Yılmaz Dağdemir

Phase stability, thermal, electrical and structural properties of (Bi2O3)1−x−y(Sm2O3)x(CeO2)y electrolytes for solid oxide fuel cells

ABSTRACT In this study, (Bi2O3)1−x−y(Sm2O3)x(CeO2)y ternary system was synthesized by using solid-state reaction method. Structural, morphological, thermal and electrical properties of the samples were evaluated by means of X-ray diffraction (XRD), scanning electron microscopy, thermo gravimetry/differential thermal analyzer and four-probe method. The XRD measurement results indicated that the samples (x = 10–15, y = 5–10–15–20) had cubic δ-phase crystallographic structure. The phase stability of the samples was checked by the differential thermal analyzer measurements, which indicates most of the samples have stable δ-Bi2O3 phase. The electrical conductivity measurement results showed that the electrical conductivity increased with mol% CeO2 molar ratio at a fixed molar ratio of Sm2O3. The highest electrical conductivity obtained for the (Bi2O3)0.65(Sm2O3)0.15(CeO2)0.20 system was 1.55 × 10−2 (Ω.cm)−1 at 600 °C. The activation energies were also calculated at low temperature range (350–650 °C) which vary from 1.1325 to 1.4460 eV and at high temperature (above 650 °C) which vary from 0.4813 to 1.1071 eV.

Chlorido[1-phenyl-3-(2,3,5,6-tetra-methyl-benz-yl)benzimidazol-2-yl-idene]silver(I).

In the title compound, [AgCl(C24H24N2)], the terminal phenyl and tetramethylbenzene rings [which form a dihedral angle of 87.92 (14)°] make dihedral angles of 59.59 (11) and 83.19 (12)° with respect to the central benzimidazole ring system. The Ag—C and Ag—Cl single-bond lengths are 2.087 (3) and 2.3267 (9) Å. The C—Ag—Cl bond angle is 172.84 (7)°. C—H⋯π interactions contribute to the stabilization of the crystal structure. A very weak π–π stacking interaction between adjacent tetramethylbenzene rings [centroid–centroid distance = 4.0610 (18) Å] is also observed.

1-(4-Meth-oxy-phen-yl)-4-(4-methyl-phen-yl)-3-phen-oxy-azetidin-2-one.

The central β-lactam ring of the title compound, C23H21NO3, is almost planar (r.m.s. deviation = 0.032Å). The methoxybenzene ring is almost coplanar with the β-lactam ring [dihedral angle = 1.87 (11)°], whereas the tolyl ring is almost normal to it [75.73 (12)°]. The dihedral angle between the β-lactam ring and the O-bonded phenyl ring is 51.95 (12)°. An intramolecular C—H⋯O interaction generates an S(6) ring. The crystal structure features intermolecular C—H⋯O hydrogen bonds, forming layers parallel to (011), and weak C—H⋯π interactions. Two aromatic π–π stacking interactions [centroid–centroid distances = 3.6744 (12) and 3.6799 (11) Å] are also observed.

Synthesis of (Bi2O3)0.9-x(Tb4O7)0.1(Sm2O3)x electrolyte for IT-SOFCs

ABSTRACT In this study (Bi2O3)0.9-x(Tb4O7)0.1(Sm2O3)x ternary solid solutions were synthesized by solid-state synthesis techniques. The products were characterized by means of X-ray powder diffraction, differential thermal analysis/thermal gravimetry, and the four-point probe technique (4PPT). Total electrical conductivity (σT) depending on the temperature and doping concentration has been measured by 4PPT. Activation energy of the four samples are calculated by Arrhenius relation. Activation energies of the samples increases with the concentration of dopant Sm2O3. Bi2O3-based ceramic system doped with Sm2O3 and Tb4O7 showed an oxide ionic-type electrical conductivity which is increased with the increasing amount of Sm2O3. The highest conductivity value is found as 3.48 × 10−1 S cm−1 for the (Bi2O3)0.85(Tb4O7)0.1(Sm2O3)0.05 ternary system at 850°C.

Butyl 4-(4-methyl­benzene­sulfonamido)­benzoate

In the title compound, C18H21NO4S, the aromatic rings are almost normal to each other, with a dihedral angle of 89.27 (18)°. The molecular conformation is stabilized by an intramolecular C—H⋯O interaction, which generates an S(6) motif. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds lead to the formation of chains propagating along [010]. Neighbouring chains are linked via a C—H⋯π interaction. The –CH2CH2CH3 atoms of the butyl group are disordered over two sets of sites, with a refined site-occupancy ratio of 0.536 (16):0.464 (16).

4′-tert-Butyl-5-chloro-3H-spiro­[1,3-benzothia­zole-2,1′-cyclo­hexa­ne]

In the title compound, C16H22ClNS, the nine-membered 2,3-dihydro-1,3-benzothiazole ring system is essentially planar, with a maximum deviation of 0.025 (2) Å for the N atom. Its plane is almost perpendicular to the main plane of the substituted cyclohexane ring, which adopts a chair conformation. In the crystal, the molecules are linked by C—H⋯π interactions.