• 암석학회지
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• 제6권2호
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• pp.88-95
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• 1997

High pressure X-ray diffraction study was carried out on a polycrystalline graphite to investigate the phase transition(s) at room temperature. Energy dispersive X-ray diffraction method was employed using a Mao-Bell type diamond anvil cell with an Wiggler synchrotron Radiation at the National Synchrotron Light Source. Sodium chloride power was used as the internal pressure sensor for the high pressure determinations as well as the pressure medium for quasihydrostatic pressure environment. Graphite transforms into a hexagonal didose not agree with the previously reported observations and this phase persists when pressure is released down to 0.1 MPa. This result dose not agree with the previously reported observations and this discrepancy would be due to the kinetics in phase transition as well as the uniaxially oriented pressure field in the diamond anvil cell.

• The Korean Journal of Ceramics
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• 제3권2호
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• pp.82-87
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• 1997

High pressure FTIR and Raman spectra of soild $C_{70}$ were measured at pressure up to 11 GPa and room temperature. The slope (dv/dp) of the frequency-pressure plots for several IR and Raman mode changed around 1.5 GPa, where a solid-solid transition might occur. In IR study, we can observe new mode appeared around 777$cm^{-1}$1 above 5.5 GPa which might indicate another solid-solid transition. Our study showed that this transition might be irreversible.

• 암석학회지
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• 제3권1호
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• pp.34-40
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• 1994

High pressure X-ray diffraction study was carried out on a graphite to investigate its compressibility as well as any possible phase transition to the hexagonal diamond structure at room temperature. Energy dispersive X-ray diffraction method was introduced using a Mao-Bell type diamond anvil cell with Synchrotron Radiation. Polycrystalline sodium chloride was compressed together with graphite for the high pressure determinations. Because of the poor resolution of the X-ray diffraction pattern of graphite, its compressibility was estimated to be almost same as that of NaCl by graphite (002) X-ray diffraction peak only. An observation of any new peak from a possible hexagonal diamond phase seems very unplausible for its definite identification based on the present data. Alternative approaches such as an Wiggler Radiation source as well as a Large Volume high pressure apparatus will be necessary for the detailed studies on a graphite in future.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2001년도 정기총회 및 춘계학술대회연구발표회(한국결정학회)
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• pp.10-11
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• 2001

• 한국광물학회지
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• 제9권1호
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• pp.35-42
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• 1996

Polycrystalline ZrH2 in tetragonal crystal system has been compressed in a modified Bassett-type diamond anvil cell up to 36.0 GPa at room temperature. X-ray diffraction data did not indicate any phase transitions at the present pressure range. The pressure dependence of the a-axis, c-axis, c/a and molar volume of ZrH2 was determined at pressures up to 36.0 GPa. Assuming the pressure derivative of the bulk modulus (K0') to be 4.11 from an ultrasonic value on Zr, bulk modulus (K0) was determined to be 160Gpa by fitting the pressure-volume data to the Birch-Murnaghan equation of state. Same sample was heated at $500^{\circ}C$ at the pressure of 9.8 GPa in a modified Sung-type diamond anvil cell. Unloaded and quenched sample revealed that the original tetragonal structure transforms into a hexagonal structured phase with a zero-pressure molar volume change of ~115.5%.

• 한국광학회지
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• 제24권5호
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• pp.279-286
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• 2013

Brillouin spectroscopy has been widely used for the investigation of acoustic properties of condensed matters in the hypersonic region. A high-pressure Brillouin spectrometer was set up by combining a diamond anvil cell and a tandem multi-pass Fabry-Perot interferometer. It was successfully applied to liquid ethanol, and the pressure dependence of the sound velocity, the refractive index and other acoustic properties were derived based on the measurements. The detailed optical setup and experimental procedure are described.

• 한국세라믹학회지
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• 제48권5호
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• pp.471-478
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• 2011

Investigations of crystal structure and phase transition of $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics doped with A-site substitution impurity (La, Nd) or B-site substitution impurity (Sb, Nb) at 2 mol% concentration were carried out. X-ray diffraction patterns of impurities doped $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics have been measured at pressures up to ~5 GPa with diamond anvil cell and synchrotron radiation. The patterns were obtained at room temperature using methanol-ethanol mixture as pressure-transmitting media. In order to refine the crystal structure, Rietveld analysis has been performed. The structures of impurities doped $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics are tetragonal in space group P4mm at ambient pressure and are transformed into a cubic phase in space group Pm$\bar{3}$m as the pressure increases. In this study, when A-site substitution donor $La^{3+}$ or $Nd^{3+}$ ion was added to $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics, the phase transition phenomena showed up at the pressure of 2.5~4.6 GPa, but when B-site substitution donor $Nb^{5+}$ or $Sb^{5+}$ ion was added to it, the phase transition appeared at relatively lower pressure of 1.7~2.6 GPa.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2007년도 춘계 지질과학기술 공동학술대회
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• pp.157-157
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• 2007

See Full Text

• 한국광물학회지
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• 제22권4호
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• pp.325-330
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• 2009

합성 FeOOH-괴타이트 분말시료에 대한 고압실험을 압축성을 검증하기 위해 상온에서 시행하였다. 방사광이용 실험장치에서 대칭다이아몬드 앤빌기기를 각분산회절방법으로 배열하여 실험을 하였다. $K_{T'}$ 값을 4.0으로 가정하였을 때, 체적탄성률은 222.8 GPa로 계산되었다. 이 값은 천연산 괴타이트로부터 얻은 기존의 값과 비교하여 볼 때 매우 높은 값으로, 시료의 생성조건에 따라 나타나는 물질의 압력에 대한 이상 거동에 대해 고찰하였다.

• 한국광물학회지
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• 제10권2호
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• pp.75-81
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• 1997

High pressure X-ray diffraction study was carried out on a natural FeO(OH)-goethite to investigate its compressibility at room temperature. Energy dispersive X-ray diffraction method was employed using Mao-Bell type diamond anvil cell with Synchrotron Radiation. MgO powder was compressed together with goethite for the high pressure determinations. Bulk modullus was determined to be 147.9 GPa by the Birch-Murnaghan equation of state under assumption of K0' of 4. This value was subjected to compare with its structural analogs and related materials.