Synthesis and oxygenation behavior of RBaCo4O7 + δ (R = Y, Dy-Lu)

Abstract

We have studied phase formation processes in the R 2 O 3 -BaO-CoO = 0.5 : 1 : 4 (R = Y, Gd-Lu) systems at temperatures from 900 to 1100°C, optimized solid state synthesis conditions for RBaCo 4 O 7 + δ (R114), and obtained single phase samples for R = Y, Dy, Ho, Er, Tm, Yb, and Lu. The behavior of R114 (R = Y, Dy, Lu) materials during thermal cycling and oxygenation has been investigated.

Structural, magnetic and electric-polarization properties of geometrically frustrated YBaCo4O7and DyBaCo4O7cobaltites

“…Experiment details. -The DyBaCo 4 O 7+δ (DBCO) and YBaCo 4 O 7+δ (YBCO) samples were synthesized by the solid-state reaction method following a procedure as reported previously [22,23]. Both powders of YBaCo 4 O 7 and DyBaCo 4 O 7 were obtained through a two-step solidstate reaction method starting from stoichiometric highpurity amounts of Y 2 O 3 , Dy 2 O 3 , BaCO 3 , and Co 3 O 4 .…”

Effect of oxygen nonstoichiometry on magnetic phase transitions in frustrated cobaltites YBaCo4O7+x (x = 0, 0.1, 0.2)

“…Polycrystalline samples YBaCo 4 O 7+x (x = 0, 0.1, 0.2) for studies have been synthesized by standard ceramic technology with three-step annealing in air and quenching sample from 900-950 о С after each stage [8]; the oxygen content after this procedure corresponds to x ~ 0.05-0.10. Further ceramic samples were exposed to additional heat treatment by using the x(t) dependence from annealing time.…”

Features of structure distortion at a phase transition in diluted YBaCo-=SUB=-4-y-=/SUB=-Zn-=SUB=-y-=/SUB=-O-=SUB=-7+x-=/SUB=- (y=0, 0.3) cobaltites

“…The character of the change in lattice parameters (lattice metric) at the structural transition, as well as the change in transition temperature and magnitude of distortion at different substitutions in Co-and RE-sublattice or deviation from stoichiometry are not sufficiently studied. The effect of structure distortion on the behavior of the frustrated Co subsystem was studied for a series of Y-cobaltites with minor deviation from stoichiometry [30]. In this work we study the effect of diamagnetic dilution in a frustrated cobalt subsystem on structural phase transitions, as well as structural and elastic characteristics in a series of layered cobaltites, YBaCo 4−y Zn y O 7+x , close to stoichiometric ones.…”