Structure of ordered and disordered materials using neutron diffraction Facilities in BARC

Knowledge of the symmetry and distribution of atoms in the unit cell and the bonding between atoms is the key point for understanding, designing and manipulating chemical behaviour or physical properties of novel materials for technological applications. This could be achieved using powder diffraction and total diffraction techniques. At the Dhruva national facility, BARC, Mumbai, a Powder diffractometer (PD2) and a High-Q diffractometer (HQD) are routinely used for such studies. We report about the studies of changes in the behaviour in the Phase Transitions in crystalline materials as a function of temperature and/or size on these diffractometers in recent years. PD2 has been extensively used in the structural/phase transition studies of ferroics, multiferroics, ferrites as a function of temperature and size of particles. On the other hand, HQD has been extensively used to understand the short and intermediate range order in disordered crystalline materials, liquids as well as glasses. We will be discussing some of the important results obtained by these two diffractometers on many of the above mentioned materials. Reverse Monte Carlo simulation studies on some of the glasses will also be discussed. (author)