Properties Of Bi2O3 Research Articles

Transformation Dynamics of Nanosized Bi Films into Semiconductor Films of Bismuth Oxide in the Cold Plasma Device

This work proposes an original method that reveals the transformation dynamics of nanosized Bi films into semiconductor films of bismuth oxide (Bi2O3) and the factors affecting the low‐energy cold plasma on the electro‐optical properties of Bi2O3. In the plasma microreactor with a photosensitive GaAs:Cr electrode, the transformed Bi films 400–1100 nm thick are analyzed by X‐ray diffraction to determine the crystal structure of Bi2O3 and by an electron probe microanalyzer to explore the evolution of the composition. The morphological properties of the Bi films exposed to electron–ion flow are examined by processing the scanning electron microscope images. It is found that as a result of the combined effect of photoactive illumination, charged particles, and active plasma components: 1) an absorption spectrum of a new substance is formed in the range λ = 330–1100 nm; 2) the optical width of the bandgap of the resulting substance is Eg ≈ 3 eV, which satisfactorily coincides with the width of the bandgap of Bi2O3; and 3) to overcome the potential barrier and formation of semiconducting Bi2O3 film energy is required, which is provided by the combined kinetic energy of electrons and negatively charged oxygen ions bombarding on the Bi film.

Microstructure and Dielectric Properties of Bi2O3 Added (Ba0.86Ca0.14)(Ti0.85Zr0.12Sn0.03)O3 Ceramics

In this works, in order to develop the composition ceramics for a capacitor with the excellent dielectric properties, (Ba0.86Ca0.14) (Ti0.85Zr0.12Sn0.03) O3(abbreviated as BCTZ) ceramics were fabricated with the amount of Bi2O3. All specimens showed a typical perovskite structure. As the Bi2O3 addition was increased, secondary phase was found. When x = 0.006, the maximum value of er = 6043 was shown at 0 °C. At the 0.003 mol Bi2O3, the most excellent dielectric and TCC properties were obtained. Namely, the dielectric constant (er), the range of TCC from − 20 to 80 °C, Curie temperature were 5015, − 2 to + 48%, and 40 °C, respectively.

Effect of Sn4+ and W6+ substitution on the dielectric properties of Bi2O3–ZnO–Nb2O5-based low firing ceramics

As a promising candidate for thermostable Low-temperature co-fired ceramic material with NP0 characteristic, (Bi1.8Zn0.2)(Zn0.6Nb1.4−2xSnxWx)O7 (x = 0.00, 0.02, 0.05, 0.10) dielectric ceramics with improved dielectric properties were prepared by conventional mixed oxide route. The effect of the chemical substitution of Sn4+ and W6+ cations on the structure and dielectric properties in this system had been investigated systematically. The Sn4+ and W6+ co-substitution was tentatively introduced in cubic-monoclinic pyrochlores co-existing ceramics and the results showed regular influence on the structure, dielectric properties with the amount of substitution. With the structure evaluation and electrical properties measurement results, the Sn4+ and W6+ substituted Nb5+ in B site showed an effective way to depress the grain growth and the ceramic with fine grains in 1–3 μm that can be obtained at a low sintering temperature of 950 °C. Based on these results, small amount of Sn4+ and W6+ substitution was successfully applied to a base ceramic with the electrical properties, which can be a promising candidate for LTCC and multilayer components applications in high frequency and microwave range.

Study of Optical Properties of Bi2O3 and Bi2Se3 Ultrathin Films by Spectroscopic Ellipsometry

Study of Optical Properties of Bi₂O₃ and Bi₂Se₃ Ultrathin Films by Spectroscopic Ellipsometry

Electrical conduction and dielectric properties of Bi2O3–B2O3–TeO2 glass

Amorphous bulk bismuth boron tellurium glass system of compositions (Bi2O3) x (B2O3)0.5−x (TeO2)0.5 with x = 0.05, 0.1, 0.2, 0.3 and 0.4 is prepared using melt quenching method. The ac and dc conductivities (σ ac and σ dc) of as-prepared samples are measured in the temperature range 303–373 K and displayed dielectric dispersion in the frequency range 100 Hz–5 MHz. The ac conductivity versus frequency plots were analyzed by considering a power law: σ ac α ω s(s ≤ 1). A comparison between values of the index s with those numerically calculated from different conduction models revealed that correlated barrier hopping is a fairly good model to describe the dominant ac conduction mechanism in the studied compositions. Besides, results of the real dielectric constant (e′), loss factor (e″), and loss tangent (tan δ) together with the optical (e ∞) and static (e s) dielectric constants, estimated from Cole–Cole diagrams, for the studied samples are given and discussed. Temperature dependence of the frequency exponent s for the studied amorphous bulk samples obtained from slopes of the relation ln σ ac = f(T). The solid curves represent the values calculated using the models: QMT, NSPT, and OLPT. The dashed curve represents the CBH model, which gives a fairly good fit with the experimental results (symbols) .

Temperature dependence of the optical properties of Bi2O3. A theoretical approach basing on the Kramers-Kronig transformation for polynomial mixed terms models

AbstractThe Kramers-Kronig transforms (KK) constitute a powerful tool to validate experimental data. The present study is implemented for Bi2O3 thin films deposited by thermal vacuum evaporation at different temperatures of the glass substrates. Since the extraordinary properties of this fabric allow us to consider particular analytical approach as it was previously shown, the reflectance properties of Bi2O3 as a function of temperature could be studied.The novelty of this article is the studying of a global effective analytical representation, based on polynomial functions, in order to obtain a general model that includes temperature dependence of the optical properties, using the Kramers-Kronig transformation type. In the mathematical expressions, were included mix combined term in order to avoid the effects of Runge phenomenon. As a case study was chosen Bi2O3 — a substance less studied in literature. In the last part are the presented and commented the results obtained for a series of eight studied models.

Study of the structural and dielectric properties of Bi2O3 and PbO addition on BiNbO4 ceramic matrix for RF applications

In this paper, the structural and dielectric properties of BNO (BiNbO4) was investigated as a function of the external RF frequency and temperature. The BNO Ceramics, prepared by the conventional mixed oxide method and doped with 3, 5 and 10 wt. % Bi2O3–PbO were sintered at 1,025 °C for 3 h. The X-ray diffraction patterns of the samples sintered, shown the presence of the triclinic phase (β-BNO). In the measurements obtained at room temperature (25 °C) was observed that the largest values of dielectric permittivity (e′ r ) at frequency 100 kHz, were for the samples: BNO5Bi (5 wt. % Bi2O3) and BNO5Pb (5 wt. % PbO) with values e′ r ~ 59.54 and e′ r ~ 78.44, respectively. The smaller values of loss tangent (tan δ) were for the samples: BNO5Bi and BNO3Pb (3 wt. % PbO) with values tan δ ~ 5.71 × 10−4 and tan δ ~ 2.19 × 10−4, respectively at frequency 33.69 MHz. The analysis as a function of temperature of the dielectric properties of the samples, obtained at frequency 100 kHz, showed that the larger value of the relative dielectric permittivity was about e′ r ~ 76.4 at temperature 200 °C for BNO5Pb sample, and the value smaller observed of dielectric loss was for BNO3Bi sample at temperature 80 °C, with about tan δ ~ 5.4 × 10−3. The Temperature Coefficient of Capacitance (TCC) values at 1 MHz frequency, present a change of the signal from BNO (−55.06 ppm/°C) to the sample doped of Bi: BNO3Bi (+86.74 ppm/°C) and to the sample doped of Pb: BNO3Pb (+208.87 ppm/°C). One can conclude that starting from the BNO one can increase the doping level of Bi or Pb and find a concentration where one have TCC = 0 ppm/°C, which is important for temperature stable materials applications like high frequency capacitors. The activation energy (H) obtained in the process is approximately 0.55 eV for BNO sample and increase with the doping level. These samples will be studied seeking the development ceramic capacitors for applications in radio frequency devices.

Mechanical and acid-etching properties of Bi2O3–ZnO–B2O3 glass-containing ceramic fillers

The properties of the composite, having a complicated microstructure, are decided by many factors such as those of glass matrix, crystal phases, fillers, and holes. We investigated how the addition of ceramic fillers to the glass matrix affects the mechanical and etching properties of the glass composite by forming new crystal phases. Different amounts of two fillers, ZnO and Al2O3, were added to a glass frit consisting of Bi2O3–ZnO–B2O3. It was sintered at 550 °C for 30 min. Based on the results of this study, the porosity and degree of crystallization of the composites could be controlled by adjusting the content of the ZnO and Al2O3 fillers. Therefore, porosity and degree of crystallization formed by the reaction between a glass matrix and fillers influence the mechanical and etching properties of the composite.

Effect of powder bed on the microstructure and electrical properties of Bi2O3- and Sb2O3-doped ZnO

The effects of powder bed on the microstructure and electrical properties of Bi2O3- and Sb2O3-doped ZnO specimens are investigated in the present study. By using a sufficient amount of powder bed, the weight loss of Bi2O3 reduces from >95 to <20%. The reduction of weight loss enhances significantly the densification and grain growth of ZnO. Furthermore, the use of powder bed can also reduce the size distribution of ZnO grains. Nevertheless, the presence of Bi2O3 residue results in the formation of a pyrochlore phase (Zn2Bi3Sb3O14) during the cooling down stage; its presence is detrimental to the nonlinear characteristics of ZnO–Bi2O3–Sb2O3 system.

Phase formation, sintering behavior and microwave dielectric properties of bismuth and manganese co-doped [(Pb, Ca) La](Fe, Nb)O3+δ solid solution

The phase formation, sintering behavior and microwave dielectric properties of Bi2O3 and MnO2 co-doped [(Pb, Ca) La](Fe, Nb)O3+δ (PCLFN) ceramics were investigated. The Bi2O3 and MnO2 binary dopants formed stable and low melting temperature solubilities at grain boundary which resulted in an effectively lowered sintering temperature by about 140 °C a more rapid sintering process and enhanced bulk densities. Sintering procedure has significant effect on grain size and porosities in ceramics. With high sintering temperature and time, the evaporation of PbO scaled up from surface toward the bulk and resulted in a Pb2+ deficient layer up to 0.25 mm depth under ceramic surface. Investigation of sintering dynamic revealed that either volume diffusion or second-order interface mechanism controlled the grain growth in present system. An optimal microwave dielectric properties of er = 91.1, Qf = 4,870 GHz and τf = 18.5 ppm/°C could be obtained in Bi2O3 and MnO2 co-doped [(Pb, Ca) La](Fe, Nb)O3+δ ceramics sintered at 1,050 °C for 4 h when the quality ratio of Bi2O3/MnO2 was 1 and the doping content w = 1 wt%.

The effect of firing conditions on the properties of Bi2O3−TiO2−Fe2O3 films

It is shown that the firing conditions have a strong bearing on the microstructure and porosity of films and the diffusion processes that take place at the film—substrate (glass) interface. This makes a certain contribution to changes in the physical and physicochemical proeprties of sol-gel coatings.

Properties of sol-gel films prepared from source materials of various composition

Properties of Bi2O3−TiO2−Fe2O3 films deposited from tetraethoxytitanium- and tetrabutoxytitanium-containing solutions are compared. Preparative procedure, solution age and annealing temperature are shown to be factors affecting the characteristics of thin sol-gel films.

Catalytic properties of bismuth molybdate and its constituent oxides in methanol oxidation

The catalytic properties of Bi2O3, MoO3 and Bi2 (MoO4)3 in methanol oxidation are considered with respect to the binding energy of surface oxygen. MoO3 and Bi2(MoO4)3 with high binding energy of oxygen are characterized by good selectivity in the oxidation of alcohol to formaldehyde. However, in this case no correlation is observed between the variations in binding energy, activity and selectivity.