Li2CO3 첨가에 따른 입방정 Bi1.5Zn1.0Nb1.5O7(c-BZN)의 상 변화 및 그에 따른 유전특성 변화 연구

이유선,김윤석,최슬원,한성민,이경호 한국마이크로전자및패키징학회 2023 마이크로전자 및 패키징학회지 Vol.30 No.4

(1-4x)Bi1.5Zn1.0Nb1.5O7-3xBi2Zn2/3Nb4/3O7-2xLiZnNbO4(x=0.03-0.21) 조성의 새로운 저온 동시 소성 세라믹(LTCC) 유전체는 Bi1.5Zn1.0Nb1.5O7-xLi2CO3(x=0.03-0.21) 혼합물을 850oC~920oC에서 4 시간 반응성 액상소결(reactive liquid phase sintering)을 하여 제조하였다. 소결이 진행되는 동안 Li2CO3는 Bi1.5Zn1.0Nb1.5O7과 반응하여 Bi2Zn2/3Nb4/3O7 과 LiZnNbO4를 생성하였고 얻어진 소결체의 상대 소결밀도는 이론 밀도의 96% 이상이었다. 초기 Li2CO3 함량(x)을 조절하여 최종 소결체내에 존재하는 Bi1.5Zn1.0Nb1.5O7, Bi2Zn2/3Nb4/3O7 및 LiZnNbO4 상의 상대적인 함량을 제어함으로써높은 유전율(r), 낮은 유전손실(tan ) 및 NP0 특성(TC ≤ ±30 ppm/oC)의 유전율 온도계수(TC)를 갖는 유전체를 개발할 수 있었다. Li2CO3의 첨가가 x=0.03 mol에서 x=0.15 mol로 증가함에 따라 얻어진 복합체 내의 Bi2Zn2/3Nb4/3O7와LiZnNbO4의 부피 분율은 증가하였고, Bi1.5Zn1.0Nb1.5O7의 부피 분율은 감소하였다. 그 결과 복합체의 유전율(r)은 148.38 에서 126.99로 유전손실(tan )은 5.29×10-4에서 3.31×10-4로 그리고 유전율 온도계수(TC)는 -340.35 ppm/oC에서 299.67 ppm/oC로 변화되었다. NP0 특성을 갖는 유전체는 Li2CO3의 함량이 x=0.09일 때 얻을 수 있었고, 이 때의 유전율(εr)은143.06, 유전손실(tan )값은 4.31×10-4, 그리고 유전율 온도계수(TC)값은 -9.98 ppm/oC 이었다. Ag전극과의 화학적 호환성 실험은 개발된 복합 재료는 Ag 전극과 동시 소성 과정에서 전극과 반응이 없음을 보여주었다. A novel low-temperature co-fired ceramic (LTCC) dielectric, composed of (1-4x)Bi1.5Zn1.0Nb1.5O7-3xBi2Zn2/3Nb4/3O7- 2xLiZnNbO4 (x=0.03-0.21), was synthesized through reactive liquid phase sintering of Bi1.5Zn1.0Nb1.5O7-xLi2CO3 ceramic at temperatures ranging from 850°C to 920°C for 4 hours. During sintering, Li2CO3 reacted with Bi1.5Zn1.0Nb1.5O7, resulting in the formation of Bi2Zn2/3Nb4/3O7, 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 Bi1.5Zn1.0Nb1.5O7, Bi2Zn2/3Nb4/3O7, and LiZnNbO4 in the final sintered body, a sample with high dielectric constant (εr), low dielectric loss (tan δ), and the temperature coefficient of dielectric constant (TCε) characterized by NP0 specification (TCε ≤ ±30 ppm/°C) was achieved. As the Li2CO3 content increased from x=0.03 mol to x=0.15 mol, the volume fraction of Bi2Zn2/3Nb4/3O7 and LiZnNbO4 in the composite increased, while the volume fraction of Bi1.5Zn1.0Nb1.5O7 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/°C to 299.67 ppm/°C. A dielectric exhibiting NP0 characteristics was achieved at x=0.09 for Li2CO3, with a dielectric constant (εr) of 143.06, a dielectric loss (tan δ) value of 4.31x10-4, and a temperature coefficient of dielectric constant (TCε) value of -9.98 ppm/°C. Chemical compatibility experiment with Ag electrode revealed that the developed composite material exhibited no reactivity with the Ag electrode during the co-firing process.

산소분리를 위한 Ba0.5Sr0.5Co0.8Fe0.2O3-δ 관형 분리막 제조 및 투과 특성

김종표 ( Jong Pyo Kim ),손수환 ( Sou Hwan Son ),박정훈 ( Jung Hoon Park ),이용택 ( Yong Taek Lee ) 한국화학공학회 2011 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.49 No.6

Ba0.5Sr0.5Co0.8Fe0.2O3-δ 조성의 관형 분리막을 압출 성형 방법으로 제조하였다. 압출성형 직후 분리막의 TGA 분석결과 3단계의 무게감소로 첨가제와 탄산염이 분해되었고, 건조 수축율은 68 h 경과 후 변화가 없었으며 외경이 큰 분리막에서 높게 나타났다. 소결 후 분리막의 XRD 및 SEM 분석결과, 분리막은 단일상의 페롭스카이트 구조를 갖는 치밀한 막을 보였고, EDS 분석을 통해 Ba0.5Sr0.5Co0.8Fe0.2O3-δ와 유사한 성분함량을 가짐을 확인하였다. 두께 0.95mm Ba0.5Sr0.5Co0.8Fe0.2O3-δ 관형 분리막의 압환강도(radial crushing strength)는 5.7 kgf/mm2이였으며, 950 ℃에서 산소투과량은 146.85 mL/min(Jo2=2.33 mL/min·cm2)를 나타냈었다. 투과 측의 진공펌프 사용이 쓸개 가스를 활용한 것보다 산소 투과량 증진에 효과가 있음을 알 수 있었다. Tubular Ba0.5Sr0.5Co0.8Fe0.2O3-δ membranes were prepared by extrusion. TGA results of green body membrane after extrusion showed three successive weight losses due to decomposition of organic additives and carbonate. Drying shrinkage rate of tubular Ba0.5Sr0.5Co0.8Fe0.2O3-δ membranes was no change after 68 h and higher in the membrane with large outer diameter. XRD and SEM results showed the sintered membranes were the single phase structure and dense. The stoichiometric molar ratio agreed well with composition ratio calculated by EDS results for Ba0.5Sr0.5Co0.8Fe0.2O3-δ membrane. Radial crushing strength of tubular Ba0.5Sr0.5Co0.8Fe0.2O3-δ membrane with 0.95 mm thickness was 5.7 kgf /mm2 and the oxygen permeation rate of same membrane was 146.85 mL/min (Jo2=2.33 mL/min·cm2) at 950 ℃. Therefore, it was known that use of vacuum pump was more effective than that of sweep gas to obtain higher oxygen permeation flux.

Microwave dielectric properties of (1 - x)(Mg0.95Co0.05)TiO3–x(Na0.5La0.5)TiO3 ceramic system

Cheng-Liang Huang,Jhih-Yong Chen,Yen-Hsing Wang,Bing-Jing Li 한국물리학회 2009 Current Applied Physics Vol.9 No.6

The microstructures and the microwave dielectric properties of the (1 - x)(Mg0.95Co0.05)TiO3– x(Na0.5La0.5)TiO3 ceramic system were investigated. Two-phase system was confirmed by the XRD patterns and the EDX analysis. A co-existed second phase (Mg0.95Co0.05)Ti2O5 was also detected. The microwave dielectric properties are strongly related to the density and the matrix of the specimen. A new microwave dielectric material 0.88(Mg0.95Co0.05)TiO3–0.12(Na0.5La0.5)TiO3, possessing an excellent combination of dielectric properties: εr ~22.36, Q × f ~ 110,000 GHz (at 9 GHz), τf ~ 2.9 ppm/℃), is proposed as a candidate dielectric for GPS patch antennas. The microstructures and the microwave dielectric properties of the (1 - x)(Mg0.95Co0.05)TiO3– x(Na0.5La0.5)TiO3 ceramic system were investigated. Two-phase system was confirmed by the XRD patterns and the EDX analysis. A co-existed second phase (Mg0.95Co0.05)Ti2O5 was also detected. The microwave dielectric properties are strongly related to the density and the matrix of the specimen. A new microwave dielectric material 0.88(Mg0.95Co0.05)TiO3–0.12(Na0.5La0.5)TiO3, possessing an excellent combination of dielectric properties: εr ~22.36, Q × f ~ 110,000 GHz (at 9 GHz), τf ~ 2.9 ppm/℃), is proposed as a candidate dielectric for GPS patch antennas.

Physical–chemical property and activity evaluation of LaB0.5Co0.5O3(B = Cr, Mn, Cu) and LaMnxCo1-xO3 (x = 0.1, 0.25, 0.5) nano perovskites in VOC combustion

Seyed Ali Hosseini,Aligholi Niaei,Dariush Salari,Samira Arefi Oskoui 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.6

The correlation between physical–chemical properties and activities of LaB0.5Co0.5O3 (B = Cr, Mn, Cu)nano perovskites was studied in combustion of toluene. LaMn0.5Co0.5O3 showed the highest activity among LaB0.5Co0.5O3 catalysts and further optimization study was focused on LaMnxCo1-xO3 (x = 0.1,0.25, 0.5). The activity and reducibility of catalysts improved due to partial substitution of Co3+ by B cation. No direct relationship was between surface area and catalyst activity. T50% of 2-propanol over LaMn0.25Co0.75O3, LaMn0.5Co0.5O3, LaMn0.1Co0.9O3 and LaCoO3 was 168, 200, 220 and 229 8C,respectively. LaMn0.25Co0.75O3 was the optimum catalyst and showed robust stability in combustion of toluene and 2-propanol.

LiMn_0.5Co_0.5BO₃ solid solution: Towards high performance cathode material for next-generation lithium-ion battery

Ragupathi, Veena,Anbu Dinesh, J.,Panigrahi, Puspamitra,Raman, Sudarkodi,Lee, Juwon,Nagarajan, Ganapathi Subramaniam Pergamon Press 2018 International journal of hydrogen energy Vol.43 No.8

<P><B>Abstract</B></P> <P>LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB> solid solution is synthesized by Sol-gel method. The crystal structure, morphology and the electrochemical properties of the LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB> solid solution are analyzed. X-ray diffraction analysis result reveals the existence of monoclinic phase with <I>C</I>2/<I>c</I> space group. Raman spectroscopy result indicates the presence of Co-O and Mn-O stretching vibration. X–ray Photoelectron spectroscopy confirms the surface oxidation of Mn in the LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB> solid solution. Transmission electron microscopy image shows the elongated spherical shaped particle with diameter of 40 nm. Galvanostatic charge – discharge studies indicate that the LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB> solid solution delivers the first discharge capacity of 110 mAh g<SUP>−1</SUP> at C/10 rate with good stability and yield 68 mAh g<SUP>−1</SUP> at 75th cycle. The enhanced electrochemical properties demonstrated in this study will give more attention to borate based cathode material as a potential alternative to current lithium-ion battery cathodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB> solid solution is synthesized by sol gel technique. </LI> <LI> A high first discharge capacity of 110 mAh g<SUP>−1</SUP> is achieved for LiMn<SUB>0.5</SUB>Co<SUB>0.5</SUB>BO<SUB>3</SUB>. </LI> <LI> The first discharge capacity is at least 10 folds higher than previous reports. </LI> <LI> Co doping and Li rich stoichiometry has improved the electrochemical performance. </LI> </UL> </P>

Oxygen permeation performance of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane after surface modification

Jung Hoon Park,Edoardo Magnone,Jong Pyo Kim,Soo Hyun Choi 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.2

The effect of minor surface modification on the performance of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane was evaluated in the temperature region from 700 to 850 oC. Oxygen permeation experiments were conducted according to membrane thickness (1.0mm and 1.6 mm) and oxygen partial pressure (0.21, 0.42, and 0.63 atm) in the absence and in the presence of carbon dioxide (300 and 500 ppm). The oxygen permeation flux of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane increased with increasing temperature and decreasing membrane thickness. The oxygen permeation flux through the membrane of 1.0 mm thickness with Ba0.5Sr0.5Co0.8Fe0.2O3−δ-modified surface was ca. 1.23 ml/cm2·min at 850 oC under air feeding condition. It was found that the Ba0.5Sr0.5Co0.8Fe0.2O3−δ-modified Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane has better oxygen permeation flux than the pristine Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane. In summary, it has been demonstrated that the surface morphology is an important factor in determining the oxygen permeation fluxes through Ba0.5Sr0.5Co0.8Fe0.2O3−δmembrane under mixed-control conditions.

Catalytic performance of LaCo0.5M0.5O3 (M = Mn, Cr, Fe, Ni, Cu) perovskite-type oxides and LaCo0.5Mn0.5O3 supported on cordierite for CO oxidation

Xiaokang Yan,Shu-Bao Shen,Qiong Huang,Bing Li,Xiaoliang Xu,Ying-Wen Chen,She-Min Zhu 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2

Catalytic combustion of CO over perovskite-type oxides LaCo0.5M0.5O3 (M = Mn, Cr, Fe, Ni, Cu) and LaCo0.5Mn0.5O3 supported on cordierite were investigated. The catalysts were synthesized by impregnation method with citrate and characterized by XRD, SEM and TPR. The LaCo0.5Mn0.5O3catalyst showed much higher activity in CO oxidation compared with LaCo0.5M0.5O3 (M = Cr, Fe, Ni, Cu)due to different kinds of valence state and lattice oxygen content. When LaCo0.5Mn0.5O3 was supported on cordierite, the activity was improved significantly. However, calcining temperature and the presence of water vapor affected the catalytic activity due to sintering and competition of H2O with CO for adsorption, respectively.

공급가스 및 스윕가스 유량에 따른 Ba0.5Sr0.5Co0.8Fe0.2O3-δ 분리막의 산소투과특성

박세형 ( Se Hyung Park ),손종석 ( Jong Suk Sonn ),이홍주 ( Hong Joo Lee ),박정훈 ( Jung Hoon Park ) 한국화학공학회 2015 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.53 No.4

고상반응법으로 제조된 Ba0.5Sr0.5Co0.8Fe0.2O3-δ 조성의 페롭스카이트 산화물 상용분말을 압축 성형 후 1100℃에서 2시간 동안 소결한 후, 1.0 mm의 두께를 가지는 평판형 분리막을 제조하였다. Ba0.5Sr0.5Co0.8Fe0.2O3-δ 분리막의 산소투과량은 온도와 산소분압이 증가함에 따라 증가하였고, 산소투과의 활성화에너지는 산소분압이 증가할수록 높은 값을 나타내었다. 950℃에서 공급가스와 스윕가스의 유량 변화에 따른 투과 특성 분석 결과, 유량이 증가할수록 높은 산소투과량을 보였으며, 공급가스보다 스윕가스의 유량에 따라 크게 변함을 확인하였다. Dense ceramic membranes have been prepared using the commercial perovsikite Ba0.5Sr0.5Co0.8Fe0.2O3-δ, powders synthesized by the solid state reaction method. The as-synthesized powders were compressed into disks with 1.0 mm of thickness and the disk was sintered at 1,100℃ for 2 hr. The oxygen permeation flux of Ba0.5Sr0.5Co0.8Fe0.2O3-δ membrane increased with the increasing temperature and oxygen partial pressure. The activation energy for oxygen permeation was increased with the increasing oxygen partial pressure. Oxygen permeation flux at 950℃ were measured at various flow rates of feed and sweep gas. It has been demonstrated that oxygen permeability increased at elevated flow rates of both gases, but the sweep gas is more influential.

Ba0.5Sr0.5Co0.8Fe0.2O3.δ 중공사 분리막의 제조 및 물성

전성일 ( Sung Li Jeon ),박정훈 ( Jung Hoon Park ),김종표 ( Jong Pyo Kim ),심우종 ( Woo Jong Sim ),이용택 ( Yong Taek Lee ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.1

외경 1.02 mm, 내경 0.437 mm를 갖는 Ba0.5Sr0.5Co0.8Fe0.2O3-δ 중공사를 상전이 방적기술로 제조하였다. 초기 Ba0.5Sr0.5Co0.8Fe0.2O3-δ 선구 분말은 착체중합법을 이용하여 합성하였고, 900 ℃에서 하소하였다. 합성한 분말을 고분자 용액에 분산시킨 후 이중관형 노즐을 통해 중공사를 사출하였다. 최종적으로 산소분리에 사용 가능한 치밀 Ba0.5Sr0.5Co0.8Fe0.2O3-δ 중공사막을 1,080 ℃에서 2 시간 동안 소결하여 얻을 수 있었다. 또한 0.58 mm의 매우 얇은 분리막임에도 불구하고, BSCF 중공사 분리막은 602.5 MPa의 적당한 기계적 강도를 유지하였다.

PrBa0.9Sr0.1Co2O5+δ 세라믹 분리막의 제조 및 산소투과 특성

표대웅,김종표,손수환,박정훈 한국막학회 2011 멤브레인 Vol.21 No.4

PrBa0.9Sr0.1Co2O5+δ 조성의 산화물을 고상반응법을 이용하여 합성하였다. 합성된 분말은 압축 성형 후 1,250℃에서 소결하여 치밀한 세라믹 분리막을 제조하였다. 제조된 PrBa0.9Sr0.1Co2O5+δ분리막은 XRD분석 결과 이중 페롭스카이트 (double perovskite)구조를 보였다. 밀봉재료로는 pyrex ring을 사용하여 가스누출 실험 및 산소투과 분석을 하였다. 산소투과량 분석은 850~950℃범위에서 측정되었다. 산소투과실험 결과, 투과량은 온도증가에 따라 0.15에서 0.32mL/㎠·min로 증가하였다. PrBa0.9Sr0.1Co2O5+δ oxide was synthesized by soild state reaction method. Dense ceramic membrane was prepared using as-prepared powder by pressing and sintering at 1250℃. XRD result of membrane showed double perovskite structure. Leakage and oxygen permeation test were conducted on the membrane sealed by pyrex ring as a sealing material. Oxygen permeation was measured in the temperature range from 850 to 950℃. The oxygen flux of PrBa0.9Sr0.1Co2O5+δ membrane was increased with the temperature from 0.15 to 0.32mL/㎠·min.