High-pressure synthesis, crystal growth, phase diagrams, structural and magnetic properties of Y2Ba4CunO2n+x, HgBa2Can-1CunO2n+2+deltaand quasi-one-dimensional cuprates

In this paper we present a review of high-gas-pressure single crystal growth studies of YBa 2 Cu 4 O 8 and Y 2 Ba 4 Cu 7 O 15- x performed in oxygen pressure up to 3000 bar and Hg 1- x M x Ba 2 Ca n -1 Cu n O 2 n +2+ (M = Pb, Re; n = 1-7) compounds in argon pressure up 11 000 bar at temperature up to 1200 °C. Chain compounds A 1- x CuO 2 (A = Sr, Ca, Ba) have been synthesized at high oxygen pressure up to 2000 bar. High-pressure phase diagram studies of the investigated systems are also discussed. Structure analyses of Y 2 Ba 4 Cu n O 2 n + x ( n = 6-8), Hg 1- x M x Ba 2 Ca n -1 Cu n O 2 n +2+ (M = Pb, Re; n = 1-8), Sr 0.73 CuO 2 and (Sr,Ca) 4 Cu 6 O 10 single crystals have been performed. The effects of substitutions and trends in bondlengths are discussed. The vortex state properties of HgBa 2 Ca 2 Cu 3 O 8+ and YBa 2 Cu 4 O 8 single crystals are compared. For Hg-based compounds, the influence of oxygen content, chemical substitutions and radiation defects on vortex pinning were determined. The quasi-one-dimensional cuprates Ca 0.83 CuO 2 and Sr 0.73 CuO 2 show an antiferromagnetically ordered state of long-range 3D character at T < 10 K. The spin dynamics of Sr 0.73 CuO 2 , measured by inelastic neutron scattering, indicate that this ordered state coexists with a dimerized singlet ground state.