• Korean Journal of Materials Research
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• v.21 no.9
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• pp.509-514
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• 2011

In this study, optical emission spectroscopy was used to monitor the plasma produced during the RF magnetron sputtering of a $BaTiO_3$ target. The intensities of chemical species were measured by real time monitoring with various discharge parameters such as RF power, pressure, and discharge gas. The emission lines of elemental and ionized species from $BaTiO_3$ and Ti targets were analyzed to evaluate the film composition and the optimized growth conditions for $BaTiO_3$ films. The emissions from Ar(I, II), Ba(I, II) and Ti(I) were found during sputtering of the $BaTiO_3$ target in Ar atmosphere. With increasing RF power, all the line intensities increased because the electron density increased with increasing RF power. When the Ar pressure increased, the Ba(II) and Ti(I) line intensity increased, but the $Ar^+$ line intensity decreased with increasing pressure. This result shows that high pressure is of greater benefit for the ionization of Ba than for that of Ar. Oxygen depressed the intensity of the plasma more than Ar did. When the Ar/$O_2$ ratio decreased, the intensity of Ba decreased more sharply than that of Ti. This result indicates that the plasma composition strongly depends on the discharge gas atmosphere. When the oxygen increased, the Ba/Ti ratio and the thickness of the films decreased. The emission spectra showed consistent variation with applied power to the Ti target during co-sputtering of the $BaTiO_3$ and Ti targets. The co-sputtered films showed a Ba/Ti ratio of 1.05 to 0.73 with applied power to the Ti target. The films with different Ba/Ti ratios showed changes in grain size. Ti excess films annealed at $600^{\circ}C$ did not show the second phase such as $BaTi_2O_5$ and $TiO_2$.

• Journal of the Korean Ceramic Society
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• v.24 no.3
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• pp.277-281
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• 1987

The various contents of MgF2 from 0 to 12.5wt% are studied in the AlF3-(Mg＋Sr＋Ba)F2-P2O5 system for the effects of various properties in glasses and the atmosphere of melting was controlled by N2 and Ar gas respectively. Density, refractive index, infrared transmission, thermal conductivity and thermal expansion coefficient of glasses are determined. Density, refractive index and thermal conductivity are decreased, micro-hardness and thermal expansion coefficient are increased according to the increasing of MgF2 contents. Infrared transmittance decreases with increasing the MgF2 contents and it slightly dropped by air than N2 and Ar atmosphere. Other properties are not influenced by atmosphere control.

• Korean Journal of Materials Research
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• v.21 no.12
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• pp.644-649
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• 2011

[ $A_{3-2x/3}Al_{1-z}In_{z}O_4F:Eu_x^{3+}$ ](A = Ca, Sr, Ba, x = -0.15, z = 0, 0.1) oxyfluoride phosphors were simply prepared by the solid-state method at $1050^{\circ}C$ in air. The phosphors had the bright red photoluminescence (PL) spectra of an $A_{3-2x/3}Al_{1-z}In_{z}O_4F$ for $Eu^{3+}$ activator. X-ray diffraction (XRD) patterns of the obtained red phosphors were exhibited for indexing peak positions and calculating unit-cell parameters. Dynamic excitation and emission spectra of $Eu^{3+}$ activated red oxyfluoride phosphors were clearly monitored. Red and blue shifts gradually occurred in the emission spectra of $Eu^{3+}$ activated $A_3AlO_4F$ oxyfluoride phosphors when $Sr^{2+}$ by $Ca^{2+}$ and $Ba^{2+}$ ions were substituted, respectively. The concentration quenching as a function of $Eu^{3+}$ contents in $A_{3-2x/3}AlO_4F:Eu^{3+}$ (A = Ca, Sr, Ba) was measured. The interesting behaviors of defect-induced $A_{3-2x/3}Al_{1-z}In_{z}O_{4-{\alpha}}F_{1-{\delta}}$ phosphors with $Eu^{3+}$ activator are discussed based on PL spectra and CIE coordinates. Substituting $In^{3+}$ into the $Al^{3+}$ position in the $A_{3-2x/3}AlO_4F:Eu^{3+}$ oxyfluorides resulted in the relative intensity of the red emitted phosphors noticeably increasing by seven times.

• Journal of the Korean Ceramic Society
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• v.24 no.4
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• pp.321-328
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• 1987

The chemical durability of six alumino fluorophosphate glass samples studied. The composition of glass varied with MgF2 content from 0 to 12.5wt% in 30AlF3-2MgF2-(50-x)MF2-10P2O5(M; Sr, Ba). Samples were maintained in distilled water at 95$^{\circ}C$ from 1 to 100hrs. Weight loss, pH change and leached elements of the solution, and IR transmittance of samples were measured and also their surfaces were observed by SEM. Chemical durabilities of these samples were increased with increasing MgF2 contents. The following various properties were increased rapidly up to 10 hours after that changed slowly. The sample after leached at 95$^{\circ}C$ during 100 hrs showed 0.5mg/$\textrm{cm}^2$ in weight loss. The pH of leached solution is 6.2 and concentration of Mg, Sr, and Ba element of that leached solution were 24,115 and 125 ppm, respectively. The infrared transmittance of leached sample decreased 7% compare to unleached one. And also SEM photomicrograph and EDS analysis showed that the corrosion of samples were decreased with respect to increasing MgF2 content.

• Current Optics and Photonics
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• v.6 no.4
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• pp.413-419
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• 2022

An oxyfluoride glass ceramic containing Eu²⁺-doped nepheline and LaF₃ crystals was modified, with BaF₂ replacing LaF₃ up to 20 mole percent, and its luminescence change was monitored. With increasing BaF₂ content, the greenish yellow emission centered at 540 nm under 400-nm excitation decreased, and a new afterglow emission from the modified ceramic was observed after removal of the excitation light source. X-ray diffraction (XRD) and transmission electron microscopy with energy dispersive spectroscopy (TEM-EDS) were used to investigate the changes in the crystalline phases within the glass matrix. Time dependent emission intensity was monitored to observe the afterglow, and the possible mechanism for the afterglow due to BaF₂ addition was considered.

• Korean Journal of Environmental Biology
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• v.27 no.4
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• pp.391-396
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• 2009

The biological effects of carcinogenic polycyclic aromatic hydrocarbons (cPAHs) including benzo[a]pyrene (BaP), dibenzo[a,h]anthracene (DBA), benzo[a]anthracene (BaA), benzo[b] fluoranthene (BbF), benzo[k]fluoranthene (BkF), and indeno[1,2,3-c, d]pyrene (InP) on transcriptomic changes were determined in the liver of Oryzias latipes. Differentially expressed genes (DEGs) by binary exposure to cPAHs (BaP+BaA, BaP+BbF, BaP+BkF, BaP+DbA, BaP+InP) were screened by annealing control primers-based polymerase chain reaction followed by sequence analysis and BLAST searching. The results showed that four DEGs were commonly expressed by cPAHs and they were identified as ribosomal protein S4, coagulation factor II, elongation factor 1 beta, and a predicted protein similar to human immunodeficiency virus type I enhancer binding protein 3. This finding suggests that binary exposure to cPAHs interferes protein synthesis required for fundamental liver functions in fish.

• Journal of the Korean Ceramic Society
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• v.32 no.4
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• pp.448-454
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• 1995

The effect of WO3 addition on microwave dielectric properties of BaTiO3-3{(1-x)TiO2-xWO3} system was studied. Addition of WO3 to this system resulted in the formation of BaWO4 and Ba2Ti9O20 phases. Both the dielectric constant (K) and the temperature coefficientof resonant frequency (Tf) were decreased with the amount of WO3 addition. The value of Q$\times$f0 was increased as the amount of WO3 was increased up to x=0.0275, and then decreased when x exceeded 0.03. At x=0.0275, this ceramic showed excellent microwave proprties of K=34-35, Q$\times$f0=50,000-53,000, and near zero ppm/$^{\circ}C$ of Tf.

• Korean Journal of Materials Research
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• v.8 no.7
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• pp.659-663
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• 1998

The effect of Bi-substitution in $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$ ceramic was studied on the formation of crystal phases, microstructure, and microwave dielectric properties. $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$, solid solution (0$\leq$x$\leq$0.2) were formed by Bi-substitution into the Nd site of $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$ ceramics. Average grain size increased with Bi-substitution. Dielectric constant(${\varepsilon}_r$) increased from 84 to U8, and the temperature coefficient of resonant frequency(${\tau}_f$) decreased from 44 ppm/$^{\circ}C$ to -30 ppm/$^{\circ}C$ when Bi contents increased up to x=0.2 in $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$ solid solutions. $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$ solid solutions with x=0.04~0.08 showed the most superior microwave dielectric properties, those are ${\varepsilon}_r$= 89-92, Q . f = 5855~6091 GHz, and (${\tau}_f$)= -7.5-7.5 ppm/$^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.476-479
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• 2001

The microwave dielectric properties of $[(Pb_{1-x}Ba_{x})_{1/2}La_{1/2}](Mg_{1/2}Nb_{1/2})O_{3}$ ceramics were investigated. When $[(Pb_{0.9}Ba_{0.1})_{1/2}La_{1/2}](Mg_{1/2}Nb_{1/2})O_{3}$ ceramics were sintered at $1250^{\circ}C$ and $1350^{\circ}C$ for 2hr, the microwave dielectric properties were obtained $\varepsilon_{r}=64\sim80$, $Q{\times}f=11,800\sim18,000$. As a result, $[(Pb_{0.9}Ba_{0.1})_{1/2}La_{1/2}](Mg_{1/2}Nb_{1/2})O_{3}$ having $\varepsilon_{r}=80$, $Q{\times}f=11,800$ (at 4 GHz) was developed.

• Journal of the Korean Magnetics Society
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• v.7 no.1
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• pp.25-30
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• 1997

Physical and magnetic behaviors of reduced Co-Zn-Ti-Sn substituted Ba-ferrite particles with hydrogen are different from those of reduced-pure Ba-ferrite particles. The coercivity of substituted Ba-feffite particles shows a peaking effect with the reduction temperature ranging from 250 to 520 $^{\circ}C$, while the coercivity of pure Ba-ferrite decreases monotonically. The reduction process of substituted Ba-ferrite has been found to be devided into three steps. At the first and second steps, the magneto-plumbite structure maintained. When the reduced-substituted Ba-ferrite particles are reoxidized, the coercivity is reversible at the first step but irreversible at the second step. During the third step of reduction process above 410 $^{\circ}C$. The magneto plumbite structure was collapsed with formation of $\alpha$-Fe and $BaFeO_{3-x}$ phases and consequently the coercivity distribution is broaden and the coercivity irreversible. The coercivity and saturation magnetization decreases and increases up to 130 emu/g respectively. In this study, it is found that the substituted elements prevent the magneto-plumbite structure from collapse during the reduction process and furthermore migrate from the magnetic sites of $2a+4f_{IV}$, 2b, and 12k to $4f_{VI}$ and 12k'. An increase in the coercivity before the collapse of magneto-plumbite structure is attributed to the migration of cations in hexagonal Ba-ferrite structure.