超导岩样磁力仪的研制

超导岩样磁力仪是以超导量子干涉器（SQUID）为磁传感器用来测量岩样剩磁的仪器,是研究岩石磁学和古地磁学的重要手段。它比常规的古地磁仪器——无定向磁力仪、旋转磁力仪具有灵敏度高、响应时间短、动态范围大、又可三分量同时测量等优点,满足了弱磁岩样测量的要求。本文叙述了超导测磁的理论基础,仪器的组成,原理,研制情况及实测结果。     

SQUID及在地球物理中的应用

SQUID(Superconducting Quantum Interference Device)技术(特别是高温SQUID)的发展，为地球物理探测技术的发展提供了巨大潜力，基于SQUID技术开发的地球物理探测系统不仅具有精度高、分辨率高的优点，而且仪器系统轻便，在野外实验和应用取得了巨大的进展，本文将近年SQUID技术应用于地球物理取得的进展进行了简要的总结，并阐述它了在地球物理勘探领域的广阔应用。     

高温超导磁强计在电偶源瞬变电磁法中的应用

研制了适用于电偶源瞬变电磁法中直接测量磁感应强度B的高温超导磁强计,并进行了电偶源瞬变电磁法大地电磁测量野外实验.测量结果表明了高温超导磁强计明显优于常规感应线圈探头,可以得到更深的探测深度.     

The distribution of Cu(II) and the magnetic properties of the synthetic analogue of tetrahedrite: Cu12Sb4S13

A wide investigation of the synthetic analogue of tetrahedrite, Cu₁₂Sb₄S₁₃, has been performed by a combination of several techniques, magnetisation and differential scanning calorimetric measurements, cw, and pulsed EPR spectroscopy, to obtain complementary information about the presence and the distribution of Cu(II). The high temperature susceptibility of the sample accounts for two Cu(II) per formula unit, in agreement with the charge balance. However, strong antiferromagnetic interactions, observed even at room temperature, are associated with a transition at 83(3) K. At lower temperatures a residual susceptibility is observed. At 4.2 K ESEEM experiments enabled observation of the chemical environment of the residual paramagnetic species. Cu(II) was found randomly distributed in the M(1) site. The statistical presence of nearest neighbouring Cu(II) ions justify the observed antiferromagnetic interactions and transition. Nevertheless, isolated paramagnetic ions have been determined below the Néel temperature: they are mainly located near the surface of the grains. A colour centre, previously observed in natural samples, has been also identified.     

EPR and SQUID magnetometry study of Cu2FeSnS4 (stannite) and Cu2ZnSnS4 (kesterite)

An EPR and SQUID magnetometry study of Cu₂FeSnS₄ (stannite) and Cu₂ZnSnS₄ (kesterite) has been performed in order to gain a deeper insight into the crystal chemistry of these minerals, in which the mixed character of bonds lends uncertainty to the determination of the metal valence states. EPR investigations were performed down to almost liquid nitrogen temperature on both natural and synthetic samples of stannite and kesterite. The interpretation of their parameters (g- and T-tensors) was refined by computer simulation. The main feature of all the spectra is the unstructured signal centered at about 0.310 T due to the presence of Cu(II). The absence of structure in the signal is due to spin-spin exchange interaction between Cu(II) and Fe(II), pointing to a diluted distribution of Cu(II). The temperature dependence of the Cu(II) signal can be related to a topological variation of the first-neighbors coordination. The SQUID measurements, while allowing a more precise interpretation of the EPR data, led to a full characterization of magnetic behavior of stannite and kesterite down to liquid helium temperature, evidencing antiferromagnetic interactions between the Fe(II) ions in all samples but in synthetic kesterite. From the EPR and SQUID experimental data no evidence was provided for the existence of two different structures for stannite and kesterite. Received: 2 August 1999 / Accepted: 7 January 2000     

超导岩样磁力仪的研制

超导岩样磁力仪是以超导量子干涉器（SQUID）为磁传感器用来测量岩样剩磁的仪器,是研究岩石磁学和古地磁学的重要手段。它比常规的古地磁仪器--无定向磁力仪、旋转磁力仪具有灵敏度高、响应时间短、动态范围大、又可三分量同时测量等优点,满足了弱磁岩样测量的要求。本文叙述了超导测磁的理论基础,仪器的组成,原理,研制情况及实测结果。     

航空重力梯度仪研究现状及发展趋势

简要介绍了重力梯度仪的发展历程,重点叙述了旋转加速度计航空重力梯度仪的工作原理及研发过程,系统调研了航空重力梯度仪的仪器现状,跟踪了航空重力梯度仪的研究动态.     

Copper valence,structural separation and lattice dynamics in tennantite (fahlore): NMR,NQR and SQUID studies

Electronic and magnetic properties of tennantite subfamily of tetrahedrite-group minerals have been studied by copper nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR) and SQUID magnetometry methods. The temperature dependences of copper NQR frequencies and line-width, nuclear spin-lattice relaxation rate T ₁⁻¹ and nuclear spin-echo decay rate T ₂⁻¹ in tennantite samples in the temperature range 4.2–210 K is evidence of the presence of field fluctuations caused by electronic spins hopping between copper CuS₃ positions via S₂ bridging atom. The analysis of copper NQR data at low temperatures points to the magnetic phase transition near 65 K. The magnetic susceptibility in the range 2–300 K shows a Curie–Weiss behavior, which is mainly determined by Fe²⁺ paramagnetic substituting ions.     

Imaging distribution patterns of magnetic minerals by a novel high-Tc-SQUID-based field distribution measuring system: application to Permian sediments

A newly developed field distribution measuring system based on a high- T _c SQUID has been employed in the study of magnetic mineral distribution in several Permian sedimentary rocks. The instrument consists of a small, 1.4×1.4 mm sized YBaCu-oxide SQUID magnetic field sensor that is operated in a thin-walled dewar, so that the sample's surface, at room temperature, can be scanned at a distance of only ∼1.5 mm. The samples were subjected to a saturation remanence perpendicular to the surface and the scanning measurements in zero field reveal that the magnetization might be carried by only a small part of a sample, in one case associated with secondary oxide phases. High-resolution magnetic scans can aid in the interpretation of the magnetic remanence acquisition process.