Tuning of superconductivity above 100 K in TlSr2CaCu2Oz by cation substitutions

2020 ◽  
Vol 596 ◽  
pp. 412407
Author(s):  
H.K. Lee ◽  
S.S. Lee ◽  
R. Abd-Shukor
Keyword(s):  
Cation Substitutions

Polyhedral characteristics of the cosalite-type crystal structures

2019 ◽  
Vol 57 (5) ◽  
pp. 647-662
Author(s):  
Sabina Kovač ◽  
Predrag Dabić ◽  
Aleksandar Kremenović ◽  
Aleksandar Pačevski ◽  
Ljiiljana Karanović ◽  
...  
Keyword(s):  
Crystal Data ◽  
Chemical Formula ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Area Detector ◽  
Octahedral Sites ◽  
Distorted Octahedral ◽  
Cation Substitutions ◽  
Type Crystal

Abstract The crystal structure of cosalite from the Trepča orefield was refined in the orthorhombic space group Pnma [a = 23.7878 (9), b = 4.0566 (3), c = 19.1026 (8) Å, V = 1843.35 (17) Å3, Z = 2] from single-crystal data (MoKα X-ray diffraction, CCD area detector) to the conventional R1 factor 0.031 for 1516 unique reflections with I > 2σ(I). The chemical formula (Cu0.15Ag0.24)+(Fe0.19Pb7.20)2+(Bi7.06Sb1.06)3+S20, calculated on the basis of 20 S atoms per formula unit, was determined by WDX. The unit cell contains 18 + 2 symmetrically nonequivalent atomic sites: 10 occupied by S; two by pure Pb (Pb3 and Pb4); one by pure Bi (Bi1); two by a combination of Bi and small amounts of Sb (Bi2/Sb2, Bi4/Sb3); two by Pb and Bi, and in one of these also by a small amount of Ag [Me1 = Pb2 >> Bi5 > Ag1, Me3 = Pb1 >> Bi3]; and finally one site, Me2 (Bi6 >> □), is partly occupied by Bi and partly split into an additional two adjacent trigonal planar “interstitial positions”, Cu1 and Cu2, where small amounts of Cu, Ag, and Fe can be situated. All atoms are at 4c special positions at y = 0.25 or 0.75. The structure consists of slightly to moderately distorted MeS6 octahedra sharing edges, bicapped trigonal PbS8 coordination prisms, and fairly distorted Cu1S6 and Cu2S4 polyhedra. The effects of the cation substitutions, bond valence sums, and the polyhedral characteristics are compared with other published cosalite-type structures. Among known cosalite-type structures, the largest volume contraction is shown by sample 4 (Altenberg) and involves the replacement of large cations (Bi3+ and Pb2+) by the smaller Sb3+, as well as Cu+ and Ag+. These replacements are reflected in the variations of individual Me–S bond distances, which are accompanied by variations in average Me–S distances. The degree of polyhedral distortion, Δ, progressively increases for the four Bi-hosting sites of nine cosalite-type structures: Me2 < Bi2 < Bi1 < Bi4. The Bi4 and Me3 are the most and the Me1 and Me2 are the least distorted octahedral sites of the nine cosalite-type structures.

Amorphous nickel-based hydroxides with different cation substitutions for advanced hybrid supercapacitors

2019 ◽  
Vol 325 ◽  
pp. 134936 ◽  
Author(s):  
Chenghao Huang ◽  
Yuzhen Hu ◽  
Sipeng Jiang ◽  
Hai Chao Chen
Keyword(s):  
Hybrid Supercapacitors ◽  
Cation Substitutions

Chemical specificity of a laryngeal apneic reflex in puppies

1982 ◽  
Vol 53 (2) ◽  
pp. 455-462 ◽  
Author(s):  
D. F. Boggs ◽  
D. Bartlett
Keyword(s):  
Phosphate Buffer ◽  
Superior Laryngeal Nerve ◽  
Critical Factor ◽  
Laryngeal Nerve ◽  
Sodium Salts ◽  
Single Fibers ◽  
Buffer Solutions ◽  
Chloride Salts ◽  
Cation Substitutions ◽  
Stimulation Of

In neonatal mammals the introduction of water and some other fluids into the larynx causes prolonged reflex apnea by stimulation of afferents in the superior laryngeal nerve (SLN). We have studied the chemical specificity of this reflex in 1- to 9-day-old anesthetized puppies. The laryngeal lumen was perfused with a variety of substances while ventilation through a tracheal cannula was recorded. Water consistently elicited apnea, which was terminated by 150 mM NaCl. Sucrose and urea solutions (100–500 mM) also elicited apnea, suggesting that osmolarity is not a critical factor. Phosphate buffer solutions containing NaCl and ranging in pH from 4.5 to 8.7 did not elicit apnea nor did cation substitutions in 150 mM chloride salts, with the exception of K+. Anion substitutions in 150 mM sodium salts indicated that anions of relatively large hydrated size (F-, acetate, formate, gluconate, tartrate, SO2–4, diatrizoate, IO-3, BrO-3, H2PO-4, HCO-3, borate, CO2–3) do induce apnea, whereas small anions (NO-3, ClO-3, SCN-, I-, Br-) similar to Cl- in size do not. Large anion salts and the nonelectrolytes sucrose, urea, and milk ceased to be effective stimuli in the presence of Cl- in concentrations of 80 or more meq/l. The principal stimulus for this apneic reflex is thus the absence or reduced concentration of Cl- (or small anions that can functionally replace Cl-) in the laryngeal fluid. Single fibers in the SLN were responsive to all the substances found capable of eliciting apnea and unresponsive to those not capable of doing so.

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