Solid State Spectroscopy

A given spectroscopic technique not only complements the bulk crystal-chemical properties characterized, for  instance, by X-ray diffraction, but also unveils unique local features to better understand the underlying properties.

Stereochemical activity of lone electron pairs (LEPs)

Main-group cations with lower oxidation states (e.g., Sn²⁺, Pb²⁺, As³⁺, Sb³⁺, Bi³⁺) contain internally spin-paired electrons in the valence shell are known as lone electron pairs (LEPs). For a given coordination, the non-bonding LEP is called stereochemically active when its lacuna locates mostly at the opposite side of the bonding electron density. My prima facie research interests involve the roles of LEPs in crystalline oxide materials, in particular, to:

• measure the stereochemical activity of LEPs in crystalline solids, proposing a periodic trend for oxide materials.
• functionalize/tune LEPs for a target physico-chemical property of oxide materials.
• correlate thermodynamic variables (e.g., mechanical pressure) with chemical pressure exerted by LEPs in oxides.
• understand the abundance of LEP-containing minerals from the available geochemical data.
• categorize the Coulombic interactions between molecular crystal and solid state crystals tailored by LEPs.

Multiferroic oxides

While type-I multiferroic exhibits higher ferro-distortive polarization, type-II carries a few order of magnitude lower spontaneous polarization values. I am particularly interested in search of type-II multiferroic oxides with high polarizability driven by ns²-LEP cations which can be tailored by suitable mixing with p-orbitals.

Lattice dynamics

Lattice dynamics is associated with the propagation of sound waves, thermodynamics, superconductivity, phase transitions, thermal conductivity and thermal expansion of crystalline solids. My particular interests lie at the characterization of lattice dynamics of functional oxide materials using Raman, FT-IR and inelastic neutron scatterings.

Research Lead: M. Mangir Murshed