• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.6
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• pp.485-492
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• 2000

The sintering characteristics and the effects of density on dielectric properties in 0.2Ba(Mg$_{1}$3(Nb$_{2}$3/)O$_3$-0.8Ba(Mg$_{1}$3//Ta$_{2}$3/)O$_3$ceramics were investigated. The samples were made by the powder mixing techniques with the two step calcining conditions. When the 1st and the 2nd calcining temperatures were 120$0^{\circ}C$ and the sintering temperature was 155$0^{\circ}C$the density of samples showed the highest value (7.45 g/cm$^3$, 98.5% of theoretical density) among them. The dielectric constant of samples was nearly independent of density but the tan $\delta$ and the temperature coefficient of dielectric constant decreased linearly with increasing of the density. The quality factor(Q$\times$f), the temperature coefficient of resonance frequency and the dielectric constant of Ba[Mg$_{1}$3(Nb$_{0.2}$/Ta$_{0.8}$)sub 2/3/]O$_3$ceramic were 79,548 GHz, +1.5 ppm/$^{\circ}C$ and 26 in the microwave range, respectively.ely.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.252-255
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• 1999

The effect of calcination temperature(1st and 2nd calcining at 110$0^{\circ}C$ , 120$0^{\circ}C$ and 130$0^{\circ}C$ respectively) on physical properties of BMNT Ceramics ware investigated. The optimum 1st and 2nd calcination temperature were 120$0^{\circ}C$ , and sintering temperature was 155$0^{\circ}C$. In this condition, the sintering density was 7.53 [g/㎤] and the dielectric constant, Q.f$_{0}$ and $\tau$$_{r}$ were 26, 80, 300[GHz] and +1.5[ppm/$^{\circ}C$] respectively in the microwave range.e.e.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1664-1666
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• 2000

The structural and microwave properties of Ba($Mg_{1/3}Ta_{2/3})O_3$-Ba($Co_{1/3}Nb_{2/3})O_3$ ceramics were investigated with composition ratio. The specimens were sintered at 1525$^{\circ}C$ for 5 hours in air. All specimens exhibited superlattice reflection planes of (100), (111), (200), (201), and (112). Increasing mole ratio of BCN ceramics, the peak intensity of superstructure reflection plane were decreased, while dielectric constant was slightly increased. The dielectric constant and quality factor of the 0.8BMT-0.2BCN ceramics were 27.51, 103,681 [at 1GHz], respectively.

• The Journal of the Petrological Society of Korea
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• v.6 no.1
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• pp.19-33
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• 1997

This study reports the results about the petrography and geochemical characteristics of 10 representative volacanic rocks. The Cretaceous volcanic rocks distributed in the vicinity of the Kageo island composed of andesitic rocks, dacitic welded tuff, and rhyolitic rocks in ascending order. Sedimentary rock is the basement in the study area covered with volcanic rocks. Andesitic rocks composed of pyroclastic volcanic breccia, lithic lapilli tuff and cryptocrystallin lava-flow. Most dacitic rocks are lapilli ash-flow welded tuff. Rhyolitic rocks consists of rhyolite tuff and rhyolite lava flow. Rhyolite tuff are lithic crystal ash-flow tuff and crystal vitric ash-flow tuff with somewhat accidental fragments of andesitic rocks, but dacitic rocks. The variation of major and trace element of the volcanic rocks show that contents of $Al_2O_3$, FeO, CaO, MgO, $TiO_2$ decrease with increasing of $SiO_2$. On the basis of Variation diagrams such as $Al_2O_3$ vs. CaO, Th/Yb vs. Ta/Yb, and $Ce_N/YB_N$ vs. $Ce_N$, these rocks represent mainly differentiation trend of calc-alkaline rock series. On the discriminant diagrams such as Ba/La and La/Th ratio, Rb vs. Y + Nb, the volcanic rocks in study area belongs to high-K Orogenic suites, with abundances of trace element and ternary diagram of K, Na, Ca. According to the tectonic discriminant diagram by Wood, these rocks falls into the diestructructive continental margin. K-Ar ages of whole rocks are from andesite to rhyolite $97.0{\pm}6.8~94.5{\pm}6.6,\68.9{\pm}4.8,\61.5{\pm}4.9~60.7{\pm}4.2$ Ma, repectively. Volcanic rocks in study area show well correlation to the Yucheon Group in terms of rock age dating and geochemcial data, and derived from andesitic calc-alkaline magma that undergone low pressure fractional crystallization dominated plagioclase at <30km.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.4
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• pp.307-324
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• 2020

Major and trace elements, and Sr, Nd, isotopic composition analysis have been carried out on the Miocene basalt (Huangsongpu basalt, 20 Ma) 25 km to northeast from the Mt. Baekdu. The basalt has Na2O+K2O=3.5~4.7 wt.%, and MgO=9.9~11.1 wt.%, containing Mg-rich olivine (Mg#=75~86), clinopyroxene (Mg#=72~85) and Ca-rich plagioclase micro-phenocrysts. These data suggest that the basalt belongs to the alkaline magma series with a primitive nature, crystallized at a near-liquidus. The basalt is also characterized by high Cr (394~479 ppm) and Ni (389~519 ppm) contents, Nb-Ta enrichment anomalies and OIB-like trace elements patterns, displaying identical signatures to those of typical intraplate magmas. The rare earth element (REE) patterns of the basalt and high (Gd/Yb)sample/(Gd/Yb)PM ratio (=2.8~3.5) suggest the parental magma was derived from relatively low-degree (3~5%) partial melting of garnet peridotite. The 143Nd/144Nd and 87Sr/86Sr composition of the basalt are higher than those of BSE. The high 87Sr/86Sr (= ~0.7058) ratio of the basalt indicates a contribution of recycled ancient oceanic crust or continental crust on the Pacific slab suggesting that the Huangsongpu basalt was generated from metasomatized mantle.