• 한국세라믹학회지
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• 제18권2호
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• pp.83-90
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• 1981

In this study, the effect of additions on magnetic properties in the system of [$Ni_{0.32}Zn_{0.68}$] 1-x Mx $Fe_2O_4$ have been investigated. The additions, Co or Mg or Cu, was added in turn in place of M, and its composition was varied from 0.1 mo1% to 0.5 mo1%. The materials were blended by hot petroleum drying method, and sintered with the rate of 30$0^{\circ}C$/h in the air. The sintering temperatures were varied from 110$0^{\circ}C$ to 130$0^{\circ}C$, with the intervals of 5$0^{\circ}C$, and matured for 3hrs. The results are: 1) The permeability decreased when the addition, MgO or CoO, was added, and it increased when CuO was added. 2) Resistivity had the lowest Value when CuO was added.

• 분석과학
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• 제10권6호
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• pp.439-444
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• 1997

압전 세라믹스 [$Pb(ZrTi)O_3$] 소재에 대하여 신속하고 정확하게 분석할 수 있는 X-선 형광분석용 표준물질 12종을 제작하였다. 특히 매질효과의 제거, 보관성, 균질성 등을 고려하여 융제($Li_2B_4O_7/LiBO_2=4/1$)로 시료를 16배 희석하여 제작하였다. 네 곳의 분석기관에서 X-선 형광분광기로 12개의 표준물질에 포함된 11 원소에 대하여 검정곡선을 작성해 본 결과 PbO, $ZrO_2$, $TiO_2$, SrO, $WO_3$, $La_2O_3$, $Cr_2O_3$, MgO, $Nb_2O_5$, $MnO_2$들은 correlation factor가 0.998을 넘는 대단히 좋은 직선을 얻었다. 그러나 ZnO의 correlation factor는 0.977로 비교적 낮았으며, 이는 표준시료 중 ZnO의 함량이 10ppm 정도로 낮았기 때문이다. 본 연구에서 제작한 XRF 분석용 표준물질을 이용하면 PZT 중의 주 부성분 원소의 함량을 간편하고 신속 정확하게 분석결과를 얻을 수 있다.

• 한국전기전자재료학회논문지
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• 제16권7호
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• pp.604-610
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• 2003

The effects of sintering additives such as B $i_2$ $O_3$ and $V_2$ $O_{5}$ on the microwave dielectric and sintering properties of (Z $n_1$$_{-xM}$ $g_{x}$)Ti $O_3$ system were investigated. Highly dense samples were obtained for (Z $n_{0.8}$M $g_{0.2}$)Ti $O_3$ at the sintering temperature range of 870~90$0^{\circ}C$ with B $i_2$ $O_3$ and $V_2$ $O_{5}$ additions of 〈1 wt.%, respectively. The microwave dielectric properties of (Z $n_{0.8}$M $g_{0.2}$)Ti $O_3$ with 0.45 wt.%B $i_2$ $O_3$ and 0.55 wt.% $V_2$ $O_{5}$ sintered at 90$0^{\circ}C$ were as follows : Q$\times$ $f_{o}$ = 50,800 GHz, $\varepsilon$$_{r}$ = 22, and $\tau$$_{f}$ = -53 ppm/$^{\circ}C$. In order to improve temperature coefficient of resonant frequency, Ti $O_2$ was added to the above system. The optimum amount of Ti $O_2$ was 15 moi.% when sintered at 87$0^{\circ}C$, at which we could obtain following results: Q$\times$ $f_{o}$ = 32,800 GHz, $\varepsilon$$_{r}$ = 26, and$\tau$$_{f}$ = 0 ppm/$^{\circ}C$.EX>.EX>.EX>.EX>.EX>.EX>.EX>.

• Journal of Electrochemical Science and Technology
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• 제12권1호
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• pp.112-125
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• 2021

The new emerging "High entropy materials" attract the attention of the scientific society because of their simpler structure and spectacular applications in many fields. A novel nanocrystalline high entropy (Be,Mg,Ca,Sr,Zn,Ni)3O4 oxide has been successfully synthesized through mechanochemical treatment followed by sintering and air quenching. The present research work focuses on the possibility of single-phase formation in the aforementioned high entropy oxide despite the great difference in the atomic sizes of reactant alkaline earth and 3d transition metal oxides. Structural properties of (Be,Mg,Ca,Sr,Zn,Ni)3O4 high entropy oxide were explored by confirmation of its single-phase Fd-3m spinel structure by x-ray diffraction (XRD). Further, nanocrystalline nature and morphology were analyzed by scanning electron microscopy (SEM). Among thermal properties, thermogravimetric analysis (TGA) revealed that the (Be,Mg,Ca,Sr,Zn,Ni)3O4 high entropy oxide is thermally stable up to a temperature of 1200℃. Whereas phase evolution in (Be,Mg,Ca,Sr,Zn,Ni)3O4 high entropy oxide before and after sintering was analyzed through differential scanning calorimetry (DSC). Electrochemical studies of (Be,Mg,Ca,Sr,Zn,Ni)3O4 high entropy oxide consists of a comparison of thermodynamic and kinetic parameters of water and hydrazine hydrate oxidation. Values of activation energy for water oxidation (9.31 kJ mol-1) and hydrazine hydrate oxidation (13.93 kJ mol-1) reveal that (Be,Mg,Ca,Sr,Zn,Ni)3O4 high entropy oxide is catalytically more active towards water oxidation as compared to that of hydrazine hydrate oxidation. Electrochemical impedance spectroscopy is also performed to get insight into the kinetics of both types of reactions.

• 한국재료학회지
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• 제23권3호
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• pp.155-160
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• 2013

ZnO thin films co-doped with Mg and Ga (MxGyZzO, x + y + z = 1, x = 0.05, y = 0.02 and z = 0.93) were prepared on glass substrates by RF magnetron sputtering with different sputtering powers ranging from 100W to 200W at a substrate temperature of $350^{\circ}C$. The effects of the sputtering power on the structural, morphological, electrical, and optical properties of MGZO thin films were investigated. The X-ray diffraction patterns showed that all the MGZO thin films were grown as a hexagonal wurtzite phase with the preferred orientation on the c-axis without secondary phases such as MgO, $Ga_2O_3$, or $ZnGa_2O_4$. The intensity of the diffraction peak from the (0002) plane of the MGZO thin films was enhanced as the sputtering power increased. The (0002) peak positions of the MGZO thin films was shifted toward, a high diffraction angle as the sputtering power increased. Cross-sectional field emission scanning electron microscopy images of the MGZO thin films showed that all of these films had a columnar structure and their thickness increased with an increase in the sputtering power. MGZO thin film deposited at the sputtering power of 200W showed the best electrical characteristics in terms of the carrier concentration ($4.71{\times}10^{20}cm^{-3}$), charge carrier mobility ($10.2cm^2V^{-1}s^{-1}$) and a minimum resistivity ($1.3{\times}10^{-3}{\Omega}cm$). A UV-visible spectroscopy assessment showed that the MGZO thin films had high transmittance of more than 80 % in the visible region and that the absorption edges of MGZO thin films were very sharp and shifted toward the higher wavelength side, from 270 nm to 340 nm, with an increase in the sputtering power. The band-gap energy of MGZO thin films was widened from 3.74 eV to 3.92 eV with the change in the sputtering power.

• Asian-Australasian Journal of Animal Sciences
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• 제17권12호
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• pp.1635-1640
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• 2004

Two experiments were conducted to evaluate developmental gene expression of antimicrobial peptide PR-39 and effect of zinc oxide on gene regulation of PR-39 in piglets using semi-quantitative RT-PCR analysis. In experiment 1, fifteen female Tai-Hu pigs (a local breed in China) in five groups, each of three pigs at 1, 14, 28, 42 and 56 days of age were used to determine effect of age and weaning on mRNA expression of PR-39. In experiment 2, nine groups of pigs (total seventy-two female 36 days-age weanling Tai-Hu piglets) were assigned to three treatments (${ZnO}_0$, ${ZnO}_{100}$ and ${ZnO}_{3000}$). The feeding experimental period lasted 15 days. After feeding experiment, nine pigs with three animals in each treatment were chosen to determine the effect of ZnO on PR-39 mRNA expression of pigs. The results showed that PR-39 mRNA levels increased steadily in postnatal day 1-28 (preweaning), and weaning significantly decreased PR-39 mRNA expression of piglets (p<0.05). ${ZnO}_{3000}$ (3,000 mg zinc/kg diet) significantly increased PR-39 mRNA expression (p<0.05) when piglets were feed ${ZnO}_{3000}$ diet for 15 days. ${ZnO}_{100}$ (100 mg zinc/kg diet) also increased PR-39 gene expression, but the result was not statistically significant (p>0.05). The result was in accordance with the effect of ${ZnO}_{3000}$ and ${ZnO}_{100}$ on weight gain of piglets and prevention of diarrhea.

• Advances in nano research
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• 제12권5호
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• pp.457-465
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• 2022

The potentials of Ni_xZn_1-xFe₂O₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) nanoadsorbents were investigated for removal of Cd and Cr from contaminated water from an electroplating industry in Himachal Pradesh, India. Optimal values were recorded under batch adsorption experiments performed to remove dissolved heavy metal ions from industrial wastewater. The specific surface area (SSA) of nanoadsorbents perceived to vary in a range 35.75-45.29 cm²/g and was calculated from the XRD data. The influence of two operating parameters, contact time and dopant (Ni) concentration was also investigated at pH ~7 with optimum dosage. Kinetic studies were conducted within a time range of 2-10 min with rapid adsorption of cadmium and chromium ions onto Ni_0.2Zn_0.8Fe₂O₄ nanoadsorbents. Pseudo-second-order kinetic model was observed to be well fitted with the adsorption data that confirmed the only existence of chemisorption throughout the adsorption process. The maximum adsorption efficiency values observed for Cd and Cr were 51.4 mg/g and 40.12 mg/g, respectively for different compositions of prepared series of nanoadsorbents. The removal percentage of Cd and Cr was found to vary in a range of 47.7%-95.25% and 21%-50% respectively. The prepared series of nanoferrite found to be suitable enough for adsorption of both heavy metal ions.

• E2M - 전기 전자와 첨단 소재
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• 제3권4호
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• pp.339-346
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• 1990

미소변위소자에 적합한 전왜세라믹스를 제조하기 위하여 0.85Pb(Zn$_{1}$3-x/MgxNb$_{2}$3/) $O_{3}$-0.10BaTi $O_{3}$-0.05PbTi $O_{3}$조성으로 Mg(mol%)를 변화시키면서 시편을 제조하고 구조적, 유전적, 전기적 특성 및 온도 안정성을 관찰하였다. 큐리온도는 Mg(mol%)가 증가함에 따라 감소하였고 Mg(mol%)가 0.15일 때 유전상수가 가장 높았으며 완만도는 -3.9, 산만도.DELTA.Tc는 21로 가장 컸다. 전계에 따른 유전상수는 감소하였고 Mg(mol%)가 증가할수록 압전정수 d$_{31}$은 감소하였으나 0.05, 0.10, 0.15일 때는 거의 일정하였다. Mg(mol%)가 0.15까지 증가함에 따라 전왜정수 Q$_{31}$은 감소하였고 그 이상에서는 Mg(mol%)가 1/3일때 가장 컸으며 ES-1시편에서의 AC 60(Hz), 11(kV/cm) 전계(electric field)에 의한 왜형을 253*$10^{-6}$을 나타냈다.

• 한국세라믹학회지
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• 제12권1호
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• pp.29-36
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• 1975

This study was conducted to research the formation, color development and application for colored glazes of the spinel solid solutions of the green pigment. On specimens prepared by calcining the oxide and basic carbonate mixture at 1250℃ for 1.5 hour, the x-ray analysis, measurement of reflectance and the test of their stabiality as a glaze pigment were carried out. The results are summarized as follows 1) Each sample is composed of single spinel and not of mixture of spinel. 2) Formation of continuous soild solution, except for a few instances, pertaining to Vegard's law was confirmed by means of the x-ray analysis. 3) The more difference between absorption and reflectance lies, the lighter colors are. When the absorption occurs at the high-reflectance, the excitation purity becomes low. On the contrary when the absorption takes place at the low-reflectance, the excitation purity becomes low. On the contrary when the absorption takes place at the low-reflectance, the excitation purity is higher. 4) Colors obtained in the CdO-MgO-Cr2O3-Al2O3 system, as the amounts of Al3+ increased, change from green through brown to pink, and the absorption peak shifts towards violet region. 5) An increase in Co2+ in the CoO-MgO-Cr2O3-Al2O3 system, changes the color from blue green to dark blue. The excitation purity is higher, and the absorption peak shifts toward regions. 6) Colors are green in the NiO-MgO-Cr2O3 and CdO-MgO-Cr2O3 systems in general, but in the ZnO-MgO-Cr2O3 system brillant hue is not obtained. 70 According to the results of the colored glaze test, the spinels turn outto be stable as brilliant glaze pigment in the calcium-magnesia glaze.

• 한국해양학회지
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• 제10권1호
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• pp.33-40
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• 1975

본 연구의 결과를 간단히 요약하면 다음과 같다. 가. KCl수용액에서의 Dowex 1-X8, Cl$^{-}$(200-400메쉬)에 의한 Hg(II), Cd(II) 및 Zn(II)의 흡착메카니즘은 고농도의 KCl수용액에서는 모두 음이온의 MCl$_{4}$ $^{2-}$ 착이온 형성에 의한 흡착이며, 저농도에서는 착이온 안정도상수가 큰 Hg(II) 는 역시 착이온 형성에 의한 흡착인데 비해 Cd(II)와 Zn(II)의 경우는 농도에 따라 다르다. 한편 D값의 크기순위는 HCl메디움에서의 MCl$_{4}$$^{2-}$ 착이온의 안정도 상수의 크기순위와 일치한다. 나. KCl-Methonol메디움에서의 Dowex 1-X8, Cl$^{-}$수지에 대한 금속이온의 흡착은 메탄올의 농도증가에 따라 증가되는데, 이것은 메탄올 첨가로 인해 수화현상이 약화되어 착이온 형성이 용이해지기 때문이며 착이온을 잘 형성하는 Hg(II)의 경우는 그 증가율이 크지 않았다. 다. 양이온교환 수지 Dowex50W-X$_{8}$ , $K^{+}$column내에서 KCl-H$_{2}$O 및 KCl-MeOH 용리액에 의한 Zn(II), Cd(II) 및 Hg(II)의 융리메카니즘은 역시 금속이온의 MCl$_{4}$$^{2-}$ 착이온 형성 및 이온쌍 형성의 차이로 용리되는데 그 부피분배 계수의 크기는 Zn(II)>Cd(II)>Hg(II)이며, MeOH의 농도가 증가하면 더욱 빨리 용리되는데 이는 역시 MeOH첨가에 인한 착이온 및 이온쌍 형성이 증대되기 때문이다. 라. MCl(M:K$^{+}$, $Na^{+}$, NH$_{4}$$^{+}$ 및 H$^{+}$) 수용액 메디움에서의 Cd(II), Mg(II) 및 Zn(II)의 Dowex 1-X8, Cl$^{-}$ 수지에 대한 흡착은 역시 어떤 메디움에서도 Cd(II) 흡착이 제일 크며, 다음이 Zn(II) 이고 착이온을 형성않는 Mg(II)이 제일 작았다. 한편 메디움 종류별 D값의 크기순위는 H$^{+}$>K$^{+}$> $Na^{+}$>NH$_{4}$$^{+}$이였다. 메디움의 종류에 따라 D값의 차이가 나는 것은 금속이온의 착이온 형성과 금속이온의 용액내에서의 이온종의 상태와 관련이 있다고 생각된다. 마. MCl(M:K$^{+}$, $Na^{+}$, NH$_{4}$$^{+}$ 및 H$^{+}$)과 MNO$_{3}$ 용리액에 의한 Cd(II), Mg(II) 및 Zn(II)의 용리는 예상한 바와 같이 MCl에서 작은 Dv 값을 갖는데, 이것은 CdCl$_{4}$$^{2-}$ 착이온을 형성하거나 ZnCl$_{4}$$^{2-}$ , ZnCl$_{3}$$^{-}$같은 이온과 MgCl$^{+}$, MgCl$_{2}$같은 이온종을 형성하기 때문인것 같다. 한편 어떠한 용리액에서던지 NH$_{4}$$^{+}$의 경우 Dv값이 제일 작았다. 바. 본 연구의 목적중의 하나인 인체유해 중금속이온인 Hg(II), Cd(II)등이 NaCl같은 염화물이 함유된 시료용액에 공해이온으로 존재할 경우 흡착에 의한 제거가 가능하다. 한편 이같은 중금속이온의 흡착실험은 특히 해수중의 금속이온의 회수연구에도 그 활용이 가능하리라고 믿는다.