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The wet chemical synthesis of Pb 10 (VO 4 ) 6 I 2 apatite has been reported for the first time. The possibility of substituting Ca 2+ for Pb 2+ and (PO 4 ) 3- for (VO 4 ) 3- in the apatite structure has been explored.
An electronic structure and magnetic properties analysis of the recently proposed Cu-doped lead apatite is performed. Here, we show that electronic structures of differently Cu-substituted structures are characterized by localized molecular Cu-O bands at or near the Fermi level. The Cu substitutions can happen at both Pb1 and Pb2 sites, leading to metallic and semiconducting systems differently. The electronic systems in these bands are highly unstable magnetically and form clusters of rigidly ferromagnetically coupled magnetic moments on Cu and neighboring oxygen atoms with a total moment of about 1µ B . The ground state of uniformly Cu-doped lead apatite appears to be magnetic and semiconducting. The nonuniform distribution of two Cu atoms at the nearest Pb2 sites leads to an antiferromagnetic semiconducting state with formation energy close to uniformly distributed Cu configurations. The inclusion of quantum spin fluctuations confirms the stability of magnetic Cu-O clusters. Our calculations revealed the absence of the long-range magnetic order between uniformly distributed Cu-O clusters, creating the spin glass type of system.
Antarctic meteorite Allan Hills A81005 is a polymict, anorthositic regolith breccia of lunar origin. Most lithic clasts in the meteorite 81005 are similar to those from other lunar rocks. However, some, such as 'hyperferroan' anorthosites, have not been reported before the discovery of 81005. On the basis of the composition of some granulitic polymict breccia clasts, it appears possible that other new lithologies are present. In the present paper, a description is provided of an unusual, apatite-rich, ferroan, mafic lithology, and its origin is discussed. Three clasts which appeared to contain two minerals were separated as samples ,32 ,28 and ,27. It is found in a study that the clast in ,32 and ,28 is an apatite-rich ferroan anorthositic troctolite which is probably pristine. This rock is unique among lunar samples. On the basis of an evaluation of the significance of the results of the study, it is concluded that complex processes were apparently involved in the evolution of the primitive lunar crust.
Melting experiments (P = 6.9 kbar, T = 850-950 deg C, NNO is less than fO2 is less than HM) were done on mafic to felsic charnockites, a dioritic gneiss, and a felsic garnet granulite, all common rock types in the Grenville basement of eastern North America. A graphite-bearing granulite gneiss did not melt. Water (H2O(+) = 0.60 to 2.0 wt %) is bound in low-grade, retrograde metamorphic minerals and is consumed during the earliest stages of melting. Most melts are water-undersaturated. Melt compositions range from metaluminous, silicic granodiorite (diorite starting composition) to peraluminous or weakly metaluminous granites (all others). In general, liquids become more feldspathic, less silicic, and less peraluminous and are enriched in FeO, MgO, and TiO2 with increasing temperature. Residual feldspar mineralogy controls the CaO, K2O, and Na2O contents of the partial melts and the behavior of these elements can be used, particularly if the degree of source melting can be ascertained, to infer some aspects of the feldspar mineralogy of the source. K-feldspar, a common restite phase in the charnockite and granulite (but not the diorite) should control the behavior of Ba and, possibly, Eu in these systems and yield signatures of these elements that can distinguish source regions and, in some cases, bulk versus melt assimilation. Apatite, a common restite phase, is enriched in rare earth elements (REE), especially middle REE. Retention of apatite in the restite will result in steep, light REE-enriched patterns for melts derived from the diorite and charnockites.
Introduction: Northwest Africa (NWA) 7034 and its pairings represent a regolith breccia of basaltic bulk composition, the finegrained matrix of which bears a strong resemblance to the major and trace element composition estimated for the ancient southern highlands crust on Mars. Therefore, NWA 7034 may represent a key sample for constraining the composition of the Martian crust, particularly the ancient highlands. Here we seek to constrain the hydrogen isotopic composition of the Martian crust using apatite [Ca5 (PO4)3(Cl,F,OH)]. Apatites across all lithologic domains in NWA 7034 have been affected by a Pb-loss event at ~1.5 Ga before present and so they are unlikely to have retained magmatic volatile composition and are more likely to have equilibrated with fluids within the Martian crust that may or may not have exchanged with the Martian atmosphere.
ChemCam is an active remote sensing instrument suite that has operated successfully on MSL since landing Aug. 6th, 2012. It uses laser pulses to remove dust and to analyze rocks up to 7 m away. Laser-induced breakdown spectroscopy (LIBS) obtains emission spectra of materials ablated from the samples in electronically excited states. The intensities of the emission lines scale with the abundances of the related element. ChemCam is sensitive to most major rock-forming elements as well as to a set of minor and trace elements such as F, Cl, Li, P, Sr, Ba, and Rb. The measured chemical composition can then be used to infer the mineralogical composition of the ablated material. Here, we report a summary of inferred apatite detections along the MSL traverse at Gale Crater. We present the geologic settings of these findings and derive some interpretations about the formation conditions of apatite in time and space.
Meteorites from Mars record fO2 values of ∆IW = -1 to +6.5 [1, 2]. This relatively large range in fO2 has been attributed to igneous processes like differentiation and assimilation, or sometimes to alteration [2, 3], modifying the range inherited from the Martian mantle, which is thought to be closer to the values recorded by lunar basalts (~∆IW -1 [e.g., 1]). Trace element compositions reveal that those Martian meteorites that are light Rare Earth Elements (LREE) enriched record higher fO2 values than those that are LREE-depleted [2]. Sulfur (S) has been used to track redox and alteration processes on Mars because it can be present in multiple redox states varying from S2- in magmatic sulfides to S6+ in sedimentary sulfate deposits and alteration products like jarosite [4, 5]. Apatite (Ca5(PO4)3(F,Cl,OH)) is found in many of the Martian meteorites as a late stage crystallizing mineral. It can incorporate both S^(2-) [6] or S^(6+) [7] or mixtures of both [7, 8] in its crystal structure, and it has been hypothesized that the relative proportions of S^(2-) and S^(6+) in apatite will depend on the prevailing fO2 in which it formed (along with P, T, and major element composition). Note: Extended abstract on document.
Bulk β-Yb 1.9 Gd 0.1 Si 2 O 7 , β-Yb 1.6 Gd 0.4 Si 2 O 7 , and γ-Yb 1.4 Gd 0.6 Si 2 O 7 , along with baseline γ-Y 2 Si 2 O 7 and β-Yb 2 Si 2 O 7 were investigated in contact with a molten silicate to determine mechanisms of thermochemical degradation. A model 30.67CaO-8.25MgO-12.81AlO 1.5- 48.27SiO 2 silicate composition was deposited on the surfaces of the samples at a loading of ~2 mg/cm 2 . Reactions with the molten silicate resulted in the formation of a silicate apatite layer, which has been shown to reduce further molten silicate infiltration. Additions of gadolinium up to 30 mol% to Yb 2 Si 2 O 7 reduced infiltration up to ~60% compared to baseline Yb 2 Si 2 O 7 , but additional exposure time at temperature resulted in loss of the apatite layer. The results herein indicate that doping with gadolinium disilicate may not be beneficial in the long term degradation of disilicate-based EBCs by molten silicates.
A method for sequestering technetium is disclosed. The method includes contacting technetium with apatite under reducing conditions whereby the technetium is absorbed by the apatite.
A method for sequestering selenium is disclosed. The method includes contacting selenium with a stannous modified apatite under conditions whereby the selenium is absorbed by the apatite.
Solvent extraction of rare earths from nitrate leach liquor of apatite using mixtures of tributyl phosphate (TBP) and di-(2-ethylhexyl) phosphoric acid (D2EHPA) was studied. The effects of nitrate and hydrogen ion concentration of the aqueous phase as well as the composition and concentration of extractants in the organic phase on the extraction behavior of lanthanum, cerium, neodymium, and yttrium were investigated. The distribution ratio of REEs increases by increasing the nitrate concentration in aqueous phase and concentration of extractants in organic phase, but the hydrogen ion concentration in aqueous phase has a decreasing effect. Yttrium as a heavy rare earth is more sensitive to these parameters than light rare earth elements. Although the composition of organic phase has a minor effect on the extraction of light rare earths, the percent of extraction of yttrium decreases dramatically by increasing the TBP content of organic phase. Mixtures of TBP and D2EHPA can show either synergism or antagonism extraction depending on the concentration and composition of extractants in organic phase. The best condition for separating rare earth elements in groups of heavy and light REEs can be achieved at high nitrate concentration, low H{sup +} concentration, and high concentration of D2EHPA in organic phase. Separation of Ce and La by TBP and D2EHPA is practically impossible in the studied conditions; however, low nitrate concentration and high hydrogen ion concentration in aqueous phase and low concentration of extractants in organic phase favor the separation of Nd from other light rare earth elements.
In this paper we report an investigation about the relationship between Bi content and conductivity for the La{sub 10−x}Bi{sub x}(SiO{sub 4}){sub 6}O{sub 3} (x = 0.5–2) specimens. Increasing Bi content in apatite-type La{sub 10−x}Bi{sub x}(SiO{sub 4}){sub 6}O{sub 3} specimen leads to increasing the average grain size and sinterability because some Bi ion deposited at grain boundaries which promotes grain growth. The relative sintered density of the La{sub 8}Bi{sub 2}(SiO{sub 4}){sub 6}O{sub 3} specimen is 98%. There is a small shift in diffraction angle of XRD peaks, complicated lattice distortion was observed in the X-ray pattern with increasing content of Bi. Electrical conductivity of La{sub 10−x}Bi{sub x}(SiO{sub 4}){sub 6}O{sub 3} specimen increased with increasing Bi contents and the value of the La{sub 8}Bi{sub 2}(SiO{sub 4}){sub 6}O{sub 3} specimen is 2.4 × 10{sup −4} S cm{sup −1} at 700 °C.
Highlights: • A series of Ca{sub 4}La{sub 6}(SiO{sub 4}){sub 4}(PO{sub 4}){sub 2}O{sub 2}:Tb{sup 3+}, Eu{sup 3+} phosphors were successfully prepared by high-temperature solid-state reaction. • CLSPO:0.40Tb{sup 3+}, yEu{sup 3+} phosphors coordinate from green to orange, and white light is exhibited at CLSPO:0.40Tb{sup 3+}, 0.3Eu{sup 3+}. • The energy transfer process between Tb{sup 3+} and Eu{sup 3+} ions was investigated and demonstrated to be a resonant type via a quadrupole-quadrupole mechanism. - Abstract: A series of Tb{sup 3+} and Eu{sup 3+} singly doped and codoped apatite-type Ca{sub 4}La{sub 6}(SiO{sub 4}){sub 4}(PO{sub 4}){sub 2}O{sub 2} phosphors have been prepared by the high temperature solid-state reaction method, and their photoluminescence properties and energy transfer behaviors were investigated in detail. Under excitation by UV light at 376 nm, tunable emission from green to red light is generated due to the Tb{sup 3+} transition of {sup 5}D{sub 4}-{sup 7}FJ and the Eu{sup 3+} transition of {sup 5}D{sub 0}-{sup 7}FJ, and emission evolution from green (0.2723, 0.3857) to orange (0.3527, 0.2876) is achieved by adjusting the concentration ratio of the Tb{sup 3+}-Eu{sup 3+} ions. In addition, the energy transfer process between Tb{sup 3+} and Eu{sup 3+} ions was investigated and demonstrated to be a resonant type via a quadrupole-quadrupole mechanism. This study indicated the potential of Ca{sub 4}La{sub 6}(SiO{sub 4}){sub 4}(PO{sub 4}){sub 2}O{sub 2}:Tb{sup 3+}, Eu{sup 3+} phosphors as candidates for color converters in phosphor-converted white light-emitting diodes.
Using the method of scanning and high-resolution electron microscopy, the zones of indentation by scratching for apatite and quartz single crystals were investigated. The textural, structural and phase transformations revealed have been conventionally ascribed to “deformation” and “diffusion” processes of plastic deformation. In zones of indentation by scratching of single crystals there have been two levels of structural transformations revealed, with a sharp boundary between them, at a stress equal to the theoretical ultimate stress limit (σ{sub TSL}). In the top zone of scratches, within the range of stress from the microhardness value H{sub s} up to the σ{sub TSL} value the substance undergoes profound structural and phase transformations. In the bed of scratches at the stress value lower than σ{sub TSL} values, single crystal fragmentation occurs with the formation of blocks and steps.
The Pb{sub 8}La{sub 2}(GeO{sub 4}){sub 4}(VO{sub 4}){sub 2} and Pb{sub 8}Nd{sub 2}(GeO{sub 4}){sub 4}(VO{sub 4}){sub 2} germanatovanadates with the apatite structure have been prepared by solid-state reactions, by sequentially firing stoichiometric mixtures of PbO, La{sub 2}O{sub 3} (Nd{sub 2}O{sub 3}), GeO{sub 2}, and V{sub 2}O{sub 5} in air at temperatures of 773, 873, 973, and 1073 K. The effect of temperature on the heat capacity of the resultant polycrystalline samples has been studied by differential scanning calorimetry at temperatures from 350 to 950 K using polycrystalline samples. The experimental C{sub p}(T) data have been used to evaluate the thermodynamic functions of the lead lanthanum and lead neodymium germanatovanadates.
The infrared (IR) and Raman spectra of three samples of fluorapatite single crystals and carbonate fluorapatite single crystal in the region of 7000–400 cm{sup –1} were studied. It has been shown that isomorphic substitution of the Ca{sup 2+} cation and the PO{sub 4}{sup 3-} anion leads to an increase in the size of the c-channels in the apatite crystal, which is accompanied by the formation of water clusters of the (H{sub 2}O){sub n} and H{sub 3}O{sup +} · (H{sub 2}O){sub n} (n = 2–5) types as a result of the diffusion processes in these local sections of the c-channels.
We obtained Pb{sub 10 –} {sub x}Nd{sub x}(GeO{sub 4}){sub 2 +} {sub x}(VO{sub 4}){sub 4 –} {sub x} (x = 0–3) compounds with an apatite structure by solid-phase synthesis from initial oxides PbO, Nd{sub 2}O{sub 3}, GeO{sub 2}, and V{sub 2}O{sub 5} with successive annealing at 773–1073 K in the air. Their high-temperature heat capacity was measured by differential scanning calorimetry. The thermodynamic functions (changes in enthalpy, entropy, and reduced Gibbs energy) are calculated using the experimental dependences of C{sub p} = f(T).
A new method for in situ formation of a calcium apatite permeable reactive barrier that is a groundbreaking technology for containing radioactive/heavy metal contaminants threatening groundwater supplies.