Synthesis and magnetic properties of novel Ln[sub 2-x]M[sub x]CuO[sub 4+y] compositions (Ln = La, Pr, Nd, Sm, Eu, Gd; M = Ca, Sr, Ba; 0 [le] x [le] 0. 2; [minus]0. 5 [le] y [le] 0. 5)

Technical Report · Mon Mar 01 04:00:00 EST 1993

OSTI ID:6895076

Cho, Jin Hyung

Ln[sub 2]CuO[sub 4] undergo transitions to reduced Ln[sub 2]CuO[sub 4-d] (Ln = La, d = 1/3; Ln = Pr, Nd, Sm, Eu, Gd, d = 1/2). The Nd[sub 2]CuO[sub 4-type] (T[prime]-phase) La[sub 2]CuO[sub 4+d] is observed after reoxidation of La[sub 2]CuO[sub 3.67] below 500C. The magnetic properties of T/O (K[sub 2]NiF[sub 4-type]) La[sub 2]CuO[sub 4] behaves differently compared with solid-state-reacted La[sub 2]CuO[sub 4]. Implications of these nonsuperconducting behaviors within superconducting carrier densities are discussed from structural point of view. La[sub 2-x]M[sub x]CuO[sub 4+d] (M = Ca, Sr; x = 0.05, 0.15), synthesized by low temperature route, also contain excess O. [sup 139]La NQR of nonsuperconducting La[sub l.85]Sr[sub 0.15]CuO[sub 4.04] show metallic properties. Tolerance factor, based on ionic radii, is to describes structures of K[sub 2]NiF[sub 4] related cuprates. With anisotropic thermal motions of apical O in La[sub 2]CuO[sub 4], we discuss the role of out-of-plane O for stabilization of cuprate structures. Magnetic phase diagram and phase separation of La[sub 2-x]Sr[sub x]CuO[sub 4+ [delta]] are reported. From Tc decrease by doping we infer localization and pair-breaking induced by doped holes. Phase separation is realized with antiferromagnetism. We also observe scaling properties of susceptibilities versus renormalized temperatures and infer the finite size effects by doped holes. [sup 139]La NQR spin-lattice relaxation are presented for La[sub 2-x]Sr[sub x]CuO[sub 4], x = 0.02 to 0.08. The rate below [approximately]2T[sub N](x) shows a power-law critical behavior while above it rate is exponential with a small x-dependent spin-stiffness constant. The spin-lattice relaxation arises from fluctations of staggered magnetization in locally ordered mesoscopic domains. Magnetically ordered state is not a conventional spin glass.

• Research Organization: Ames Lab., IA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6895076
• Report Number(s): IS-T-1536; ON: DE93011359
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
360207 -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
665100 -- Nuclear Techniques in Condensed Matter Physics -- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
CUPRATES
DIAGRAMS
EUROPIUM COMPOUNDS
EUROPIUM OXIDES
GADOLINIUM COMPOUNDS
GADOLINIUM OXIDES
HIGH-TC SUPERCONDUCTORS
INTERMEDIATE MASS NUCLEI
ISOTOPES
LANTHANUM 139
LANTHANUM COMPOUNDS
LANTHANUM ISOTOPES
LANTHANUM OXIDES
MAGNETIC PROPERTIES
NEODYMIUM COMPOUNDS
NEODYMIUM OXIDES
NUCLEAR QUADRUPOLE RESONANCE
NUCLEI
ODD-EVEN NUCLEI
OXIDES
OXYGEN COMPOUNDS
PHASE DIAGRAMS
PHASE STUDIES
PHYSICAL PROPERTIES
PRASEODYMIUM COMPOUNDS
PRASEODYMIUM OXIDES
RARE EARTH COMPOUNDS
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
RELAXATION
RESONANCE
SAMARIUM COMPOUNDS
SAMARIUM OXIDES
SPIN-LATTICE RELAXATION
STABLE ISOTOPES
STOICHIOMETRY
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTORS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS