CURRICULUM VITAE ET STUDIORUM

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  Degree: Dr.habil.phys.
  Academic Title: Full Member of the Latvian Academy of Sciences
  Date and place of birth:  August 29, 1952, Riga, Latvian Republic
  Marital status:  Married, one daughter
  Place of work:   Institute of Solid State Physics, University of Latvia
  Present position:   Head of Laboratory, Leading Researcher
  Address:   Kengaraga street 8, LV-1063 Riga, Latvia
  Phone:   (+371) 67251691
  FAX:   (+371) 67132778
  E-mail:   purans@cfi.lu.lv


   ResearcherID    Juris Purans    ScopusID    ORCID

   EDUCATION EXPERIENCE ACTIVITIES INTERESTS PUBLICATIONS


EDUCATION

1969-1974
B.S. + M.S. degrees: Dept.of Physics, Latvian State University, Riga, Latvia
Advisor Prof. J.Kliava
Title of Thesis: "EPR of tungsten oxide glasses"
1980
Ph.D degree (Cand. of Science) Latvian State University, Riga, Latvia.
Advisors Prof. Prof. J.Kliava and Prof. J.Zakis
Title of Thesis: "EPR of disordered solid state materials"
1993
Doctor Habilitatum in Physics, University of Latvia, Riga, Latvia
Title of Thesis: "XAFS Spectroscopy of Transition Metal Oxides".

ACADEMIC AND PROFESSIONAL EXPERIENCE

1974-1975
Junior researcher scientist at Institute of Solid States Physics( ISSP) of the Latvian State University, Riga, Latvia;
1976-1979
Post-graduate studies at ISSP of the Latvian State University, Riga, Latvia;
1980-1983
Researcher Scientist at ISSP of the Latvian State University, Riga, Latvia;
1984-1988
Senior Researcher at ISSP, Latvian State University, Riga, Latvia;
1988-1998
Leading Researcher Scientist and head of the XAFS group at the ISSP of the University of Latvia, Riga, Latvia;
1998-
Head of the EXAFS Laboratory at the ISSP of the University of Latvia, Riga, Latvia.

PROFESSIONAL ACTIVITIES, FELLOWSHIPS

1982-1983
Senior visiting Fellow, Frascati National Laboratories and University of Roma, Italy - Invited by Prof. A. Balzarotti;
1986-1993
Senior visiting Fellowships, Frascati National Laboratories University of Roma, Italy -Invited Prof. E. Burattini;
03.1994
Fellowship of high level scientist "Ministere de la Recherche et de l'Espase pour l'accueil de checheurs éntrangers de haut niveau", LURE (Orsay), France -Invited by Dir. Ad. H. Dexpert;
06-07.1994, 05.1995
Associated Professor, Laboratouré de Réactivité et de Chimie des Solides, Université de Picardie, France -Invited by Prof. M. Figlarz;
09-10.1995
Associated Professor, Universita di Roma "La Sapienza", Dip. di Chimica, Italy -Invited by Prof. M. Barteri;
04.1995
Associated Professor, Laboratouré de Spectroscopie Moleculairé et Crisralline, Université Bordoaux I, France -Invited by Dir. J.C.Lasségues;
11-12.1995
Fellowship of senior scientist of CNR, ITC (Trento), Italy -Invited by Dr. F. Rocca
05-06.1996, 04.1997
Associated Professor, Université Paris-Sud, France -Invited by Prof. Ch. Souleau;
02.1997, 06-09.1995
Associated Professor, Physics Dept., Université Marseille II, France -Invited by Prof. Y. Mathey;
01-02.1998, 11-12.1996
Fellowships of INFM, Physics Dept., Universita di Trento, Italy -Invited by Prof. G. Dalba.

Research supervisor of National research programmes:

1991-1996
Latvian National grant "X-Ray Absorption Spectroscopy of Disordered Metal Oxide Compounds and Amorphous Solids" Latvian Council of Science.
1997 -
Latvian National grant "X-Ray Absorption Spectroscopy of Mixed Transition Metal Oxides and Chalcogenides". Latvian Council of Science.

Research supervisor of International research programmes:

1993-1994
(co-head) CNR Collaboration project Universita di Trento (Italy) - ISSP, Riga "Local structure of beta-alumina doped by RE ions".
1994-1996
International Science Foundation - LV 8001 and LJ 8001 "X-Ray Absorption Spectroscopy of Itercalated Transition Metal Oxides".
1991-1997
LURE (French National SR Laboratory, Orsay) Head of XAFS - projects: "Multiple Scattering study of octahedral molybdenum oxides" (1992-1993); "In situ XAFS study of phase transitions in WO3-MoO3 system" (1994-1996); "O K-edge XANES study of ReO3, WO3 and MoO3 oxides" (1996-1997-present)

Participation in International scientific programmes:

Italy - 1982, 1983, 1986, 1988 - 1993 LNF INFN Frascatti (Roma).

"EXAFS study of electrochromic and superionic oxides" Advisor Prof. E. Burattini;

"EXAFS study of BaBiPbO3 oxides and glasses" Advisor Prof. A. Baldzarotti;

"Multiple - Scattering effect in ReO3" Advisor Prof. C.R.Natoli.

USSR - 1984, 1986, 1988 programme on synchrotron radiation, Institute of Nuclear Physics AS Novosibirsk. Advisor Prof. G. Kulipanov.

USSR - 1988-1991 (Responsible of EXAFS part) "EXAFS spectroscopy with SR".

USSR National Project on SR (Zelenograd (Moscow) - Advisor Prof. M. Kovalchuk;

France - 1995-1997 PECO CEE LURE (French National SR Laboratory, Orsay)

(Responsible of part of International Project). "In-situ XAFS study of transition metal oxides". PECO International (CE) project on applying of synchrotron radiation. Advisor Dir. Ad. H. Dexpert.

Italy - 1996 - 1998 INFM Universita di Trento (Italy)

"Local structure and anharmonic properties of crystalline Ge" Advisor Prof. G. Dalba.

Member of the:

- Head of Latvian Synchrotron Radiation Society 1997-present

- European Synchrotron Radiation Society Committee, 1993-1996

- Synchrotron Radiation Committee of Zelenograd, 1988-1993

- Latvian Physics Society, 1991-present

- Association of Latvian Scientists, 1991-present

RESEARCH SUPPORT AND AGENCY

1993 International Science Foundation travel grant

1994-1996 International Science Foundation - LV 8001 and LJ 8001

1994-1997 PECO International (CE) project - LURE (Orsay)

SCIENTIFIC ADVISOR

Alexei KUZMIN - was awarded the Academia European Baltic Prize for a young scientists in 1996 for the work "X-Ray Absorption Spectroscopy Study of Transition Metals Oxide Compounds and Related Materials".

Alexei KUZMIN - Ph.D. in Physics - 1992, LU Riga, "Study of 4d and 5d transition metals oxide compounds by X-ray absorption spectroscopy";

Vera BARANOVA - MSc in Physics - 1989, LU Riga, "Optical emission spectroscopy of silicide sputtering process".

Alexei KUZMIN - MSc in Physics - 1989, LU Riga, "EXAFS and XANES of tungsten oxides";

Armand PLATE - MSc in Physics - 1988, LU Riga, "Properties of the amorphous silicon prepared by magnetron sputtering";

Gints KARKLINS - MSc in Physics - 1987, LU Riga, "Optical emission spectroscopy of magnetron sputtering process".

TEACHING EXPERIENCE

During last ten years I lectured in the University of Latvia at both undergraduate and graduate levels giving courses on "Structural methods in condensed matter characterization" and "Synthesis, properties, and application of thin films".

Also I was invited as associated Professor at French (Paris-Sud, Marseille, Bordoaux I, Amiens) and Italian (Trento, Rome) Universities and gave a lectures on XAFS spectroscopy and a course on "X-ray absorption fine structure data analysis".

I have supervised 12 B.S. and M.S. theses and two Ph.D. theses.

 

RESEARCH INTERESTS

My scientific activities are concerned with the X-ray absorption spectroscopy (XAS) study of condensed matter: experimental and theoretical research on local atomic structural and dynamical properties, breaking the pico-metre barrier (10-12 m) in XAS, e.g. research at the picoscopic (10-2 Å) and subpicoscopic (10-3 Å) scale. The research activity is carried out in collaboration with several Synchrotron Radiation Facilities: PWA and PULS at ADONE (Frascati), LURE DCI and SUPER ACO (Orsay), VEPP-3 (Novosibirsk), DESY-HASYLAB (Hamburg), ESRF (Grenoble). Results of simultaneous in-situ and ex-situ x-ray absorption fine structure (XAFS) measurements using hard (metal K- and L-edges) and soft (O K-edge) synchrotron radiation on different transition metal (TM) and rare-earth metal (RE) edges (HxWO3-MoO3, NiO-MgO, WO3-ReO3, WO3-NiO, and CeO2-TiO2) show that this method is very well-suited to study the mixed TM:TM and RE:TM oxides and to follow their phase transitions. We use the excellent sensitivity of the method to probe local (short and medium range order) rearrangements in the several nearest coordination shells around absorbing center and changes in the electronic structure of the TM, RE ions during reduction/oxidation processes in a wide range of temperatures (4 - 800 K).

I apply the EDA (EXAFS Data Analysis) software package, developed in my XAS group by Dr. A.Kuzmin, that include the standard (non-linear best fit analysis with the cumulant expansion etc.) and original methods for the analysis of the XAFS of crystalline and disordered materials. The package allows to reconstruct the radial distribution functions (RDF) around an absorbing center with a picoscopic resolution without any prior assumption on the RDF shape. Besides the XAFS signals can be analyzed in terms of single scattering (SS) and multiple scattering (MS) contributions. The EDA package was successfully applied to the analysis of below mentioned materials allowing to determine a set of structural parameters and RDFs for the local environment of several metal ions.

I study the role of the focusing and superfocusing (MS) effect in the formation of XAFS is considered for cubic ReO3, non-stoichiometric tungsten oxides WO3-x and FeF3 having the perovskite-type structure. Using an ab initio multiple-scattering approach two cases are mainly analysed: (1) MS effect in ReO3 and WO3-x crystals and (2) high-order superfocusing effect in Me-O(F)-Me-O(F)-Me atomic chain. For all main structures (MoO3-WO3 oxides and MoO3nH2O hydretes) we have done MS calculations on the basis of the X-ray structural data and we have used the full XAFS signals and there characteristic Fourier transforms up to 6 Å as a fingerprints of the different phases.

I carry out the experimental research on advanced materials for electrochromic application obtained by vacuum deposition techniques (mainly DC multi-target sputtering) and I develop the plasma Optical emission spectroscopy (OES). Multi-target and multi-magnetron sputtering techniques can be more versatile, and widely applicable, as techniques can be applied to nearly any TM:TM and RE:TM meatal composition, opening up the perspective of the generation of new nonstructural thin films.

MAIN FIELD OF RESEARCH AT PRESENT:

X-ray absorption spectroscopy:

  • XAS with Synchrotron Radiation: breaking the picometre barrier - picoscopy (10-12 m), e.g. research of local structure at the picoscopic (10-2 Å) and subpicoscopic (10-3 Å) scale;
  • In-situ x-ray absorption fine structure (XAFS) study using hard (metal K- and L-edges) and soft (O K-edge) x-rays (XANES);
  • EDA (EXAFS Data Analysis) software package - reconstruction of radial distribution functions (RDF) with a picoscopic resolution;
  • Ab initio multiple-scattering approach: focusing and superfocusing effects in the perovskite-type or layered-type structures (for example, ReO3 and MoO3-WO3, non-stoichiometric WO3-x and FeF3);
  • Laboratory EXAFS-spectroscopy;

Local atomic and electronic structure, dynamics and phase-transitions of transition metal oxides:

  • Local atomic and electronic structure, dynamics and phase-transitions in perovskite like TM (Re, W, Mo, Ta, Nb) oxides: ReO3, m-WO3,, KNb(Ta)O3; the nature of mixed valence state and metal-insulator (MI) phase transitions, small radius polaron formation, Jahn-Teller effect);
  • Local atomic and electronic structure, dynamics and phase-transitions in intercalated TM (Re, W, Mo, Nb, Ta -cathodic) mixed valence (d0, d1, d2) oxides ReO3-x, WO3-x, MoO3-x, Mo1-xWxO3, CaWO4, NiWO4 and their bronzes HxReO3, HxMo1-yWy O3;
  • Local atomic and electronic structure of TM (anodic) oxides: rock-salt type crystalline structures MexNi1-xO, MexCo1-xO (Me=Li, Mg) and nanocrystalline thin films LiyNixCo1-xO; rutile type crystalline structures IrO2-x and nanocrystalline thin films;
  • Local structure and dynamics in perovskite like HTSC Ba(K)Pb(Bi)O3;

Advanced materials for electrochromic application:

  • XAFS, XRD, Raman, IR, EPR characterisations of advanced materials for electrochromic application;
  • Magnetron sputtering of new mixed TM:TM (WO3-IrO2, WO3-TiO2, WO3-NiO, WO3-MoO3, WO3-ReO3, IrO2-TiO2) and RE:TM (CeO2-WO3, CeO2-TiO2) microcrystalline, nanocrystalline, amorphous oxides;
  • Process control by Plasma Optical Emission Spectroscopy;
  • Local atomic and electronic structure of nanocrystalline, amorphous octahedral TM (Re, W, Mo, V, Ti, Ni, Co, Ta, Nb) oxides and new mixed TM:TM (WO3-IrO2, WO3-TiO2, WO3-NiO, WO3-MoO3, WO3-ReO3, IrO2-TiO2) and RE:TM (CeO2-WO3, CeO2-TiO2);

Local atomic and electronic structure, dynamics of disordered materials and bio-inorganic molecules:

  • Local structure and dynamics in solid state electrolytes (b ¢ - and b ² -aluminas) and glasses doped with RE (Nd, Eu, Pr, Gd) ions;
  • Local structure, dynamics, CDW and phase-transitions in low dimensional TM chalcogenide crystals (Me-Te, Se; Me=Nb, Zr, W, Ir, etc.); layered TM oxides and blue bronze K0.33MoO3 charge-density waves (CDW);
  • Local structure and dynamics (harmonic and anharmonic effects) in crystalline and amorphous semiconductors (Ge, SexTe1-x);
  • Local structure and molecular dynamics of TM and RE aquaions and bio-inorganic molecules (GdDOTA, GdDTPA, Cu(BiK), Cu(Bim),Cu(TIK) etc.) in solutions at different pH and temperature;
  • EPR (Electron Paramagnetic Resonance) of TM ions (Mn2+, Fe3+, Mo5+, W5+) in disordered oxides, glasses, and thin films.

As a result of this study, we have obtained the original information on:

1) the nature of hydrogen insertion in TM oxides;

2) the local structure of amorphous-nanocrystalline oxides and glasses with octahedral structural units;

3) the nature of phase transitions in perovskite-like and layered-like compounds with octahedral structural units;

4) the nature of the atomic rearrangement during small-polarons formation in mixed valence compounds;

5) the nature of the atomic rearrangement around optically active RE ions in b ¢ - and b ² -aluminas exchanged crystals;

6) the nature of the MS processes in compounds based on octahedral structural units;

7) the local structure of TM and RE aquaions and bioinorganic molecules (GdDOTA, Cu(BiK), etc.).

 

I am the author and co-author of more than 160 scientific publications, which were published in the leading international and soviet journals.