tertiary amines in the semiquantitative, multi-element inductively coupled plasma mass spectrometric analysis of biological materials

A semiquantitative inductively coupled plasma mass spectrometric (ICP-MS) analysis protocol for biological materials was developed to include water-soluble tertiary amines with microwave heated sample preparation. Certified reference materials digested with HNO3, H2O2 and HF required addition of H3BO3 and a solution of tertiary amines (CFA-C reagent) to dissolve insoluble fluorides and neutralize free fluorides. Commercial semiquantitative analysis software that evaluates the entire m/z range and includes pre-programmed corrections for spectroscopic interferences was applied to investigate matrix interferences resulting from 10% tertiary amines and chlorides (added as 1% HCl). Measurement parameters including m/z range, spectrometer sensitivity and number of elements in the external calibration were evaluated. The accuracy of the semiquantitative analysis improved when the standard solution was matrix matched; interference-free isotopes were selected for some elements instead of scanning the whole m/z range, and additional elements with m/z values of under 80 were included for updating the instrument pre-calibration response factor. This semiquantitative analysis approach can be applied successfully for the multi-element analysis of biological materials when optimum instrumental conditions are employed. Thirty-eight elements were determined in six certified reference materials and food samples with a precision of 1–20% and accuracy of 1–50%. The determinations of Al, K, Na and Si were unreliable.

Preparation and properties of raney nickel electrodes on Ni-Zn base for H2 and O2 evolution from alkaline solutions Part I: electrodeposition of Ni-Zn alloys from chloride solutions

Experimental results for the electrodeposition of Ni-Zn alloys from chloride solutions, with addition of H3BO3 and without other additives, in a laboratory cell with a perforated nickel sheet cathode and with recirculating electrolyte are presented. The dependence of the zinc content in the alloy on the following operating conditions was investigated: cathodic current density, 1.0–20.0 A dm−2; temperature, 35–65°C; pH 1.5–5.5; total molarity,M tot=M Ni 2+ +M Zn 2+ =1.1–2.8 M; and, molar ratio,P=M Ni 2+ /M Zn 2+ =1.0–15. Depending on the operating conditions the Zn content in the alloy varied over the range 22–88 mol%. In separate experiments galvanostatic polarization curves were measured in the direction of increasing and then decreasing cathodic current density in the range 0.1–20.0 A dm−2 with all other operating conditions as used for electroplating experiments. In all cases significant hysteresis effects were observed. It was found that the current efficiency for the electrodeposition of Ni-Zn alloys from chloride solutions as a function of the zinc content in the alloy showed a sharp minimum of about 55% atX Zn=55 mol % irrespective of other operating conditions.

SIMPLE MICROWAVE DIGESTION TECHNIQUE FOR ELEMENTAL ANALYSIS OF MINERAL SOIL SAMPLES

A new, rapid, and inexpensive method is described for digestion and dissolution of mineral soil and clay samples for determination of total elemental abundance. Standard soil samples were dissolved using HF and HNO3 in 60 mL Teflon bombs. Dissolution was complete after 7 min using a household microwave oven operating at 350 W. Addition of H3BO3 stabilized the digests against loss of silicon. Precise and accurate results were obtained for digests analyzed by inductively coupled plasma atomic emission spectrometry for total content of Si, Al, Fe, Mg, Ca, Na, K, and Mn. Key words: Elemental composition, standard soils, soil analysis

Influence of cations and borate on the alkaline extraction of xylan and glucomannan from pine pulps

AbstractSouthern pine pulp fibers were extracted with Na, K, and Li hydroxides at several concentrations from 0.5 to 4.0 m (molal). The amounts of extracted xylan and glucomannan increased with the swelling of the cellulose structure up to 2.0–2.5 m. The addition of H3BO3 to alkaline solutions produced the B(OH) anion, which had less swelling power than OH−. It was not effective for removal of xylan except for some very accessible xylan of holocellulose. Removal of xylan from chemical pulps depended upon OH− in molar excess over H3BO3. In the same extractions, glucomannan removal was enhanced by B(OH) alone and further increased by additional OH−. The formation of anions (carboxylate in xylan and borate complex of glucomannan) appeared to be important for the release of polymer from within the cellulose structure. Some glucomannan was more accessible in oxygen pulp than in holocellulose. The resorbed xylan of kraft pulp was less accessible than the xylans of either holocellulose or oxygen pulp.

Titanium Determination for Correction of Plant Sample Contamination by Soil1

AbstractAn accurate method for determining Ti in plant material and soil was developed. Titanium concentrations in plant and soil were used to correct analytical data of plant materials for contamination by soil. Different digestion schemes were used in the analysis of National Bureau of Standards (NBS) reference materials for Ti. A satisfactory result was obtained when the sample was digested in a Teflon beaker containing HNO3 and HClO4, taken to dryness, baked at 185°C, and then dissolved overnight at room temperature in HF. The solution was made to volume with 3M HCl, in polyethylene, after addition of H3BO3 to complex excess F . Titanium was determined by inductively coupled argon plasma (ICP) spectrometry. Certified Ti values for NBS mineral samples 120b and 692 are 899 and 270 mg kg 1, respectively. This method gave values of 898 ± 14 and 264 ± 6 mg kg 1, respectively. Correction of elemental analysis for soil contamination of plant, rumen fistula, and feces samples using this method agreed well with corrections using Fe or Al as a reference element as well as with determination for Ti by x‐ray fluorescence. Using residual ash content (Si) as a reference element appeared to be less reliable. The assumptions needed to make this correction using Ti are less prone to error than the assumptions needed when Fe, Al, or residual ash are used. It was imperative to use HF in the digestion procedure for quantitative determination of Ti in some samples.

Electrodeposition of Nickel from Ni(CF3COO)2, -HCONH2, Bath Containing Various Additives

Bright and adherent nickel depesits were obtained in a wider range of current densities from Ni(CF3COO)2-HCONH2 baths containing H3BO3, saccharin, sulfamic acid, urea, AlCl3 or NH4Cl, compared to Ni(CF3COO)2-HCONH2, bath without any additive.The addition of H3BO3 in Ni(CF3COO)2-HCONH3 bath gave adherent nickel deposits in a wider range ef current densities.The appearance of nickei deposits obtained from Ni(CF3COO)2-HCONH2 bath containing thiourea or saccharin was dull.For tre electrodeposition ef nickel-from Ni(CF3COO)2-HCONH2-H3BO3-thiourea bath, the apparent current efficiencies on both cathode and anode were about 120% at 60 C and 70 C.For the bath containing AlCl3 or NH4Cl the anode current efficiencies were high, and in the letter case the cathode current efficiency also high.The rate determining step of the electrodeposition of nickel from Ni(CF3COO)2-HCONH2bath containing additives, except thiourea, was the charge transfer reaction at current densities ranging between O.9 and 4 A/dm2.The activation overvoltage for hydrogen evolution on nickel was lewered by addition of H3BO3, sulfamic acid, chloride or thiourea into the CF3COOH-HCONH2 bath.

Determination of Aluminum in the Presence of Fluoride by Emission Spectroscopy

Fluoride greater than 0.1 N interfered negatively in the determination of Al by the rotatingdisk-electrode technique. Fluoride interference was eliminated by the addition of H3BO3. Aluminum in the 1–100 ppm range was successfully determined in the presence of 0.25 N fluoride by making the solutions 2.5% in H3BO3. The coefficients of variation among six determinations for solutions containing 10 and 100 ppm Al were 3.0% and 0.9%, respectively. Recovery of known amounts of Al added to fluoride-extracts of soils ranged from 98.4% to 102.2%. The proposed method thus gave acceptable accuracy and precision. The method is simple and rapid since it does not require the removal of fluoride by distillation as H2SiF0 nor does it prevent the determination of Si in the same sample.

Preferred orientation of electrodeposited cobalt crystallites

Theoretical calculations for the work of formation of two-dimensional nuclei, Whkl, of the h.c.p. lattice are presented. The dependence of Whkl on supersaturation is given graphically.The calculations have been proved in the case of cobalt electrodeposition. The polarization curves in the deposition of cobalt from pure solutions of cobalt sulphate with the addition of 5, 10 and 20 g/l H3BO3 have been studied at 15, 20, 30, 40, 60 and 80°C and pH 5. At high temperatures and low current densities, cobalt is deposited with low overvoltage and the orientation is along the [0001] axis. Orientations along the axes [1120] and [1010] [1120] are obtained when cobalt is deposited with medium overvoltage and at low temperatures: at high current densities and high overvoltage, a texture along the [1010] axis is developed. The addition of H3BO3 leads to an increase of overvoltage, which results in a change of the orientation axis. Thus with a content of 1O g/l H3BO3 it is not possible to obtain a texture along [0001] under any conditions, while with 20 g/l H3BO3, besides the absence of [0001], no pure orientation can be obtained along [1120]. The experiments are in general agreement with the two-dimensional theory of preferred orientation.