Studies of nonstoichiometry and magnetic properties of the Perovskite Gd[sub 1-x]Sr[sub x]CoO[sub 3[minus]y] system

Journal Article · Sun Aug 01 00:00:00 EDT 1993 · Journal of Solid State Chemistry; (United States)

OSTI ID:7284128

Hyun Ryu, K; Sun Roh, K; Joo Lee, S; Hyun Yo, C ^[1]

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1. Yonsei, Univ., Seoul (Korea, Republic of)

A series of samples in the Gd[sub 1[minus]x]Sr[sub x]CoO[sub 3[minus]y] (x = 0.00, 0.25, 0.50, 0.75, and 1.00) system with perovskite-type oxide have been prepared at 1200[degrees]C under an atmosphere with and without oxygen gas flow. X-ray diffraction analysis of the solid solution assigns the structure of the compositions of X = 0.00, 0.25, and 1.00 to the orthorhombic system, x = 0.50 to the cubic system, and x = 0.75 to the tetragonal system. The reduced lattice volume of the system is increased as the x value gets higher. The amount of Co[sup 4+] ion or the mixed valence state between Co[sup 3+] and Co[sup 4+] ions is quantitatively analyzed by the iodometric titration method. The mole ratio of the Co[sup 4+] ion, the [tau] value, is maximized at the composition of x = 0.50 and the y value, the oxygen deficiency, increases as the x value increases. Nonstoichiometric chemical formulas are obtained with the x, [tau], and y values. The electrical conductivity of the GdCoO[sub 3.00] sharply increases within the experimental temperature range; therefore, the activation energy of this compound is higher than those of the other compositions. The electrical conductivity measurement of the composition (x = 0.50) indicates a metallic property. The compounds of the compositions (x = 0.00 [approximately] 0.75) show a paramagnetic property. The magnetic measurement shows that the paramagnetic Curie temperature ([theta][sub p]) is a positive value in the case of x = 0.50 with the maximum amount of the Co[sup 4+] ion. The [mu][sub eff-Co] is decreased as the [tau] value gets higher. The SrCoO[sub 2.52] has the Neel temperature of 550 K.

• OSTI ID: 7284128
• Journal Information: Journal of Solid State Chemistry; (United States), Vol. 105:2; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COBALT OXIDES
PHYSICAL PROPERTIES
STRUCTURAL CHEMICAL ANALYSIS
GADOLINIUM OXIDES
STRONTIUM OXIDES
ACTIVATION ENERGY
CUBIC LATTICES
CURIE POINT
ELECTRIC CONDUCTIVITY
ORTHORHOMBIC LATTICES
PARAMAGNETISM
SOLID SOLUTIONS
STOICHIOMETRY
TETRAGONAL LATTICES
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
COBALT COMPOUNDS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DISPERSIONS
ELECTRICAL PROPERTIES
ENERGY
GADOLINIUM COMPOUNDS
MAGNETISM
MIXTURES
OXIDES
OXYGEN COMPOUNDS
RARE EARTH COMPOUNDS
SOLUTIONS
STRONTIUM COMPOUNDS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
360202* - Ceramics
Cermets
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360204 - Ceramics
Cermets
& Refractories- Physical Properties