Crystallization Of Bi Research Articles

Microstructure and properties of YIG ferrite joint brazed by Fe2O3-doped bismuth composite glass

Bismuth composite glasses doped with Fe 2 O 3 nanoparticles were utilized to braze yttrium iron garnet (YIG) ferrite. The effect of Fe 2 O 3 doping on the thermal property and structure of the composite glasses was studied. The microstructure, mechanical and dielectric properties of YIG/YIG joint were systematically investigated as well. The Fe 2 O 3 doping promoted the crystallization of Bi 2 SiO 5 and the conversion of [BO 4 ] units to [BO 3 ] units. [BO 3 ]/[BO 4 ] in the glass matrix reacted with Y 3+ and Fe 3+ diffusing from YIG base material to form Fe 2 O 3 blocks and lamellar YBO 3 . The gray YBO 3 changed from lamellar phase to needle-like phase with the brazing temperature increasing. The concentration of Fe 3+ increased along with the dissolution of Fe 2 O 3 nanoparticles, resulting in the extensive formation of Fe 2 O 3 nuclei. Consequently, the amount of the Fe 2 O 3 blocks increased with the Fe 2 O 3 doping increasing. The shear strength could reach 68.4 MPa via the combined strengthening of block Fe 2 O 3 and gray YBO 3 phases. The dielectric constant of YIG/YIG joint decreased with the Fe 2 O 3 doping and brazing temperature increasing due to the growth of Fe 2 O 3 and YBO 3 phases. The dielectric loss tangent of the YIG/YIG joint was close to that of the original YIG material with the frequency increasing.

Estimation of Formation Temperature of the Noble Metal Mineralization of the Kovdor Alkaline-Ultrabasic Massif (Kola Peninsula)

In this work, mineralogical and geochemical data are presented for sulfide-rich phoscorites and carbonatites in the Kovdor massif. The PGE and Ag-bearing mineralization of bornite–chalcopyrite and Ag‑bearing mineralization of pyrrhotite–chalcopyrite associations were investigated. In carbonatite stage formation of massif, the noble metal minerals occurred during evolution of alkaline–ultrabasic melt and after separation of primary sulfide melt enriched in PGE, Au and Ag. According to the observed relationships, the minerals of PGE, Au, and Ag in bornite–chalcopyrite association are crystallized sequentially from magmatic to hydrothermal stages. Crystallization of Os, Ir, Pt and Pd minerals (erlichmanite, rustenburgite, isoferroplatinum, mertieite–II, etc.) occurred at temperature close to 480°С, while further decrease in the temperature and an increase in the Cu and Fe activity in the melt leads to the crystallization of Sb, Pb, As, Bi and Te-bearing minerals (sperrylite, tatyanaite, moncheite, stumpflite, etc.). Formation of Au and Ag-bearing minerals (electrum, silver, stromeyerite, lenaite, etc.) occurred at temperatures below 300 °C with relatively low sulfur activity. In carbonatites and phoscorites of the middle and late magmatic stages enriched with magnetite, pyrrhotite–chalcopyrite association with silver-bearing minerals was formed at temperatures below 300°C. Ag-bearing minerals were produced during hydrothermal recrystallization of Cu–Fe–Ni sulfides at temperature close to 150°C.

In situ crystallization study of impurity phases in Bi–Fe–O thin films grown by atomic layer deposition

We report on the phase evolution of pure and Fe-doped bismuth oxide (Bi–O and Bi–Fe–O) thin films grown by atomic layer deposition. In situ X-ray diffraction was used to map the evolution of phase formation and orientational growth of the oxides during the gradual crystallization of the films from the amorphous state on single-crystalline substrates. The formation of (001)-oriented Bi2O2.3 was observed at temperatures as low as 300 °C on (001)SrTiO3, with a gradual transformation into Bi2O3. A similar crystallization of Fe-doped Bi2O3 on (111)ZrO2(Y2O3) leads to the formation of (111)-oriented δ-Bi2O3 above 400 °C instead of the sillenite phase. We thus demonstrate that epitaxial stabilization of the metastable phases can take place during atomic layer deposition of oxides as well as post-deposition annealing. In situ crystallization of the amorphous Bi–Fe–O films revealed the evolution of oxide phases in the film with the sillenite composition. Our results are important for the design of annealing procedures to obtain phase-pure epitaxial BiFeO3 thin films from amorphous stoichiometric Bi–Fe–O grown by atomic layer deposition.

One-Dimensional Single- and Dual-Cavity Magnetophotonic Crystal Fabricated by Bonding

Dual-cavity magnetophotonic crystals (MPCs) based on bismuth-substituted yttrium iron garnet (Bi:YIG) have been fabricated by a bonding method, and their structural, optical and magneto-optical properties have been studied. Identical structure of bonded fractions revealed the existence of the Fabri-Perot resonances in transmission spectra of single- and dual-cavity MPCs and corresponding enhancement of the Faraday rotation. However, the bonding interface was found to be unstable because of the bonding surfaces' roughness introduced by crystallization of Bi:YIG.

The thermal behavior of alumina borate whisker with Bi(OH) 3–Sn(OH) 4 coatings

An alumina borate whisker with Bi(OH) 3–Sn(OH) 4 was prepared using a chemical method. The thermal decomposition of Bi(OH) 3 and the evolution process of Bi 2O 3 (decomposition products of Bi(OH) 3) as well as the thermal stability of the whiskers with coatings were described in detail. It was found that the whiskers are an important factor for accelerating the crystallization and decomposition of Bi(OH) 3. The presence of the whiskers reduced the transition temperature of α- γ Bi 2O 3, but enhanced the transition temperature of γ- δ Bi 2O 3. The reaction between the whiskers and Bi 2O 3 is responsible for the phenomena. In addition, it can be found that the presence of whisker does not change the thermal process of mixed Bi(OH) 3 •Sn(OH) 4.

ChemInform Abstract: Tunable and Rapid Crystallization of Phase Pure Bi2MoO6 (Koechlinite) and Bi2Mo3O12 via Continuous Hydrothermal Synthesis.

AbstractPhase pure nanoparticles of Bi2MoO6 and Bi2Mo3O12 are prepared in a continuous hydrothermal flow synthesis reactor from solutions of acidified Bi(NO3)3 and basic H2MoO4 with Bi:Mo ratios of 2:1, and 2:3, respectively, using supercritical water of 375—450 °C at a pressure of 24.1 MPa as a crystallization medium (82 and 86% yield of Bi2Mo3O12 and Bi2MoO6, respectively).

Crystallization and electrical characteristics of ferroelectric Bi 3.15Nd 0.85Ti 3O 12 thin films prepared by a sol–gel process

Ferroelectric Bi 3.15Nd 0.85Ti 3O 12 (BNdT) thin films were deposited on Pt/Ti/SiO 2/Si substrates using a sol–gel process and Bi(NO 3) 3 was used as one of starting materials. Upon heating the major weight loss of the wet films occurred below 320 °C and nitrogen was almost completely removed at 650 °C. The films began to crystallize around 520 °C. The films annealed at 750 °C contain grains of 50–100 nm in diameter. The BNdT film capacitors with Pt top electrodes exhibited well-saturated hysteresis loops with a remanent polarization (2 P r) of 57.4 μC/cm 2 and a coercive field of 108.3 kV/cm. The Pt/BNdT/Pt capacitors did not show any significant fatigue up to 6×10 10 read/write switching cycles, and the retained charges remained nearly constant up to 10 4 s after applying a writing pulse. The leakage current density of the BNdT films is less than 5×10 −8 A/cm 2 under a low external field below 73 kV/cm.

Morphogenesis and Crystallization of Bi2S3 Nanostructures by an Ionic Liquid‐Assisted Templating Route: Synthesis, Formation Mechanism, and Properties.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.

Crystallization of bismuth titanate and bismuth silicate grown as thin films by atomic layer deposition

Bismuth silicate and bismuth titanate thin films were deposited by atomic layer deposition (ALD). A novel approach with pulsing of two Bi-precursors was studied to control the Si/Bi atomic ratio in bismuth silicate thin films. The crystallization of compounds formed in the Bi 2O 3–SiO 2 and Bi 2O 3–TiO 2 systems was investigated. Control of the stoichiometry of Bi–Si–O thin films was studied when deposited on Si(1 0 0) and crystallization was studied for films on sapphire and MgO-, ZrO 2- and YSZ-buffered Si(1 0 0). The Bi–Ti–O thin films were deposited on Si(1 0 0) substrate. Both Bi–Si–O and Bi–Ti–O thin films were amorphous after deposition. Highly a-axis oriented Bi 2SiO 5 thin films were obtained when the Bi–Si–O thin films deposited on MgO-buffered Si(1 0 0) were annealed at 800 °C in nitrogen. The full-width half-maximum values for 200 peak were also studied. An excess of bismuth was found to improve the crystallization of Bi–Ti–O thin films and the best crystallinity was observed with Ti/Bi atomic ratio of 0.28 for films annealed at nitrogen at 1000 °C. Roughness of the thin films as well as the concentration depth distribution were also examined.

Crystallization of (Bi,Nd)4Ti3O12 films in N2 environment by chemical solution deposition

(Bi,Nd)4Ti3O12 (BNT) ferroelectric films were deposited on Pt/Ti/SiO2/Si substrates by chemical solution deposition and crystallized in an N2 environment after pre-annealing in air at 500 °C. The effect of crystalline temperature on the structural and electrical properties of the BNT films was studied. The BNT films annealed in N2 in the temperature range of 630 °C to 670 °C were crystallized well and the average grain size increased with increasing crystalline temperature, while the remanent polarization and dielectric constant of the films are not a monotonic function of the crystalline temperature. The BNT films crystallized at 650 °C have the largest remanent polarization value of 2Pr=63.6 μC/cm2, a dielectric constant of 344 at 10 kHz, and a fatigue-free characteristic. A positive correlation between the remanent polarization and the dielectric constant of the BNT films has been observed.

Fabrication and Properties of (Bi,La)4Ti3O12 Thin Films through Metal-Organic Compounds

(Bi,La)4Ti3O12 thin films of Bi-layered perovskite structure were fabricated on Pt/TiOx/SiO2/Si substrates by chemical solution deposition (CSD) method. The crystallization and microstructure of the (Bi,La)4Ti3O12 thin films markedly depended upon the kind of used La-sources when the precursor solutions were prepared. Synthesized Bi3.35La0.75Ti3O12 (BLT) thin films from the precursor solution using a La(OiPr)3 as a starting material revealed (00l ) preferred orientation and anisotropic grain growth. On the other hand, BLT thin films using a La(OAc)3 as a La-source showed random orientation with a strong (117) reflection and homogeneous microstructure. This is due to the difference in the pyrolysis and crystallization behaviors of the precursor films. The BLT thin films exhibited the well-saturated ferroelectric P-E hysteresis loops. The BLT thin film prepared from a La-acetate showed the Pr value of 15.6 μC/cm2, which was higher than that of the BLT thin films from a La-alkoxide.

Effect of bismuth excess on the crystallization of Bi 3.25La 0.75Ti 3O 12 thin films on Pt/Ti/SiO 2/Si substrates

Bismuth lanthanum titanate (BLT) thin films with excess Bi contents were prepared onto a Pt/Ti/SiO 2/Si substrate by a metalorganic decomposition technique (MOD). The effect of Bi excess on the microstructure and ferroelectric properties was investigated. When a 10% of Bi excess was added, the BLT thin films showed a polycrystalline structure. The remanent polarization and dielectric constant decreased with more than 10% of Bi excess. Bi deficiency or Bi excess over 10% in the BLT films resulted in poor fatigue properties. This was attributed to the structure defects and a presence of a secondary phase, which coexists with a layered perovskite phase. The BLT thin films with 10% of Bi excess have the remanent polarization (2 P r) value of 25.66 μC/cm 2 and a coercive field of 84.75 kV/cm. The BLT thin films with 10% of Bi excess showed no fatigue even after 1 × 10 9 bipolar switching cycles.

Polaron dynamics and bipolaron condensation in cuprates

Based on the exact cluster diagonalization and recent Quantum Monte Carlo simulations we analyze dynamic properties of small polarons and bipolarons formed by short-range (Holstein) and long-range (Fr\ohlich) electron-phonon interactions. We show that the exact results agree well with canonical Holstein theory for a cluster and with Lang-Firsov theory for a lattice. Lang-Firsov theory of a single polaron and our $1/\ensuremath{\lambda}$ perturbation expansion for a multipolaron system are practically exact in a wide range of the adiabatic parameter $\ensuremath{\omega}/t$ and the electron-phonon coupling \ensuremath{\lambda} for a long-range interaction. (Bi)polarons exist in the itinerant Bloch states at temperatures below the characteristic phonon frequency no matter which values the parameters of the system take. We show that recent claims by several authors with regards to a breakdown of Holstein-Lang-Firsov theory of a small polaron and the ``impossibility'' of bipolaronic superconductivity are the result of an erroneous interpretation of the electronic energy levels of the two-site Holstein model and a misunderstanding of the electron-phonon interaction in ionic solids with polaronic carriers. A ``phase'' diagram in $t/\ensuremath{\omega}\ensuremath{-}\ensuremath{\lambda}$ space is proposed to elucidate the BCS and (bi)polaronic domains. Bipolaron theory provides a parameter-free expression for the superconducting critical temperature of layered cuprates. Crystallization of the (bi)polaronic liquid is shown to be impossible in the range of the parameters typical for cuprates. The small Fr\ohlich polaron has spectral features compatible with single-particle tunneling and photoemission in cuprates.

Vapor-Growth of Bismuth on Oriented Organic Films.

To investigate the possibility of the control over crystal growth on oriented organic film surfaces, bismuth (Bi) metal was vacuum-deposited on cadmium stearate Langmuir-Blodgett (LB) films with surfaces of either hydrophilic head groups or hydrophobic tail groups at room temperature. Interaction in both geometric and chemical senses between organic functional groups and evaporated metal seems critical for its growth. Different growth manner of Bi was observed on different surfaces in the initial stage of deposition ; A very low deposition rate, 0.01 nm/s, resulted in the large crystals grown on the hydrophilic surfaces, while fine particles formed on the hydrophobic surfaces. Time dependence of the average size of fine particles (∝t1/3) indicated high diffusivity of Bi adatoms on the hydrophobic surface, while crystallization of Bi on the hydrophilic surface possibly implied their strong chemical interactions.

Preparation, Characterization, and Thermal Behavior of a New High Oxide Ion Conductor: Bismuth Uranium Lanthanum Oxide

This paper describes the structural characterization and crystallization of the mixed oxide Bi{sub 2}U{sub 0.5}La{sub 0.5}O{sub 5.25}. The ionic conductivity was also measured.

The crystallization of Bi in the annealed a-Ge/Bi bilayer and its effect on conductivity

In this paper, the crystallization behaviors and transport properties are investigated for a-Ge/Bi bilayers annealed at different temperatures. For 200 nm/100 nm bilayers, it is found that the orientations of Bi in the bilayers annealed at 200°C and 340°C are preferred, as well as the original one. But they are random when the bilayers are annealed at temperatures between 240°C and 300°C. For 200 nm/50 nm bilayers, the orientations of Bi are always preferred. Corresponding to the orientations mentioned above, the minimum on the R(300 K)-Ta curve appears only in the case of 200 nm/100 nm bilayers.

Effects of oxygen partial pressure on the crystallization of amorphous Bi–Sr–Ca–Cu–O and Bi–Sr–Ca–Cu–O + Ag

The temperatures and pathways of crystallization for amorphous Bi–Sr–Ca–Cu–O are strongly dependent on oxygen partial pressure (Po2), the oxidation state of the glass, and the presence of Ag. Reducing the Po2 from 1 to 0 bar lowers the onset of melting 100 °C, but does not change the onset of crystallization. Decreasing Po2 does inhibit the formation of (CaSr)CuO3 (011). Although Ag appears to be immiscible in Bi–Sr–Ca–Cu–O, finely distributed Ag lowers the onset of melting by 20 to 35 °C, depending on Po2. In oxygen-deficient glass, two exotherms are observed upon heating. The first exotherm at 460 °C is independent of Po2, and Ag and corresponds with the formation of Bi2Sr2CuO6 (Bi-2201). The second exotherm occurs at 486 °C with Ag or 500 °C without Ag. The onset temperature of the second exotherm does not change with Po2, but the exotherm decreases in intensity with decreasing Po2. EXAFS indicates that in the as-quenched amorphous material, Cu is in a reduced state. Annealing the amorphous material in oxygen below the first exotherm (i.e., glass relaxation) increases the oxidation state of the Cu to that necessary for the formation of the Bi2Sr2CaCu2O8 (Bi-2212) without additional oxygen diffusion. This relaxation of the glass increases the crystallization temperature of the Bi-2201 to 500 °C. The crystallization sequence of Bi-2201 to Bi-2212 occurs at all Po2 ≥ 0.1 bar, but the composition of the secondary phases changes in the unrelaxed glass. Relaxing the glass eliminates liquid formation at low temperatures, allowing for rapid formation of the Bi-2212 phase with minimal formation of secondary phases for 0.1 ⋚ Po2 ⋚ 0.2 bar.

Kinetics of Nonisothermal Crystallization of Bi2Sr2CaCu2Ox Glasses with Different Copper Valence States

The kinetics of the nonisothermal crystallization process in Bi2Sr2CaCu2Ox glasses with different copper valance states, R(Cu+) = Cu+/(Cu++ Cu2+) = 0.79–0.99, were examined by using differential scanning calorimetry. Four different kinetic equations were used for the data analyses. It was found that the values of activation energy for crystal growth, Ea, decreased with increasing Cu+ content. The value of Ea, which was estimated from the modified Ozawa equation, for the glass with R(Cu+) = 0.79 was 483 kJ·mol‐1 and for the glass with R(Cu+) = 0.99 was 353 kJ·mol‐1. In the former glass, the number of crystal nuclei was almost independent of the heating rate. But, in the latter glass, the number of crystal nuclei varied significantly with the heating rate. The crystallization mechanism in the glasses was closely related to the thermal stability and viscosity of glasses: the glass with R(Cu+) = 0.99 showing a high thermal stability and a low activation energy for viscous flow had a small value of Ea. The plot of In (Tp2/α) against 1/Tp, where Tp and α are crystallization peak temperature and heating rate, respectively, gave a reasonable value of Ea for the glass with R(Cu+) = 0.79 but was unsuitable for the evaluation of Ea for crystal growth of the glass with R(Cu+) = 0.99.

Growth of precipitates in Bi2Sr2Ca1Cu2O8

In the formation of Bi 2 Sr 2 Ca 1 Cu 2 O 8 from a Ca and Cu rich melt, the partial pressure of oxygen is a central factor controlling the phases that form as precipitates in the host superconductor. At a high oxygen pressure, a sample with a stoichiometry of Bi 2 Sr 2 Ca 2 Cu 3 O 10 will form (Sr,Ca) 2 Cu 1 O 3 as the dominant precipitate coexisting with the liquid from which Bi 2 Sr 2 Ca 1 Cu 2 O 8 forms. During the crystallization of Bi 2 Sr 2 Ca 1 Cu 2 O 8 from this liquid, part of the (Sr,Ca) 2 Cu 1 O 3 phase is consumed. By contrast, at low oxygen partial pressure a sample with the same stoichiometry will form CaO as the dominant precipitate co-existing with the liquid from which B 2 Sr 2 Ca 1 Cu 2 O 8 forms. In this case, some of the CaO is consumed and a Ca rich (Sr,Ca) 2 Cu 1 O 3 phase forms during the Bi 2 Sr 2 Ca 1 Cu 2 O 8 crystallization. Oxygen partial pressure is a key factor controlling the sequence of precipitates that form in the host superconductor.

Crystallization of Bi–Sr–Ca–Cu–O glasses in oxygen

A detailed study of the crystallization process for compositions near Bi2Sr2Ca1Cu2Oy was undertaken using differential thermal analysis (DTA), transmission and scanning electron microscopy (TEM and SEM), and x-ray diffraction (XRD). Glasses prepared by a splat-quench technique were free of secondary phases in most cases. A two-step crystallization process in oxygen was observed in which partial crystallization of the glass occurs initially with the nucleation of “2201” and Cu2O, and is completed with the formation of SrO, CaO, and Bi2Sr3−xCaxOy. No specific thermal event could be associated with the formation of the “2212” phase. Rather, formation occurs via conversion of 2201 into 2212. This was a kinetically limited process at temperatures below 800 °C as other phases were found to evolve in addition to the 2212 phase during extended anneals. In contrast, a nearly full conversion to the 2212 phase occurred after only 1 min of annealing at 800 °C and above. However, changes in resistivity data, secondary phases, and the measured 2212 composition upon extended anneals at 865 °C showed that considerably longer heat treatments were necessary for the sample to reach its equilibrium state.