Frontiers in Materials Science, Engineering, and Technology: An FMD Symposium in Honor of Sungho Jin: Process-Property-Performance Correlations: Titanates, Transition Metal Oxides, Chalcogenides & Beyond
Sponsored by: TMS Functional Materials Division, TMS: Biomaterials Committee, TMS: Electronic Packaging and Interconnection Materials Committee, TMS: Nanomaterials Committee, TMS: Thin Films and Interfaces Committee
Program Organizers: Fay Hua, Intel Corporation; Tae-Kyu Lee, Portland State University; Young-Ho Kim, Hanyang University; Roger Narayan, UNC/NCSU Joint Department of Biomedical Engineering; Choong-un Kim, University of Texas at Arlington; Nuggehalli Ravindra, New Jersey Institute of Technology

Tuesday 2:00 PM
February 28, 2017
Room: 33B
Location: San Diego Convention Ctr

Session Chair: Tae-Kyu Lee, Portland State University; Yuntian Zhu, North Carolina State University

2:00 PM Introductory Comments

2:10 PM  Invited
What are in a Phase with Property Anomaly?: Zi-Kui Liu1; 1The Pennsylvania State University
    Anomaly in a phase refers to dramatic response of properties of a phase with respect to external stimulus such as temperature, pressure, and stress/electric/magnetic fields. From thermodynamics, it is known that properties of a phase diverge at a critical point because the phase becomes unstable and transforms into a mixture of phases. Consequently a critical point may also be viewed as a mixture of various configurations when viewed from the direction of the mixture of phases. We show that anomaly at a critical point can be predicted by a statistic mixture of relevant configurations or originates from the competition of various configurations when viewed from the phase mixture or the single phase, respectively. A molar quantity with respect to a non-conjugate thermodynamic potential, such as thermal expansion (dV/dT), can diverge either positively and negatively. This is further observed in the ab initio molecular dynamic simulations of the ferroelectric-paraelectric transition in PbTiO3.

2:40 PM  Invited
Interface Magnetism in La0.7Sr0.3MnO3/SrRuO3 Bilayers Integrated on Silicon: Srinivasa Rao Singamaneni1; John Prater2; Jay Narayan2; 1University of Texas, El Paso; 2North Carolina State University
    Transition metal oxides of pervoskite structure have gained a great research interest due to strong coupling of spin, charge and orbital degrees of freedom. Unexpected properties emerge when two distinct materials conjoined. In this invited talk, I choose to present and discuss the data related to two such magnetic layers, when they are in contact. One is La0.7Sr0.3MnO3 (LSMO) layer, which is room temperature ferromagnetic metallic; and the other one is SrRuO3 (SRO) layer, which is hard ferromagnetic metallic below 160K. Magnetometry measurements as a function of biasing layer (SRO) and biased layer (LSMO) thicknesses reveal tunable coercivity (6334-489Oe). Furthermore, it was found that the easy-axis magnetization reversal process of the LSMO layer not only depends on the spin structure of the SRO layer frozen-in during the cooling process, but also strongly depends on the thickness of the LSMO layer, and the order of LSMO and SRO in the BL.

3:10 PM  Invited
Interfacial Reactions at the Joints in the Bi2Te3-based Thermoelectric Modules: Sinn-wen Chen1; Tz-wen Liou1; Hsu-shen Chu1; 1National Tsing Hua University
    Development of thermoelectric modules is very important because thermoelectric modules can recover waste heat, convert it directly into electricity, and thus enhance the energy usage efficiencies. There are many joints in a thermoelectric module which connect arrays of thermoelectric devices to the metallic conducting plates. To prevent direct contact and interactions between solders and thermoelectric materials, Ni(P) diffusion barrier layer is introduced between solders and thermoelectric substrates. The Bi2Te3-based thermoelectric materials, P-type (BixSb1-x)2Te3 and N-type Bi2(TeySe1-y)3 alloys, are the most common commercially used thermoelectric materials. In a Bi2Te3-based thermoelectric module, there are two kinds of joints, solder/Ni(P)/(BixSb1-x)2Se3 and solder(Au)/Ni(P)/Bi2(TeySe1-y)3, i.e. three kinds of interfaces, solder/Ni(P), Ni(P)/(BixSb1-x)2Te3 and Ni(P)/Bi2(TeySe1-y)3. The interfacial reactions at these contacts are examined. Although three intermediate phases, Ni3Te2, NiTe0.775 and NiTe2, are formed in the Ni/Te couples, only the NiTe2 phase is formed at the (Bi0.25Sb0.75)2Te3/Ni(P) interfaces. At the Ni(P)/Bi2(TeySe1-y)3 contact, NiTe2 and (Bi2)m(Bi2Te3)n phases are formed.

3:40 PM Break

3:55 PM  
Microstructure and Mechanism Studies of Epitaxial TiN Oxidation in Different Growth Orientations: Adele Moatti1; Jagdish Narayan1; 1NCSU
     We have devised a novel method to create epitaxial heterostructures by oxidation of single-crystal TiN. This paper is focused on designing novel heterostructures with different growth orientations. These heterostructures TiO2(110)/TiN(100)/Si(100) and TiO2(101)/TiN(111)/c-sapphire have been achieved through innovative oxidation of TiN buffer layer and the mechanism behind discovered. The main focus of this study is placed on the growth orientation and oxidation mechanism correlation in TiN based epitaxial heterostructures where the oxidation rate is tuned through microstructural characteristics. The epitaxial growth of TiO2 buffered with TiN through oxidation on different substrates was explained. The Ɵ-2Ɵ and Φ X-Ray diffraction scans, and detailed high resolution electron microscopy studies confirmed the epitaxial growth and crystallographic alignments across the interfaces. Also, it was shown that Ti out-diffusion is a main source of oxidation for both substrates with the aid of high resolution TEM images. Moatti A, Bayati R, Narayan J. Acta Materialia 2016;103:502.

4:15 PM  Invited
Novel Iron-lanthanide Based High-mobility, Ferromagnetic and Transparent Amorphous Semiconducting Oxides: Humaira Taz1; Abhinav Malasi1; Tamil Sakthivel2; N Yamoah3; Connor Carr1; Annette Farah1; Benjamin Lawrie4; Raphael Pooser4; Maulik Patel1; Arthur Baddorf4; Dhananjay Kumar3; Sudipta Seal2; Hernando Garcia5; Gerd Duscher1; Ramki Kalyanaraman1; 1University of Tennessee; 2University of Central Florida; 3North Carolina A&T; 4Oak Ridge National Laboratory; 5Southern Illinois University
    Amorphous semiconductors combining transparency and conductivity are attractive materials for transparent conductors in solar energy, displays, and flexible electronics. Worldwide focus has been on post-transition metal oxides due to their large s-band character in the conduction band. We discuss here a profoundly different class of oxides based on iron-lanthanides that are expected to be insulating, but instead, show extraordinary conductive properties. Using a variety of characteriation tools, we have investigated the structure and properties of Fe-Tb-Dy-O amorphous thin films synthesized by pulsed laser deposition or e-beam co-evaporation at room temperature. Some of the exceptional properties include high light transparency (>90%), low sheet resistance <200 Ohm-Sq), high mobility (>30 cm2/V-s), semiconducing character and room temperature ferromagnetism. Ongoing investigations hope to unravel the origins of these properties leading to use in electronics and spintronics. Refs:, * This work has been supported partly by grants from the ARO, NSF and ORNL-JDRD

4:45 PM  
Tuning of Semiconductor-to-metal Transition in Epitaxial VO2 through Strain Engineering in the Heterostructures: Adele Moatti1; Jagdish Narayan1; 1NCSU
    We have studied semiconductor-to-metal transition (SMT) characteristics of VO2 in different epitaxial heterostructures of VO2(011)/TiO2(110)/TiN(100)/Si(100) and VO2(001)/TiO2(101)/TiN(111)/c-sapphire. The abrupt change in electrical property and infrared transmittance of VO2 lend themselves to many interesting applications. We have integrated VO2 through TiO2/TiN buffer layers to Si(100) and c-sapphire. The epitaxial TiO2 was achieved by novel method of TiN oxidation. The transition temperature of VO2 depends on the epitaxial growth characteristics and the residual misfit strains associated with the TiO2/VO2 interface. The rutile epilayers with different out-of-plane orientations were grown and used as a platform for epitaxial VO2 with the aim of manipulating its microstructure and electrical properties. It has been shown that the SMT can be tuned through microstructural engineering. These results facilitate the VO2 based single crystalline heterostructures as a promising candidate for a wide range of applications where different transition temperatures are required. Moatti et al. Acta Materialia 2016; 103:502.

5:05 PM  Invited
Synchrotron X–ray Structure–resolved Study of Photovoltaic Titanium Oxide Phthalocyan: E­-wen Huang1; Wei-Jie Huang1; Yu­-Hsiang Hsu2; Tsun­-Hsu Chen2; 1National Chiao Tung Univeristy; 2National Taiwan University
    Titanium oxide phthalocyanine (TiOPc) is an photovoltaic materials. It possesses an excellent light–sensitive property for optical tweezer application and microfluiducs actuator. Using Dip coating methods, we control the performance such as resistance and capacitance. We will report the relationships between the XRD–resolved structure and resistance.