Srx La₁_x Fe₃_y계의 결정학적 구조와 비화학양론에 관한 연구

여철현,편무실,강삼룡 明知大學校 産業技術硏究所 1984 産業技術硏究所論文集 Vol.3 No.-

The solid solutions of the ?? systems with χ=1.00, 0.75 and 0.50 are prepared from stoichiometric mixtures of carbonate (SrCO₃), nitrate (Fe (NO₃)₃·9H₂O) and oxide (La₂O₃) by heating at 1300℃ for three days. Crystallographic structures of the solutions are all simple cubic systems and the lattice parameters of the cubic unit cells are enlarged with the introduction of lantanium according to their X-ray diffraction analysis. The mixed valence state of two kinds of Fe ion in the ferrite systems is analyzed by the Mohr salt titration method. It is possible to produce the nonstoichiometric compounds such as ?? by the appropriate heating treatment of the solutions under atmospheric air or oxygen pressure for a long time. The crystallographic structure and the nonstoichiometric compositions of the ?? systems are discussed with relation to their physical properties.

방사선에 의한 결정의 결함구조에 관한 연구

片茂實,呂鐵鉉 명지대학교 1983 明大論文集 Vol.14 No.-

Single crystal of pottassium, Hydrogen, sulfate(KHSO_4) have been grown from the saturated solution by the evaporation method at the optimum conditions. Radiation damages in the single crystal caused by r-irradiation of 11.25×10^6 Rentgen have given rise to several paramagnetic centers. Electron spin resonance (ESR) spectra of the crystals are obtained with the X-bond EPR spectrometer at room temperature. The ESR Reaks of the paramagnetic species are found to be anisotropic but an isatlopic peak of Gaussian shape at g=2.0036 is assigned to SO_3 -radical. The g-values of all the species at various angles between the other oxis besides the rotating axes and the magenetic field are obtained from the distances between anisotropic peaks of the species and the isotropic peak of SO_3 -radical. The principal g-values of the trapped radicals are calculated from the plots of g^2 vs θ. All the species are identibud with the corresponding principal g-values and the defect structure of the KHSO_4 crystal is also discussed in terms of the species.

Study of the Nonstoichiometry and Physical Properties of the$Nd_{1-x}Sr_xFeO_{3-y}$ System

Chul Hyun Yo,Hyung Rak Kim,Kwang Hyun Ryu,Kwon Sun Roh,Jin Ho Choy Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.8

The nonstoichiometric perovskite solid solutions of the $Nd_{1-x}Sr_xFeO_{3-y}$ system for the compositions of x=0.00, 0.25, 0.50, 0.75, and 1.00 have been prepared at $1150^{\circ}C$ in the air pressure. The compound of x=0.00, NdFe$O_{3.0}$, contains only $Fe^{3+}$ ion in octahedral site and the others involves the mixed valence state between $Fe^{3+}$ and $Fe^{4+}$ ions. The mole ratio of $Fe^{4+}$ ion or the ${\tau}$-value increases steadily with the x-value and then is maximized at the compositionof x= 1.00. The nonstoichiometric chemical formulas of the system are formulated from the x, ${\tau}$ and y values. From the Mossbauer spectroscopy, the isomer shift of $Fe^{3+}$ ion decreases with the increasing x-value, which is induced by the electron transfer between the$Fe^{3+}$ and $Fe^{4+}$ ions. The transfer is made possible by the indirect interaction between $Fe^{3+}$ and$Fe^{4+}$ ions via the oxygen ion. The eg electrons of the$Fe^{3+}$ ions are delocalized over all the Fe ions. Due to the electron transfer, the activation energy of electrical conductivity is decrease with the increasing amount of $Fe^{4+}$ ion.

Nonstoichiometry of the Terbium Oxide

Yo Chul Hyun,Ryu Kwang Sun,Lee, Eun Seok,Kim Keu Hong Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.1

The x values of nonstoichiometric chemical formula, $Tb_4O_{7-{\delta}}\;or\;TbO_{1.5+x}$, have been determined in temperature range from 600$^{\circ}$C to 1000$^{\circ}$C under oxygen partial pressure of 2 ${\times}$ 10$^{-1}$ to 1 ${\times}$ 10$^{-5}$ atm by using quartz microbalance. The x values varied from 0.0478 to 0.1964 in the above conditions. The enthalpy of formation for x' in TbO$_{1.5+(0.25-xo-x')}$, ${\delta}H_f$, was 4.93-3.40 kcal mol$^{-1}$ and the oxygen partial pressure dependence was -1/8.80∼-1/11.8 under these conditions. The electrical conductivity of the $TbO_{1.5+x}$ was measured under the same conditions and the values varied from about 10$^{-3}$ to 10$^{-6}\;{\Omega}^{-1}cm^{-1}$ within semiconductor range. The activation energies for the conduction increase with oxygen partial pressure from 0.83 to 0.89 eV under the above conditions. The l/n values obtained from the oxygen pressure dependence of the conductivity are 1/4.4-1/5.2. The conduction mechanism, defect structure, and other physical properties of the oxides are dicussed with the x values, the electrical conductivity values, and the thermodynamic data.

Structural Ordering Effect on Photoluminescence Properties of $Eu^{3+}$ Doped Perovskite Tungstate $A_2BWO_6$ System

Yo, Chul-Hyun Korean Society of Photoscience 1998 Journal of Photosciences Vol.5 No.4

The optical spectroscopic properties of the ordered perovskite structure A2BWO6 doped with Eu3+ have been studied. The experimental result about Eu3+ ordering in the system of A2BWO6 indicate the different structural conditions. Some influence of Eu3+ substitutioin on the different types of cation site have been investigated.

산화네오디뮴의 비화학량과 반도성에 관한 연구

呂鐵鉉,金旭成,鄭元陽,片茂實 연세대학교 자연과학연구소 1980 學術論文集 Vol.5 No.-

NdO_(1.5+x)로 표시되는 비화학양론적 조성식의 x값을 측정한 결과, 200℃~1200℃ 온도범위와 10^-6~0.2기압 산소압력 범위에서 7.49×10^-6~1.06×10^-2이었다. 같은 실험조건에서 산소과잉의 생성엔탈피, ΔH_f,는 2.72~20.32 Kcal/mole 범위에서 변하였다. Log x를 Log Po_2에 대하여 (또는 Log x=1/n Log Po_2) 도시하면 직선관계가 성립하며 그 직선의 기울기로 부터 1/n값을 계산하였다. Nd_2O_3의 전기전도도(σ)를 유사한 조건에서 측정한 결과, 3.98×10^-7~6.31×10^-4 ohm^-1cm^-1이었다. A형 Nd_2O_3의 전도성 활성화에너지는 0.61~0.99eV이고, C형 Nd_2O_3의 활성화에너지는 0.11~0.33eV이었다. 전기전도도의 산소압력의 존성에서 얻은 1/n값은 1/4.6~1/6.2이었다. x값, σ값과 열역학적인 데이타를 사용하여 Nd_2O_3의 전도성 메카니즘, 결함구조 및 기타 물성등을 고찰하였다. The x-values of the nonstoichiometric chemical formula, Nd_2O_(1.5+x) have been measured in a temperature range of 200 to 1200℃ under oxygen pressures of 0.2 to 10^-6atm and the values varied between 7.49×10^-6 and 1.06×10^-2. The enthalpies of formation of excess oxygen in neodymium sesquioxide, ΔH_f, are 2.72~20.32Kcal/mole under above experinental conditions. The plots of log x vs. log Po_2 (or, log x=1/n log Po_2)show linearity, and 1/n values are calculated from the slopes of the plots. The electrical conductivity of the neodymium sesquioxide, σ, have also been measured under similar conditions, and the σ values varied between 3.98×10^-7 and 6.31×10^-4ohm^-1cm^-1. The activation energies of A-form and C-form of the oxide are 0.61~0.99eV and 0.11~0.33eV, respectively. The 1/n values obtained from the oxygen pressure dependences of the conductivity are 1/4.6~1/6.2. The conduction mechanism, defect structure and other physical properties of the oxide are discussed with x-values, σ values and the above thermodynamic data.

산화이트륨 및 산화홀뮴의 비화학양론

장순호,여철현,최재시,편무실,Chang, Soon-Ho,Yo, Chul-Hyun,Choi, Jae-Shi,Pyun, Mu-Sil 대한화학회 1984 대한화학회지 Vol.28 No.4

$YO_{1.5+x}$와 $HoO_{1.5+x}$로 표시되는 산화이트륨과 산화홀뮴의 비화학양론적 조성식의 x-값을 700$^{\circ}$C에서 1000$^{\circ}$C까지의 온도영역과 대기압에서 $1{\times}10^{-6}$기압 산소압력까지의 구간에서 중량 분석법에 의하여 측정하였다. 측정된 x-값은 온도가 상승하면 증가하고 산소압력이 증가하면 또한 증가하였다. 비화학양론적 조성의 생성엔탈피 $({\Delta}H_f)$는 산소압력이 감소하면 감소하였고 그 값이 양의 값을 갖는 것으로 과잉산소의 형성 과정이 흡열과정임을 알 수 있다. 산소압력 의존성 1/n-값은 온도가 상승하면 상승하고 양의 값을 갖는 것으로 높은 온도일수록 산소압력 의존성이 커짐을 보여 주었다. 그리고 x-값과 열역학적 자료로 부터 비화학양론적 결합과 전도성메카니즘을 규명하였다. The x-values in the nonstoichiometric chemical formulas $YO_{1.5+x}\;and\;HoO_{1.5+x}$, have been measured in the temperature range from 700$^{\circ}$C to 1000$^{\circ}$C under oxygen pressures from $2{\times}l0^{-1}\;to\;1{\times}10^{-6}$ atm by gravimetric method. The observed x-values increase with increasing temperature and oxygen pressure. The enthalpies of formation of excess oxygen in yttrium oxide and holmium oxide decrease with decreasing oxygen pressure and are all positive values representing an endothermic process. The 1/n values calculated from the slopes of the plots of log x vs. log $P_{O2}$ increase with temperature and are positive values which means the higher oxygen pressure dependence at higher temperature. We have examined the nonstoichiometric defect and conduction mechanism from x-values and thermodynamic data.

Sr_xLa_(1-x)FeO_(3-y)계의 결정학적 구조와 비화학양론에 관한 연구

여철현,이성주,장순호,편무실 연세대학교 자연과학연구소 1983 學術論文集 Vol.12 No.-

Sr_xLa_(1-x)FeO_(3-y)계의 고용체는 x=1.00,0.75 및 0.50인 경우 탄산염(SrCO_3), 질산염(Fe(NO_3)_3·9H_2O)및 산화물(La_2O_3)의 화학양론적 혼합물을 1300℃에서 3일간 가열하여 제조하였다. 이 고용체의 결정학적 구조는 모두 단순입방이고 그 단순입방 단위결정의 격자 상수는 La의 양을 많이 가할수록 커지는 것을 X-선 회절분석을 통하여 알수 있다. 이 훼라이트계들에서 두가지 종류의 철이온의 혼합원자가 상태는 Mohr염 적정법에 의하여 분석한다. 그 고용체들을 대기중 또는 산소압력하에서 장시간 적절한 열처리를 함으로써 SrFe^3+_0.50Fe^4+_0.50O_2.750, Sr_0.75La_0.25Fe^3+_0.50Fe^4+_0.50O_2.875 및 Sr_0.50La_0.50Fe^3+_0.50Fe^4+_0.50O_3.000과 같은 비화학 양론적인 화합물을 생성할 수 있었다. 그 Sr_xLa_(1-x)FeO_(3-y) 고용체들의 결정학적 구조와 비화학양론적 조성들을 그들의 물리적인 성질과 관련하여 고찰하였다. The solid solutions of the Sr_xLa_(1-x)FeO_(3-y) systems with x=1.00,0.75 and 0.50 are prepared from stoichiometric mixtures of carbonate(SrCO_3), nitrate(Fe(NO_3)_3·9H_2O)and oxide(La_2O_3) by heating at 1300℃ for three days. Crystallographic structures of the solutions are all simple cubic systems and the lattice parameters of the cubic unit cells are enlarged with the introduction of lantanium according to their X-ray diffraction analysis. The mixed valence state of two kinds of Fe ion in the ferrite systems is analyzed by the Mohr salt titration method. It is possible to produce the nonstoichiometric compounds such as SrFe^3+_0.50Fe^4+_0.50O_0.2750, Sr_0.75La_0.25Fe^3+_0.50Fe^4+_0.50O_2.875 and Sr_0.50La_0.50Fe^3+_0.50Fe^4+-0.50O_3.000 by the appropriate heating treatment of the solutions under atmospheric air or oxygen pressure for a long time. The crystallographic structure and the nonstoichiometric composition of the Sr_xLa_(1-x)Fe)_(3-y) systems are discussed with relation to their physical properties.

방사선에 의한 결정의 결함구조에 관한 연구

呂鐵鉉,鄭元陽,片茂實,崔在時 연세대학교 자연과학연구소 1979 學術論文集 Vol.3 No.-

황산수소칼슘(KHSO_4) 포화용액으로부터 증발법으로 KHSO_4 단결정을 최적조건에서 생성시킨다. 11.25×10^6 렌트겐의 방사선(r-선)조사로 생긴 단결정의 방사선손상은 몇개의 상자성 중심을 형성한다. 그 결정들의 전자스핀공명 스펙트라를 상온에서 X-띠 전자스핀공명 분석기로 얻는다. 상자성종들의 전자스핀공명(ESR) 피-크들은 무등방성을 보이지만 g=2.003인 Gauss형 등방성 피-크가 생기는 것은 SO_3^-기 때문이다. 회전축 이외 제삼의 축과 자장간에 이루는 여러 각도에서 모든 상자성종들의 g-값들은 그종들의 무등방성 피-크들과 SO_3^-기의 등방성 피-크간의 거리로부터 구할 수 있다. 결정내에 성성된 기들의 주 g-값은 g^2을 Θ에 대하여 도시한 곡선으로부터 계산하였다. 모든 상자성종들은 대응되는 특성 주-값들로부터 확인되고 결정의 결함구조는 또한 이들 종으로 고찰된다. Single crystals of Potassium Hydrogen Sulfate(KHSO_4) have been grown from the saturated solution by the evaporation method at the optimum conditions. Radiation damages in the single crystal caused by r-irradiation of 11.25×10^6 Rentgen have given rise to several paramagnetic centers. Electron spin resonance(ESR) spectra of the crystals are obtained with the X-band EPR spectrometer at room temperature. The ESR peaks of the paramagnetic species are found to be anisotropic but an isotropic peak of Gaussian shape at g=2.0036 is assigned to SO_3 radical. The g-values of all the species at various angles between the other axis besides the rotating axes and the magnetic field are obtained from the distances between anisotropic peaks of the species and the isotropic peak of SO_3^- radical. The principal g-values of the trapped radicals are calculated from the plots of g^2 vs.Θ. All the species are identified with the corresponding principal g-values and the defect structure of the KHSO_4 crystal is also discussed in terms of the species.

CoO의 Nonstoichiometry에 관한 연구

여철현,최재시,최승락 연세대학교 대학원 1973 延世論叢 Vol.10 No.1

The Y values of the nonstoichiometric chemical formula, CoO1+Y, have been measured by a specially made quartz micro-balance in a temperature range from 0℃ to 1200℃ under oxygen pressures from 152 mmHg to 10-3 mmHg. The y values varied between 0.01850 and 0.00148 and the activation energies are usually less than 5 Kcal/mole in the above condition. The plots of log y vs log P02(or log Y= 1/n log P02) show linearity and 1/n values calculated from the slopes of the plot are 1/4.8∼1/2.7 in the temperature range of 1000℃-1200℃ under 10-3~10-1 mmHg O2 pressures. The most of physical properties of the cobaltous oxide, such as the electrical conductivity, oxidation, diffusion and catalytic effect along with the mechanism, could be explained through y values and the nonstoichiometric mechanism of the oxide.