• 한국광물학회지
• /
• 제17권3호
• /
• pp.201-208
• /
• 2004

천연산 헤덴버자이트(Ca,Fe) $SiO_3$ 시료에 대해 일정한 압력 하에서 약 $1200^{\circ}C$ 정도로 가열한 후, x-선 회절실험을 시행하였더니 14～24 GPa 압력구간에서 등축정계에 속하는 석류석 상이 관찰 되었다. $CaSiO_3$-석류석 상에 대한 체적탄성률 = 155 GPa 및 $V_{\Phi}$ = 6.58 km/sec 및 기타 탄성특성을 유사구조의 계통과 $KV_{m}$ = 상수 및 $V_{\Phi}$$M^{$\frac{1}{2}$}$ = 상수 관계식을 이용하여 추정하였다 석류석 상은 천연산 헤덴버자이트에 상당량 포함되어 있는 Mn과 많은 미량원소에 의해 상당히 넓은 압력에 걸쳐 안정영역을 구축하며, 비가역적 반응을 보인다. Ca의 포용광물로 $CaSiO_3$-석류석 상은 맨틀전이대의 주요 광물상의 하나로 간주할 수 있다.

• 한국결정성장학회:학술대회논문집
• /
• 한국결정성장학회 1996년도 The 9th KACG Technical Annual Meeting and the 3rd Korea-Japan EMGS (Electronic Materials Growth Symposium)
• /
• pp.351-374
• /
• 1996

Various types of garnet compounds were synthsized by iso-and aliovalent substitutions and sintering method. Among them, fiber shapes of garnet crystals were grown from the $Ca_3Li_xNb_{(1.5+x)}Ga_{(3.5-2x)}O_{12}$ melt where x = 0 ~ 0.5 by modified micro-pulling down method in air using Pt crucibles. The measured lattice constants as a function of solidification fraction of grown fiber crystals are about $12.54\;{\AA}$ irrespective of x. It was found that the $Ca_3Li_{0.275}Nb_{1.775}Ga_{2.95}O_{12}$ garnet melts congruently at about $1450\;^{\circ}C$ based on the purities of garnet phase and variations of lattice parameter. Transparent and bubble-free crystals of x = 0.25 and 0.275 were grown by Czochralski techniques in air using Pt crucibles. An absorption spectrum is also reported.

• 한국지구과학회지
• /
• 제25권1호
• /
• pp.39-47
• /
• 2004

In the FMAS system the effect of iron on alumina solubility in orthopyroxene has been determined by experiments with crystalline starting mixtures of garnet and orthopyroxene of known initial compositions at 20 kb, 975$^{\circ}C$ and 25 kb, 1,200$^{\circ}C$. These data have been modeled to develop a thermodynamic method for the calculation of Al$_{2}$O$_{3}$ in orthopyroxene as a function of P, T and composition. The direct application of the alumina solubility data in the MAS system to natural assemblages could lead to significant overestimation of pressure, probably by about 5kb for the relatively common garnet-lherzolites with abot 25 mol per cent Ca + Fe$^{2+}$ in garnet and about 1 wt. per cent Al$_{2}$O$_{3}$ in orthopyroxene since the effect of Fe is similar to that of Ca and Cr$^{3+}$in reducing the alumina solubility in orthopyroxene in equilibrum with garnet relative to that in the MAS system.

• 한국세라믹학회지
• /
• 제47권6호
• /
• pp.608-612
• /
• 2010

Uvarovite Garnet is green pigment prepared by using $Cr_2O_3$, CaO and $SiO_2$ which are widely used in ceramic industry. The synthesis of above pigment was carried out by mixing $K_2Cr_2O_7$, $SiO_2$ and $CaCO_3$ as formulated and then firing at $1000{\sim}1200^{\circ}C$. To investigate the optimum synthesis condition of the Uvarovite Garnet. it was prepared by using CaO to replace $CaCO_3$, $CaF_2$ and $CaCl_2$. To get green brighter color, $Al^{3+}$ was substituted for $Cr^{3+}$. They were characterized by X-ray diffraction, UV-Vis spectroscopy, Raman spectroscopy and SEM analysis. When the pigments were applied to lime glazes (6 wt%), color parameters of Uvarovite Garnet showed the $L^*$=40.99, $a^*$=-16.23 and $b^*$=17.04.

• 자원환경지질
• /
• 제24권4호
• /
• pp.335-346
• /
• 1991

It is observed that calcareous nodules of the Hwajeol Formation are locally skarnized in the Sangdong district, in which the skarn mineralization extends 5 Km westward from the Sangdong mine area to the Hwajeolchi area. After a hidden granite beneath the Sangdong mine was discovered by exploration drillings, the exploration teams of the Sangdong mine and the Korean Mining Promotion Corporation have assumed that the skarn nodule of the Hwajeol Formation was derived from emplacement of a granite in deep place and the occurrence of hidden ore bodies below the skarn, and they have discovered high grades of tungsten orebody in the same horizon of the Sangdong ore body. Mutual genetic relatioships between epidote and garnet may be explained by following chemical reactions $Ca_2FeA_{12}$ $Si_3O_{12}(OH)+CaCO_3=Ca_3(Fe,\;Al)_2$ $SiO_{12}+1/2CO_2+1/2H^+Ca_3FeSi_3O_{12}+SiO_2+CO_2=2CaFeSi_{12}O_6+CaCO_3+1/2O_3$. It is concluded that epidote and garnet are useful as target minerals indicating a potential occurrence of deep seated hidden ore body. Since the epidote may inform the emplacement of the granite, while the garnet in the skarn nodule of the Hwajeol Formation may reflect a strong hydrothermal mineralization taking place from the depth.

• 암석학회지
• /
• 제2권2호
• /
• pp.63-73
• /
• 1993

The assemblage epidote and grandite garnet occurs in low-to medium-grade metabasites and calc schists of various geotectonic settings and in hydrothermally altered calcareous rocks in skarn deposits. The compositions of sixteen epidote-garnet paris have been analysed by means of electron microprobe. Al-Fe partitioning between coexisting grandite garnet and epidote is considered and measured at the grain boundaries on the supposition that the surface equilibrium was maintained in the following exchange reaction: 2$Ca_2Al_3Si_3O_12$(OH)+$Ca_3Fe_2Si_3O_12$=2$Ca_2A_l2FeSi_3O_12$(OH)+$Ca_3Al_2Si_3O_12$ Partition coefficients confirms the differences in thermal conditions between low-grade and medium-grade metamorphic rocks. $K_D$ values ($X_{$CO_2$}$=($Fe^{+3}$/Al)$^{Ep}$/($Fe^{+3}$/Al)$^{Gr}$, where Fe=$Fe^{+3}$) from greenschist facies rocks of the estimated metamorphic temperatures, 330~$390^{\circ}C$, range approximately between 0.02 and 0.17. Epidote-amphibolite facies rocks and calcareous skarns of the estimated temperatures, 400~$550^{\circ}C$, have $K_D$ values between 0.24 and 0.37. $K_D$ values from the rocks of the temperatures, 640~$700^{\circ}C$, range nearly between 0.58 and 0.75. The diagrams in Figs. 2 and 3 can serve as a mineralogic thermometer for relatively shallow rocks, assuming that the pressure dependence of partition coefficients for the iron-exchange reaction in the two minerals can be neglected.

• 전자공학회논문지D
• /
• 제34D권12호
• /
• pp.14-21
• /
• 1997

This study was conducte dto fabricate 2GHz circulator using Ca,Sn substituted UIG(yttrium iron garnet)ceramics. When the electric, magnetic and microwave properties were measured in Ca, Sn substituted YIG, the measured perimittivity and perfmeability in microwave frequencies were 16.25, 0.8964. For $Y_{2.4}$C $a_{0.3}$A $n_{0.3}$F $e_{3.5}$A $l_{1.5}$ $O_{12}$ garnet ceramics sintered at 1400.deg. C, the ferrimagnetic resonance line width (.DELTA.H) at 10GHz was 53 Oe and saturation magnetization was 375G. The strip-line circulator was simulated with 3-D FEM (finite element method) software and designed at the center frequency of 2GHz. The fabricated strip-line junction circulator using above YIG ceramics had insertion loss of 1.271dB, return loss of 23.843dB, isolation of 21.751dB at the center frequency 1.855GHz.z.z.z.z.z.z.

• 자원환경지질
• /
• 제18권2호
• /
• pp.139-150
• /
• 1985

Skarn at the Dielette formed largely in calc-silicate hornfels at the contact with the Flamanville granite. The skarn consists mainly of garnet and pyroxene, and less frequently vesuvianite. Traversing toward calc-silicate hornfels wall rock from a central zone of the skarn, the general sequence of formation of mineral assemblages is: (1) dark brown garnet (2) pale brown garnet-vesuvianite-pyroxene, and (3) pyroxene-prehnite-scapolite-wollastonite envelopes (designated as transition zone) developed between skarn and calc-silicate hornfels. The central zone of the skarn consists mainly of dark brown garnets (garnet I) that contain little or no pyroxene. The pale brown garnet (garnet II) is associated with pyroxene and vesuvianite. The sequence of these garnets results from the zonal growth outward. There is an abrupt discontinuity in composition between garnet I formed in early stage and garnet II in late stage, while each garnet shows relatively uniform composition. At the zone in contact with the granite, the iron contents of garnets decrease toward the marginal zone of the skarn, from an average value of 36 mole % andradite in garnet I to 18 mole % andradite in garnet II. At the zone distant from the granite, the andradite component decreases from 28 mole % in garnet 1 to 19 mole % in garnet II. The variation of the iron contents of pyroxenes is also similar to that of garnets. The sharp discontinuity in composition of garnets and pyroxenes suggests that the skarn of study area was formed by infiltration metasomatic process. The results of the analyses of mineral assemblages of the transition zone by chemical potential diagrams suggest that the transition zone was made by the diffusion of the elements Ca, K and Fe from the skarn to the calc-silicate hornfels contact zone. The estimated temperatures and $Xco_2$ for the formation of the transition zone show $300^{\circ}C$$440^{\circ}C$ and $0.07{\pm}0.05<Xco_2<0.02{\pm}0.01$ at 1 Kb respectively.

• 자원환경지질
• /
• 제38권2호
• /
• pp.187-196
• /
• 2005

석류석 구조에서, 양이온이 점할 수 있는 구조적 위치는 사면체, 팔면체 및 이들과 능을 공유하고 있는 배위다면체의 중심 등이다. 이들 중, 사면체의 자리를 차지하는 양이온의 크기는 석류석의 단위포의 크기와 밀접한 관계를 가진다. 따라서 4-배위 자리에 비교적 이온반경이 큰 철을 함유하고 있는 석류석은 방사성 폐기물 내에 함유된 비교적 이온반경이 큰 악티나이드 원소를 고정시키기 위한 유망한 매트릭스로써 고려될 수 있다. 따라서 본 연구에서는 $Ca_{1.5}GdCe_{0.5}ZrFeFe_3O_{12}$인 조성을 가진 석류석을 합성하여 이들의 상평형 관계 및 특성을 연구하였다. 혼합된 시료는 $200{\~}400{\cal}kg/{\cal}cm^2$의 압력으로 성형한 후, $1100{\~}1400^{\circ}C$ 범위에서 온도 및 분위기를 변화시키면서 소결하였으며, 합성된 시료는 XRD 및 SEM/EDS를 사용하여 상분석과 정량분석을 실시하였다. 실험결과, 석류석은 소결온도 $1300^{\circ}C$에서 최적의 합성상을 얻을 수 있었지만, 미량의 페로브스카이트 및 미지의 상이 공존하였다. 석류석과 페로브스카이트의 화학조성은 각각 $[Ca_{l.2-1.8}Gd_{0.9-1.4}Ce_{0.3-0.5}]^{VIII}[Zr_{0.8-1.3}Fe_{0.7-1.2}]^{VI}[Fe_{2.9-3.1}]^{IV}O_{12}$ 및 $Ca_{0.1-0.5}Gd_{0.0-0.8}Ce_{0.1-0.5}\;Zr_{0.0-0.2}Fe_{0.9-1.1}O_3$ 이었다. 특히 화학양론적 조성과 비교 시, 합성된 석류석의 8-배위 자리를 점하고 있는 Ca의 초과 및 Ce의 결핍된 양상을 보였다. 이는 6-배위 자리에서의 Zr 및 Fe의 화학조성과 밀접한 관계를 지닌다.

• 한국광물학회지
• /
• 제16권4호
• /
• pp.307-320
• /
• 2003

Fe­석류석인 경우, 사면체 배위를 하는 Fe의 이온반경이 Si보다 크기 때문에 고준위 방사성 폐기물에 다량 함유되어 있는 악티나이드 원소들을 고정화시킬 수 있는 매트릭스로 고려되고 있다. 따라서 본 연구에서는 $Ca_{2,5}$C $e_{0.5}$Z $r_2$F $e_3$ $O_{12}$ 및 $Ca_2$CeZrFeF $e_3$ $O_{12}$인 조성을 가진 석류석을 합성하여 이들의 상평형 관계 및 특성을 연구하였다. 혼합된 시료는 200∼400 kg/$\textrm{cm}^2$의 압력으로 성형한 후, 1100∼140$0^{\circ}C$ 범위에서 온도 및 분위기를 변화시키면서 소결하였으며 합성된 시료는 XRD, SEM/EDS를 사용하여 상분석과 정량분석을 실시하였다. 실험결과, 이들 조성을 가진 석류석들은 130$0^{\circ}C$로 가열하였을 때, 최적 합성상을 얻을 수 있었지만 소량의 페롭스카이트 등 부수상이 공존하였다. $Ca_{2,5}$C $e_{0.5}$Z $r_2$F $e_3$ $O_{12}$ 및 $Ca_2$CeZrFeF $e_3$ $O_{12}$인 조성으로부터 합성된 Fe­석류석의 조성이 각각 $Ca_{2.5­3.2}$C $e_{0.3­0.7}$Z $r_{1.8­2.8}$F $e_{1.9­3.2}$ $O_{12}$ 및 $Ca_{2.2­2.5}$C $e_{0.8­1.0}$Z $r_{1.3­1.6}$F $e_{0.4­.07}$ F $e_{3­3.2}$ $O_{12}$였다. 특히 화학양론적 조성과 비교시, 합성된 석류석의 8배위 자리를 점하고 있는 Ca이 초과된 양상을 보였고, Ce의 함량은 초과 또는 결핍된 양상을 보였다. 이는 8배위 자리에서의 Ca과 Ce의 이온반경의 상대적인 차이 및 전하보상적 차원에서 비롯된 것으로 해석된다.에서 비롯된 것으로 해석된다.