海南蓬莱蓝宝石的光致发光谱学特征及意义

从光致发光光谱角度探讨了海南蓬莱蓝宝石的呈色机理.结果发现:与蓝宝石吸收光谱的500～700 nm吸收宽带相比,在500～720 nm发光波段内存在566.8 nm锐峰、600 nm左右肩峰和Cr~(3+)的694.2 nm特征峰.600 nm肩峰与其吸收峰镜像对称,566.8 nm处锐峰的产生原因复杂.600 nm肩峰可能与Fe~(2+)-Fe~(2+)离子对的电子跃迁有关;566.8 nm锐峰因532 nm激光激发Fe~(2+)-Ti~(4+)或Fe~(2+)-Fe~(3+)间的电荷迁移带,通过晶格造成Si~(4+)、Mg~(2+)等微量杂质离子敏化而产生.光致发光谱中呈现更多谱峰,能呈现离子跃迁时不同离子间发生的相互作用,为500～700 nm吸收宽带由不同致色机制的叠加给出了直接证明,是一种能全面地研究宝石矿物中致色元素能级结构的有效方法.     

X射线衍射-红外光谱-扫描电镜表征超声辅助合成GdPO_4:Ce,Tb纳米材料形貌及光学性质

超声辅助方法是制备纳米材料的有效手段,可提高纳米材料的磁学、光学等特殊性能。本文在不同p H条件下超声辅助合成GdPO_4:Ce,Tb三元体系荧光粉,采用X射线粉末衍射、傅里叶变换红外光谱、扫描电镜、透射电子显微镜及光致发光荧光光谱分析方法对样品进行了表征。结果表明:①样品仅在p H=1时,才能生成规则的15 nm×104nm六方晶系纳米棒状正磷酸盐绿色荧光粉,晶体优先选择(102)及(200)晶面生长;p H1无法得到样品;p H1为颗粒状的正磷酸盐绿色荧光粉。②进一步验证了Gd、Ce、Tb三元体系中Ce~(3+)离子能量较高的5d组态将能量传递给Gd~(3+)离子,而Gd~(3+)离子的跃迁发射与Tb~(3+)离子的吸收峰有较大的光谱重叠,故传递途径是Ce~(3+)→Gd~(3+)→Tb~(3+);少量Ce~(3+)的引入可提高以GdPO_4基质发光材料的发光强度。此结果可为开发稀土材料提供理论依据。     

不同变生程度锆石的阴极射线发光谱

变生使矿物的物理、化学性质发生显著变化。本文着重研究变生对锆石阴极射线发光谱的影响。为此,对若干锆石样品进行了X射线粉晶分析,差热分析和室温阴极射线发光谱测量。衍射和差热分析结果表明,这些样品具有不同的变生程度,有些样品已完全变生,有些部分变生,有些则是晶质的。所研究样品的阴极射线发光谱中,主要的发光谱线均来源于Dy~(3+)离子的~4F9/2→~6H_(13/2)和~4F_(9/2)→~6H_(15/2)跃迁。与晶质锆石相比,变生锆石发光谱线的强度降低、宽度增加表明在变生过程中,锆的局部环境发生畸变,无序程度增加。根据发光谱的特征,可以定性地估计锆石的变生程度。     

稀土磷酸盐矿物合成的一些实验

本文研究了稀土磷酸盐类矿物的形成条件及矿物中各稀土元素相互置换的可能性和物理化学条件。 实验表明,独居石的形成条件范围很宽,它可在压力70—1000bar、温度>130℃、pH=2—10的范围内形成。磷钇矿的形成条件与独居石相似。在不同的温、压及pH条件下,从La—Tb的磷酸盐呈独居石的结构,而Tb—Lu却突变为磷钇矿的结构。     

桂东北豆乍山产铀花岗岩的铀源矿物研究

豆乍山花岗岩是桂东北重要的产铀花岗岩之一,通过精细矿物学研究,豆乍山花岗岩中绿泥石主要为铁绿泥石和辉绿泥石,而含铀副矿物的蚀变和形成温度相对较高的铁绿泥石密切相关.花岗岩中主要富铀副矿物为晶质铀矿、锆石、独居石、磷钇矿和铀钍石,其中晶质铀矿是公认铀源矿物,而其他副矿物的赋存状态及蚀变特征决定了其是否为铀源矿物.锆石多未发生蚀变,U仍保持其结构中,因此不是铀源矿物;而铁绿泥石附近的独居石和磷钇矿均发生不同程度的蚀变,蚀变作用不仅使独居石和磷钇矿结构中的U 得以释放进入热液,而且原磷钇矿包裹的铀钍石变为赋存于次生磷灰石中,其所含铀容易活化而成为铀源矿物.总之,在豆乍山产铀花岗岩含铀副矿物中,晶质铀矿、蚀变的独居石和磷钇矿、次生磷灰石中铀钍石是铀源矿物.     

硬石膏、重晶石、天青石及其合成类似物的发光中心

所有硫酸盐类中的SO_4~(2-)本征的发光中心(LC)出现在360nm,但在含大量杂质的硫酸盐中是不存在的。在硬石膏的发光光谱中已观测到三个非等效的Gd~(3+)LC,在天青石中确立了Gd~(3+)、Ce~(3+)和O_2LC。硫酸盐中光致发光(PL)带分配如下:Ca和Ba的硫酸盐中,该带在460nm,它与Eu~(2+)有关(同样可能与Al~(3+)或施主—受主对相联系);520和590nm的带与VO_4、MoO_4和TiO_4置换SO_4有关;660nm谱带由Ti引起,在620nmX射线的发光(XL)带由Ag引起。     

北京十三陵地区前寒武纪岩石中稀土矿物的发现及对同位素测年的意义

华北中、新元古代地层的年龄数据很混乱(表1),本文建议将北京十三陵地区新发现的稀土矿物用SHRIMP方法测年,有助于问题的解决。北京十三陵地区保存了新太古代五台群和新—中元古代较完整的地层,电子耦合等离子体分析(即原子收光谱分析)(ICP)的定量分析数据表明,在这些地层中,岩石中所含钾和稀土元素含量都比北美页岩(NASC)、欧洲页岩(ES)和澳大利亚后太古宙页岩(PAAS)高出很多,经电子扫描+能谱仪+波谱仪(SEM+EDS+WDS)分析证明,在岩石中包含独居石(碎屑的和自生-成岩的)和磷钇矿(自生-成岩的),并首次发现钍石-独居石环带状混合矿物(变质的)以及显微脉状稀土硅酸盐矿物(地下流体形成的)等稀土矿物。利用激光拉曼光谱鉴定发现稀土矿物的分布状态包括:1在太古宙五台群的片麻岩中,云母、石英和长石之间有非自形晶独居石,而且在石英单晶里还有独居石的自形晶包裹体;并发现独居石和钍石-独居石环带状混合矿物,这些稀土矿物都是变质成因的;2在新太古代五台群片麻岩的准平原化风化面上,沉积的元古宙常沟组的底砾岩中发现了碎屑的独居石,这些独居石的同位素年龄对于元古宇的底界定年意义重大;3在常州沟组下部压扁-透镜状层理的粉砂岩中,普遍发现碎屑锆石的外缘生长出自生-成岩磷钇矿,磷钇矿的同位素定年对于常州沟组的地层年代有代表性意义;4串岭沟组的粉砂岩中发现了无形晶状自生-成岩独居石和磷钇矿,并且较多出现在显微缝合线内外,可作为SHRIMP测年的对象;5大红峪组粉砂岩中除了发现碎屑独居石外还发现脉状硅-铝稀土矿物,可能与后元古宙热液活动有关。事实上这些自生-成岩的稀土矿物的形成,都是源自太古宙富含稀土元素的变质岩石,其形成机理也与地下流体活动有关。笔者认为北京十三陵以及至华北地区,前寒武系富稀土元素形成的自生-成岩的稀土矿物,有助于用SHRIMP方法对前寒武纪地层的同位素测年研究。     

应用元素分析-电子顺磁共振能谱研究不同颜色青海软玉致色元素

颜色是软玉价值的重要体现,青海软玉颜色丰富,而致色方面的研究较为滞后。近年来青海软玉致色研究多为翠青玉和烟青玉,认为Cr~(3+)和Mn~(2+)分别为翠青玉和烟青玉致色元素。青海软玉的颜色非单一色彩,如青白色、翠绿色、灰紫色等,因此青海软玉致色应包含多种致色元素。本文在前人研究的基础上,利用X射线荧光光谱法(XRF)、化学滴定法、电感耦合等离子体质谱法(ICP-MS)和电子顺磁共振能谱(EPR)测试数据,根据分析数据与色调变化之间的关系揭示了8种颜色青海软玉的致色元素。结果表明:白玉致色元素为Fe~(3+);青白玉和碧玉致色元素为Fe~(2+)和Fe~(3+);青玉致色元素为Fe~(2+)、Fe~(3+)和高价态的Mn;翠青玉致色元素为Fe~(2+)、Fe~(3+)、Cr~(3+);黄玉和糖玉致色元素为Fe~(3+)和高价态的Mn;烟青玉致色元素为Fe~(3+)和Ti~(4+)。研究认为青海软玉中绿色调与Fe~(2+)有关,黄色调与Fe~(3+)和高价态的Mn有关,而蓝紫色调与Fe~(3+)和Ti~(4+)有关。本研究基本确定了不同颜色青海软玉的致色元素,为青海软玉致色机制的研究提供了理论依据。     

云南省稀土金属资源概况及成矿规律

云南省共有稀土金属矿床（点）10余处,其中,大型矿床3处,中型矿床3处,小型矿床2处;其稀土资源量位居全国第四。稀士金属矿产以独居石及磷钇矿砂矿为主,次为风化壳离子吸附型稀土矿,另外有一定量的伴生稀土金属资源。 机械沉积型砂矿共有4处,其中独居石大型矿床2处;磷钇矿中、小型矿床各1处。主要分布于临沧—勐海矿带的勐海地区,矿体主要赋存于古河床冲积砂砾层中,为层状、似层状、小扁豆状矿体,且多集中于第四纪冲积盆地的中部,向边部变薄;在含矿层剖面垂直方向上,有中部较富,上、下较贫的特点;成矿物质主要来源于汇水区内的海西期花岗岩。     

广东(大陆部分)滨海砂矿成矿地质条件及分布规律

广东大陆海岸线漫长,滨海砂矿资源丰富,大、小矿床(点)90处.本省滨海砂矿独居石、磷钇矿、锆英石、钛铁矿和金红石的储量,在全国同类型矿床中名列首位,是我国上述矿产的重要产区.六十年代以来,前人曾对本区滨海砂矿的地质特征、分布规律和找矿方法进行过总结.我队从     

Xenotime in the Lower Buntsandstein of Central Europe: Evidence from cathodoluminescence investigation

Xenotime and zircon in heavy mineral separates of siliciclastic sediments can easily be distinguished by means of cathodoluminescence (CL). All shades of bright blue, yellow and grey to white colours have been reported for zircon while only bottle green to greenish yellow colours have been found in xenotime in heavy mineral separates of Lower Buntsandstein samples as well as in two samples from crystalline rocks from Bahia (Brazil) and the Karpaty Mts. (Slovakia). The CL-spectra of both minerals are commonly dominated by narrow emission bands of rare earth elements, especially Dy³⁺. The two different crystal lattices induce differences in the intensity ratios of the emission lines that are thought to be the reason for the different CL-colours. Additionally, intrinsic broad bands that may occur in the CL-spectra of zircon are missing in the xenotime spectra. The possibility to distinguish minerals with similar optical properties underlines the large potential of cathodoluminescence in sedimentary petrology.     

High-resolution spectrometric analysis of rare earth elements-activated cathodoluminescence in feldspar minerals

Cathodoluminescence (CL) investigations of igneous, metamorphic and sedimentary feldspars indicate that rare earth elements (REE)-activated CL in feldspars is more common than previously assumed. Hot-cathode CL microscopy combined with high-resolution spectrometric analysis of CL emission allow to detect some REE below the detection limits of electron microprobe and proton-induced X-ray emission analysis (PIXE) and reveal variations in the REE distribution within single feldspar crystals. Differently luminescing zones can reflect changes during feldspar crystallization and/or element fluctuations during secondary alteration processes which are not discernible using conventional polarizing microscopy. The results of the study document Eu²⁺, Sm³⁺, Dy³⁺, Tb³⁺, and Nd³⁺-activated CL in feldspars of different origin. The influence of the crystal field on shape and position of REE luminescence spectra significantly differs for divalent and trivalent REE ions. Whereas Eu²⁺ shows a broad band emission (∼420 nm) which is influenced by the local crystal field, trivalent ions of the rare earth show narrow emission lines which reflect the transitions between excited state wave functions lying inside closed electronic shells. The positions of these peaks and the characteristic energies are described for the different REE³⁺.     

Factors affecting the Nd3+ (REE3+) luminescence of minerals

In this paper, possibilities and limits of the application of REE³⁺ luminescence (especially the Nd^{3+ 4}F_3/2 → ⁴I_9/2 emission) as structural probe are evaluated. Important factors controlling the Nd³⁺ luminescence signal are discussed, including effects of the crystal-field, crystal orientation, structural state, and temperature. Particular attention was paid to the study of the accessory minerals zircon (ZrSiO₄), xenotime–(Y) (YPO₄), monazite–(Ce) (CePO₄) and their synthetic analogues. Based on these examples we review in short that (1) REE³⁺ luminescence can be used as non-destructive phase identification method, (2) the intensities of certain luminescence bands are strongly influenced by crystal orientation effects, and (3) increased widths of REE³⁺-related emission bands are a strong indicator for structural disorder. We discuss the potential of luminescence spectroscopy, complementary to Raman spectroscopy, for the quantitative estimation of chemical (and potentially also radiation-induced) disorder. For the latter, emissions of Nd³⁺-related centres are found to be promising candidates.     

New genetic type of rare-earth mineralization in Precambrian migmatites of European U.S.S.R.

Rare earth mineralization, in the form of xenotime and monazite, occurs along tear faults at an unidentified locality in the Precambrian terrane of European part U. S. S. R. The petrographic and geologic relationships of the last rocks appear to reflect Mg-Fe metasomatism followed by metasomatisrn. The rare earth mineralization appears to have accompanied the K metasomatism. Chemical analyses are presented for one xenotime and two monazites; emission and X-ray spectroscopic analyses are presented for the xenotime. — R.V. Dietrich.     

Formation of monazite and xenotime inclusions in fluorapatite megacrysts, Gloserheia Granite Pegmatite, Froland, Bamble Sector, southern Norway

Xenotime and monazite inclusions in fluorapatite megacrysts from a granitic pegmatite, Gloserheia, Froland, Bamble Sector, southern Norway are described utilizing high contrast backscattered electron imaging of cross sections of a selection of fluorapatite crystals. Electron microprobe analysis is then used to further characterize the xenotime and monazite, as well as (Y+REE) normal and depleted regions in the fluorapatite. In the (Y+REE) normal regions Y₂O₃ ranges from 0.4 to 1.3 whereas it ranges from below the electron microprobe detection limit to around 0.4 in the depleted regions. Low Y values in monazite (X_Y?=?0.01?0.05) co-existing with xenotime indicates that inclusion formation in the originally (Y+REE)-enriched fluorapatite must have occurred below 300°C. Formation of the xenotime and monazite inclusions is attributed to fluid-aided coupled dissolution-reprecipitation processes during the later stages of subsolidus cooling of the pegmatite. The fluorapatite megacrysts are hypothesized to have under gone two major fluid-induced alteration events. The first occurred sometime after crystallization was complete at temperatures below 300°C and resulted in the initial formation of the xenotime and monazite inclusions. The second occurred at some later time as the product of a relatively limited fluid infiltration, also under T?<?300°C. This resulted in the formation of (Y+REE)-depleted regions along lattice and cleavage planes while at the same time promoting Ostwald ripening of the xenotime inclusions resulting in larger grains in the (Y+REE)-depleted areas.     

福建碧田Au-Ag-Cu矿床含金石英脉中磷灰石的阴极发光研究

碧田Au Ag Cu矿床含金石英脉中的磷灰石在阴极射线激发下发明亮的黄绿色光 ,特征峰波长为 5 70～5 80nm。阴极发光 (CL)图像揭示了磷灰石的内部环带结构 ,不同环带微量和稀土元素含量具有明显的差异。发光带w(MnO) >0 .4%、n(Mn) /n(Fe) >2、n(Mn) /n(La+Ce) >4;Mn2 + 为CL的主要激发元素。磷灰石晶体结构中以LREE3 + +Si4+ =Ca2 + +P5+ 为主要的元素替代形式。磷灰石微量与稀土元素的分布特征表明 ,该矿床形成于近地表的低温热液体系 ,成矿流体在矿物共沉淀的晚期向富Si、Na方向演化。     

Laser excited luminescence of rare earth impurities in natural and synthetic CaF2

This work explores the potential of laser excited luminescence for the study of type and concentration of rare-earth (RE) luminescence centres in CaF₂. A comparison with X-ray excited luminescence is made. The luminescence spectra of several natural and synthetic samples are obtained at low and room temperatures using different Ar⁺ and Kr⁺ laser lines for excitation. Tentative assignment of the luminescent lines to different RE²⁺ and RE³⁺ ions is made. The excitation is shown to take place predominantly through the emission of one phonon. The possibilities for concentration measurements of luminescent centres are discussed.     

Interaction of rhyolite melts with monazite,xenotime, and zircon surfaces

The interfacial contact region between a rhyolite melt and the accessory minerals monazite, xenotime, and zircon is investigated using molecular dynamics simulations. On all surfaces, major structural rearrangement extends about 1 nm into the melt from the interface. As evidenced by the structural perturbations in the ion distribution profiles, the affinity of the melt for the surface increases in going from monazite to xenotime to zircon. Alkali ions are enriched in the melt in contact with an inert wall, as well as at the mineral surfaces. Melt in contact with zircon has a particularly strong level of aluminum enrichment. In xenotime, the enrichment of aluminum is less than that in zircon, but still notable. In monazite, the aluminum enrichment in the contact layer is much less. It is expected that the relative surface energies of these accessory minerals will be a strong function of the aluminum content of the melt and that nucleation of zircon, in particular, would be easier for melts with higher aluminum concentration. The crystal growth rate for zircon is expected to be slower at a higher aluminum concentration because of the effectiveness of aluminum in solvating the zircon surface. The variable interfacial concentration profiles across the series of accessory minerals will likely affect the kinetics of trace element incorporation, as the trace elements must compete with the major elements for surface sites on the growing accessory minerals.     

Monazite–xenotime miscibility gap thermometry. I. An empirical calibration

Rare earth element (REE) and yttrium concentrations of coexisting monazite and xenotime were determined from a suite of seven metapelites from the Variscan fold belt in NE Bavaria, Germany. The metapelites include a continuous prograde, mainly low-P (3–5 kbar) metamorphic profile from greenschist (c. 400 °C) to lower granulite facies conditions (c. 700 °C). The LREE (La–Sm) are incorporated preferentially in monoclinic monazite (REO₉ polyhedron), whereas the HREE plus Y are concentrated in tetragonal xenotime (REO₈ polyhedron). The major element concentrations of both phases in all rocks are very similar and do not depend on metamorphic grade. Monazite consists mainly of La, Ce and Nd (La_0.20–0.23, Ce_0.41–0.45, Nd_0.15–0.18)PO₄, all other elements are below 6 mol%. Likewise, xenotime consists mainly of YPO₄ with some Dy and Gd solid solutions (Y_0.76–0.80, Dy_0.05–0.07, Gd_0.04–0.06). In contrast, the minor HREE concentrations in monazite increase strongly with increasing metamorphic grade: Y, Dy and Gd increase by a factor of 3–5 from greenschist to granulite facies rocks. Monazite crystals often show zonation with cores low in HREE and rims high in HREE that is interpreted as growth zonation attained during prograde metamorphism. Similarly, Sm and Nd in xenotimes increase by a factor of 3–4 with increasing metamorphic grade. Prograde zonation in single crystals of xenotime was not observed. The X_HREE+Y in monazite and X_LREE in xenotime of the seven rocks define two limbs along the strongly asymmetric miscibility gap from c. 400 °C to 700 °C. The empirical calibration of the monazite miscibility gap limb coexisting with xenotime is appropriate for geothermometry. Due to its contents of U and Th, monazite has often been used for U–Pb age determination. The combination of our empirical thermometer on prograde zoned monazite along with possible age determination of zoned single crystals may provide information about prograde branches of temperature–time paths.     

铬铁矿中的次近邻效应

本文使用穆斯堡尔效应对三个铬铁矿进行了研究,测量了铬铁矿L-1在150K和298K温度下的穆斯堡尔谱和铬铁矿L-2和L-3在298K温度下的谱。使用次近邻效应解释了铬铁矿中的多重Fe~(2+)双峰,并使用二项式分布计算了Cr~(3+)、Fe~(3+)和Al占据次近邻位置的几率。在穆斯堡尔面积和二项式分布计算的基础上做出了Fe~(2+)双峰的指派。铬铁矿L-1谱在150K下进一步分裂,表明用来解释铬铁矿谱的模型是正确的。