• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2608-2612
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• 2009

The unequivocal solid-state structure and stereochemistry of the hetaryl leuco-TAM dye, 2,2’-(2-phenyl propane- 1,3-diylidene) bis(1,3,3- trimethylindoline) derivatives were established using X-ray single crystal analysis. The X-ray crystal analysis showed that the (Z, E)-isomers only formed stereoselectively, with a so-called “threebladed propeller” conformation, from the reaction of a Fischer base and benzaldehyde derivatives. These isomers were stacked in a juxtaposition to form a dimer or a double dimer, adopting either a triclinic, with P-1, or monoclinic crystal system with a space group P21/n in the unit cell of the crystal.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.630-635
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• 2011

Bismuth vanadate($BiVO_4$) with monoclinic phase as photocatalyst under visible light is synthesized by precipitation reaction in hot water. Properties such as crystal phase, particle morphology and visual light absorbance as well as the effects of thermal treatment for $BiVO_4$ powders are investigated. $BiVO_4$ powders with both single monoclinic phase and 0.2 ${\mu}m$ in particle size are synthesized when precipitate is stirred in water for 5 h at 95$^{\circ}C$. Well-developed monoclinic phase and light absorption property under 535 nm are observed as a result of thermal treatment for 1 h at 300$^{\circ}C$ after precipitation reaction in water for 5 h at 95$^{\circ}C$. Degradation of monoclinic crystal is found in firing above 350$^{\circ}C$, and particle growth is occurred in firing above 550$^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.4
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• pp.171-174
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• 2004

The $Ag_2Te$ crystal was grown by the Bridgman method. The $Ag_2Te$ crystal was an monoclinic structure with lattice constance a = $8.1686{\AA}$, b = $9.0425{\AA}$, c = $8.0065{\AA}$. Hall effect shows a n-type conductivity in the $Ag_2Te$ crystal. The electrical resistivity was 1.080e-$3{\Omega}cm$ and electron mobility was $-5.48{\times}10^3cm^2/V{\cdot}sec$ at room temperature(RT).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.5
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• pp.205-211
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• 2022

The Granule Spray in Vacuum (GSV) process is a method of forming a dense nanostructured ceramic coating film by spraying ceramic granules on a substrate at room temperature in a vacuum. In the Granule Spray, the granules made by agglomerating particles with the size from submicrometer to micrometer can be sprayed into the substrate. Once the granules were squashed upon collision with the substrate, they become several dozens of nanometer-sized crystals in vacuum process. The zirconia of the monoclinic phase transform into tetragonal phase at 1150℃. At this time, its volume is changed by about 6.5 %. For this reason, it is widely held that it is difficult to acquire a compact of monoclinic zirconia sinter. In this study, the effect of particle treatment temperature and standoff distance on the substrate of zirconia granules were investigated in GSV. Also, particle treatment temperature, standoff distance, coating efficiency, and microstructure of the film were considered in forming the monoclinic zirconia coating film in GSV without any heating process. The deposited films exhibited monoclinic zirconia phase without any other detectable phase by X-ray diffractometer (XRD).

• Proceedings of the Korean Magnestics Society Conference
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• 2011.06a
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• pp.7-8
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• 2011

Basically, the lattice mismatch between film and substrate can make those BiFeO3(BFO) films distorted with strain structure. BFO phase can be stabilized on LaAlO3(LAO) represents the example of a multiferroic with giant axial ratio. Its crystal structure is not strictly tetragonal, but tetragonal with a slight monoclinic distortion and related to the rotation of the oxygen octahedra. In this study, we show that phases with a tetragonal-like epitaxial BFO films can indeed be ferroelectric and also can be stabilized via epitaxial growth onto LAO. Recent reports on epitaxial BFO films show that the crystal structure changes from nearly rhombohedral ("R-like") to nearly tetragonal("T-like") at strains exceeding approximately -4.5%, with the "T-like" structure being characterized by a highly enhanced c/a ratio. While both the "R-like" and the "T-like" phases are monoclinic, our detailed x-ray diffraction results reveal asymmetry change from MA and MC type, respectively. By applying additional strain or by modifying the unit cell volume of the film by substituting Ba for Bi, the monoclinic distortion in the "T-like" MC phase is reduced, i.e. the system approaches a true tetragonal symmetry. There are two different M-H loops for $Bi_{1-x}Ba_xFeO_{3-{\delta}}$(BBFO) and BFO films on SrTiO3(STO) & LAO substrates. Along with the ferroelectric characterization, these magnetic data indicate that the BFO phase stabilized on LAO represents the first example of a multiferroic with giant axial ratio. However, there is a significant difference between this phase and other predicted ferroelectrics with a giant axial ratio: its crystal structure is not strictly tetragonal, but tetragonal with a slight monoclinic distortion. Therefore, in going from bulk to highly-strained films, a phase sequence of rhombohedral(R)-to-monoclinic ["R-like" MA-to-monoclinic, "T-like" MC-to-tetragonal (T)] is observed. This sequence is otherwise seen only near morphotropic phase boundaries in lead-based solid-solution perovskites (i.e. near a compositionally induced phase instability), where it can be controlled by electric field, temperature, or composition. Our results show that this evolution can occur in a lead-free, stoichiometric material and can be induced by stress alone. Those major results are summarized as follows ; 1) Ba-doping increases the unit cell volume, 2) BBFO on LAO can be fully strained up to x=0.08 as a strain limit (Fig. 1), 3) P(E) & M(H) properties can be tuned by the variation of composition, strain, and film thickness.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.2
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• pp.62-67
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• 2008

An Organometallic compound, $C_{12}H_{20}B_{10}S_2Co_2$, was synthesized from o-carborane, $Cp^*Co(S_2B_2B_{10}H_{10})$ and $BH_3{\cdot}THF$. The molecular structure of this complex has been determined by X-ray diffraction. Crystallographic data: monoclinic, space group Cc, a=15.981(4) ${\AA}$, b=15.478(17) ${\AA}$, c=12.0562(17) ${\AA}$, ${\beta}=115.063(16)^{\circ}$, Z=4, V=9683(4) ${\AA}^3$. The structure was solved by direct methods and refined by full-matrix leat-squares methods to give a model with a reliability factor R = 0.0630 for 9948 reflections.

• Coupled systems mechanics
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• v.6 no.1
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• pp.41-54
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• 2017

Shape-memory alloys (SMA) have interesting behaviors and important mechanical properties due to the solid-solid phase transformation. These phenomena are dominated by the evolution of microstructures. In recent years, the microstructures in SMAs have been studied extensively and modeled using molecular dynamics (MD) simulations. However, it remains difficult to identify the crystal variants in the simulation results, which consist of large numbers of atoms. In the present work, a method is developed to identify the austenite phase and the monoclinic martensite crystal variants in MD results. The transformation matrix of each lattice is calculated to determine the corresponding crystal variant. Evolution of the volume fraction of the crystal variants and the microstructure in Ni-Ti SMAs under thermal and mechanical boundary conditions are examined. The method is validated by comparing MD-simulated interface normals with theoretical solutions. In addition, the results show that, in certain cases, the interatomic potential used in the current study leads to inconsistent monoclinic lattices compared with crystallographic theory. Thus, a specific modification is applied and the applicability of the potential is discussed.

• Korean Journal of Crystallography
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• v.7 no.2
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• pp.196-200
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• 1996

The transformation processes from unit cell data, Miller indices and atomic coordinates of non-standard space groups to the ones of the standard space groups in monoclinic system and the calculation processes of their standard deviations have been shown and computerized. The computer programs can be applied to all the seven crystal systems.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1568-1571
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• 2005

We have evaluated thermal stability of a $BaAl_2Si_2O_8:Eu^{2+}$ $(BAS:Eu^{2+})$, which have polymorph property such as hexagonal, monoclinic structure depending upon firing temperature. When both polymorph $BAS:Eu^{2+}$ were baked in air at 500 $^{\circ}C$ for 30 min, the photoluminescence (PL) intensity of $monoclinic-BAS:Eu^{2+}$ was maintained of the initial intensity. However, the PL intensity of $hexagonal-BAS:Eu^{2+}$ decreased significantly, corresponding to about 34 %. From analyses of Rietveld refinement, the difference of thermal stability of both $BAS:Eu^{2+}$ can be ascribed to both crystal structure of host materials and the average interatomic distances between $Eu^{2+}$ ion and oxygen their crystal structure which plays a key role of shield for Eu2+ ions against oxidation atmosphere.

• Bulletin of the Korean Chemical Society
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• v.16 no.9
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• pp.835-839
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• 1995

Mer,trans-Re(≡NC6H5)(PPh3)2Cl3, Ⅰ, reacted with trimethylphosphine to give a mixture of two stereoisomers, mer,trans-Re(≡NC6H5)(PMe3)2Cl3,Ⅱ, and fac,cis-Re(≡NC6H5)(PMe3)2Cl3, Ⅲ. These compounds could also be prepared from the reaction of Re(≡NC6H5)(PMe3)(PPh3)Cl3 with trimethylphosphine. In both reactions the mer,trans-isomer is a major product. The products have been characterized by NMR, elemental analysis, and X-ray crystallography. Crystal data for Ⅱ: monoclinic space group P21, a=10.053(1) Å, b=10.844(1) Å, c=10.058(2) Å, β=113.45(2)°, Z=2, R(wR2)=0.0348 (0.0894). Crystal data for Ⅲ: monoclinic space group P21/n, a=7.183(2) Å, b=16.983(4) Å, c=15.543(4) Å, β=90.38(2)°, Z=4, R(wR2)=0.0603 (0.1484).