• Journal of the Korean Chemical Society
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• v.17 no.2
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• pp.105-114
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• 1973

The crystal structure of morpholinothiosemicarbazide has been determined by single crystal X-ray analysis. The lattice constants are a = 4.19(2), b = 6.56(2) and c = 26.67(4)${\AA}$. The unit cell contains 4 molecules and the space group is$P2_12_12_1$. The atomic parameters have been refined by least-squares method to a final R value of 0.07, based on the 651 observed reflexions. The amino nitrogen atom forms hydrogen bonds to the sulfur atoms of the other molecules related by the two-fold screw axis parallel to the a-axis, the distances of the hydrogen bonds being 3.48 and 3.49${\AA}$. On the other hand, the imino nitrogen atom forms a hydrogen bond to the amino nitrogen atom of the other molecule related by the two-fold screw axis parallel to the a-axis, the distance of the hydrogen bond being 3.04${\AA}$. These three hydrogen bonds arrange the molecules around the two-fold screw axis. Apart from the hydrogen bonding system the structure is held together by van der Waals forces.

• Journal of Magnetics
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• v.21 no.1
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• pp.40-45
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• 2016

Nickel substituted nano-sized ferrite powders, $Co_{1-x}Ni_xFe_2O_4$, $Mn_{1-x}Ni_xFe_2O_4$ and $Mn_{1-2x}Zn_xNi_xFe_2O_4$ ($0.0{\leq}x{\leq}0.2$), were fabricated using a sol-gel method, and their crystallographic and magnetic properties were subsequently compared. The lattice constants decreased as quantity of nickel substitution increased, while the particle size decreased in $Co_{1-x}Ni_xFe_2O_4$ ferrite but increased for the $Mn_{1-x}Ni_xFe_2O_4$ and $Mn_{1-2x}Zn_xNi_xFe_2O_4$ ferrites. For the $Co_{1-x}Ni_xFe_2O_4$ and $Mn_{1-x}Ni_xFe_2O_4$ ($0.0{\leq}x{\leq}0.2$) ferrite powders, the $M{\ddot{o}}ssbauer$ spectra could be fitted as the superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. However, the $M{\ddot{o}}ssbauer$ spectrum of $Mn_{0.8}Zn_{0.1}Ni_{0.1}Fe_2O_4$ consisted of two Zeeman sextets and one single quadrupole doublet due to the ferrimagnetic and paramagnetic behavior. The area ratio of the $M{\ddot{o}}ssbauer$ spectra could be used to determine the cation distribution equation, and we also explain the variation in the $M{\ddot{o}}ssbauer$ parameters by using this cation distribution equation, the superexchange interaction and the particle size. The saturation magnetization decreased in the $Co_{1-x}Ni_xFe_2O_4$ and $Mn_{1-2x}Zn_xNi_xFe_2O_4$ ferrites but increased in the $Mn_{1-x}Ni_xFe_2O_4$ ferrite with nickel substitution. The coercivity decreased in the $Co_{1-x}Ni_xFe_2O_4$ and $Mn_{1-2x}Zn_xNi_xFe_2O_4$ ferrites but increased in the $Mn_{1-x}Ni_xFe_2O_4$ ferrite with nickel substitution. These variations could thus be explained by using the site distribution equations, particle sizes and spin magnetic moments of the substituted ions.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.16-21
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• 2001

Optical properties of $Ag_2CdSnSe_4$ and $Ag_2CdSnSe_4:Co^{+2}$ quaternary semiconductor single crystals grown by the chemical transport reaction method were investigated. The analysis of the X - ray powder diffraction measurements showed that these crystals have a wurtzite structure with lattice constants a = 4.357 $\AA$, c = 7.380 $\AA$, for $Ag_2CdSnSe_4$ and a = 4.885 $\AA$, c = 7.374 $\AA$, for $Ag_2CdSnSe_4:CO^{2+}$. The direct band gap at 298K, obtained from the optical absorption measurement, is found to be 1.21 eV for $Ag_2CdSnSe_4$ and 1.02 eV for $Ag_2CdSnSe_4:CO^{2+}$. The shrinkage of the band gap due to Co-doping is observed and is about 190 meV, We observed four absorption bands of $Co^{2+}$ ions in two near infrared regions of optical absorption spectra of $Ag_2CdSnSe_4$:$Co^{+2}$. These absorption bands were assigned as due to electronic transitions between the split energy levels of $Co^{2+}$ ions in $T_d$ crystal field under spin-orbit interactions.

• Journal of Magnetics
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• v.15 no.4
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• pp.159-164
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• 2010

The Zn, Co and Ni substituted manganese ferrite powders, $Mn_{1-x}$(Zn, Co, Ni)$_xFe_2O_4$, were fabricated by the solgel method, and their crystallographic and magnetic properties were studied. The Zn substituted manganese ferrite, $Zn_{0.2}Mn_{0.8}Fe_2O_4$, had a single spinel structure above $400^{\circ}C$, and the size of the particles of the ferrite powder increased when the annealing temperature was increased. Above $500^{\circ}C$, all the $Mn_{1-x}$(Zn, Co, Ni)$_xFe_2O_4$ ferrite had a single spinel structure and the lattice constants decreased with an increasing substitution of Zn, Co, and Ni in $Mn_{1-x}$(Zn, Co, Ni)$_xFe_2O_4$. The Mossbauer spectra of $Mn_{1-x}Zn_xFe_2O_4$ (0.0$\leq$x$\leq$0.4) could be fitted as the superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. For x = 0.6 and 0.8 they showed two Zeeman sextets and a single quadrupole doublet, which indicated they were ferrimagnetic and paramagnetic. And for x = 1.0 spectrum showed a doublet due to a paramagnetic phase. For the Co and Ni substituted manganese ferrite powders, all the Mossbauer spectra could be fitted as the superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. The variation of the Mossbauer parameters are also discussed with substituted Zn, Co and Ni ions. The increment of the saturation magnetization up to x = 0.6 in $Mn_{1-x}Co_xFe_2O_4$ could be qualitatively explained using the site distribution and the spin magnetic moment of substituted ions. The saturation magnetization and coercivity of the $Mn_{1-x}$(Zn, Co, Ni)$_xFe_2O_4$ (x = 0.4) ferrite powders were also compared with pure $MnFe_2O_4$.

• Journal of the Korean Magnetics Society
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• v.19 no.3
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• pp.106-112
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• 2009

$Ni_{1-x}Mg_xFe_2O_4$ ferrite system was studied by using X-ray diffraction and $M{\ddot{o}}ssbauer$ spectroscopy. The samples were prepared by ceramic sintering method with Mg content x. The X-ray diffraction patterns of samples show phase of cubic spinel structure. There are no remarkable changes of lattice constants in $Ni_{1-x}Mg_xFe_2O_4$ ferrite system. The $M{\ddot{o}}ssbauer$ spectra were consisted of two sets of six lines, respectively, corresponding to $Fe^{3+}$ at tetrahedral and octahedral sites. The magnetic hyperfine field of samples was decreased as increasing Mg contents x in both sites and it was shown Yafet-Kittel magnetic structure. $NiFe_2O_4$ was shown complete inverse spinel, but $NiFe_2O_4$ was shown partial inverse spinel which absorption area ratio (oct/tet) was 1.449 in $M{\ddot{o}}ssbauer$ spectrum.

• Journal of the Korean Magnetics Society
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• v.24 no.2
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• pp.35-40
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• 2014

We investigate magnetism and magnetocrystalline anisotropy of CoFe thin films, using VASP code in GGA. In this study Co-terminated and Fe-terminated 5-layer CoFe thin films are employed. The Co-terminated CoFe thin film shows two total energy minima at 2-dimensional lattice constants of $2.45{\AA}$ and $2.76{\AA}$. The film of $2.45{\AA}$ has fcc-like structure and the film of $2.76{\AA}$ has bcc-like structure similarly to a bulk CoFe alloy. And the fcc-like film is more stable by the energy difference of about 160 meV compared to the bcc-like film. The Fe-terminated CoFe film shows very complicated behaviour of total energy which is suspected to be closely related to its complex magnetic structure. The Co-terminated CoFe film of $2.76{\AA}$ shows perpendicular magnetocrystalline anisotropy (MCA), while the film of 2.45 does parallel MCA. The Fe-terminated CoFe film also exhibits similar MCA behaviour.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.182-187
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• 2015

The growth and characterization of micro sized AlGaN array structures selectively grown by metal organic chemical vapor deposition (MOCVD) on GaN stripes are reported. The shape of the AlGaN array structures depends on the size of exposed area for selective growth. The AlGaN array structures grown selectively on relatively large exposed area have regular shapes resembling those of the GaN stripes on the substrate, while samples selectively grown on relatively small exposed area have irregular shapes. The phonon frequency of the AlGaN array structures increases with increasing Al composition in the AlGaN structure. However, at relatively high Al composition (x = 0.28 in this research), the phonon frequency decreases slightly from the expected value not only because of large tensile strain associated with large differences between the lattice constants of the AlGaN structure and underlying GaN stripes but also changes of crystal facet direction during the selective growth.

• Korean Journal of Crystallography
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• v.7 no.1
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• pp.44-56
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• 1996

CuInTe2 synthesised in a horizontal electric furnace was found to be polycrystalline. Single crystals of CuInTe2 were grown with the vertical Bridgman technique. The structure, Hall effect of the crystals were measured in the temperature range 30 to 293K. Both the polycrystals and single crystals of CuInTe2 were tetragonal in structure. The lattice constants of the polycrytals were measured as a=6.168Å and c=12.499Å, with c/a=2.026, these of the single crystals were measured as a=6.186Å and c=12.453Å, with c/a=2.013. The growth plane of the oriented single crystals was confirmed to be a (112) plane from the back-reflection Laue patterns. The Hall effect of the CuInTe2 single crystals was measured with the method of van der Pauw The Hall data of the samples measured at room temperature showed a carrier concentration of 2.14×1023holes/m3, a conductivity of 739.58Ω-1m-1, and a mobility of 2.16×10 -2m 2/V·s for the sample perpendicular to the c-axis. Values of 1.51×1023holes/m3, 717.55Ω-1m-1, and 2.97×10-2 m2/V·s were obtained for the sample parallel to the c-axis. The Hall coefficients for the samples both perpendicular and parallel to the c-axis in the temperature range 30K to 293K were always positive values. Thus the CuInTe2 single crystal was determined to be a p-type semiconductor.

• Journal of Sensor Science and Technology
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• v.2 no.1
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• pp.3-10
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• 1993

Polycrystalline CdS thin films were grown on ceramic substrate using a chemical bath deposition method. They were annealed at various temperature and X-ray diffraction patterns were measured by X-ray diffractometer in order to study CdS polycrystal structure. Using extrapolation method of X-ray diffraction patterns for the CdS samples annealed in $N_{2}$ gas at $550^{\circ}C$ it was found hexagonal structure whose lattice constants $a_{o}$ and $c_{o}$ were $4.1364{\AA}$ and $6.7129{\AA}$, respectively. Its grain size was about $0.35{\mu}m$. Hall effect on this sample was measured by Van der Pauw method and studied on carrier density and mobility defending on temperature. From Hall data, the mobility was likely to be decreased by piezo electric scattering at temperature range of 33K and 150k and by polar optical scattering at temperature range of 150K and 293K. We measured also spectral response, sensitivity (${\gamma}$), maximum allowable power dissipation and response time on these samples.

• Journal of Sensor Science and Technology
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• v.2 no.1
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• pp.109-115
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• 1993

A CdS single crystal was grown by using sublimation method. Lattice constants, $a_{o}$ and $c_{o}$, obtained by using extrapolation were $4.131{\underline{8}}{\AA}$ and $6.712{\underline{2}}{\AA}$, respectively. The carrier density was${\sim}10^{23}m^{-3}$ and the mobility was $2.93{\times}10^{-2}m^{2}$/V sec from measured Hall data at room temperature. The mobility has a increasing tendency in proportion to $T^{1/2}$ from 33 K to 150 K and a decreasing tendency in proportion to $T^{-2}$ from 180 K to room temperature. The short wavelength band peak measured from photocurrent was due to intrinsic transition, and the energy value of this peak was equal to the energy band gap of CdS photoconductor.