• Bulletin of the Korean Chemical Society
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• v.18 no.1
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• pp.91-97
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• 1997

In the course of magnetic study on several perovskite-type oxides, A2Fe(Ⅲ)BO6 (A = Ca, Sr, Ba and B = Sb, Bi), we have observed a strong irreversibility in their dc-magnetizations. When the structural data and the Mossbauer spectra are considered, such an irreversibility is to be associated with some competitions between the nearest-neighbors (nn) and the next-nearest-neighbors (nnn) in their magnetic sublattices. Particularly, the Mossbauer spectra indicate that Sr2FeBiO6 of cubic perovskite-structure is apparently well ordered crystalline compound. Nontheless this antiferromagnet shows a magnetic property which resembles that of a spin-glass. The strong history dependence is observed below 91 K and the irreversible magnetic behavior is also observed from the measurement of hysteresis loops at 10 K after zero-field-cooled (zfc) and field-cooled (fc) processes. Considering the nn and the nnn superexchanges of almost same order in ordered perovskite, it is proposed that there exists a competition and cancellation of antiferromagnetic and ferromagnetic superexchange between the nearest-neighbors and the next-nearest-neighbors, thus introducing a certain degree of frustration.

• Journal of Photoscience
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• v.5 no.4
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• pp.153-155
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• 1998

The optical spectroscopic properties of the ordered perovskite structure A2BWO6 doped with Eu3+ have been studied. The experimental result about Eu3+ ordering in the system of A2BWO6 indicate the different structural conditions. Some influence of Eu3+ substitutioin on the different types of cation site have been investigated.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.1
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• pp.36-41
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• 2002

Abstract The stoichiometric and double-ordered perovskite $Sr_2FeMoO_6$ (SFMO) polycrystalline ceramics were fabricated by sintering at above $900^{\circ}C$ in $H_2$(5%)/Ar reductive ambient. SMO polycrystals showed good ferromagnetic properties andmagnetrotesistqnce ratios of about 15 % at 8K and 3 % at room temperature. Amorphous SFMO thin films were deposited on $LaA1O_3$ and $SrTiO_3$ single crystal substrates using rf sputtering method with the SFMO polycrystalline ceramic target. Double-ordered perovskite polycrystalline SFMO thin films were fabricated by solid state crystallization by annealing the deposited amorphous films at above $680^{\circ}C$ in $H_2$(5%)/Ar reductive ambient. SFMO thin films exhibited ferromagnetic behavior. Their magnetroresistance ratios, however, were only 0.3~0.5% at 8K and disappeared with increasing the measuring temperature. This was attributed to the absence of magnetic spin tunneling between grains due to the porous structure and non-stoichiometric composition of the deposited films.

• Journal of the Korean Ceramic Society
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• v.30 no.11
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• pp.925-932
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• 1993

The perovskite phase in PZN-PMN-PT (Pb(Zn, Mg)1/3Nb2/3O3-PbTiO3) pseudoternary ceramics was stabilized by the addition of excess constituent divalent oxides (PbO, MgO and ZnO). The excess addition of 5mol% MgO or 7.5mol% PbO fully stabilized the perovskite phase. The enhanced diffuse phase transition (DPT) and the decrease in the electrical resistivity observed in the presence of excess ZnO or MgO were interpreted in terms of the additional formation of negatively charged, short-range ordered 1:1 domains with a concomitant generation of charge carriers, holes.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.3
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• pp.112-115
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• 2021

Herein, a correlation between B-site cation order and spin-phonon coupling in La₂NiMnO₆ double perovskite has been investigated. Raman spectra of La₂NiMnO₆ double perovskite annealed at 950 and 1400℃ have been measured in the 140-598 K range. A substantial softening of the phonon modes has been observed below the Curie temperature, which emphasized the presence of the spin-phonon coupling in the system. The spin-phonon coupling was found to be stronger in relatively more ordered La₂NiMnO₆ double perovskite. Thus, the magnitude of spin-phonon coupling was influenced by the Ni/Mn cation order.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.190-190
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• 2003

• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.447-449
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• 1992

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.283-287
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• 2003

Crystal structure of $(Ba_{1-x}La_x)[Mg_{(1+x)/3}Nb_{(2-x)/3}]O_3$ (BLMN) ceramics with $0{\leq}x{\leq}1$ was investigated using synchrotron X-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). When La content, x, is above 0.1, the 1:2 ordered hexagonal structure found in $Ba(Mg_{1/3}Nb_{2/3})O_3$ (BMN) was transformed into 1:1 ordered cubic structure. The 1:1 ordered cubic structure was maintained up to x=0.7. However, when x exceeded 0.7, BLMN was transformed 1:1 ordered structure which has cation displacement and in-phase and anti-phase tilt of octahedra.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.7
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• pp.718-723
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• 2004

Crystal structure of $(Ba-{1-x}La_x)[Mg_\frac{1+x}{3}}Nb_\frac{{2-x}{3}}]O_3$ (BLMN) ceramics with 0\leq1x \geq was investigated using synchrotron X-ray powder diffraction (XRD) and high reso(B $a_{l-x}$L $a_{x}$)[M $g_{(1+x)}$3/N $b_{(2-x)/3}$］ $O_3$lution transmission electron microscopy (HRTEM). When the La content, x, is above 0.1, the 1:2 ordered hexagonal structure found in Ba($Mg_\frac{1}{3}Nb_\frac{2}{3}})O_3$(BMN) was transformed into 1:1 ordered cubic structure. The 1:1 ordered cubic structure was maintained up to x=0.7. When x exceeded 0.7, however, BLMN was transformed into 1:1 ordered structure which has cation displacement and in-phase and anti-phase tilt of octahedra.

• The Korean Journal of Ceramics
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• v.2 no.3
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• pp.157-161
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• 1996

Cry structures of $Na_xWO_3$ (0.5$\leq$x$\leq$1.0) were investigated. Transmission electron microscopy (TEM) studies indicate that there is an ordering of sodium ions when x=0.75. The direction of ordering is [110] and the wavelength of ordering is twice of the interplanar distance of (110) plane. It has been confirmed that a superlattice containing eight $Na_{0.75}WO_3$ is the unit cell of ordered structure. In this unit cell, Na sites at (000) and ($\frac{2}{1}\frac{2}{1}\frac{2}{1}$) are vacant. The ordered phase was preserved after the annealing at $600^{\circ}C$ in the air. In reduced $Na_xWO_3$ with x=0.5 and 1.0, extra phases were found with the partially ordered perovskite phase. After annealing at $600^{\circ}C$, theses phases transformed to the phases found in calcined specimens.