• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.245-245
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• 2007

본 연구는 $Bi_2O_3$, ZnO 및 $Nb_2O_5$로 이루어진 두 가지의 $Bi_2(Zn_{1/3}Nb_{2/3})_2O_7$와 $(Bi_{1.5}Zn_{0.5})(Zn_{0.5}Nb_{1.5})O_7$ pyrochlore를 제조한 후, ZBS 및 BZBS 유리를 각각 첨가하여 저온 소결 및 마이크로파 유전 특성을 고찰하였다. 두 가지의 pyrochlore에 대하여 하소 온도에 따른 상 합성 유무를 고찰한 결과 $900^{\circ}C$에서 단일 상을 갖는 pyrochlore를 제조할 수 있었다. 두 가지의 pyrochlore에 ZnO-rich ZBS 유리와 $Bi_2O_3$-rich BZBS 유리를 3, 5 wt%로 첨가한 후 $800{\sim}950^{\circ}C$에서 소결한 결과 ZBS 및 BZBS 유리를 5wt%를 첨가하였을 때 $900^{\circ}C$에서 소결이 가능하였다. 또한 마이크로파 유전 특성을 고찰한 결과, $(Bi_{1.5}Zn_{0.5})(Zn_{0.5}Nb_{1.5})O_7$의 pyrochlore는 고주파에서 유전 특성 측정이 되지 않았다. $Bi_2(Zn_{1/3}Nb_{2/3})_2O_7$의 pyrochlore의 경우 5 wt% ZBS 및 BZBS 유리를 첨가하여 $900^{\circ}C$에서 소결한 시편의 마이크로파 유전 특성은 ${\varepsilon}_r$= 62.8~68.3, $Q{\times}f$ value= 3,500~2,700 GHz을 나타내었다.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.79-85
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• 2023

A novel low-temperature co-fired ceramic (LTCC) dielectric, composed of (1-4x)Bi_1.5Zn_1.0Nb_1.5O₇-3xBi₂Zn_2/3Nb_4/3O₇-2xLiZnNbO₄ (x=0.03-0.21), was synthesized through reactive liquid phase sintering of Bi_1.5Zn_1.0Nb_1.5O₇-xLi₂CO₃ ceramic at temperatures ranging from 850℃ to 920℃ for 4 hours. During sintering, Li₂CO₃ reacted with Bi_1.5Zn_1.0Nb_1.5O₇, resulting in the formation of Bi₂Zn_2/3Nb_4/3O₇, and LiZnNbO₄. The resulting sintered body exhibited a relative sintering density exceeding 96% of the theoretical density. By altering the initial Li₂CO₃ content (x) and consequently modulating the volume fraction of Bi_1.5Zn_1.0Nb_1.5O₇, Bi₂Zn_2/3Nb_4/3O₇, and LiZnNbO₄ in the final sintered body, a sample with high dielectric constant (ε_r), low dielectric loss (tan δ), and the temperature coefficient of dielectric constant (TCε) characterized by NP0 specification (TCε ≤ ±30 ppm/℃) was achieved. As the Li₂CO₃ content increased from x=0.03 mol to x=0.15 mol, the volume fraction of Bi₂Zn_2/3Nb_4/3O₇ and LiZnNbO₄ in the composite increased, while the volume fraction of Bi_1.5Zn_1.0Nb_1.5O₇ decreased. Consequently, the dielectric constant (εr) of the composite materials varied from 148.38 to 126.99, the dielectric loss (tan δ) shifted from 5.29×10^-4 to 3.31×10^-4, and the temperature coefficient of dielectric constant (TCε) transitioned from -340.35 ppm/℃ to 299.67 ppm/℃. A dielectric exhibiting NP0 characteristics was achieved at x=0.09 for Li₂CO₃, with a dielectric constant (ε_r) of 143.06, a dielectric loss (tan δ) value of 4.31×10^-4, and a temperature coefficient of dielectric constant (TCε) value of -9.98 ppm/℃. Chemical compatibility experiment with Ag electrode revealed that the developed composite material exhibited no reactivity with the Ag electrode during the co-firing process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.96-96
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• 2007

Low voltage organic TFTs (OTFTs) and ZnO based TFTs (<5V), utilizing room temperature deposited $Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7$ (BZN) thin films were recently reported, pointing to high-k gate insulators as a promising route for realizing low voltage operating flexible electronics. $Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7$ (BZN) thin film is one of the most promising materials for gate insulator because of its large dielectric constant (~60) at room temperature. However their tendency to suffer from relatively high leakage current at low electric field (>0.3MV/cm) hinder the application of BZN thin films for gate insulator. In order to improve leakage current characteristics of BZN thin film, we mixed 30mol% MgO with 70mol% BZN and their dielectric and electric properties were characterized. We fabricated field-effect transistors with transparent oxide semiconductor ZnO serving as the electron channel and high-k $(Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7)_{0.7}(MgO)_{0.3}$ as the gate insulator. The devices exhibited low operation voltages (<4V) due to high capacitance of the $(Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7)_{0.7}(MgO)_{0.3}$ dielectric.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.284-284
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• 2007

In this study, the microwave dielectric property variations of (1-x)$BiNbO_4-(x)ZnNb_2O_6$ composites (x=0.3, 0.5 and 0.7) with 10wt% zinc borosilicate(ZBS) glass was investigated as a function of the substitution of $ZnNb_2O_6$ with a view to applying thes system to LTCC technology. The all composition addition of 10wt% ZBS glass ensured a successful sintering below $900^{\circ}C$. In addition, a small amount of $Bi_2SiO_5$ as the secondary phase was observed in the all composition. The substitution of $ZnNb_2O_6$ on the $BiNbO_4$ composites increased the $Q{\times}f$ values, but it decreased the sinterability and dielectric constant due to the high sintering temperature and low dielectric constant of $ZnNb_2O_6\;than\;BiNbO_4$ ceramics. The increasing of $ZnNb_2O_6$ content from 0.3 to 0.7 in the (1-x)$BiNbO_4-(x)ZnNb_2O_6$ composites with 10wt% ZBS glass sintered at $900^{\circ}C$ demonstrated 28.1~15.6 in the dielectric constant$({\varepsilon}_r)$, 5,500~8,700GHz in the $Q{\times}f$ value.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.260-260
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• 2007

Low-temperature sintering and dielectric properties of the $1-xBiNbO_4-xZnNb_2O_6$ ceramics (x=0.3, 0.5, and 0.7) with 10 wt% zinc borosilicate (ZBS) glass was investigated as a function of the substitution of $ZnNb_2O_6$ with a view to applying this system to LTCC technology. The all composition addition of 10 wt% ZBS glass ensured a successful sintering below $900^{\circ}C$. The the amount of $ZnNb_2O_6$ on $ZnNb_2O_6$ ceramics increased the $Q{\times}f$ values, but it decreased the sinterability and dielectric constant due to the higher $Q{\times}f$ value and sintering temperature of $ZnNb_2O_6$ than that of $ZnNb_2O_6$ ceramics. The increase of $ZnNb_2O_6$ content from 0.3 to 0.7 in the $1-xBiNbO_4-xZnNb_2O_6$ ceramics with 10 wt% ZBS glass sintered at $900^{\circ}C$ demonstrated 30~20 in the dielectric constant (${\varepsilon}_r$), 3,500~4,500 GHz in the $Q{\times}f$ value.

• Transactions on Electrical and Electronic Materials
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• v.8 no.2
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• pp.84-88
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• 2007

[ $Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7$ ] (BZN), $Bi_2Mg_{2/3}Nb_{4/3}O_7$ (BMN), and $Bi_2Cu_{2/3}Nb_{4/3}O_7$ (BCN) pyrochlore thin films were prepared on $Cu/Ti/SiO_2/Si$ substrates by pulsed laser deposition and the micro-structural and electrical properties were characterized for embedded capacitor applications. The BZN, BMN, and BCN films deposited at $25\;^{\circ}C$ and $150\;^{\circ}C$, respectively show smooth surface morphologies and dielectric constants of about $39\;{\sim}\;58$. The high dielectric loss of the films deposited at $150\;^{\circ}C$ compared with films deposited at $25\;^{\circ}C$ was attributed to the defects existing at interface between the films and copper electrode by an oxidation of copper bottom electrode. The leakage current densities and breakdown voltages in 200 nm thick-BMN and BZN films deposited at $150\;^{\circ}C$ are approximately $2.5\;{\times}\;10^{-8}\;A/cm^2$ at 3 V and above 10 V, respectively. Both BZN and BMN films are considered to be suitable materials for embedded capacitor applications.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.177-193
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• 2009

The Samgwang deposit consists of eight massive mesothermal quartz veins that filled NE and NW-striking fractures along fault zones in Precambrian granitic gneiss of the Gyeonggi massif. The mineralogy and paragenesis of the veins allow two separate discrete mineralization episodes(stage I=quartz and calcite stage, stage II-calcite stage) to be recognized, temporally separated by a major faulting event. The ore minerals are contained within quartz and calcite associated with fracturing and healing of veins that occurred during both mineralization episodes. The hydrothermal alteration of stage I is sericitization, chloritization, carbonitization, pyritization, silicification and argillization. Sericitic zone occurs near and at quartz vein and include mainly sericite, quartz, and minor illite, carbonates and chlorite. Chloritic zone occurs far from quartz vein and is composed of mainly chlorite, quartz and minor sericite, carbonates and epidote. Fe/(Fe+Mg) ratios of sericite and chlorite range 0.45 to 0.50(0.48$\pm$0.02) and 0.74 to 0.81(0.77$\pm$0.03), and belong to muscovite-petzite series and brunsvigite, respectiveIy. Calculated $Al_{IV}$-FE/(FE+Mg) diagrams of sericite and chlorite suggest that this can be a reliable indicator of alteration temperature in Au-Ag deposits. Calculated activities of chlorite end member are $a3(Fe_5Al_2Si_3O_{10}(OH)_6$=0.0275${\sim}$0.0413, $a2(Mg_5Al_2Si_3O_{10}(OH)_6$=1.18E-10${\sim}$7.79E-7, $a1(Mg_6Si_4O_{10}(OH)_6$=4.92E-10${\sim}$9.29E-7. It suggest that chlorite from the Samgwang deposit is iron-rich chlorite formed due to decreasing temperature from high temperature(T>450$^{\circ}C$). Calculated ${\alpha}Na^+$, ${\alpha}K^+$, ${\alpha}Ca^{2+}$, ${\alpha}Mg^{2+}$ and pH values during wallrock alteration are 0.0476($400^{\circ}C$), 0.0863($350^{\circ}C$), 0.0154($400^{\circ}C$), 0.0231($350^{\circ}C$), 2.42E-11($400^{\circ}C$), 7.07E-10($350^{\circ}C$), 1.59E-12($400^{\circ}C$), 1.77E-11($350^{\circ}C$), 5.4${\sim}$6.4($400^{\circ}C$), 5.3${\sim}$5.7($350^{\circ}C$)respectively. Gain elements(enrichment elements) during wallrock alteration are $TiO_2$, $Fe_2O_3(T)$,CaO, MnO, MgO, As, Ag, Cu, Zn, Ni, Co, W, V, Br, Cs, Rb, Sc, Bi, Nb, Sb, Se, Sn and Lu. Elements(Ag, As, Zn, Sc, Sb, Rb, S, $CO_2$) represents a potential tools for exploration in mesothermal and epithermal gold-silver deposits.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.502-508
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• 2020

This paper focuses on the electrical properties and stability against DC accelerated aging stress of ZnO-V₂O₅-MnO₂-Nb₂O₅-Bi₂O₃-Co₃O₄-Dy₂O₃ (ZVMNBCD) varistor ceramics sintered at 850 - 925 ℃. With the increase of sintering temperature, the average grain size increases from 4.4 to 11.8 mm, and the density of the sintered pellets decreases from 5.53 to 5.40 g/㎤ due to the volatility of V₂O₅, which has a low melting point. The breakdown field abruptly decreases from 8016 to 1,715 V/cm with the increase of the sintering temperature. The maximum non-ohmic coefficient (59) is obtained when the sample is sintered at 875 ℃. The samples sintered at below 900 ℃ exhibit a relatively low leakage current, less than 60 mA/㎠. The apparent dielectric constant increases due to the increase of the average grain size with the increase of the sintering temperature. The change tendency of dissipation factor at 1 kHz according to the sintering temperature coincides with the tendency of the leakage current. In terms of stability, the samples sintered at 900 ℃ exhibit both high non-ohmic coefficient (45) and excellent stability, 0.8% in 𝚫E_B/E_B and -0.7 % in 𝚫α/α after application of DC accelerated aging stress (0.85 E_B/85 ℃/24 h).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.230-231
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• 2009

펄스 레이저 층착법 (이하 PLD)은 다성분계 산화물 박막 또는 다층구조의 박막 제작에 매우 유용한 기술이다. 본 실험에서는 KrF 엑시머 레이저를 이용하여 pt on Si 기판 위에 150nm 두께의 $Bi_{1.5}ZnNb_{1.5}O_7$(이하 BZN) 박막을 다양한 기판온도에서 제작하였다. XRD를 이용하여 BZN 박막의 구조적 특성을 분석하였고, 박막을 MIM 구조로 제작하여 유정적 특성을 측정하였다. 제조한 BZN 박막은 $500^{\circ}C$ 이상에서 결정질을, $500^{\circ}C$ 이하의 온도에서는 비정질 특성을 보였다. 유전 특성은 100 - 400$^{\circ}C$ 영역에서는 온도가 증가함에 따라 졸은 특성을 나타내었고, $500^{\circ}C$에서부터는 감소하였다. 증착 온도 $400^{\circ}C$에서 제작한 BZN 박막이 유전상수가 67.8, 유전 손실이 0.006으로 가장 줄은 유전특성을 나타내었다.

• Korean Journal of Materials Research
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• v.29 no.3
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• pp.175-182
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• 2019

This study examines paraelectric $Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7$ (BZN), which has no hysteresis and high dielectric strength, for energy density capacitor applications. To increase the breakdown dielectric strength of the BZN film further, poly(vinylidene fluoride) BZN-PVDF composite film is fabricated by aerosol deposition. The volume ratio of each composition is calculated using dielectric constant of each composition, and we find that it was 12:88 vol% (BZN:PVDF). To modulate the structure and dielectric properties of the ferroelectric polymer PVDF, the composite film is heat-treated at $200^{\circ}C$ for 5 and 30 minutes following quenching. The amount of ${\alpha}-phase$ in the PVDF increases with an increasing annealing time, which in turn decreases the dielectric constant and dielectric loss. The breakdown dielectric strength of the BZN film increases by mixing PVDF. However, the breakdown field decreases with an increasing annealing time. The BZN-PVDF composite film has the energy density of $4.9J/cm^3$, which is larger than that of the pure BZN film of $3.6J/cm^3$.