LTHMFL - Faraday Balance Laboratory

Faraday Balance

The Faraday System for magnetization measurements is a facility enabling determinations in the range 2-300 K, using fields up to 7 T and gradients up to 10 T/m. The force is measured with a microbalance with a sensitivity of 0.01 mg, making it particularly appropriated for susceptibility measurements of powder samples in small quantities and/or low magnetic signals.
It has been used mainly to study molecular materials and compounds that are being prepared and studied by C2TN initiative or, on a scientific collaboration basis, different compounds prepared by other research laboratories, such as the Institut de Ciencia de Materials de Barcelona, ITQB, IST, and UNL.

LTHMFL - Multipurpose Magnetic and Specific Heat Characterization Facility

MagLab 2000

(Funding: Contract PRAXIS/PCEX/P/FIS/1/96 (50´106 PTE - 40´106 PTE to ITN).

MagLab 2000 (Oxford Inst.) is a facility capable of multipurpose characterization measurements at low temperatures and under fields up to 12 T. The system comprises a variable temperature insert, operating in the range 1.5-400 K inside a 12 T magnet with a 50 mm bore with several easily interchangeable probes:
• One type of probe allows either magnetisation measurements by an extraction technique or AC-susceptibility measurements with a considerable high sensitivity (10-8 emu) and large range of frequencies (10-10000 Hz) which allows to perform dynamic studies.
• Another type of probe, allows specific heat measurements of small samples (~5 mg) in the range 2-200 K using a relaxation technique and under different magnetic fields up to 12 T.

MagLab 2000 Facility

All these measurements are highly automated in a user-friendly environment. These characteristics allow either routine magnetic measurements complementary to those obtained with other techniques, for instance with the SQUID magnetometer, or easy specific heat determinations in small samples.
This facility is mainly used to magnetically characterize a wide variety of different materials such as:
• Intermetallics with d and f elements (rare earth and/or actinides) in both permanent magnetic and heavy fermion systems
• New multifunctional molecular-based materials (from transition metals to rare earth and/or actinides) with unconventional magnetic behaviour such as spin glass, spin crossover and single molecule magnets
• Molecular Conductors
• Magnetic oxides and magnetic nanoparticles

Responsible Researcher: Laura C. J. Pereira.

Access to the equipment:

This equipment is available to the scientific community, on the basis of research cooperation and co-authorship of publications in international scientific journals and presentations in Conferences.

LTHMFL - SQUID Magnetometer Facility

(REEQ/322/QUI/2005; Equipment financed by Managing Authority and Funding FCT – Fundação para a Ciência e a Tecnologia)

The SQUID facility (Cryogenic Ltd., model S700X) is one of the most sensitive instruments for DC and AC measurements of magnetic properties as a function of magnetic field and temperature, with a resolution down to 10^-11 Am².

SQUID Magnetometer Facility                                             3He insert

This unit S700X comprises a standard variable temperature insert operating in the range 1.5-400 K inside a 7 T magnet. The temperature range of operation can be extended down to 0.3 K with a 3He insert. In addition to static magnetization, the AC magnetic susceptibility can be measured from 0.01 to 500 Hz.
The presence of a secondary pick-up coil in the main magnet assembly allows the simultaneous measurement of both axial and transverse components of the magnetization. This transverse axis facility and a motor to rotate the sample, in steps of 0.1 degree, enable the determination of sample anisotropic effects.
This equipment is mainly dedicated to study samples with relatively low moments such as multifunctional molecular-based materials, molecular materials with transition metal complexes and electro active organic molecules, small single crystals, films and nanoparticles.

Responsible Researcher: Laura C. J. Pereira.

Access to the equipment:

This equipment is available to the scientific community, on the basis of research cooperation and co-authorship of publications in international scientific journals and presentations in Conferences.

LTHMFL - Mössbauer Spectroscopy Facility

Mössbauer spectroscopy is a nuclear technique that has been developed in CTN (former ITN) for applications in CTN coordinated research on Solid State Science and Earth Sciences. This facility has also been supporting, since its very first steps, research programs from other national or foreign Research Institutes and Universities. This interaction with other institutions has always been performed on the basis of scientific collaboration and formation of young scientists (graduate and post-graduate students) since expert interpretation of the Mössbauer spectra based on the electronic structure of the studied samples is necessary.

Main Equipment

Presently two transmission Mössbauer Spectrometers are available. These spectrometers may be coupled to a continuous-flow liquid-He cryostat or a bath cryostat enabling studies with the absorber in the temperature range 2-300 K. Conversion electron Mössbauer spectra of surface layers, thin films, multilayers, etc. may also be obtained at room temperature. Existing and currently used sources are 57Co and 151Sm for 57Fe and 151Eu Mössbauer spectroscopy, respectively. Other sources such as 119mSn are acquired whenever a research program justifies it.

Examples of on-going research in Materials Science and Earth Sciences
• Multifunctional Materials (Metal-organic frameworks, molecular switchable materials). Magnetic properties and Fe electronic state (collaboration with the Univ. of Valencia, Spain).
• Oxide materials for high-temperature electrochemical devices: electrodes of solid oxide fuel cells, ceramic membranes for partial oxidation of hydrocarbons. Study of the Fe oxidation state and coordination in crystalline and amorphous materials (collaboration with the Univ. of Aveiro).
• Ternary intermetallics of A-Fe-M systems (A=rare-earth, U; M = Al, Si, Ga, Ge, Sn, Sb). Structural characterization and investigation of the magnetic properties of the Fe sublattices (collaboration with Charles University, Prague, Czech Republic and University of Rennes, France).
• Mineral chemistry. Efficient methods for extraction of Rare Earth Elements from secondary sources, alteration mechanisms of rocks used as building materials, characterization of clays for pharmaceutical, medical and cosmetic applications. Oxidation state and distribution of Fe atoms in different crystallographic sites. Identification of nano-sized Fe-containing phases (collaboration in transnational project coordinated by Chalmers University of Technology, Göteborg, Sweden, and with the Faculty of Sciences of Lisbon Univ.).

Responsible Researcher: João C. Waerenborgh.

Access to the equipment:

This equipment is available to the scientific community, on the basis of research cooperation and co-authorship of publications in international scientific journals and presentations in Conferences.