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1.
R. H. Mitchell A. R. Chakhmouradian P. M. Woodward 《Physics and Chemistry of Minerals》2000,27(8):583-589
Perovskite-type compounds in the series tausonite-loparite, (Sr1?2 x Na x La x )TiO3, were synthesized by solid-state reaction (final heating at 1200–1300?°C), and studied using “conventional” and synchrotron X-ray powder diffractometry. The structures of intermediate compositions were determined using the Rietveld profile refinement method. In the compositional range 0?≤x?≤ 0.1, the series comprises perovskites characterized by an undistorted cubic structure (space group Pm3¯m, a?≈ 3.905–3.902?Å, Z?=?1). Intermediate compounds in the range 0.15?≤?x?≤?0.35 crystallize with tetragonal symmetry (I4/mcm, a?≈? , c?≈? , Z?=?4) derived from the cubic aristotype by antiphase rotation of the TiO6 octahedra about a fourfold axis. The angle of rotation estimated from the positional parameters of oxygen atoms ranges from 2.5(7)° to 5.5(4)°. The cubic-to-tetragonal transition arises from substitution of Sr2+ by the comparatively smaller Na1+ and La3+ cations. A further transition from the tetragonal to rhombohedral symmetry (R3¯c, a?≈? , c?≈?2 , Z?=?6) occurs between x?=?0.35 and 0.40, and apparently does not involve formation of perovskite with an intermediate two-tilt structure (Imma). The rhombohedral structure is characterized by a multicomponent octahedral tilt about a threefold axis ranging in magnitude from 6.5(2)° to 7.7(2)°. In the series (Sr1?2 x Na x La x )TiO3, the unit-cell dimensions decrease, and the degree of structural distortion increases with x. 相似文献
2.
Mag. Ronald Miletich 《Mineralogy and Petrology》1993,48(2-4):129-145
Summary The crystal structures of copper-substituted manganese-denningites, Mn(Mn1–x
Cu
x
)(Te2O5)2 (0 x 1), were refined in space groupP42/nbc from single-crystal X-ray data. Single crystals with different degree of Cu-substitution suitable for X-ray investigation were synthesized under hydrothermal conditions, varying the Cu/Mn ratio and thepH-value. One main feature of the crystal structure is the distribution of Mn and Cu atoms among an eight and a six-coordinated site, respectively. Bond strength calculations support the site occupancies of the MnO8-polyhedra and MeO6-octahedra (Me = Cu., Mn1–x
). The decrease in length of the four Me[6]-O bonds clearly correlates with the increase of the Cu-substitution resulting in a distortion of the octahedra according to the Jahn-Teller effect of divalent copper. The stronger decrease of the lattice parameterc as compared toa is probably due to the variations of the bond lengths.
Dedicated to Prof Dr. Josef Zemann on the occasion of his 70th birthday
With 10 Figures 相似文献
Kupfer-substituierte Mangan-Denningite, Mn(Mn1–x Cu x )(Te2O5)2 (0 x 1): Synthese und Kristallchemie
Zusammenfassung Die Kristallstrukturen von Kupfer-substituierten Mangan-Denningiten, Mn(Mn–x Cu x )(Te2O5)2 (0 x 1) wurden mittels Einkristall-Röntgenbeugungsdaten in der RaumgruppeP42/nbc verfeinert. Geeignete Einkristalle mit unterschiedlich starker Cu-Substitution wurden unter hydrothermalen Bedingungen durch Variieren des Cu/Mn-Verhältnisses bzw. despH-Wertes dargestellt. Ein wesentlicher struktureller Gesichtspunkt ist die Verteilung der Mn und Cu-Atome auf eine acht- bzw. sechskoordinierte Punktlage. Die Verringerung von vier Me[6]-O Bindungslängen ist klar korrelierbar mit zunehmender Cu-Substitution, und führt zu einer Verzerrung der Oktaeder gemäß dem für zweiwertiges Kupfer bekannten Jahn-Teller Effekt. Bindungsstärkenberechnungen belegen die Besetzung der MnO8-Polyeder und MeO6-Oktaeder (Me = Cu x Mn1–x ). Die bevorzugte Verkleinerung der Gitterkonstantec gegenübera kann auf die Variationen der Bindungslängen zurückgeführt werden.
Dedicated to Prof Dr. Josef Zemann on the occasion of his 70th birthday
With 10 Figures 相似文献
3.
本文的特色在于不仅研究了黄铁矿的ｘ衍射特征，同时还详细探讨和挖掘了黄铁矿ｘ衍射特征与其含金性之间的关系。研究表明，黄铁矿的ａ０值和某些特定面网的ｘ衍射强度比值对金矿的找矿评价具有标型意义。越是偏离（大于或小于）标准ａ０值的黄铁矿，其含金性越好。Ｉ３１１／Ｉ２１１、Ｉ２００／Ｉ２１０、Ｉ２００／Ｉ１１１的大小变化与含金性变化具有良好的一致性。其中尤以Ｉ３１１／Ｉ２１１反应最为灵敏。 相似文献
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Three (Cr1?x Al x )N (x = 0.33, 0.5, 0.66) coatings were deposited on Ni-super alloy IN718 using reactive magnetron sputtering. The oxidation behavior of all coatings at 900 °C up to 500 h in air was studied. Furthermore, the corrosion behavior of the (Cr0.33,Al0.66)N coating at 900 °C (corrosion type I) by spraying a uniform salt scale of Na2SO4 on the sample surface (1 mg/cm2) was investigated. It was found that the coated samples indicate significantly higher oxidation and corrosion resistance compared to uncoated Ni super alloy. This is mainly due to the formation of protective Cr2O3 and Al2O3 layers on the coating surface. With the increase of Al content, the coatings exhibited improved oxidation resistance. The formation of thin and adherent Al2O3 scale on the surface of Al rich coating is the reason for its better oxidation behavior. The detailed structures of the oxide scales and the interdiffusion between coating and substrate were studied using energy dispersive X-ray spectroscopy-analysis. 相似文献
7.
成都地质学院、重庆地质仪器厂共同研制的HYX－3微型机x射线荧光仪,于1985年12月13日在重庆通过技术鉴定。 相似文献
8.
x我国金矿样加工制备及其设备的选择 总被引：1，自引：0，他引：1
简述金矿样加工制样的原理、规范以及合格的加工设备.对金矿样细磨设备选型从技术、标准化管理和法律、法规的角度进行了分析.确定了细碎金矿样的设备,为棒磨和盘磨保证了金矿样制备的合理性. 相似文献
9.
本文介绍了使用威猛D35x45水平导向钻机实施一个演示的施工案例,文中详细介绍了整个施工过程中的施工工艺及注意事项。 相似文献
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F. Hatert 《Mineralogy and Petrology》2004,81(3-4):205-217
Summary Phosphates of compositions (Na1–xLix)1.5Mn1.5Fe1.5(PO4)3 were synthesized by solid state reactions in air, and pure alluaudite-type compounds were obtained for x=0.00, 0.25, and 0.50. Rietveld refinements of X-ray powder diffraction data indicate the occurrence of Mn2+ in the M(1) site, and of Fe3+ and Mn2+ in the M(2) site. For x=0.25 and 0.50, A(1) is occupied by Li+ and Na+, whereas A(2) is occupied by Na+ and vacancies. A careful examination of the number of electrons occurring in the A sites of the alluaudite-type compounds (Na1–xLix)MnFe2(PO4)3 and (Na1–xLix) CdIn2(PO4)3 confirms that lithium occupies only the A(1) crystallographic site of the alluaudite structure. 相似文献
12.
本文简要介绍了定州市唐河循环经济产业园雨污水管网敷设采用威猛D60x90水平导向钻机、威猛ST7509E浆混合系统等施工概况。 相似文献
13.
“勘查金矿的现场x射线荧光测量”方法的研究成果,由成都地质学院于1987年2月18日至20日在成都组织评审。经过评审会广泛、深入的讨论、评议,一致通过。该方法基于金矿在成生过程中,与某些指示元素(例如,砷、亲铜元素等)有密切的相关关系的特 相似文献
14.
XC气田T3x气藏属于深层陆相致密碎屑岩气藏,具有致密、低孔渗、薄层交互、多层叠置和强非均质性等特点。长期以来,勘探成功率低、效益差。近年来,以高精度地震资料为主线,多学科协同,深入研究含气地震响应特征,充分利用地震资料信息,取得了一系列油气勘探开发的重大突破。在此期间,形成了基于地震波小波变换的AG(吸收梯度:AbsorptionGrads)含气性检测方法技术,此项技术在XC气田T3x气藏取得了较好的应用效果。实践表明,XC气田T3x气藏含气砂岩储层具有低AG异常特征,应用这样的异常特征信息,可以较好地进行非均质致密砂岩储层的含气性检测。 相似文献
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鄂尔多斯盆地杭锦旗地区二叠系P1x—s储层特征 总被引：9，自引：2，他引：9
鄂尔多斯盆地北部伊盟隆起杭锦旗地区二叠系P1x-s直接覆盖在太古界变质结晶基底之上，为一套辫状河沉积和曲流河沉积砂岩。砂岩以岩屑砂岩为主。长石大部分蚀变为高岭石，但保持长石颤粒外形。由于压实作用和胶结作用的影响，砂岩中原生孔隙较少。孔隙以次生溶孔为主，由于长石含量低，粒内溶孔和铸模孔亦不发育，以粒间溶孔和溶蚀扩大扎为主。砂岩中不同产状的高岭石对储层孔渗的贡献不同。砂岩裂缝不发育，孔隙度和渗速率都较低，属中孔低渗的孔隙性储层。按储层分类的标准将本区储层划分为属Ⅱ类和Ⅲ类储层。 相似文献
17.
Gianluca Iezzi Zhenxian Liu Giancarlo Della Ventura 《Physics and Chemistry of Minerals》2009,36(6):343-354
The high-pressure behavior of three synthetic amphiboles crystallized with space group P21/m at room conditions in the system Li2O–Na2O–MgO–SiO2–H2O has been studied by in situ synchrotron infrared absorption spectroscopy. The amphiboles have compositions ANa B(Na
x
Li1 − x
Mg1) CMg5 Si8 O22(OH)2 with x = 0.6, 0.2 and 0.0, respectively. The high-P experiments up to 32 GPa were carried out on the U2A beamline at Brookhaven National Laboratory (NY, USA) using a diamond
anvil cell under non-hydrostatic or quasi-hydrostatic conditions. The two most intense absorption bands in the OH-stretching
infrared spectra can be assigned to two non-equivalent O–H dipoles in the P21/m structure, bonded to the same local environment M1M3Mg3–OH–ANa, and pointing toward two differently kinked tetrahedral rings. In all samples these bands progressively merge to give a
unique symmetrical absorption with increasing pressure, suggesting a change in symmetry from P21/m to C2/m. The pressure at which the transition occurs appears to be linearly correlated to the aggregate B-site dimension. The infrared
spectra collected for amphibole B(Na0.2Li0.8Mg1) in the frequency range 50 to 1,400 cm−1 also show a series of changes with increasing pressure. The data reported here support the inference of Iezzi et al. (Am
Miner 91:479–482, 2006a) regarding a new high-pressure amphibole polymorph. 相似文献
18.
Masaki Akaogi Nanami Horiuchi Takayuki Ishii Hiroshi Kojitani 《Physics and Chemistry of Minerals》2012,39(10):797-802
Phase relations in the system TiO2–ZrO2 were examined in the pressure range of 3.5–12?GPa at 1,800?°C, using multianvil apparatus. At 1,800?°C, TiO2 rutile transforms to αPbO2 structure at 10?GPa, and the αPbO2-type solid solution is stable in compositional range between TiO2 and about (Ti0.6, Zr0.4)O2 at 3.5–12?GPa. Combination of the present results with the published data at 0–3?GPa demonstrates that continuous solid solution with the αPbO2-type structure is stable between TiO2 and (Ti1?x , Zr x )O2 (x?≈?0.6) at 0–12?GPa. This indicates that both the αPbO2-type TiO2 and srilankite Ti2ZrO6 with the same structure belong to the continuous solid solution system though the two phases have been regarded as different minerals. With increasing ZrO2 content, lattice parameters of a- and c-axes of the αPbO2-type solid solution increase, but b-axis is almost constant or slightly decreases. At higher pressure, the αPbO2-type solid solution dissociates into two phases, αPbO2-type phase and tetragonal zirconia. Srilankite with more TiO2-rich composition than Ti2ZrO6 might be found in natural rocks derived from the deep upper mantle. 相似文献
19.
阐述了基于WIN9x、NT系统开发的防汛实时的水情传输软件，与目前在全国防汛计算机，广域网上采用UNIX系统软件相比，具有方便、简单、经济、实用的优点，更加适合我国的实际情况。 相似文献
20.
Radon变换是地球物理数据处理中的重要方法之一,传统的Radon变换有t-x 法、F-K法和F-x法.与目前发展起来的方法比较,传统方法具有稳定性高和容易实现的优势,在实际的资料处理中仍占有重要的位置.在这三种传统方法中, t-x 法和F-K 法由于涉及到插值,所以不可避免地存在误差;F-x法不需插值,计算精度较高,但是由于存在着大量的复数运算,所以影响了计算效率.这里针对F-x域Radon变换的数据计算特征,把矩阵与向量相乘改写为向量与向量卷积的形式,并利用快速傅立叶变换(FFT)来实现快速卷积运算,提高了F-x法的计算效率. 相似文献