Growth and characterization of electro-ceramic thin films, ceramics, and nano-structured materials; especially ferroelectrics, piezoelectrics, and semiconductors for the development of devices, such as micro-electro-mechanical systems, nonvolatile memories, microwave dielectrics, and display devices; Material arquitecture and charge transport in solid state ionics for rechargeable Li ion batteries; investigations using laser Raman, infrared, dielectric, and photo-luminescence spectroscopies; phonon dynamics.
SPECLAB article selected for cover of Materials Research Bulletin
Piezoresponse Force Microscopy (PFM) technique has been employed to acquire out-of-plane (OPP) piezoresponse images and local piezoelectric hysteresis loop in rhombohedrally distorted Bi1−xPrxFe1−yCoyO3 [x = 0, 0.05; y = 0.05] polycrystalline thin films fabricated via chemical solution deposition method. PFM images revealed that piezoelectric contrast is dependent upon the film composition. Furthermore, negative self-polarization effect was observed in the cobalt substituted BFO film. Well saturated local piezo-hysteresis loops were monitored and an increase was noticed in the piezoelectric coefficient (d33) value with cobalt doping (25.1 pm/V) whereas with Pr co-substitution in BFCO film, the piezoelectric behavior was almost suppressed. Pr and cobalt co-substituted film exhibited the lowest leakage current density. Magnetic behavior (M–H curves) exhibited nearly eight times enhancement in the saturation magnetization values in the Co- and Co–Pr substituted films. The present study provides the different elements’ substitution effect on the local piezoelectric and magnetic properties of BiFeO3multiferroic thin film.
Speclab article has been selected for the cover picture/page of the January 2014 issue of Phys. Status Solidi B
Properties of the new electronic device material LaGdO3,
Shojan P. Pavunny, Ashok Kumar, Pankaj Misra, James F. Scott, and Ram. S. Katiyar
Phys. Status Solidi B 251, No. 1, 131–139 (2014) /http://dx.doi.org/10.1002/pssb.201349257.As the semiconductor technology approaches size limitation (according to Moore's law), significant efforts need to be focused to develop alternative gate dielectric materials that can facilitate low electrical functional thicknesses for future logic and memory nodes. Over the last few years there has been considerable interest in the application of inter-lanthanide compounds in modern electronic devices. Researchers at University of Puerto Rico led by Professor Ram S. Katiyar have developed a novel alternative low-loss high-k dielectric lanthanum gadolinium oxide in their laboratory which is a significant development for nano-electronic device applications, such as dynamic random access memories (DRAMs), resistive switching memory elements (RRAMs) and related logic electronic components (MOSFETs). Pavunny et al. (pp. 131–139) utilized X-ray crystallography and Raman spectroscopy to characterize the crystal structure of this oxide and also discussed its high-temperature phase transition near 900 K. This new material has a dielectric constant greater than five times that of silicon oxide which is higher than that of any of the presently used hafnium-based high-k dielectrics. Therefore it can have a broader impact on feature size reduction in the fabrication of CMOS logic and memory devices.