First experimental observation and thermodynamic description of elastic softening in a mineral

A. Tröster, W. Schranz and R. Miletich

How to Couple Landau Theory to an Equation of State

Phys. Rev. Lett.88 055503 (2002)

 

BD10267_Phenomenological Theory (Landautheory, Pseudospinmodels,..) of Phase Transitions in nonmetallic Solids in combination with Experiments

BD10267_ Sound Propagation in crystals near Phase Transitions

BD10267_Ultralow Frequency Elastic Behaviour in Crystals near Structural Phase Transitions

BD10267_ Optical Properties of Crystals

BD10267_ Orientational Disorder in molecular Crystals (KSCN, C60, C70,...)

BD10267_ Domains and Domainwall Properties

BD10267_ incommensurate Phases, Theory of the Lock-In Transition, Elastic Properties of Incommensurate Crystals

BD10267_ Influence of Defects (Point Defects, Dislocations, Domains,..) on the Phase Transition Properties of Crystals

BD10267_ Mesoscopic Structures near Phase Transitions

BD10267_ Mineral Physics

BD10267_High Pressure Physics BD15184_

Equipment

Characterisation of crystals

By using Lang¹s x-ray topography (Mo, Ag, Co anode materials, 1.2 kW max. power) crystals can be characterised according to their structural defects. Temperatures are covered from 100 K to 500 K. Neutron activation analysis is available for determining chemical defects (in collaboration with the Geochemical Institute).

 

Dynamical mechanical analysis Perkin Elmer DMA 7)

The equipment can be used for determining the thermal expansion and the elastic compliances of crystals. The complex compliances can be routinely measured in a frequency range from 10 mHz to 50 Hz and for temperatures between 100 K and 1300 K. In co-operation with Oxford Instruments we have adapted the measurement cell for temperatures down to 6 K. The resolution in the length change of the sample is 30 nm, the force resolution in determining elastic compliances is 1 mN.

 

Differential scanning calorimetry Perkin Elmer DSC 7)

The temperature range covered ranges from 100 K to 1000 K with heating and cooling rates between 0.1 K up to l00Kper minute.

 

High thermal resolution specific heat

The measurement of the specific heat is performed using ac-calorimetry. A thin sample (thickness 100 m - 300 m , diameter about 3 mm) is periodically (0,5Hz - 1,5Hz) heated by a light beam. The temperature change of the sample thus created (+0,01 K) is measured by Lock-In technique using a thin thermocouple (30 m) as a sensor. The whole experiment is automated using a personal computer. The temperature of the sample in the range from 90 K to 600 K is controlled by a commercial temperature controller. The smallest temperature steps in this experiment are 10 mK. The temperature resolution of the experimental setup is + 2.5 mK.

 

Dielectric permittivity

Dielectric constants for frequencies between I kHz and 10 MHz are determined by measuring the admittance of oriented crystal plates with electrodes either evaporated or silver painted (HP4] 92A and HP4191A). At the low frequency end a Stanford Research Systems DSP Lock-In amplifier (SR850) enables measurements down to I mHz. The temperature of the sample chamber is regulated by a commercial temperature controller (EUROTHERM 818) between 80 K and 550 K or by a closed cycle Helium refrigerator between 20 K and 300 K.

 

The polarising microscope (ZEISS AMOPHOT)

The relative temperature change of the birefringence can be measured using the polarising microscope and the Senarmont compensation method. In a temperature range from 3.8 K to 1700 K the absolute value of the birefringence can be measured using a tilting compensator. The birefringence measurements (even within a single domain) can be performed with uniaxial stress or electric field applied. Domain structure studies as a function of temperature and uniaxial stress and phase front studies can also be performed. The change of the orientation of the index ellipsoid can be studied in the temperature range mentioned. The microscope is equipped with photographic and video facilities for documentation.

 

Ultrasonic equipment

Using the echo-overlap-technique the determination of elastic constants and of the sound attenuation with ultrasound is possible for frequencies of 5 MHz - 90 MHz.

BD15184_

Cooperations

 

Laboratory of Complex Systems, University of Picardie, Amiens, France

P. Tolédano

 

Institut für Mineralogie und Kristallographie, Geozentrum, Universität Wien
E. Tillmanns, E. Libowitzky, M. Götzinger, et al.

 

Intitut für Geowissenschaften, Universität Heidelberg, Im Neuenheimer Feld, Heidelberg, Germany

Ronald Miletich

Institute of Physics, Czech Academy of Sciences, Prague
J. Petzelt, S. Kamba, J. Hlinka,  I. Rychetsky, V. Janovec, et al.

Institute of Nuclear Physics, Cracow.
K. Parlinski, P. Zielinski, et al.

Jozef Stefan Institute, University  Ljubljana
R. Blinc, J. Dolinsek, I. Drevensek-Olenik, I. Musevic, et al

Laboratoire de Mineralogie et Crystallographie, Universite de Langduoc, Montpellier, France.
P. St. Gregoire

Department on Earth Sciences, University of Cambridge, UK.
E.K.H.Salje, M. Carpenter

Lviv Polytechnic National University, Lviv, Ukraine

A.S. Andrushchak

 

Institute for Computer Science, Technical University of Czestochova, Czestochova, Poland

A. Kityk

 

Nationaler Forschungspartner im FWF-Projekt P 29563-N36 „Relaxors“

Projektleiter: Dr. Marco Deluca, Materials Center Leoben Forschung GmbH

https://www.researchgate.net/project/Origin-of-relaxor-behaviour-in-Ba-based-lead-free-perovskites

 

Origin of relaxor behaviour in Ba-based lead-free perovskites

 

Goal: We aim to uncover the relationship between polar order and chemical order in Ba-based relaxors using a combination of Raman spectroscopy and atomistic modelling. In particular we're going to study homovalent and heterovalent systems based on Zr- and Nb-doping.

Methods: Dielectric Spectroscopy, Raman Spectrum Analysis, Raman Spectroscopy, X-Ray Diffraction, Ferroelectrical Properties, Relaxor Ferroelectrics, Ab Initio Methods

 

https://www.researchgate.net/profile/Marco_Deluca/project/Origin-of-relaxor-behaviour-in-Ba-based-lead-free-perovskites/attachment/58ef6a7e1042bf333c682f97/AS:482655197241344@1492085374726/image/IMG_1369_Kick-off_2.JPG

 
  BD15184_

Projects

BD10267_ FWF-project P 6758 P (1988-1992): Strukturumwandlungen in reinen und gestörten Kristallen

BD10267_ FWF-project P 8285-TEC (1991-1994). Glasbildung und Phasenübergänge/KSCN Familie

BD10267_ BuMiWuF 45.131/4-IV/6a/92 (1990-1994): Phase Transitions in non-metallic systems into inhomogeneous or disordered phases

BD10267_ BuMiWuF GZ 45.113/3-27/90 (1990-1992): Theoretical description of orientationally disordered crystals

BD10267_ BuMiWuF  GZ 45.223/2-27b/91(1991-1994): Dipolar and Quadrupolar Glasses

BD10267_ FWF-project P 09793-PHY (1994-1997): From weakly to strongly disordered systems

BD10267_ FWF-project P 10924-PHY (1995-1998): Disorder and Glassbehaviour in Fullerites

BD10267_ FWF-project P 12226-PHY (1997-2000): Mesoscopic Structures near Phase Transitions

BD10267_ ÖAD-WTZ project (1998-2000): Investigation of Phase Transitions in Synthetic Crystals and Minerals

BD10267_ ÖAD-WTZ project  18/00 (2000-2002): Microscopic mechanical properties of Technologically important Materials studied by theory and experiment

BD10267_ ÖAD-WTZ project 14/02 (2002-2004): Elastic and vibrational properties of selected minerals and other important materials

BD10267_ EC-TMR-Network (1998-2001): Interdisciplinary European network for the quantitative analysis of transformation processes in natural minerals

BD10267_ FWF-project P 15016 (2001-2003): New approaches to strain and elasticity near phase transitions

BD10267_ EU-STCU project No 1712 (2002-2004) Acoustooptic devices for control of superpowerful laser radiation

BD10267_ EU-STCU Coordinator of project No. 3222 (2005-2007) Spatial Anisotropy complete 3D-analysis in geometry optimizations of electro-, piezo- and acoustooptical interactions

BD10267_ Universitäres Schwerpunktsprojekt: "Bulk Nanostructured Materials: Synthesis, Microsctructures and Properties" FS 513002
Project Manager: Prof. H.P. Karnthaler
Research Proposers: H.P. Karnthaler, M. Zehetbauer, C. Rentenberger, T. Waitz, G. Krexner, W. Schranz, P. Rogl (FWF)

BD10267_ FWF P19284-N20 (1.12.2006-30.11.2009) "Dynamic Elasticity of Complex Materials" P19284-N20 (duration 3 years)

BD10267_   Initiativkolleg I022-N on „Experimental Materials Science-Nanostructured Materials“

BD10267_   EU-STCU project No 4584 (2009-2011) Development of most efficient acoustooptic cell creation methodology for super-high- frequency control of powerful laser radiation

BD10267_   ÖAD-WTZ project Sl 19/2009 (2009-2010): Dynamische Eigenschaften lichtempfindlicher Flüssigkristall-Elastomere

 

logo  

 COST project MP0902 (2009-2013) COINAPO “Composites of Inorganic Nanotubes and Polymers”

 

BD10267_ FWF P23982-N20 (1.11.2011-31.10.2015) "Multiscale properties of disordered ferroics and glasses" P23982-N20

BD10267_ FWF P28672-N36 (1.1.2016-31.12.2018) "Structure and dynamics of interfaces in ferroic materials" P28672-N36

 

 BD15184_

organized Conferences

BD15184_

 


 
 
 
 

translated from TEX by TTH, version 2.25.
On 30 Mar 2000, 17:21.