Research Interests

Piezoelectric hetereostructures
Geometrical and interface engineering of thin films grown by physical vapor deposition (PLD). By using different orientations, anisotropic strain and combining different materials together we aim to control and design specific functionality to different applications. We are looking into piezoelectric ceramics on top of metals, multifunctional (multiferroic) ceramics, piezoelectric ceramics on 2D materials and freestanding. We are also developing novel methods of characterization, for example in-situ transmission electron microscopy (TEM) - where we can see how the structure of our films react to voltages og mechanical loads.

Tetragonal Tungsten Bronzes
The tetragonal tungsten bronzes (TTBs) with the general formula A1₂A2₄C₄B₁₀O₃₀ represent the second most common ferroelectric materials after perovskites. TTBs exhibit a complex crystal structure characterized by five different cation sites, which opens for a rich chemistry and compositions which may lead to lead-free alternatives to conventional lead-zirconate-titanate (PZT). Via compositional engineering we are working towards understanding and tailoring ferroelectric properties in TTBs with particular emphasis on candidates with a high Curie temperature. We combine experimental synthesis and characterization with the latest in multi-scale modelling. In doing so, we aim to understand and tailor the fundamental structural, compositional and electronic properties of the TTBs.

Hexagonal manganites and bismuth-based lead-free perovskites
We investigate the structure, stability and phase transitions of hexagonal manganites and bismuth-based lead-free perovskites combining Density Functional Theory (DFT) calculations and total scattering methods with synchrotron X-rays or spallation neutrons.

Relationship between structural mechanisms and dielectric functionalities
The functional responses of ferroelectric materials are determined by many factors, e.g. domain wall motion, domain nucleation and phase transitions. All of these mechanisms leave their fingerprints in the permittivity hysteresis loops (PHL), which can be used to decipher their individual contributions to the ferroelectric characteristics. We combine PHL measurements with electric-field dependent studies of the crystal structure to pinpoint the mechanisms that give rise to the specific features in the PHL. Materials of interest are bulk ceramics, single crystals and thin films of ferroelectric and relaxor-type materials.

Strain engineered thin films by aqueous chemical solution deposition
We utilize aqueous chemical solution deposition to develop piezoelectric thin films on different type of substrates to optimize their functional response through substrate-induced strains. Both in-plane and out-of-plane response of the films are of interest and we correlate functional behavior with crystallographic substrate/film orientation.

In situ characterization of decomposition, nucleation and growth during thin film deposition.
We investigate the different processes occurring during thin film deposition using synchrotron X-rays and spectroscopic methods. We develop specifically designed sample cells that allow a wide range of processing conditions (temperature, atmosphere, heating rates).

Functional characterization:

• Dielectric and piezoelectric testing of film and bulk samples
• Temperature-dependent dielectric spectroscopy with high voltage option
• Corona discharge poling setup

Structural characterization:

• In situ set-ups for X-ray diffraction and infrared spectroscopy during thin film decomposition and crystallization.
• In situ TEM with structural information during external stimuli of voltages and mechanical loads (in collaboration with NORTEM).

Computational resources:

• DFT with VASP using Norwegian supercomputers (Sigma2 Uninett).
• MD with LAMMPS using Norwegian supercomputers (Sigma2 Uninett).

2022

T. Frömling, Y. Liu, A. P. Hoang, M. Gehringer, S. Steiner, M. Zhuk, J. Glaum and B.-X. Xu
Modulus spectroscopy for the detection of parallel electric responses in electroceramics
Journal of Materiomics 8 (2022) 556-569

I.-E. Nylund, N. S. Løndal, J. Walker, P. E. Vullum, M.-A. Einarsrud and T. Grande
Cation Disorder in Ferroelectric Ba₄M₂Nb₁₀O₃₀ (M = Na, K, and Rb) Tetragonal Tungsten Bronzes
Inorganic Chemistry (2022)

V. H. Pedersen, A. B. Blichfeld, K. Bakken, D. Chernyshov, T. Grande and M.-A. Einarsrud
Crystallization and Texturing of Sr_xBa_1–xNb₂O₆ Thin Films Prepared by Aqueous Solution Deposition─An In Situ X-ray Diffraction Study
Cryst. Growth Des. (2022)

2021

P. Pomyai, D. Munthala, T. Sonklin, R. Supruangnet, H. Nakajima P.Janphuang S.M.Dale, J.Glaum and S.Pojprapai
Electrical fatigue behavior of Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ ceramics under different oxygen concentrations
J. Eur. Ceram. Soc. 41 (2021) 2497-2505

2019

M. Hinterstein, K. Y. Lee, S. Esslinger, J. Glaum, A. J. Studer, M. Hoffman and M. J. Hoffmann
Determining fundamental properties from diffraction: Electric field induced strain and piezoelectric coefficient
Phys. Rev. B 99 (2019) 174107

J. Glaum, Y. Heo, M. Acosta, P. Sharma, J. Seidel and Manuel Hinterstein
Revealing the role of local stress on the depolarization of BNT-BT-based relaxors
Phys. Rev. Mater. 3 (2019) 054406

2018

E.W. Yap, J. Glaum, J. Oddershede and J.E. Daniels
Effect of porosity on the ferroelectric and piezoelectric properties of (Ba_{0. 85}Ca_{0. 15})(Zr_{0. 1}Ti_{0. 9})O₃ piezoelectric ceramics
Scripta Materialia 145 (2018) 122-125

L. M. Denis, J. Glaum, M. Hoffman, J. E. Daniels, R. J. Hooper, G. Tutuncu, J. S. Forrester and J. L. Jones
Effect of mechanical depoling on piezoelectric properties of Na_0.5Bi_{0. 5}TiO_3–xBaTiO₃ in the morphotropic phase boundary region
J. Mater. Sci. 53 (2018) 1672-1679

Alumni

Postdocs/Researchers

PhD students

Master students

2020/21

Sondre Bolstad Bjørø

2018/19

Elin Hagen Johnson

Guests

2022

Vojtěch Lindauer - Technical University of Liberec, Czech Republic

Prof. Pierre-Eymeric Janolin - CentraleSupélec, France

2019

Prof. Pavel Mokrý, Technical University of Liberec, Czech Republic