Indian Institute of Technology Hyderabad (IITH) is a premier institute of science and technology established in 2008. IITH has been consistently ranked in the&nbsp;<a href="https://iith.ac.in/reports/" rel="noopener noreferrer">top 10 institutes</a>&nbsp;in India for Engineering&nbsp;<a href="https://www.nirfindia.org/2021/EngineeringRanking.html" rel="noopener noreferrer" target="_blank">according to NIRF</a>&nbsp;making it one of the most coveted schools for science and technology in the country.

IITH offers&nbsp;<a href="https://iith.ac.in/academics/under-graduate/">undergraduate programs</a>&nbsp;in all the classical engineering disciplines, applied sciences, design, as well as several modern interdisciplinary areas. Students are given a flexibility to explore a broad set of areas, and potentially pursue a minor or double major in a discipline that is not their own. Students who wish to seek a deeper understanding of their own discipline are strongly encouraged to get involved in cutting-edge research with the help of a faculty to mentor them, and earn an Honors in their own field.

The very foundation of IIT Hyderabad is based on&nbsp;<a href="https://iith.ac.in/research/">research and innovation</a>. The vibrant research culture is evident from the number of patents and publications that IITH produces consistently every year. IITH offers&nbsp;<a href="https://iith.ac.in/academics/programmes-offered/">graduate programs</a>&nbsp;at both a masters, and a doctoral level, in several diverse areas. There are separate programs for technology, design, science, and liberal arts. The&nbsp;<a href="https://iith.ac.in/academics/post-graduate/">MTech program</a>&nbsp;is offered in various modes and durations to cater to the ever-growing need of postgraduate level professionals in the country.

IITH encourages and supports&nbsp;<a href="https://iic-iith.netlify.app/index.html" rel="noopener noreferrer" target="_blank">innovation and entrepreneurship</a>&nbsp;at every stage. The minor program in entrepreneurship is open to all students of IITH, and many of the courses are offered by industrialists who are entrepreneurs themselves. There are various&nbsp;<a href="https://iith.ac.in/research/centres-incubators/">innovation centers and incubators</a>&nbsp;that promote entrepreneurship and help mentor young innovators. IITH has been very successful in building tie-ups with leading academic institutions around the globe.

IITH enjoys a very special relationship with Japanese universities and industries that goes beyond academic and research collaborations. In fact, some of the iconic buildings in IITH campus will carry the signature of Japanese architecture.

IITH creates a unique holistic ecosystem for education that offers interactive learning, a very flexible academic structure, cutting-edge research, strong industry collaboration, and entrepreneurship. This is an environment which enables students and faculty to translate their dreams into realities.

IIT Hyderabad

Department of Materials Science and Metallurgical Engineering

World University root node

Physical Review B - Condensed Matter and Materials Physics

Erratum: Interfacial coupling and its size dependence in PbTiO3 and PbMg1/3 Nb2/3 O3 multilayers (Physical Review B - Condensed Matter and Materials Physics (2006) 74, (184104))

(1-x) Pb (Mg1/3 Nb2/3) O3 - (x) PbTiO3 (PMNPT) a relaxor ferroelectric has gained attention due to its interesting physical properties both in the bulk and thin film forms from a technological and fundamental point of view. The PMNPT solid solution at the morphotropic phase boundary composition has superior properties and is potentially used as an electrostrictive actuator, sensor, and in MEMS applications. Deposition of phase pure PMNPT thin films on bare platinized silicon wafers has been an impossible task so far. In this study the role of the LSCO template on the phase formation and the influence of platinum surface on the same have been studied. It was observed that formation of hillocks in Pt coated silicon wafers is associated with an ATG type of instability while roughening through strain relaxation. The hillocks formation was observed only on the troughs of the strain waves on the surface of Pt. The nucleation and growth of the PMNPT films were analyzed using AFM studies and the nucleation nucleates only at the tips of the hillocks and grows along the same direction with a new nucleus adjacent to the first one. A wavy pattern of PMNPT nuclei was observed and later the lateral growth of the islands takes place to cover the surface and minimizes the roughness to 2 nm. Hence, a template layer with a minimum of 40 nm is required to have a complete coverage with a roughness of less than 2 nm. The chemical states of the PMNPT films grown with and without the template layer were analyzed using x-ray photoelectron spectrum. The XPS spectrum of PMNPT deposited on a Pt surface exhibited a reduced oxidation state of niobium ions and a metallic state of Pb at the initial stage of the growth, which effectively destabilizes the perovskite phase of PMNPT in which the charge states and the ordering of Nb and Mg are more crucial to have a stable perovskite structure. © 2007 American Institute of Physics.

Fulltext

Journal of Applied Physics

Role of template layer on microstructure, phase formation and polarization behavior of ferroelectric relaxor thin films

A set of symmetric and asymmetric superlattices with ferromagnetic La0.6 Sr0.4 Mn O3 (LSMO) and ferroelectric 0.7Pb (Mg13 Nb23) O3 -0.3 (PbTi O3) as the constituting layers was fabricated on LaNi O3 coated (100) oriented LaAl O3 substrates using pulsed laser ablation. The crystallinity, and magnetic and ferroelectric properties were studied for all the superlattices. All the superlattice structures exhibited a ferromagnetic behavior over a wide range of temperatures between 10 and 300 K, whereas only the asymmetric superlattices exhibited a reasonably good ferroelectric behavior. Strong influence of an applied magnetic field was observed on the ferroelectric properties of the asymmetric superlattices. Studies were conducted toward understanding the influence of conducting LSMO layers on the electrical responses of the heterostructures. The absence of ferroelectricity in the symmetric superlattice structures has been attributed to their high leakage characteristics. The effect of an applied magnetic field on the ferroelectric properties of the asymmetric superlattices indicated strong influence of the interfaces on the properties. The dominance of the interface on the dielectric response was confirmed by the observed Maxwell-Wagner-type dielectric relaxation in these heterostructures. © 2007 American Institute of Physics.

Realization of biferroic properties in La0.6 Sr0.4 Mn O3 0.7Pb (Mg13 Nb23) O3 -0.3 (PbTi O3) epitaxial superlattices

Three-component ferroelectric superlattices consisting of alternating layers of SrTiO3, BaTiO3, and CaTiO3 (SBC) with variable interlayer thickness were fabricated on Pt (111) / TiO2 / SiO2 /Si (100) substrates by pulsed laser deposition. The presence of satellite reflections in x-ray-diffraction analysis and a periodic concentration of Sr, Ba, and Ca throughout the film in depth profile of secondary ion mass spectrometry analysis confirm the fabrication of superlattice structures. The Pr (remnant polarization) and Ps (saturation polarization) of SBC superlattice with 16.4-nm individual layer thickness (SBC16.4) were found to be around 4.96 and 34 μC/ cm2, respectively. The dependence of polarization on individual layer thickness and lattice strain were studied in order to investigate the size dependence of the dielectric properties. The dielectric constant of these superlattices was found to be much higher than the individual component layers present in the superlattice configuration. The relatively higher tunability (∼55%) obtained around 300 K indicates that the superlattice is a potential electrically tunable material for microwave applications at room temperature. The enhanced dielectric properties were thus discussed in terms of the interfacial strain driven polar region due to high lattice mismatch and electrostatic coupling due to polarization mismatch between individual layers. © 2007 American Institute of Physics.

Nonlinear dielectric behavior in three-component ferroelectric superlattices

Multilayers of Pb (Mg1 3 Nb2 3) O3 (PMN)- PbTiO3 (PT) were deposited through pulsed laser ablation deposition with different periodicities (d=10, 20,30,40,50,60, and 70 nm) for a constant total thickness of the film. The presence of superlattice reflections in the x-ray diffraction pattern clearly showed the superlattice behavior of the fabricated structures over a periodicity range of 20-50 nm. Polarization hysteresis and the capacitance-voltage characteristics of these films show clear size dependent ferroelectric and antiferroelectric (AFE) characteristics. Presence of long-range coupling and strain in multilayers with lower periodicity (∼10 nm) exhibited a clear ferroelectric behavior similar to a solid solution of PMN and PT. Multilayers with higher periodicities (20-50 nm) exhibited antiferroelectric behavior, which could be understood from the energy arguments. On further increase of periodicity, they again exhibit ferroelectric behavior. The polarization studies were carried out beyond the Curie temperature Tc of PMN to understand the interlayer interaction. The interaction is changed to a ferroelectric- paraelectric interlayer and tends to lose its antiferroelectric behavior. The behavior of remnant polarization Pr and d Pr dT with temperature clearly proves that the AFE coupling of these superlattices is due to the extrinsic interfacial coupling and not an intrinsic interaction as in a homogeneous conventional AFE material. The evidence of an averaged behavior at a periodicity of ∼10 nm, and the behavior of individual materials at larger periodicities were further confirmed through dielectric phase transition studies. The presence of AFE interfacial coupling was insignificant over the dielectric phase transition of the multilayers. © 2006 The American Physical Society.

Interfacial coupling and its size dependence in PbTiO3 and PbMg1 3 Nb2 3 O3 multilayers

We report on the dielectric properties of bismuth aluminate and gallate with Bi:Al(Ga) ratio of 1:1 and 12:1 prepared at high temperature and ambient pressure. These compounds crystallize in a noncentrosymmetric body-centered cubic structure (space group I23) with a ∼ 10.18 Å rather than in the perovskite structure. This cubic phase is related to the γ - Bi2 O3 structure which has the actual chemical formula Bi243 + (Bi3 + Bi5 +) O40 - δ. In the aluminates and gallates studied by us, the Al and Ga ions are distributed over the 24 f and 2 a sites. These compounds exhibit ferroelectric hysteresis at room temperature with a weak polarization. © 2006 Elsevier Ltd. All rights reserved.

Solid State Communications

Ferroelectricity in Bi26 - x Mx O40 - δ (M=Al and Ga) with the γ - Bi2 O3 structure

Multilayers of (1-x) Pb (Mg13 Nb23) O3 -x PbTiO3 thin films were prepared with a compositional variation of PbTiO3 on each layer across the film by pulsed laser ablation technique. The fabricated films were found to possess an enhanced diffusiveness in the dielectric phase transition, which actually seemed to be an envelope of the phase transition of the individual layer relaxor ferroelectrics of a particular composition. They also showed a very high nonlinear dielectric response and hence a high tunability about 70%, an increase of about 40% than that observed for single layer composition. This increase in tunability has been attributed to the lattice strain and the artificially enhanced chemical heterogeneity of the system. These multilayer films also showed a slim hysteresis loop characteristic with a saturation and remnant polarization of 20 and 6 μC cm2, respectively. © 2005 American Institute of Physics.

Applied Physics Letters

Enhanced tunability and phase transition studies in compositionally varying lead magnesium niobate-lead titanate multilayered thin films

Ferroelectric properties of chemically heterogeneous multilayers and graded composition thin films of (1-x) Pb (Mg13 Nb23) O3 -xPbTi O3, a well-known relaxor, were prepared using a multitarget pulsed laser ablation system. Target materials with different values of x (0.0, 0.1, 0.2, and 0.3) were used for ablation growth. Films with sharp interfaces and graded interfaces were prepared and were characterized for their electrical properties. The stepped films were found to have a phase-transition behavior dominated by the individual layer behavior with their corresponding local dielectric maxima. The graded films showed an overall averaged effect of the system. The graded films showed an enhanced diffusiveness in the phase transition and the γ value was found to be 2.43, which is a measure of diffusivity. The tunability of these graded films was found to be high around 60% and was twice that of any of the film of homogeneous composition films. The room-temperature polarization hysteresis curves exhibited slim loop characteristics with a saturation polarization of about 40 μC cm2 in the case of both stepped and graded films. © 2005 American Institute of Physics.

Dielectric phase-transition and polarization studies in stepped and compositionally graded lead magnesium niobate-lead titanate relaxor thin films

Ba1-x Cax TiO3 targets were prepared by conventional solid state reaction with varied amounts of the calcium content (5 at.%, 10 at.%) and the thin films were deposited on Pt(111) coated Si substrate using pulsed laser ablation technique. The thin films were deposited at different pressures and temperatures, so as to determine the optimized growth parameter for the good quality BCT thin films. The pressure variation on the growth parameters made a dramatic impact in tailoring the dielectric constant and phase transition. The phase evolution of the BCT thin films evolves from 450°C and at higher substrate temperatures (∼700°C) for different partial pressures of oxygen, the preferred orientation of the thin films were observed. The SIMS analysis reveals a sharp interface exist at the bottom electrode (Pt)-BCT thin films indicating no interdiffusion taking place which might lead to the degradation of devices. The BCT thin films deposited at higher pressures (&gt;60 mtorr) exhibited higher Ba content indicating the possibility of the Ca occupying the Ti site and is reflected in the decrease of the dielectric phase transition temperature. The ferroelectric hysteresis and Capacitance voltage measurement shows the signature of ferroelectricity.

Integrated Ferroelectrics

Growth and studies of calcium doped laser ablated barium titanate thin films

Recently, there has been growing interest in Ca modified BaTiO3 structures due to their larger electro-optic coefficients for their use in optical storage of information over conventional BaTiO3 crystals. Barium Calcium Titanate (BCT) shows promising applications in advanced laser systems, optical interconnects and optical storage devices. BaTiO3 thin films of varied Ca (3 at. % - 15 at. %) doping were deposited using pulsed laser ablation (KrF excimer laser) technique over Pt/Si substrates. The stoichiometric and the compositional analysis were carried out using EDAX and SIMS. The dielectric studies were done at the frequency regime of 40 Hz to 100 kHz at different ambient temperatures from 200 K to 600 K. The BCT thin films exhibited diffuse phase transition, which was of a typical non lead relaxor behavior and had high dielectric constant and low dielectric loss. The phase transition for the different compositions of BCT thin films was near the room temperature, showing a marked departure from the bulk phase transition. The C - V and the hysteresis behavior confirmed the ferroelectric nature below the phase transition and paraelectric at the room temperature.

Materials Research Society Symposium - Proceedings

Dielectric studies of laser ablated Ca doped BaTiO3 thin films

Thin films of BaZrO3 (BZ) were grown using a pulsed laser deposition technique on platinum coated silicon substrates. Films showed a polycrystalline perovskite structure upon different annealing procedures of in-situ and ex-situ crystallization. The composition analyses were done using Energy dispersive X-ray analysis (EDAX) and Secondary ion mass spectrometry (SIMS). The SIMS analysis revealed that the ZrO2 formation at the right interface of substrate and the film leads the degradation of the device on the electrical properties in the case of ex-situ crystallized films. But the in-situ films exhibited no interfacial formation. The dielectric properties have been studied for the different temperatures in the frequency regime of 40 Hz to 100kHz. The response of the film to external ac stimuli was studied at different temperatures, and it showed that ac conductivity values in the limiting case are correspond to oxygen vacancy motion. The electrical modulus is fitted to a stretched exponential function and the results clearly indicate the presence of the non-Debye type of dielectric relaxation in these materials.

Growth and study of BaZrO3 thin films by pulsed excimer laser ablation

The growth of Ca-doped barium titanate thin films using a pulsed laser ablation technique were analyzed. The x-ray diffraction and scanning electron microscope studies revealed a polycrystalline nature with significant orientation along the (111) direction. The presence of a sharper interface was exhibited by the secondary ion mass spectrometer analysis. The results show that the dielectric constant and dielectric phase transition temperature of the thin films decreased with an increase in the calcium content.