Temperature dependence of the cation distribution in nickel aluminate (NiAl2O4) spinel: a powder XRD study

NiAl₂O₄ is a largely inverse spinel, which in detail shows increasing randomisation with temperature of Ni and Al between the octahedral and tetrahedral cation sites of the spinel structure. We have used powder XRD to determine this cation distribution in various samples of NiAl₂O₄ quenched after annealing between 700 and 1400° C. The inversion parameter (x) can be measured with a precision of ± 0.004 (one standard deviation), and a comparison of different methods of synthesis, X-ray diffraction and refinement techniques, suggests a probable accuracy of better than 0.01. The results are supported by some preliminary single crystal refinements on flux-grown samples.Below 800° C the rate of cation ordering becomes very slow, and, despite reaching an apparently steady state, it is doubtful if our samples attained complete internal equilibrium. Above 1250° C the cation redistribution becomes so fast that the quenching method becomes unreliable. Between 800 and 1250° C inclusive, the degree of inversion changes smoothly from 0.87 at 800° C to 0.79 at 1250° C, and is accompanied by linear changes in u, the oxygen parameter, from 0.2555 to 0.2563 (±0.0002), and a₀, the lattice parameter, from 8.0462 to 8.0522 Å (±0.0002 Å).     

遥感特征信息提取的综合分析——以红外细分波段新疆铁木尔特航带矿化特征信息提取为例

本文以红外细分波段新疆铁木尔特航带为例,依据不同地质体各自的光谱特征,运用主成分分析、多种信息复合等技术与综合分析方法,使该地段的矿化特征提取收到了良好效果。 本航带的矿化特征信息在图像处理结果中表现为黄色异常色调。它反映了当地多金属成矿带中二氧化硅含量低、全铁含量较高的岩矿矿化特征。团块状黄色异常色调表示出地表出露的铁帽、磁铁矿化和矽卡岩化的分布状况。野外验证表明,黄色调的分布地域与实地的地表矿化范围相吻合。 遥感特征信息提取的综合分析方法包括信息基本特征分析、图像处理、后验分析和机理解释等四个相互联系的步骤。研究表明,只有经过综合分析,才能揭示出特征信息的内在规律性,使特征信息具有较好的实用价值。     

Biochemische Abbaubarkeit ausgewählter alicyclischer Verbindungen

Thirteen alicyclic compounds (C₅… C₇) are examined for their biochemical degradability in a laboratory activating tank and in two respirometers (Warburg, Sapromat). The tests were performed with adapted and nonadapted activated sludge. In addition, the COD was determined by three different methods. With the exception of cycloheptane (BOD < 25% of the BOD_theor.), six compounds prove to be easily degradable (BOD > 45% of the BOD_theor.) and six compounds prove to be degradable (BOD 45… 25% of the BOD_theor.).     

Thermodynamics of Co3O4: a possible electron spin unpairing transition in Co3+

The free energy of the reaction: $$Co_3 O_4 \rightleftarrows 3C_O O + \tfrac{1}{2}O_2$$ has been studied between 890 and 1,240 K using an e.m.f. technique. There is a phase transition in Co₃O₄ at 1,120±20 K which is accompanied by a large change in entropy (～47 JK^?1 mol^?1 of Co₃O₄), and a rapid increase in unit cell volume and in electical conductivity. This is interpreted to be due to a partial change in electronic spin states in Co^{3 +} from the spin-paired (low spin) configuration observed at room temperature to the spin-unpaired (high spin) state. The transition is probably not first order.     

吉林省北部A型花岗岩的初步认识

分布在吉林省北部的香水、治安一带的正长花岗岩、碱长花岗岩，研究后认为属Ａ型花岗岩。其行征钾长石为微斜长石一条纹长石，斜长石大部分为奥长石Ａｎ＝１３－１７。并有碱性碱物无辉石。     

兴1井水位的映震特征

兴1井是辽宁省内最早建成的静水位观测井，已有近20年的观测历史。系统分析预测以来的资料，发现该井水位有很强的映震能力并有一定的映震规律，可进行单井水位异常预报地震震级与发震时间的科学试验。     

房山花岗闪长岩体长石斑晶的数学特征及相带划分

对北京房山花岗闪长岩体中长石斑晶进行了系统测量,测点密度平均4.37个/km~2,测量标志为长石斑晶长轴长度和长石斑晶线含量等。对测得数据进行了分布统计、有序样品最优分割、和趋势变化分析等处理。揭示了长石斑晶在岩体中的分布规律和数学特征,划分了趋势岩相带,从而提出了较为合理的岩相带划分原则。     

矿体储量及其计算参数的误差公式和金属储量误差的回归模型

据个旧锡矿开发勘探资料,在计算机上实现不同网度稀空试验的结果、讨论了误差估计问题,提出了矿石品位、矿体厚度、矿体投影面积、矿体体积和金属储量等误差估值公式。以实例建立了不同穿透样锡品位变化系数值的金属储量误差与工程数量的回归模型,并将其应用于金属储量误差估计和工程效果的预测。     

Structure of the upper mantle in the Northeastern Atlantic close to the azores-gibraltar ridge from surface-wave and body-wave observations

Phase velocities of teleseismic Rayleigh waves have been measured in the central North Atlantic on both sides of the Azores-Gibraltar Ridge (AGR) by means of a specially designed long-period station network. The dispersion data obtained were regionalized and then subjected to a “hedgehog” inversion, which gives a set of upper mantle models compatible with the observational data within specified error bounds.Reasonable model solutions were selected by using regional body-wave observations, such as P_n- and S_n-wave velocities determined from earthquakes along the AGR. The S_(itn) velocities measured indicate that the shear-wave velocity in the mantle part of the lithosphere is much higher on the northern side of the AGR. Strongly negative P-wave residuals in this area indicate faster seismic propagation than implied by the Jeffreys-Bullen travel-time tables, while propagation is much slower in the Gulf of Cadiz area. Furthermore the residuals show a clear difference for paths through oceanic and continental domains and suggest that the transition between these two domains extends much further into the ocean on the southern side of the AGR than on the northern side.The proposed model for the structure of the upper mantle in that region shows that there exists a pronounced velocity contrast across the AGR. Thickening of the lithospheric plate with increasing plate age is indicated to the south of the ridge. The greatest thickness is reached close to the continental margin within a zone about 500 km wide, whose velocity close to the Canary Islands and Madeira is significantly lower, probably due to the well-known volcanic activity there. These observations together with the travel time residuals reveal that this zone seems to be of a transitional nature somewhere between a continental and oceanic structure.