Synthesis and Properties of X-Type Alkyl Sulfonate Gemini Surfactants Derived from Cyanuric Chloride

A series of X-type alkyl sulfonate Gemini surfactants (XC_n, n?=?6, 8, 10) was synthesized by a simple method. The chemical structures of the prepared compounds were confirmed by ¹H NMR, ¹³C NMR, ESI?CMS and Elementary analysis. The surface activity and thermodynamic properties of micellization of the X-type alkyl sulfonate Gemini surfactants were compared with sodium dodecylsulfate by means of surface tension. The properties of XC_n are superior to those of SDS such as the ??_CMC and CMC of XC₁₀ are 26.3?mN/m and 0.2?mmol/L respectively. The adsorption isotherms for XC_n were established by fitting the pre-CMC surface tension data with a quadratic function. The thermodynamic parameters of micellization ( $ \Updelta G_{m}^{ \circ } $ , $ \Updelta H_{m}^{ \circ } $ , $ \Updelta S_{m}^{ \circ } $ ) derived from electrical conductivity indicate that the micellization of XC_n is entropy-driven.     

Surface and Solution Properties of Amphiphilic Drug-Nonionic Surfactant Systems

A surface tension study was performed on mixed amphiphilic drug-nonionic surfactant systems. The drugs used were adiphenine hydrochloride and nortriptyline hydrochloride whereas surfactants were ethoxylated sorbitan esters and polyethylene oxide?Cpolypropylene oxide?Cpolyethylene oxide triblocks. The critical micelle concentration (CMC) and CMC^id (CMC at ideal mixing condition) values suggest nonideal and attractive interactions among the components. The micellar mole fraction $ (X_{ 1}^{\text{m}} ) $ values calculated using Rubingh??s model indicate predominance of the nonionic surfactant in micelle formation. The mole fraction of surfactant in mixed monolayer $ (X_{1}^{\sigma } ) $ values are greater than $ X_{ 1}^{\text{m}} $ values, indicating a greater contribution of surfactant in monolayer formation. Thermodynamic parameters, viz. Gibbs energy of micellization $ (\Updelta G_{\text{m}}^{\text{o}} ) $ , Gibbs energy of adsorption $ (\Updelta G_{\text{ad}}^{\text{o}} ) $ , and excess free energy of mixed micelles $ (\Updelta G_{\text{ex}}^{\text{m}} ) $ and monolayers $ (\Updelta G_{\text{ex}}^{\sigma } ) $ were also evaluated. All these values suggest stable mixed micelle and mixed monolayer formation.     

Thermodynamic Properties of Sulfobetaine-Type Surfactants

Sulfobetaine-type surfactants containing a hydroxy group were synthesized by the reaction of long chain monoalkyl dimethyl tertiary amine with 3-chloro-2-hydroxypropanesulfonic acid sodium salt. The structures were characterized by ¹H NMR and ESI-MS. Their critical micelle concentrations (CMC) in aqueous solution were determined by the plate method in the temperature rang from 298.15 to 328.15 K. The thermodynamic parameters of micellization ( $\Delta G_{\text{mic}}^{\theta}$ , $\Delta H_{\text{mic}}^{\theta}$ and $\Delta S_{\text{mic}}^{\theta}$ ) and surface adsorption ( $\Delta G_{\text{ad}}^{\theta}$ , $\Delta H_{\text{ad}}^{\theta}$ and $\Delta S_{\text{ad}}^{\theta}$ ) were calculated from CMC data. The results showed that the micellization and surface adsorption of these surfactants in aqueous solution was a spontaneous and entropy-driven process. The micellization and surface adsorption became easier when the alkyl chain length increased from 12 carbon atoms to 14. The enthalpy–entropy compensation of micellization and adsorption was investigated. The compensation temperature were found to be (311 ± 2) K for both micellization and adsorption. The $\Delta H_{\text{mic}}^{*}$ and $\Delta H_{\text{ad}}^{*}$ decreased, but the $\Delta S_{\text{mic}}^{*}$ and $\Delta S_{\text{ad}}^{*}$ increased with increasing the hydrophobic chain length from 12 to 14.     

Crystallization conditions effect on molecular weight of solid-state polymerized poly(ethylene terephthalate)

Number-average molecular weight ( $ \overline{M}_{n} $ ) variation of polyethylene terephthalate with respect to crystallization temperature and time, and solid-state polymerization (SSP) time were studied using response surface experimental design method. All experiments were conducted in a fluidized bed reactor. $ \overline{M}_{n} $ values were calculated by Mark?CHouwink equation upon determining intrinsic viscosity (IV) of samples. Two suitable models were proposed for $ \overline{M}_{n} $ and IV, based on the regression coefficient. It was observed that $ \overline{M}_{n} $ increases with decrease in crystallization temperature and increase in crystallization time and SSP time. It was shown that SSP time is the most important parameter based on statistical calculations. Crystallization time, crystallization temperature and SSP time were determined 60?min, 160?°C and 8?h, respectively, in order to achieve maximum $ \overline{M}_{n} $ . Density measurements were applied to study the overall crystallinity of samples. Based on density results it was revealed that percent of crystallinity is not the only factor that affects the $ \overline{M}_{n} $ of polymer. Differential scanning calorimeter was used to analyze thermal properties of the samples. All samples showed two melting peaks. It was observed that the lower melting temperature peak is related to the isothermal crystallization process temperature. Polarized light microscopy was used to study spherulitic structures of polymer films after crystallization process. It was shown that the sample with smallest spherulite size had the maximum $ \overline{M}_{n} $ equal to 26,000?g/mol.     

Hansen solubility parameters of cellulose acetate butyrate–poly(caprolactone) diol blend by inverse gas chromatography

The specific retention volumes, $ V_{\text{g}}^{0} $ , for adsorption of 21 solute probes on the solid surface of cellulose acetate butyrate (CAB)–poly(caprolactone) diol (PCLD) blend determined in the temperature range by inverse gas chromatography were used to evaluate Hansen solubility parameters (HSP). The effect of plasticizer, PCLD, on the HSP of CAB was investigated. The three components of HSP namely dispersive $ \delta_{2}^{\text{d}} $ , polar $ \delta_{2}^{\text{p}} $ , and hydrogen bonding $ \delta_{2}^{\text{h}} $ of the blend surface were compared with the CAB surface. The $ \delta_{2}^{\text{h}} $ of CAB was increased due to the addition of PCLD, while the change in the dispersive and polar components was found to be insignificant. The three HSP were decreasing linearly with increase of temperature for the blend as well as for pure CAB. The variation of HSP with weight fraction of CAB shown that the $ \delta_{2}^{\text{p}} $ was positively deviating from linearity whereas $ \delta_{2}^{\text{d}} $ and $ \delta_{2}^{\text{h}} $ were negatively deviating from linearity.     

Active Sites of a NiSO4/γ-Al2O3 Catalyst for the Oligomerization of Isobutene

Structural characterization, the mechanism of catalytic activity generation and the nature of active sites of a NiSO₄/γ-Al₂O₃ catalyst for isobutene oligomerization were studied by temperature programmed reduction (TPR), X-ray diffraction (XRD), diffuse reflectance infrared fourier transformed (DRIFTS) and X-ray photoelectron spectroscopy (XPS) techniques. The TPR measurements together with the XRD data indicated that calcination of the catalyst at 500 °C did not form either nickel oxide or nickel aluminate. The presence of only one type of surface nickel species formed by the incorporation of nickel ions into the surface vacant sites of γ-alumina lattice was indicated by XPS with Ar⁺ ions sputtering and TPR measurements. XPS analysis of the calcined catalyst suggested that the oxidation state of nickel ions in the calcined catalyst was (+2) and after calcination the nickel ions were coordinated to relatively more basic ligands. The surface acid centers of the catalyst were found to be only Lewis type. SO₄ ^2? ions were found to be present as a chelating bidentate ligand and enhanced the acidity of metal ( $ {\text{Al}}^{3 + } $ and/or $ {\text{Ni}}^{2 + } $ ) Lewis acid centers. The results suggested that the combined effects of the presence of the bidentate SO₄ ^2? ligand and dehydroxylation generate coordinatively unsaturated $ {\text{Ni}}^{2 + } $ that interact with isobutene during the oligomerization reaction. The formation of lower-valent nickel ions ( $ {\text{Ni}}^{x + } ,x\; \le\; 1 $ ) was demonstrated by in situ DRIFTS using CO as a probe molecule and by XPS measurements. Formation of a binuclear bridging carbonyl complex, $ [{\text{Ni}}({\text{CO}})^{ + } ]_{2} $ suggested that some lower-valent nickel species were formed via in situ reduction by isobutene. Analysis of Ni 2p photolines indicated the appearance of a new lower-valent nickel species ( $ {\text{Ni}}^{x + } ,x \;\le\; 1 $ ) during the course of isobutene oligomerization. Hence it is plausible that lower-valent nickel species might act as the active center for the oligomerization reaction, while the SO₄ ^2? ions enhance the acidity of the Lewis acid sites on the surface and assist in the adsorption of reactant molecules on the surface.     

Polymerization of cyclohexene oxide by methyl-4-[bis(4-bromophenyl)amino]benzoate cation radical salts

Methyl-4-[bis(4-bromophenyl)amino]benzoate cation radical salts having non-nucleophilic anions such as $ {\text{SbF}}^{ - }_{6} $ , $ {\text{PF}}^{ - }_{6} $ and $ {\text{AsF}}^{ - }_{6} $ were newly prepared and found to be very active initiators for the polymerization of cyclohexene oxide at room temperature, in dichloromethane without any external stimulation. The effects of counter ion structure, salt and monomer concentration on the polymerization yield and molecular weight, and the mechanism of initiation are presented.     

Structure and Biological Behaviors of Some Metallo Cationic Surfactants

In this study, different cationic surfactants were prepared by esterification with bromoacetic acid of different fatty alcohols, i.e., dodecyl, tetradecyl and hexadecyl species. The products were then reacted with diphenyl amine, and the resulting tertiary amines were quaternized with benzyl chloride to produce a series of quaternary ammonium salts. The metallocationic surfactants were prepared by complexing the cationic surfactants with nickel and copper chlorides. Surface tension of these surfactants were investigated at different temperatures. The surface parameters including critical micelle concentration (CMC), maximum surface excess (Γ _max), minimum surface area (A _min), efficiency (PC₂₀) and effectiveness (π _CMC) were studied. The thermodynamic parameters such as the free energy of micellization ( $\Updelta G_{\text{mic}}^{^\circ }$ ) and adsorption ( $\Updelta G_{\text{ads}}^{^\circ }$ ), enthalpy ( $\Updelta H_{\text{m}}^{^\circ }$ ), ( $\Updelta H_{\text{ads}}^{^\circ }$ ) and entropy ( $\Updelta S_{\text{m}}^{^\circ }$ ), ( $\Updelta S_{\text{ads}}^{^\circ }$ ) were calculated. FTIR spectra and ¹H-NMR spectra were obtained to confirm the compound structures and purity. In addition, the antimicrobial activities were determined via the inhibition zone diameter of the prepared compounds, which were measured against six strains of a representative group of microorganisms. The results indicate that these metallocationic surfactants exhibit good surface properties and good biological activity on a broad spectrum of microorganisms.     

Inverse gas chromatography characterization of polyaniline complexes: application to volatile organic compounds sensing

Surface thermodynamic characteristics of two polyaniline complexes with inorganic and organic acids were investigated using inverse gas chromatography technique. Thirteen solutes were injected into two separate chromatographic columns packed with polyaniline (PANI) complexes as stationary phases without any chromatographic support. The retention volumes of these solutes were measured to show their strong retention with both PANI complexes, particularly the xylene isomers: ortho, meta and para. The free energy of adsorption, $\Updelta G_{a}$ Δ G a , consisting of dispersive term $\Updelta G_{a}^{d}$ Δ G a d and the acid–base interaction term, $\Updelta G_{a}^{s}$ Δ G a s was also determined showing that it is mainly based on its dispersive contribution. The dispersive surface energy of hydrochloric acid polyaniline complex is ranging from 70.39 mJ/m² at 130 °C to 65.75 mJ/m² at 150 °C while the surface energy of dodecylbenzenesulfonic acid polyaniline complex has shown slight upper difference ranging from 70.90 to 66.23 mJ/m² in the same temperature’s interval, thus reflecting a behavior comparable to that of high surface energy materials. Furthermore, the obtained PANI complexes powders were characterized using fourier transform infrared spectrometry, Raman spectroscopy, UV–visible, XRF and SEM techniques. The measured retention volumes were combined with linear solvation energy relationship (LSER), called Abraham law, to determine physicochemical parameters describing dispersive, polar and acid–base properties, the surface of both polyaniline was found out exhibiting a basic nature.     

Magnetic cobalt-zinc ferrite/PVAc nanocomposite: synthesis and characterization

Metal oxide nanoparticles are the subject of current interest because of their unusual optical, electronic, and magnetic properties. In this work, cobalt zinc ferrite ( $ {\text{Co}}_{0.3} {\text{Zn}}_{0.7} {\text{Fe}}_{2} {\text{O}}_{4} $ ) nanoparticles have been synthesized successfully through redox chemical reaction in aqueous solution. The synthesized $ {\text{Co}}_{0.3} {\text{Zn}}_{0.7} {\text{Fe}}_{2} {\text{O}}_{4} $ nanoparticles have been used for the preparation of homogenous polyvinyl acetate-based nanocomposite ( $ {\text{Co}}_{0.3} {\text{Zn}}_{0.7} {\text{Fe}}_{2} {\text{O}}_{4} /{\text{PVAc}} $ ) via in situ emulsion polymerization method. Structural, morphological and magnetic properties of the products were determined and characterized in detail by X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The XRD patterns of the $ {\text{Co}}_{0.3} {\text{Zn}}_{0.7} {\text{Fe}}_{2} {\text{O}}_{4} $ confirmed that the formed nanoparticles are single crystalline. According to TEM micrographs, the synthesized $ {\text{Co}}_{0.3} {\text{Zn}}_{0.7} {\text{Fe}}_{2} {\text{O}}_{4} $ nanoparticles had nano-needle morphology with an average particle size of 20 nm. The calculated coefficient of variation (CV) of nanoparticles diameters obtained by TEM micrographs was 16.77. The $ {\text{Co}}_{0.3} {\text{Zn}}_{0.7} {\text{Fe}}_{2} {\text{O}}_{4} $ nanoparticles were dispersed almost uniformly in the polymer matrix as was proved by SEM technique. The magnetic parameters of the samples, such as saturation magnetization (M _s) and coercivity (H _c) were measured, as well. Magnetization measurements indicated that the saturation magnetization of synthesized $ {\text{Co}}_{0.3} {\text{Zn}}_{0.7} {\text{Fe}}_{2} {\text{O}}_{4} /{\text{PVAc}} $ nanocomposites was markedly less than that of $ {\text{Co}}_{0.3} {\text{Zn}}_{0.7} {\text{Fe}}_{2} {\text{O}}_{4} $ magnetic nanoparticles. However, the nanocompoites exhibited super-paramagnetic behavior at room temperature under an applied magnetic field.     

Micellization of Some Bile Salts in Binary Aqueous Solvent Mixtures

The micellization behavior of bile salts—sodium cholate and sodium deoxycholate was studied in aqueous methanol, ethanol and ethylene glycol mixtures (10–20 % v/v) over a temperature range (300–320 K) by surface tension and conductivity methods. Critical micelle concentration, extent of counter ion binding (α), interfacial property (A _min, ζ_max, π-CMC, $ \Updelta G_{\text{ad}}^{ \circ } $ ) and thermodynamic parameters ( $ \Updelta G_{\text{m}}^{ \circ } $ , $ \Updelta H_{\text{m}}^{ \circ } $ , $ \Updelta S_{\text{m}}^{ \circ } $ ) for the micellization process are reported and discussed.     

Surface characterization of cellulose acetate propionate by inverse gas chromatography

The purpose of this paper is to study the surface energetics of the polymer excipient cellulose acetate propionate (CAP) in the solid form. The net retention volumes, V _N, for n-alkanes and polar solutes have been measured in the temperature range 353.15–403.15 K by inverse gas chromatography. The dispersive surface free energy, $ \gamma_{\text{S}}^{\text{d}} $ , and Lewis acid–base parameters $ K_{\text{a}} $ and $ K_{\text{b}} $ , have been determined using V _N values. The $ \gamma_{\text{S}}^{\text{d}} $ values are decreased linearly with increase of temperature. The $ \gamma_{\text{S}}^{\text{d}} $ value at 353.15 K is 24.50 ± 1.54 mJ/m², and the temperature gradient was found to be ?0.287 mJ/m²/K¹. The $ K_{\text{a}} $ and $ K_{\text{b}} $ values are 0.410 ± 0.021 and 1.708 ± 0.388, respectively, which suggest that the CAP solid surface contain relatively more basic sites. The K _a and K _b values of CAP are compared with the similar values obtained on the cellulose acetate butyrate solid surface.     

Total concentration of main components in solutions for metal electroplating as a criterion for classifying and choosing resource-saving compositions of solutions

A comparative analysis is performed of the variations in the total concentration of the main components $\left( {\sum\limits_i {c_i } } \right)$ , in the solutions proposed and used in different years for electroplating individual metals (Cr, Cu, Ni, Zn, Sn, Cd, Pb, and Fe). A quantitative concentration criterion is determined for classifying solutions into resource-saving ( $\left( {\sum\limits_i {c_i \leqslant 2.32} } \right)$ mol-equiv/L) and resourceintensive ( $\left( {\sum\limits_i {c_i \geqslant 2.78} } \right)$ mol-equiv/L) compositions. In addition to scientific interest, this material can be useful for developing studies aimed at reducing the negative environmental impact of electroplating shops or sections.     

Characterization and Evaluation of Methylcyclopentane and Cyclohexane Ring Opening over Ir/ZrO2–MoO3 Catalysts

Methyl bromide was synthesized by reacting methane with oxygen and hydrogen bromide over Rh/SiO₂ catalyst. The reaction started from the oxidation of HBr to form active bromine species (Br^? radicals and Br* surface species), which in turn reacted with CH₄ to form CH ₃ ^? radicals and $\hbox{CH}_{3}^{\ast}$ surface species. These CH ₃ ^? and $\hbox{CH}_{3}^{\ast}$ species reacted with the active bromine species to form CH₃Br and CH₂Br₂. The presence of HBr inhibited the deep oxidation and the steam reformation of CH₄ and therefore, guaranteed the high selectivity of CH₃Br. In the presence of HBr, CO was formed from the oxidation and steam reformation of CH₃Br, while CO₂ was formed from the oxidation and steam reformation of CO over Rh/SiO₂ at reaction temperature higher than 560 °C.     

Heteronuclear Cu(II)–Mn(II)–Cu(II) Complex Constructed from Metallo-Ligand Through Carboxylate Oxygens: Coexistence of Water Hexamers

A heteronuclear complex of [Mn(H₂O)₄(CuL)₂]₂·4H₂O 1 (H₂L = 2-hydrogen benzaldehydeneglycylglycine) has been synthesized and characterized by IR spectra, TGA, and single crystal X-ray diffraction analysis. The molecule consists of one $\text{Mn}{(\text{H}_{2}\text{O})_{4}}^{2+}$ Mn(H₂O) ₄ ²⁺ group and two symmetric groups [CuL]^? which are connected by carboxylate oxygen atoms. A discrete water hexamer composed of a planar tetrameric water ring and two pendent water molecules acts as a ‘glue’ to assemble adjacent [CuL]^? into a two-dimensional structure.     

Facile Electrospinning Preparation and Up-Conversion Luminescence Performance of Y3Al5O12:Er3+, Yb3+ Nanobelts

Electrospinning technique was used to prepare $ {\text{PVP}}/\left[ {{\text{Y}}\left( {{\text{NO}}_{ 3} } \right)_{ 3} + {\text{Yb}}\left( {{\text{NO}}_{ 3} } \right)_{ 3} + {\text{Er}}\left( {{\text{NO}}_{ 3} } \right)_{ 3} + {\text{Al}}\left( {{\text{NO}}_{ 3} } \right)_{ 3} } \right] $ composite nanobelts and novel structures of Y₃Al₅O₁₂:Er³⁺, Yb³⁺ (denoted as YAG:Er³⁺, Yb³⁺ for short) nanobelts have been successfully fabricated after calcination of the relevant composite nanobelts at 900 °C for 8 h. YAG:Er³⁺, Yb³⁺ nanobelts were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and fluorescence spectroscopy. XRD analysis indicated that YAG:Er³⁺, Yb³⁺ nanobelts were cubic in structure with space group I_a3d. SEM analysis and histograms revealed that the width of YAG:Er³⁺, Yb³⁺ nanobelts was ca. 1.8 ± 0.37 μm under the 95 % confidence level, and the thickness was ca. 81.8 nm. Up-conversion emission spectra analysis manifested that YAG:Er³⁺, Yb³⁺ nanobelts respectively emitted strong green and red emissions centering at 522, 554 and 648 nm under the excitation of a 980-nm diode laser. The green emissions were assigned to the energy levels transitions of $ ^{ 2} {\text{H}}_{ 1 1/ 2} ,^{ 4} {\text{S}}_{ 3/ 2} \to^{ 4} {\text{I}}_{ 1 5/ 2} $ of Er³⁺ ions, and the red emission originated from the energy levels transition of $ ^{ 4} {\text{F}}_{ 9/ 2} \to ^{ 4} {\text{I}}_{{{\text{l5}}/ 2}} $ of Er³⁺ ions. The up-conversion luminescence of YAG:Er³⁺, Yb³⁺ nanobelts doped with various concentrations of Yb³⁺ and Er³⁺ was studied and the optimum molar ratio of Yb³⁺ to Er³⁺ was found to be 15:1. CIE analysis demonstrated that color-tuned luminescence can be obtained by adjusting doping concentrations of Yb³⁺ and Er³⁺ ions, which could be applied in the fields of optical telecommunication and optoelectronic devices. The up-conversion luminescent mechanism and the formation mechanism of YAG:Er³⁺, Yb³⁺ nanobelts were also proposed.     

Thermodynamics of Micellization of Sulfobetaine Surfactants in Aqueous Solution

The thermodynamics of micellization of the sulfobetaine (SB) amphoteric surfactants, that is N-alkyl-N,N-dimethyl-3-ammonio-1-propanesulfonate and N-alkyl-N,N-dimethyl-3-ammonio-1-butanesulfonate (the carbon atom number of the alkyl chain is 12, 14 and 16 respectively) in aqueous solution, have been studied by surface tension measurements with the temperature range from 298.15 to 318.15?K. The critical micelle concentrations (CMC) of SB n-3 and SB n-4 surfactants were determined from the drop-volume methods at different temperatures. The obtained results indicated that the values of critical micelle concentration strongly depended on the surfactants species and temperatures. Thermodynamic parameters ( $ \Updelta G_{\text{mic}}^{ \circ } $ , $ \Updelta H_{\text{mic}}^{ \circ } $ and $ \Updelta S_{\text{mic}}^{ \circ } $ ) of the micelle formation were determined. The micellization was found to be enthalpy-driven at lower temperatures, while this process was entropy-driven at higher temperatures. The enthalpy?Centropy compensation were also investigated. The compensation temperature T _c and $ \Updelta H_{\text{mic}}^{*} $ decreased, while $ \Updelta S_{\text{mic}}^{*} $ increased with the increase in the hydrophobic chain length.     

Curable polyester precursors from polylactic acid glycolyzed products

Curable precursors are prepared from chemical recycling of degradable polylactic acid (PLA) for development of aliphatic polyester thermoset materials. PLA resin (NatureWork 4042D) was de-polymerized via glycolysis under various conditions to produce PLA glycolysates (GlyPLAs), whose chain-ends mainly consist of hydroxyl groups with $\bar{M}_{n}$ M ¯ n ranging from 3,600 to 17,000 g/mol. Unsaturated double bonds (DB) were introduced into GlyPLA structures by end-capping with methacrylic anhydride to generate curable LA-precursors. The end-capping efficiency is strongly dependent on the molecular weight of GlyPLAs, where smaller-sized glycolysates produce LA-precursors with higher DB content. Curing behaviors of the precursors are thoroughly examined. DSC and FTIR results show that curing reactions at 140 °C are completed after 2 h for all samples. Results on gel fraction indicate that LA-precursor with $\bar{M}_{n}$ M ¯ n  ~ 3,600 g/mol is the most effective candidate for producing network products with high crosslink density.     

Magnetic properties of ferrites-cobaltites Bi1 − x La x Fe1 − x Co x O3 (1.0 ≥ x ≥ 0.7) with a perovskite structure

The molar magnetic susceptibility (χ_mol) of Bi_{1 ? x} La _x Fe_{1 ? x} Co _x O₃ solid solutions (x = 1.0, 0.9, 0.8, or 0.7) with a crystal structure of rhombohedrally distorted perovskite (R $\bar 3$ c) has been investigated in the temperature range of 5–300 K in a 0.86 T magnetic field. In the temperature range where χ_mol depends on temperature T according to the Curie-Weiss law, the resulting effective magnetic moments of Fe³⁺ and Co³⁺ ions ( $\mu _{eff,Fe^{3 + } ,Co^{3 + } ,} \mu _{eff,Fe^{3 + } } $ and $\mu _{eff,Co^{3 + } } $ ) have been determined for the solid solutions under study. Fe³⁺ ions in the solid solutions have been found to be in the mixed intermediate spin (IS) and high spin (HS) states ( $\mu _{eff,Fe^{3 + } } $ is 4.26μ_B and 4.68μ_B for the temperature range of 5–100 and 150–300 K, respectively). It is shown that 8% Co³⁺ ions in LaCoO₃ at 5–19 K are in the paramagnetic IS state and they determine to a great extent the magnetic susceptibility. It is established that only 9% and 18% Co³⁺ ions in Bi_{1 ? x} La _x Fe_{1 ? x} Co _x O₃ solid solutions (x = 0.9 or 0.8) are in the paramagnetic IS state in the temperature ranges of 5–30 and 5–110 K, respectively, while the other ions are diamagnetic.     

The thermoelectric power in Bi2O3

The thermo electric power, ΔE/ΔT, of the cell $$\begin{gathered} O_2 + N_{2, } Pt/Bi_2 O_3 (\delta phase)/Pt, O_2 + N_2 \hfill \\ (T + \Delta T) (T) \hfill \\ \end{gathered}$$ has been measured as a function of oxygen pressure (10^?4 atm ? p(O₂) ? 1 atm) in the temperature range 650–800° C. The experimental result can be described by: $$[ \in ({\rm O}_2 /{\rm O}^{2 - } ) - \in (e, Pt)] = [45.6 \pm 5.6 log p(O_2 ) - 261](\mu VK^{ - 1} )$$ within experimental error, where ε(O₂/O²), the Seebeck coefficient ofδ-Bi₂O₃, stands for \(\mathop {\lim }\limits_{\Delta T \to 0} \Delta E/\Delta T\) The change of ΔE/ΔT with oxygen pressure corresponds to the change of the partial molar entropy of O₂. The heat of transport of O^2? ions is calculated to be 0.13 eV ± 0.01 whereas the activation enthalpy for ionic conduction is 0.30 eV. From this discrepancy it is concluded that the free ion model of Rice and Roth cannot be applied, while the extended lattice gas model of Girvin might explain the results when strong polaron coupling is assumed.