Research History

University of Genoa (Italy), postdoctoral researcher

I received my master's degree (chemistry) from the University of Genoa, Italy in 1996 and my Ph.D. (chemistry) from the same university in 2000, focusing on solid-state synthesis and single crystal growth of the YBa2Cu3Ox (YBCO) ceramic and related superconductors. Both works have been conducted at the Physical Chemistry Section of the Department of Chemistry.

After getting my Ph.D. degree, I worked as a postdoctoral fellow at the University of Genoa (2000-2003). My main research interest was the synthesis and characterization of high-temperature superconductor ceramics. In addition, I have succeeded in growing needle shaped YBCO and REBCO single crystals using a new method [ ]. I also researched the magnetic superconductor RuSr2CuGd2O8, especially on the addition of Nd to the Gd site [ ].

ISTEC-SRL (Tokyo), JSPS foreign research fellow

In April 2003, I became JSPS Foreign Research Fellow at ISTEC-SRL (International Superconductivity Technology Research Center / Institute of Superconductivity Technology). I was engaged in the synthesis and characterization of YBCO and (Y-RE) BCO thin films using TFA-MOD (Trifluoroacetic Acid Metal-Organic Deposition).

JST-CREST, Kyoto University, postdoctoral fellow

From April 2004 to March 2007, I was part of the group of Prof. K. Matsumoto of the Department of Materials Engineering, Kyoto University as a postdoctoral researcher of JST-CREST, Kyoto University has dramatically advanced the synthesis and characterization of YBCO thin films using PLD (pulsed laser deposition). I focused my research to increase the critical current and global pinning force of YBCO by introducing multiple artificial pins (Artificial Pinning Centers, APCs) into superconducting oxide thin films. The main research result is that the enhancement of the pinning force of the YBCO + Y2O3 mixed thin film FP = 189 N×m−3 at 40 K [ ].

Kyushu Institute of Technology and Fukuoka Prefecture IST-LSI Cluster researcher

From April 2008 to February 2011, I was a cluster researcher of the Fukuoka Prefectural Industrial Science and Technology Promotion Foundation (Fukuoka IST). I belonged to Kyushu Institute of Technology at the Department of Materials Engineering under the guidance of Prof. K. Matsumoto.

I succeeded for the first time in the world in producing an epitaxial thin film of iron-based Fe-Te-S superconductor, and I obtained remarkable results clarifying its basic characteristics [ ].

I continued research on the APC-added superconducting thin films and studied BaZrO3 [ ] and BaSnO3 [ , ] added YBCO. Notably, the BaSnO3 nanocolumn was used to achieve the world's highest (2008) pinning force (FP = 28.3 GN×m−3 at 77 K) in lab-size superconducting samples at the time [6], This achievement was selected as one of the best papers of the year and received high praise in the field of superconductivity.

In addition, I boldly challenged the development of thermoelectric materials, as a new field of mine, and I succeeded in producing bulk bodies such as Ca3Co4O9 (p-type) and Al-doped ZnO (n-type) with high conversion efficiency [ ].

Hiroshima University, Lecturer

From March 2011 to March 2015, I was a tenure track lecturer at the Institute for Sustainable Sciences and Development (ISSD) of Hiroshima University. The research on APCs-added YBCO and Fe-Te-X (X = S, Se) superconductors continued. By improving the quality of the Fe-Te-Se thin film, I was able to measure a high critical current density value (JC = 1MA/cm2) [ ]. The addition of BaSnO3 nanocolumn and Y2O3 nanoislands to YBCO were combined in multilayers succeeding to obtain a complex pinning landscape [ ].

I started studying thermoelectric oxide thin films. I succeeded in producing the n-type Al-doped ZnO (AZO) as an epitaxial thin film using the PLD method and obtained remarkable results to clarify its heat transfer characteristics. I confirmed that the figure of merit (ZT) of AZO film is superior to that of bulk: for example, at T = 600 K, ZTAZO-on-STO = 0.03 while ZTbulk = 0.014 [ ]. The superior performance of films is due to their lower thermal conductivity: AZO-on-STO (300 K) = 6.5 W/m×K [11] while BULK (300 K) = 34 W/m×K.

Muroran Institute of Technology, Associate Professor

From April 2015 to March 2018, I was Associate Professor at Muroran Institute of Technology joining the Research Institute for Environmentally Friendly Materials. I was especially focused on the improvement of the performance of AZO thin films by use of different substrates and deposition techniques: insertion of hydroquinone nanolayers in AZO films prepared by atomic layer deposition (ALD): ALD (300 K) = 3.56 W/m×K [ ]; addition of polymethylmethacrylate (PMMA) particles to AZO films prepared by multi-beam multi-target matrix-assisted PLD (MBMT/MAPLE-PLD): MAPLE (300 K) = 5.9 W/m×K and ZTMAPLE (600 K) = 0.07 [ ]; formation of nanopores in AZO films prepared by Mist-Chemical Vapor Deposition (Mist-CVD): porous (300 K) = 0.60 W/m×K and ZT porous (300 K) = 0.06 [ ]; dispersion of Al2O3 nanoparticulate in AZO films prepared by surface-modified target PLD: nanoAl2O3 (300 K) = 3.98 W/m×K and ZTnanoAl2O3 (600 K) = 0.0007 [ ].

Even if the control of size and distribution of the defects was not reached at this stage, depression of is 1/10 ~1/100 and ZT enhancement 3~5 times with respect to the typical bulk AZO values was achieved.

Shibaura Institute of Technology, Professor

In April 2018 I was enrolled by Shibaura Institute of Technology as tenured full professor. I started to study p-type thermoelectric oxides such as Ca3Co4O9 and CuAlO2 and I was able to build a module based on oxide thin films with a power output of 10 pW [ ]. I also started to study another category of thermoelectrics, the RE-filled skutterudites. At first, the bulk was considered, discovering a correlation between the composition of the material and its electronic properties [ , ]. Therefore, the first thin films ever of these specific compositions were fabricated by PLD and resulted to have excellent performances [ ]. Firstly, developed skutterudites`modules showed a power output of 0.16 μW. I also started to fabricate transparent oxide thin films by MOD, looking forward to optoelectronic other than thermoelectric applications. More recently, I am developing a full-printed thermoelectric module based on p-type organic PEDOT and n-type silver legs on paper substrates, for room temperature thermoelectric harvesting. The first module promisingly generated a power output of 0.045 W. These results are promising for the utilization of thermoelectric modules as power source for out-of-the grid tiny devices as IoT nodes or sensors.