• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.290-291
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• 2006

The effect of praseodymium substitution on the ferroelectric properties of $Bi_4Ti_3O_{12}$ thin films have been investigated. Ferroelectric Pr-substituted $Bi_4Ti_3O_{12}$ thin films were fabricated by chemical solution deposition onto Pt/Ti/$SiO_2$/Si substrates. The structure and morphology of the films were analyzed using Xray diffraction, and scanning electron microscopy, respectively. About 200-nm-thick BPT films grown at $720^{\circ}C$ exhibited a polycrystalline structure and showed excellent ferroelectric properties with a remanent polarization ($2P_r$) of $28.21\;{\mu}C/cm^2$ at an applied voltage of 5 V. The films a1so demonstrate fatigue-free behavior up to $10^{11}$ read/write switching cycles with 1 MHz bipolar pulses at an electric field of ${\pm}5\;V$.

• Bulletin of the Korean Chemical Society
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• 제11권6호
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• pp.564-567
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• 1990

A lithiated compound $Li_{0.1}Pr^{3+}Ba_2Cu_3O_y$ has been successfully prepared by electrochemical method, which is achieved with a two electrode cell of the type: Metal(Li)/($Li^+\;,\;ClO_4^-$) + propylene carbonate/$PrBa_2Cu_3O_y$. All Pr ions in the lithiated compound are stabilized with a trivalent state as the other rare earths (Ⅲ) substituted in the 90K superconductor lattice ($Y_{1-x}Ln_x^-Ba_2Cu_3O_{7-{\delta}}$). Powder X-ray diffraction analysis shows that both compounds, $PrBa_2Cu_3O_y$ and $Li_{0.1}PrBa_2Cu_3O_y$ are isostructural with the 90 K superconductor, ($YBa_2Cu_3O_{7-{\delta}}$), nevertheless both of them are non-metallic and also non-superconducting down to 10 K. Magnetic susceptibility ${\chi}$ vs. temperature data indicate that Curie contribution from the magnetic ions (Pr and Cu) is weakened on the one hand, but on the other hand temperature-independent part of susceptibility ${\chi}_o$ increases depending upon the rate of lithium intercalation in $PrBa_2Cu_3O_y$ lattice.

• 약학회지
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• 제32권3호
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• pp.164-169
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• 1988

$^{13}C$ NMR chemical shifts for 18 ${\alpha}-susbstituted$ toluenes at high dilution in $CCl_4$ solution have been determined. Substituents are as follows: H, Me, Et, n-Pr, iso-Pr, Ph, F, Cl, Br, $NH_2$, NHMe, $NMe_2$, OH, OMe, OCOMe, $CO_2Me$, $CO_2Et$, CN. Those chemical shifts of the methylene carbon of the toluene and the ${\alpha}-carbon$ of the n-butane systems are correlated well. (r=.975, slope=.962)

• 한국자기학회지
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• 제2권1호
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• pp.61-68
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• 1992

전이 금속(Ni, Co), 희토류(Ce, Pr, Eu) 및 Al이온 치환 Ba 훼라이트박막을 스퍼터법으로 제조하여, 그 구조, 자기적 및 자기광학적 성질(1.0eV~3.2eV)을 조사하였다. 막 제작시의 투입 rf 전역 밀도를 조절하는 것에의해, 막 중의 결정립의 크기를 수 100 nm-수 nm로 제어하는데 성공했다. Fe를 Al으로 치환하는 것에의해 각형 히스테리시스 루우프를 얻는데 성공했다. Ni이온이 가시역에서 페러데이 회전을 크게 증가시키는 것을 발견했다. Co이온이 근적외선 영역에서 페러데이 회전을 크게 증가시키는것을 확인했다. Ce, Pr, Eu이온데 의한 페러데이 회전의 증가는 관찰되지 않았다. 이들 이온 치환 막의 자기적 및 자기광학적 성질의 기원에 대해 고찰했다.

• 한국세라믹학회지
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• 제43권11호
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• pp.688-692
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• 2006

Ferroelectric lanthanides-substituted $Bi_4Ti_3O_{12}$ $(Bi_{4-x}Ln_xTi_3O_{12}, BLnT)$ thin films approximately 200 nm in thickness were deposited by metal organic chemical vapor deposition onto Pt(111)/Ti/SiO$_2$/Si(100) substrates. Many researchers reported that the lanthanides substitution for Bi in the pseudo-perovskite layer caused the distortion of TiO$_6$ octahedron in the a-b plane accompanied with a shift of the octahedron along the a-axis. In this study, the effect of lanthanides (Ln=Pr, Eu, Gd, Dy)-substitution and crystallization temperature on their ferroelectric properties of bismuth titanate $(Bi_4Ti_3O_{12}, BIT)$ thin films were investigated. As BLnT thin films were substituted to lanthanide elements (Pr, Eu, Gd, Dy) with a smaller ionic radius, the remnant polarization (2P$_r$) values had a tendency to increase and made an exception of the Eu-substituted case because $Bi_{4-x}Eu_xTi_3O_{12}$ (BET) thin films had the smaller grain sizes than the others. In this study, we confirmed that better ferroelectric properties can be expected for films composed of larger grains in bismuth layered peroskite materials. The crystallinity of the thin films was improved and the average grain size increased as the crystallization temperature,increased from 600 to 720$^{\circ}C$. Moreover, the BLnT thin film capacitor is characterized by well-saturated polarization-electric field (P-E) curves with an increase in annealing temperature. The BLnT thin films exhibited no significant degradation of switching charge for at least up to $1.0\times10^{11}$ switching cycles at a frequency of 1 MHz. From these results, we can suggest that the BLnT thin films are the suitable dielectric materials for ferroelectric random access memory applications.

• 대한화학회지
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• 제34권6호
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• pp.652-657
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• 1990

각종 일차아민과 1,6-헥산디올을 촉매량의 $RuCl_3{\cdot}3H_2$O와 $PR_3$의 존재하 180$^{\circ}C$에서 5시간 반응시켜 N-치환 과수소아제핀을 높은 수득률로 얻었다. 방향족 아민인 아닐린 유도체에 대해서는 $RuCl_3{\cdot}3H_2$O와 PR3을 이용한 촉매계가 적당하고, 한편으로 지방족 아민에 대해서는 $RuCl_3{\cdot}3H_2$O와 $PBu_3$을 이용한 촉매계가 효과적인 것으로 확인되었다. 이러한 차이점은 염기성이 작은 방향족 아민에 대해서는 염기성이 작은 포스핀 배위자인 $PPh_3$가 유용하고 염기성이 큰 지방족아민에 대해서는 염기성이 큰 포스틴 배위자인 $PBu_3$가 유용함을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제20권3호
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• pp.314-320
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• 1999

Several bisphosphine- and bisphosphite-substituted Re-imido complexes have been prepared from Re(NPh)(PPh3)2Cl3, 1, and Re(N-C6H3-i-Pr2)2Cl3(py), 4. Compound 1 reacted with trimethyl phosphate (P(OMe)3) to give a mixture of two isomers,mer,trans-Re(NPh)(P(OMe)3)2Cl3, 2, and fac,cis-Re(NPh)(P(OMe)3)2Cl3, 2a. In this reaction, the mer,trans-isomer is a major product. Complex 1 also reacted with triethylphosphine (PEt3) to exclusively give mertrans-Re(NPh)(PEt3)2Cl3, 3. Compound 4 reacted with trimethylphosphine (PMe3) to give mer,trans-Re(N-C6H3-i-Pr2)(PMe3)2Cl3, 5, which was converted to mer-Re(N-C6H3-i-Pr2)(PMe)(OPMe3)Cl3, 6, on exposure to air. Crystallographic data for 2: monoclinic space group P21/n, a = 8.870(2) Å, b = 14.393(3) Å, c = 17.114(4) Å, β = 101.43(2)°, Z = 4, R(wR2) = 0.0521(0.1293). Crystallographic data for 5: orthorhombic space group P212121, a = 11.307(l) Å, b = 11.802(l) Å, c = 19.193(2) Å, Z = 4, R(wR2) = 0.0250(0.0593). Crystallographic data for 6: orthorhombic space group P212121, a = 14.036(4) Å, b = 16.486(5) Å, c = 11.397(3) Å, Z = 4, R(wR2) = 0.0261(0.0630).

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.196-199
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• 2007

The chemical states of oxygen on the surfaces of $Pr_{1-x}Sr_{x}CoO_{3}$ (x=0.5 and 0.7) oxide systems were investigated by X-ray photoelectron spectroscopy. Merged oxygen peaks of $Pr_{1-x}Sr_{x}CoO_{3}$ (x=0.5 and 0.7) oxides could be divided as five sub-peaks. These five sub-peaks could be defined as lattice oxygen ($O_{L}$). chemisorbed oxygen peaks ($O_{C}$) and hydroxyl condition oxygen peak ($O_{H}$). In case of the $Pr_{0.5}Sr_{0.5}CoO_{3}$ and $Pr_{0.3}Sr_{0.7}CoO_{3}$, the binding energy (BE) of oxygen lattice were located at same BE. However, the BE of chemisorbed oxygen peaks including oxygen vacancy shows different BE. Especially, it was found that BE of chemisorbed oxygen peaks was increased when more Sr were substituted. Comparing atomic percentages of oxygens of $Pr_{0.5}Sr_{0.5}CoO_{3}$ and $Pr_{0.3}Sr_{0.7}CoO_{3}$, the ratio of $Pr_{0.3}Sr_{0.7}CoO_{3}$ was higher than that of $Pr_{0.5}Sr_{0.5}CoO_{3}$. It showed more chemically adsorbed site including oxygen vacancies were existed in $Pr_{0.3}Sr_{0.7}CoO_{3}$.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2006년도 추계학술대회 발표 논문집
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• pp.170-173
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• 2006

Ferroelectric $Bi_{3.35}Sm_{0.65}Ti_3O_{12}(BST)$ thin films were deposited on $Pt(111)/Ti/SiO_2/Si(100)$ substrates by a sol-gel spin-coating process. In this experiments, $Bi(TMHD)_3$, $Sm_5(O^iPr)_{13}$, $Ti(O^iPr)_4$ were used as precursors, which were dissolved in 2-methoxyethanol. Thereafter, the thin films with the thickness, of 240nm were annealed from 600 to $720^{\circ}C$ in oxygen atmosphere for 1 hr, and post-annealed in oxygen atmosphere for 1 hr after deposition of Pt electrode to enhance the electrical properties. The remanent polarization and coercive voltage of the BST thin films annealed at $720^{\circ}C$ were $19.48\;{\mu}C/cm^2$ and 3.40 V, respectively, and a fatigue-free characteristics. As a result, Sm-substituted bismuth titanate films with good ferroelectric properties and excellent fatigue resistance are useful candidates for ferroelectric memory applications.

• Bulletin of the Korean Chemical Society
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• 제16권2호
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• pp.120-125
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• 1995

Solid solutions of Pr2-xBaxNiO4±δ with K2NiF4-type structure were prepared in air and characterized by powder X-ray diffraction, Rietveld refinements, iodometry titrations, and conductivity measurements. The range of the solid solution was 0 ≤ x < 0.5. The crystal structure changes from orthorhombic (Fmmm) for x ≤ 0.1 to pseudo-tetragonal (I4/mmm) for x ≥ 0.2. The orthorhombic structure of x=0.1 transforms to tetragonal at low temperature. The bond distances obtained from the Rietvel analyses did not vary significantly with the Ba content except that of Ni-O (parallel to the c-axis) which showed an abrupt increase from x=0.1 to 0.2. The excess oxygen content (δ) decreases from 0.241 to 0.03 with increasing substituted Ba contents within the solution range. The samples are all semiconductors at the temperature range 4 < T < 300 K.