• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2737-2740
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• 2013

The layered $KTiNbO_5$ was successfully synthesized with titanium(IV) isopropoxide and niobium oxalate by a novel polymerized complex (PC) method. The morphology and structure of the as-prepared sample was characterized by means of High-Resolution Transmission Electron Microscope, powder X-ray diffraction, and Laser Raman Spectroscopy. The spectral response characteristic was recorded by using UV-vis Diffuse Reflectance Spectroscopy. Results show that $KTiNbO_5$ as-prepared by PC method presents an uniform morphology of nano-particles, the mean particle sizes is ca. 28 nm corresponding to the (002), and the crystal structure can be well indexed to the orthorhombic phase. The sample as-prepared by PC method has higher band gap energy than that of the sample prepared by a solid-state reaction method due to the quantum size effect.

• Polymer(Korea)
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• v.30 no.5
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• pp.373-379
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• 2006

Polymerizable discotic liquid crystals containing diacetylene and acryloyl groups were formed through hydrogen bonding between phloroglucinol core and polymerizable pyridine derivatives, and their photopolymerization behavior was investigated. The discotic complexes exhibited discotic columnar and rectangular columnar mesophases depending on the number of aromatic rings. Photopolymerization of the discotic complexes was carried out by UV irradiation in the liquid crystalline state. IR and UV-Vis spectroscopy affirmed that diacetylene and acryloyl groups were selectively Polymerized, and that crosslinked polymers containing short conjugated diacetylene oligomers were produced by 1,4-addition. X-ray diffraction experiment showed that the columnar order in the discotic complex containing phenyl-pyridine moiety was maintained after photopolymerization, and that the rectangular columnar order in he discotic Complex with biphenyl units was changed to the lamellar order.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1297-1299
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• 2009

A series of $Eu^{2+}/Mn^{2+}$ co-activated $Ba_{1.98-x}Sr_xZnS_3$ red emission phosphors was synthesized using the polymerizable complex method. The excitation spectra of the materials contain two wide bands centered at 345nm and 445nm, implicating their possible use for white LED lighting applications. In addition, substitution of Sr for Ba by 20% (x=0.4) improved drastically the emission intensity as well as the internal quantum efficiency compared to those for Sr-free $Ba_2ZnS_3:Eu^{2+}/Mn^{2+}$ phosphor.

• Bulletin of the Korean Chemical Society
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• v.20 no.8
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• pp.893-896
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• 1999

Novel citric acid based Ti, Nb and Ta precursors that are highly stable in the presence of water were developed. No alkoxides of Ti, Nb and Ta were utilized in the preparation, instead much less moisture-sensitive metallic Ti, NbCl5 and TaCl5 were chosen as starting chemicals for Ti, Nb and Ta, respectively. The feasibility of these chemicals as precursors is demonstrated in the powder synthesis of BaTi4O9, Y3NbO7 and LiTaO3. The water-resistant Ti precursor was employed as a new source of water-soluble Ti in the amorphous citrate method, and phase pure BaTi4O9 in powdered form was successfully synthesized at 800 ？. The Pechini-type polymerizable complex method using the water-resistant Nb and Ta precursors was applied to the synthesis of Y3NbO7 and LiTaO3, and both the powder materials in their pure form were successfully synthesized at reduced tempera-tures, viz. 500-700 ？. The remarkable retardation of hydrolysis of these water-resistant precursors is explained in terms of the partial charge model theory.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1679-1683
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• 2018

Polycrystalline $BaSrCo_2(Fe_{1-x}Al_x)_{12}O_{22}$ (x = 0.00, 0.01, 0.05, and 0.10) samples were synthesized by polymerizable complex method. Based on the Rietveld refinement, crystal structures of the samples were found to be single-phased and determined to be rhombohedral with space group of R-3m. The hysteresis curves of the samples were measured under 15 kOe at various temperatures ranging from 4.2 and 295 K. It shows that they were not saturated with increasing Al ion contents due to the reduction of magnetic anisotropy. $M_{15kOe}$ was decreased with increasing Al ions contents. We expect that non-magnetic Al ions preferentially occupy the up-spin site of $18h_{VI}$, $3b_{VI}$, and $3a_{VI}$. The $M{\ddot{o}}ssbauer$ spectra of the samples were obtained at 295 K, and analyzed with sixsextets for Fe sites corresponding to the Y-type hexaferrite crystallography sites. The <$E_Q$> shows abrupt changes, and the <$H_{hf}$> shows abrupt decreases around x = 0.05 due to the coexistence of magnetic secondary phases.