High-Pressure Synthesis of Homologous Series of High Critical Temperature (T_c) Superconductors

Abstract

Under high pressure, a variety of elements can be accommodated at the cation sites in the charge reservoirs of cuprate superconductors. Furthermore, high pressure allows the insertion of higher number of CuO2 planes (i.e., the insertion period of a charge reservoir becomes variable). Because of these effects, many new high critical temperature (T c) superconductors have been discovered under high pressure. In this paper, we will survey their structural and superconducting properties. The role of high pressure and its effect on the size mismatch between the charge reservoir and the CuO2 plane will also be discussed.

Synthesis, Crystal Structure, and Magnetic Order of the Layered Iron Oxycarbonate Sr4Fe2O6CO3

“…The magnetic moments order antiferromagnetically within the FeO /SrO/SrO/FeO block, and ferromagnetically between the blocks. The ordered magnetic moment at 10 K is 3.88 (3) , smaller than that expected for high-spin Fe> (3d, t g e g ,…”

The kinetic effect on formation of disordered intergrowth structures in mixed bismuth-layered (Bi3NbTiO9)2(Bi4Ti3O12)1 compounds

“…The layered intergrowth structures commonly exist in inorganic solid compounds and have long been widely interested because of a variety of novel properties, such as high-temperature superconductivity, high-temperature piezoelectricity, colossal magnetoresistance and low thermal conductivity [1][2][3][4][5]. The intergrowth bismuth-layered structures are one of the most important systems among these compounds, which are built up by the regular stacking of two different bismuth layered blocks (Bi 2 O 2 ) 2 þ (A mÀ 1 B m O 3m þ 1 ) 2À and (Bi 2 O 2 ) 2 þ (A nÀ 1 B n O 3n þ 1 ) 2À , always with n=mþ 1 and mainly with Bi to occupy A sites [6][7][8].…”

“…As shown in Fig. 1, the intergrowth (Bi 3 TiNbO 9 ) 1 (Bi 4 Ti 3 O 12 ) 1 compound is formed by equal number of Bi 3 TiNbO 9 (m¼ 2, abbreviated as BTN) and Bi 4 Ti 3 O 12 (n¼ 3, abbreviated as BiT) blocks [9], or simplified as BTN 1 BiT 1 with perovskite sequences in -23- [10]. Such unique intergrowth relationships provide opportunities to tailor and design novel electrical properties.…”

The origin of the modulated structure in Sr2CuO3+δ (δ = 0.4): [CuO2] in‐plane oxygen vacancy or apical oxygen vacancy?

“…20 Therefore, high pressure can alter the number of the carriers and result in different T c s in copper oxides. For example, high pressure can affect T c through varying the type of insertion period of a charge reservoir layer where carriers are created and doped into the [CuO 2 ] planes.…”