Superconducting fluctuation behavior and infrared absorption properties of Tl1−Cu Sr1.6Yb0.4CaCu2O7 and Tl0.5Pb0.5Sr2−Mg Ca0.8Yb0.2Cu2O7− ceramics

Influence of Ce Substitution at Sr-Site on Superconducting Fluctuation Behavior and Infrared Absorption of Tl0.9Bi0.1Sr2−x Ce x Ca0.9Y0.1Cu1.99Fe0.01O7−δ (x=0–0.20) Ceramics

“…Some examples are Tl 0.5 Pb 0.5 Sr 2 (Ca 0.8 RE 0.2 )Cu 2 O x where RE = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tb, and Yb [12], Tl 0.5 Pb 0.5 Sr 1.8 Yb 0.2 Ca 1−y Mg y Cu 2 O 7−δ [13], TlSr 2 Ca 1−x R x Cu 2 O 7 (R = Dy, Ho, and Tb) [14], TlSr 2 Ca 1−x Yb x Cu 2 O 7 [15], Tl 0.5 Pb 0.5 Sr 2 Ca 1−y Y y Cu 2 O 7 [16], Tl 0.5 Pb 0.5 Sr 2 Ca 1−x Ce x Cu 2 O y [17], and TlSr 2 Ca 1−x Ce x Cu 2 O 7−δ [18]. Although the Sr site is less extensively studied, works on Tl 0.5 Pb 0.5 Sr 2−y Mg y Ca 0.8 Yb 0.2 Cu 2 O 7−δ [19], Tl 0.5 Pb 0.5 Sr 2−y Yb y CaCu 2 O [20], Tl 0.9 Bi 0.1 Sr 2−x Ti x Ca 0.9 Y 0.1 Cu 2 O 7−δ [8], Tl 0.9 Bi 0.1 Sr 2−y V y Ca 0.9 Y 0.1 Cu 2 O 7−δ [21], Tl(Sr 2−x Nd x ) 2 CaCu 2 O 7 [22], Tl 0.9 Bi 0.1 Sr 2−y In y Ca 0.9 Y 0.1 Cu 2 O 7 [23], and TlSr 2−x Ce x CaCu 2 O 7−δ [18] superconductors, among others, have been reported. Overall, such studies have shown that elemental substitutions in Tl1212 were able to produced changes in superconducting and normal state behaviors by tuning average Cu valence through over-doped, optimally doped and underdoped regions.…”

“…Interestingly, previous works have also shown that fluctuation conductivity can also be influenced by elemental substitution. For Tl-based superconductors, several studies on excess conductivity have been investigated such as that of Tl 2 Ba 2 CaCu 2 O 8+δ [43,44] [19], and Tl 0.5 Pb 0.5 Sr 2−x Yb x Ca 2 Cu 2 O 7−δ [48] showed strong influence of the substitutions on 2D to 3D fluctuation behavior. For Tl 0.85 Cr 0.15 Sr 2 CaCu 2−x Ge x O 7−δ [13], Ge 4+ substitution was able to induce 2D to 3D transition from an originally 2D behavior observed in Ge-free Tl 0.85 Cr 0.15 Sr 2 CaCu 2 O 7−δ .…”

“…It is of interest to analyze oxygen related phonon modes as the larger amplitude of vibration of lighter oxygen atoms may possibly bring about some form of interaction between electrons and phonons in the formation of Cooper pairs [13,19]. In CuTl-based oxide high temperature superconductors, the vibrations of phonon modes of apical oxygen of types Tl-O A -Cu(2) and Cu(1)-O A -Cu (2) are observed at 420-480 cm −1 and 540 cm −1 , respectively, whereas the planar oxygen mode is observed around 540-600 cm −1 [19,[51][52][53]. Whereas for Tl1212, our study on Tl 0.85 Cr 0.15 Sr 2 CaCu 2−x Ge x O 7−δ [13] showed hardening of Ge/Cu(2)-O(2)-Cr and the softening of Ge/Cu(2)-O(2)-Tl apical oxygen modes accompanied with softening of CuO 2 planar modes with increasing Ge 4+ .…”

Electrical Conductivity and Magnetic Susceptibility of Thallium 1223-Based Superconductor in the Fluctuation Range

“…This concerns the ceramics, single crystals as well as the thin film samples [23][24][25][26]. A crossover from 2D to 1D was also reported for Hg-Tl 1223 ceramic superconductor [27].…”

Influence of KMnO4 Substitution on the Structural and Transport Properties of Tl2Ba2Ca(Cu1-xRx)2Oδ+6 System

“…[1][2][3][4][5][6][7][8] The optimum hole concentration in the conducting CuO 2 planes is the source of the highest critical temperature in the high T c Tl 2 Ba 2 Ca(Cu 1-x R x ) 2 O δ+6 (Tl-2212) superconductor.…”