• 한국광물학회지
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• 제16권1호
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• pp.65-73
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• 2003

이 연구에서는 X-선 회절법으로 측정한 수소결합의 거리를 보정하는 두 가지 방법을 제시하였다 O…O 거리가 2.5 $\AA$ 이상인 수소결합의 경우는 저온에서 측정한 중성자 회절에 의한 수소결합 데이터를 이용하여 얻은 최적화 곡선 식 d(O-H)=exp((2.173-d(O…O))/0.138)+0.958을 이용하여 수소결합 거리를 보정한다. O…O 거리가 2.5 $\AA$ 이하의 짧은 수소결합의 경우는 결합원자가 최적화 방법(valence-least-squares)을 이용하는 것이 효과적이다. X-선 회절분석으로 얻은 긴 O…O 거리를 갖는 분자간 수소결합의 경우는 수소결합의 거리보정을 해주어야 한다.

• International Journal of Internet, Broadcasting and Communication
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• 제7권1호
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• pp.75-92
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• 2015

This paper presents the application of the bond valence method to estimate the valence charge distribution in several perovskite systems: $La_{{\tilde{1}}x}Pb_xMnO_3$ (x=0.1-0.5), $La_{0.6}Sr_{0.{\tilde{4}}x}Ti_xMnO_3$ (x=0.0-0.25) and $La_{{\tilde{1}}x}Sr_xCoO_3$ (x=0.1-0.5); the reviewing of their crystal structures is also incorporated. The results showed the failure of the elastic bonding mechanism in all studied systems and revealed the general deficit of the valence charge in their unit cells. This valence deficit was not associated with the structural defects and was not equally localized in all coordination spheres. As the content of substitution increased, the charge deficit declined systematically from balanced level, signifying the transfer of valence charge from the ${\tilde{B}}O_6$ to ${\tilde{A}}O_{12}$ spheres. This transfer depended on the valence deviation of spheres and the average reached near 2 electron per unit cell. The possible impact of the limitted accuracy of the available structural data on the bond valence results has also been considered.

• Bulletin of the Korean Chemical Society
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• 제2권3호
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• pp.79-82
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• 1981

A calculation method of the dipole moments for square planar and tetrahedral complexes by the valence bond method has been developed and an example calculation was carried out choosing the square planar and tetrahedral $[M(Ⅱ)N_2Se_2]$ type complexes. The calculated values of the dipole moments by the valence bond method are higher than those of the approximate orbital method. We found that we may predict the geometric structure of the transition metal complexes comparing the calculated values of the dipole moments with the experimental values. A new method for definition of C' parameter has also developed on the basis of extended Huckel theory.

• 대한화학회지
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• 제23권4호
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• pp.198-205
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• 1979

금속이온의 $d^2sp^3$ 혼성궤도함수와 리간드의 singIe basis set 궤도함수를 사용하여 팔면체 [M(II)O_3S_3]$형태 착물의 쌍극자모멘트를 계산하는 원자가결합법을 발전시켰다. [M(III)=V(III), Cr(III), Mn(III), Fe(III), Co(III), Ru(III), Rh(III) 및 Os(III)]. 이 새로운 방법에 있어서 금속이온의 valence basis sets와 리간드 궤도함수사이의 혼성계수가 같다고 가정할 필요가 없으며 이것이 근사분자궤도함수법에 의한 팔면체 전이원소 착물의 쌍극자모멘트를 계산하는 방법과 다른점이다. 원자가결합법에서는 근사분자궤도함수법에서 보다도 훨씬 쉽게 팔면체착물의 쌍극자 모멘트를 계산할 수 있으며 계산한 쌍극자 모멘트의 값이 또한 실험치 범위에든다.

• 한국세라믹학회지
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• 제44권3호
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• pp.175-181
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• 2007

Molecular dynamics simulation (MD) of $(62-x)CaO{\cdot}38Al_{2}O_{3}{\cdot}xBaO$ glasses has been carried out using empirical potentials with the covalent term. The simulations closely reproduce the total neutron correlation functions of glass with 5 mol% BaO and physical properties of these glasses such as elastic constants. For these glasses, aluminum is tetrahedrally coordinated by oxygen, but there is a part of five-fold and six-fold coordination of aluminum. There are no major changes to the mid-range structure of glass, as barium is substituted for calcium. To predict the barium coordination number, we have used the bond valence (BV) theory and also compared the results of simulation with Bond valence. The coordination number for oxygen around barium atoms is close to 8 and the average distance of barium and oxygen is nearly 2.80 A. The viscosity of these glasses increases with the content of barium oxide substituted for calcium oxide.

• 한국세라믹학회지
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• 제44권10호
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• pp.537-541
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• 2007

Microwave dielectric properties of $0.95 Ca_{0.85}Nd_{0.1}TiO_3-0.05LnAlO_3$ (Ln=Sm, DH, Er) were investigated as a function of sintering temperature and lanthanide ion type. A single perovskite phase with an orthorhombic structure was obtained throughout the entire range of composition. The dielectric constant (K) was dependent upon the dielectric polarizabilities and the B-site bond valence in the $ABO_3$ perovskite structure. The quality factor (Qf) of the specimens with $ErAlO_3$ was smaller than those with $SmAlO_3\;and/or\;DyAlO_3$ due to the smaller grain size. The temperature coefficient of resonant frequency (TCF) could be controlled from $107.28ppm/^{\circ}C$ at Ln=Sm to $87.23ppm/^{\circ}C$ at Ln=Er due to the changes of B-site bond valence in the $ABO_3$ perovskite structure.

• 한국재료학회지
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• 제16권6호
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• pp.394-399
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• 2006

Ferroelectric $HoMnO_3$ thin films were deposited on the Si(100) substrate at $700^{\circ}C$ for 2 hrs by metalorganic chemical vapor deposition (MOCVD) and post-annealed at 850oC by rapid thermal process (RTP). Electrical properties and crystalline phases of $HoMnO_3$ thin films were investigated as a function of postannealing time. Single phase of hexagonal symmetry with c-axis preferred orientation was obtained from $HoMnO_3$ thin films post-annealed at $850^{\circ}C$ for 5 min, while the c-axis preferred orientation was decreased with the increase of post-annealing time, and the thin films post-annealed at $850^{\circ}C$ for 15 min showed the mixture phases of hexagonal and orthorhombic symmetry. P-E (Polarization-Electric field) hysteresis loop of ferroelectric $HoMnO_3$ thin films was observed only for the single phase of hexagonal symmetry, but that was not observed for the mixture phases of the hexagonal and orthorhombic symmetry, which was discussed with the bond valence of Mn ion of crystalline phase. Leakage current density was dependent on the microstructure of thin films as well as the change of valence of Mn ion.

• 한국세라믹학회지
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• 제45권5호
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• pp.251-255
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• 2008

Microwave dielectric properties of $MgTiO_3,\;MgWO_4,\;MgNb_2O_6$, and $MgTa_2O_6$ were investigated based on the structural characteristics. The dielectric constant (K) was dependent on the dielectric polarizabilities of the specimens, and the deviation of the observed dielectric polarizabilities (${\alpha}_{obs.}$) from the theoretical dielectric polarizabilities (${\alpha}_{theo.}$) were decreased with increasing of Mg-site bond valence. Quality factors (Qf) were affected by the sharing type of $MgO_6$ and $BO_6$ octahedra. Temperature coefficient of resonant frequency (TCF) was decreased with increasing of average octahedral distortion.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2000년도 춘계총회,특별강연,심포지움,연구발표회
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• pp.89.2-89.2
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• 2000

• Bulletin of the Korean Chemical Society
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• 제34권4호
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• pp.1250-1252
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• 2013