• 한국결정성장학회지
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• 제14권1호
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• pp.21-26
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• 2004

HPHT(고온고압) 처리된 type IIa 다이아몬드의 분광분석 결과를 나타내었다. 그리고 HPHT 처리된 다이아몬드 spectrum의 특성을 이와 유사한 color와 type을 가진 처리되지 않은 다이아몬드와 비교하였다. 325nm 에서 여기된 He/Cd laser로는 HPHT 처리된 다이아몬드와 처리되지 않은 다이아몬드에 현저한 변화가 있음을 알 수 있었는데 이는 HPHT 처리된 다이아몬드의 spectrum에서 H3, H4에 관련된 peak가 제거되고 N3 system에 관련된 peak의 emission이 증가함을 보여 주었다. 또한 514nm에서 여기된 Ar-ion laser로 측정된 spectrum은 575nm와 637.1 nm에서 Nitrogen과 vacancy가 관련되어있는 N-V center가 발견 되었는데 이러한 center가 존재하고 있을 경우 637.1 nm의 FWHM의 값은 HPHT 처리된 다이아몬드와 처리되지 않은 다이아몬드를 구분할 수 있음을 보여주었다. 본 실험에서 측정된 HPHT 처리된 다이아몬드의 637.1nm $(N-V)^-$의 FWHM 값은 $19.8{\textrm}{cm}^{-1}$에서$32.1{\textrm}{cm}^{-1}$였다.

• 한국세라믹학회지
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• 제49권3호
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• pp.221-225
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• 2012

It is possible to enhance the color of the natural diamond with a high pressure high temperature(HPHT) process. We employed a pyrophyllite tube cell and cubic press apparatus for HPHT treatment on the brown colored Type II (5.6 GPa/ $1700^{\circ}C$/ 52 min), and Type I aB(5.6 GPa/ $1650^{\circ}C$/ 30 min) diamond samples. We investigated the microstructure, Types, fluorescence, properties of the diamonds with an optical microscopy, FT-IR, photoluminescence(PL) spectroscopy, Diamond-View, and micro-Raman spectroscopy. Two tinted brown diamonds changed into colorless just after the HPHT process. Optical microscopy showed that no crack and significant inclusion evolution occurred during the HPHT process except the small graphite spot appeared in Type I aB sample. FTIR spectrum confirmed that no Type, amber center, and platelet defect change with the HPHT treatment. Diamond-View could not distinguish the HPHT treated diamonds from the naturals. PL spectroscopy showed that N3 and H3 color centers remained even after HPHT process. Consequently, we successfully changed the color of diamonds into colorless by 5.6 GPa HPHT process.

• 한국세라믹학회지
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• 제49권6호
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• pp.614-619
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• 2012

We investigated color and graphite layer formation on the surface of Type I tinted brown diamonds exposed for 5 minutes under a high-pressure high-temperature (HPHT) condition in a stable graphite regime. We executed the HPHT processes of Process I, varying the temperature from $1600^{\circ}C$ to $2300^{\circ}C$ under 5.2 GPa pressure for 5 minutes, and Process II, varying the pressure from 4.2 to 5.7 GPa at $2150^{\circ}C$ for 5 minutes. Optical microscopy and micro-Raman spectroscopy were used to check the microstructure and surface layer phase evolution. For Process I, we observed a color change to vivid yellow and greenish yellow and the growth of a graphite layer as the temperature increased. For Process II, the graphite layer thickness increased as the pressure decreased. We also confirmed by 531 nm micro-Raman spectroscopy that all diamonds showed a $1440cm^{-1}$ characteristic peak, which remained even after HPHT annealing. The results implied that HPHT-treated colored diamonds can be distinguished from natural stones by checking for the existence of the $1440cm^{-1}$ peak with 531 nm micro-Raman spectroscopy.

• 한국결정성장학회지
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• 제13권1호
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• pp.31-35
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• 2003

PL data에 의해 다이아몬드가 HPHT(고온고압)으로 처리하는 과정을 거치면서 격자 내에 불순물 원자뿐만 아니라 공공과 침입형 원자의 움직임과 감소, 소멸, 생성 등으로 일부 격자가 재배열됨이 드러났다. 특히, PL spectrum은 Type IIa 다이아몬드가 가지는 매우 작은 양의 질소 불순물도 명확히 나타났으며, 이로 인해 상당한 수의 점결함이 결정 격자 내에 분산되어 있음을 알 수 있었다.

• 한국재료학회지
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• 제20권5호
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• pp.278-288
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• 2010

High Pressure High Temperature (HPHT) treatment can significantly change the color of diamonds. We studied the variation of the optical properties according to the nitrogen arrangement in natural brown diamonds of various types (type IaAB, type IaB, type IaA > B, type IaA < B, IaA = B) after HPHT treatment. The diamonds with different arrangements of nitrogen were annealed at temperatures in the range $1700-1800^{\circ}C$ under a stabilizing pressure of 5 GPa. HPHT treated samples were analyzed using UV-Vis-NIR, FT-IR, and PL spectroscopy. The absorption and luminescence spectra were measured to compare the variations of nitrogen arrangement in the natural brown diamonds before and after HPHT treatment. After HPHT treatment, the brown coloration in all types of diamonds was reduced and a decrease in the peaks related to the A-aggregate of nitrogen was more predominant than the B-aggregate. Furthermore, the peaks related to N3 (415.4 nm), H4 (496.4 nm), and platelet decreased and the peaks related to H3 (503.2 nm) and G-band increased after HPHT treatment. In conclusion, spectroscopic analysis of natural brown diamonds after HPHT treatment showed that a yellow color was produced by absorption in the H3 centers and a green color was generated by interaction between absorptions of the H3 and H2 centers.

• 한국축산식품학회지
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• 제33권4호
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• pp.474-480
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• 2013

This study was performed to investigate the effects of high pressure/high temperature (HPHT) treatment on the recovery efficiency and characteristics of porcine placenta hydrolysates. The placenta hydrolysates were characterized by solubility, free amino acid contents, gel electrophoresis, gel permeation chromatography (GPC) and amino acid composition. Placenta was treated at 37.5 MPa of pressure combined with various temperatures (150, 170, and $200^{\circ}C$) or various holding times (0, 30, and 60 min at $170^{\circ}C$). Insoluble raw placenta collagen was partially solubilized (> 60% solubility) by the HPHT treatment. Free amino group content of placenta collagen was increased from 0.1 mM/g collagen to > 0.3 mM/g collagen after HPHT treatment, reflecting partial hydrolysis of collagen. The molecular weight ($M_w$) distribution showed evidence of collagen hydrolysis by shifting of $M_w$ peaks toward low molecular weight when treated temperature or holding time was increased. Alanine (Ala), glycine (Gly), hydroxyproline (Hyp), and proline (Pro) contents increased after the HPHT treatments compared to a decrease in the others. In particular, the increase in Gly was obvious, followed by Hyp and Pro, reflecting that placenta hydrolysates were mainly composed of these amino acids. However, increasing temperature or holding time hardly affected the amino acid compositions. These results indicate that the HPHT treatment is advantageous to hydrolyze collagen derived from animal by-products.

• 한국세라믹학회지
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• 제49권6호
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• pp.493-497
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• 2012

We propose a new reliable, fast, and low cost identification method for similarly looking 0.3ct vivid yellow color of natural, HPHT treated, and synthesized diamonds. Conventional optical microscopy as well as low temperature PL(photoluminescence), FT-IR, UV-VIS-NIR, micro-Raman spectroscopy, and vibrating sample magnetometry(VSM) characterization were executed. We could not distinguish the natural diamonds from the treated or the synthesized stones with an optical microscopy, PL, FT-IR, and UV-VIS-NIR spectroscopy. However, we could identify the treated diamond with micro-Raman spectroscopy due to unique $1440cm^{-1}$ peak appearance. VSM revealed easily the synthesized diamond because of its ferromagnetic behavior. Our preliminary propose on employing the Micro-Raman spectroscopy and VSM might be suitable for identification of the similar looking vivid yellow colored diamonds.

• 한국산학기술학회논문지
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• 제7권5호
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• pp.817-822
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• 2006

다이아몬드는 산업적으로도 보석으로서도 경제적으로 매우 유용한 소재이다. 최근의 소형 고압고온 처리기의 발달로 저급한 갈색의 보석용 천연다이아몬드를 쉽게 고부가가치의 보석인 무색 또는 팬시칼라의 다이아몬드로 향상시키는 처리기술이 가능하게 되었다. 이러한 처리 다이아몬드는 천연의 무색, 팬시칼라 다이아몬드와 물성이 동일하여 기존의 보석감정 방안으로는 구별이 어려워서, 처리 다이아몬드를 경제적이고, 신속하고, 비파괴적으로 천연다이아몬드로부터 감별해 낼 필요성이 생겼다 기존의 광학적인 확대분석으로는 천연석과 처리석의 감별이 불가능하였다. 마이크로 라만 분석기를 이용하여 다이아몬드의 고유피크가 고압고온 처리시의 잔류응력에 의해 이동되는 현상으로 처리석의 감별 가능성을 확인하였다. Type I 다이아몬드는 처리에 의해 $10^4$ 정도의 압축스트레인이, Type II는 인장 잔류 스트레인이 존재하였다. 따라서 적절한 처리전의 기준시료가 있다면 이러한 잔류응력을 확인하는 것이 가능하였다.

• 한국표면공학회지
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• 제39권5호
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• pp.229-234
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• 2006

Diamonds have been widely employed as polishing media for precise machining and noble substrates for microelectronics. The recent development of the split sphere press has led to the enhancement of low quality natural diamonds. Synthesized and treated diamonds are sometimes traded deceptively as high quality natural diamonds because it is hard to distinguish among these diamonds with conventional gemological characterization method. Therefore, we need to develop a new identification method that is non-destructive, fast, and inexpensive. We proposed using new methods of UV fluorescence and X-ray Lang topography for checking the local HPHT stress field to distinguish these diamonds from natural ones. We observe unique differences in the local stress field images in treated diamonds using UV fluorescence and Lang topography characterization. Our result implies that our proposed methods may be appropriate for identification of the treated diamonds.

• 한국광물학회지
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• 제21권4호
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• pp.435-442
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• 2008

천연, 합성, 그리고 처리된 보석용 다이아몬에 대한 NMR과 EPR 실험을 수행하였다. 동일한 실험조건에서 비교적 짧은 100 분의 실험시간 동안에 얻어진 $^{13}C$ NMR 스펙트럼을 통해 천연과 합성다이아몬드, 처리된 다이아몬드와 처리되지 않은 다이아몬드, 그리고 고온고압 처리된 다이아몬드와 전자빔 처리된 다이아몬드가 각각 서로 구별될 수 있는 가능성을 확인하였다. 보석용 합성 다이아몬드는 촉매제로 흔히 사용되는 전이금속의 상자기성 영향으로 $^{13}C$ NMR의 선폭이 1.6 ppm 이상으로 얻어졌고, 보석용 천연 다이아몬드는 처리방법에 무관하게 그 선폭이 0.5 ppm 이하로 얻어졌다. 고온고압 처리된 보석용 천연 다이아몬드의 선폭(0.5 ppm)은 전자빔 처리된 다이아몬드의 선폭(0.2 ppm) 보다 두 배 이상 넓은 것으로 나타났다. 처리된 보석용 천연 다이아몬드의 $^{13}C$ NMR 신호 세기는 처리되지 않은 보석용 천연 다이아몬드의 신호 세기에 비해 10배 이상 높게 얻어졌다. EPR 스펙트럼을 이용해 얻은 각 다이아몬드의 상자기성 결함(전자)의 농도와의 상관성을 검토해 본 결과, $^{13}C$ NMR 신호의 상대적 세기는 각 시료들에 함유되어 있는 상자기성 전파의 농도에 비례하여 증가하지만 전자빔 처리된 다이아몬드의 경우는 예외임이 밝혀졌다. 이를 통해 전자빔 처리된 다이아몬드의 경우 NMR 신호의 세기를 정하는 인자로 상자기성 불순물 성분 이외에 격자 성분도 고려해야 됨을 알 수 있었다.