Glass - Back to the Future!

Presenting Author:
Himanshu Jain

article posted 4 April 2016

Himanshu Jain is the T.L. Diamond Distinguished Chair in Engineering and Applied Science, and Professor of Materials Science and Engineering at Lehigh University. He is a recipient of the Otto Schott Research international prize, Zachariasen international award for outstanding contribution to glass research, Alfred University’s Scholes Lecture award, Lehigh University’s Libsch award for research and Hillman award for long-term excellence, Fulbright Fellowship for lecturing and research at Cambridge and Aberdeen universities in UK, and a Humboldt Fellowship for research in Germany. An author of over 350 research publications, editor or author of nine books, inventor of four patents, a Principal Editor of Journal of Materials Research, he is a Fellow of the American Ceramic Society. His current research interests include: functionality in glass through fundamentals; glass surfaces; corrosion of glass in relation to manufacturing; light-induced phenomena in glass; nano-macro porous glass bioactive scaffolds for bone regeneration; conductivity and dielectric properties of amorphous and crystalline ceramics; glasses for IR biosensors, photo- and nano-lithography, and photonics; active single-crystal architecture in glass; and metal–glass nano-composites.

Conversion of glass to single crystal via solid-solid transformation

Dmytro Savytskii1, Volkmar Dierolf2 & Himanshu Jain1,*
1 International Materials Institute for New Functionality in Glass, Lehigh University, Bethlehem, PA 18015, USA
2 Physics Department, Lehigh University, Bethlehem, PA 18015, USA

The transformation of glass to stable crystalline state is achieved readily by heating it to a particular temperature that inevitably leads to nucleation of many crystals. This process leads to well-known glass-ceramics. By contrast, for producing a single crystal, the creation of multiple nuclei must be avoided. For this reason, most single crystals are produced today not by solid-solid, but by liquid-solid transformation in which the formation of extraneous nuclei during the growth of the initially formed nucleus is unstable in the surrounding liquid phase. However, there is a serious drawback of single crystal growth from melts: such methods are not useful for fabricating crystals of compositions that decompose, transform to some undesirable phase, or melt incongruently on heating. Consequently, it has been extremely difficult or impossible to grow single crystals of many complex oxides such as high Tc superconductors, organometallic halide perovskites for solar cells of exceptional efficiency, etc. For these materials, elevated temperatures and melting need to be avoided.
Here we demonstrate a strategy to overcome this hurdle by avoiding the gaseous or liquid phase, and directly converting glass into a single crystal.(1) In our strategy, the glassy material is heated locally by a laser to just its crystallization temperature (Tx,), which is well below the melting temperature. Using glass as a precursor and a focused laser as a localized heating source, offer the combined advantages of low cost, of allowing broad composition ranges, and of easy formability of single crystals in complex shapes including wires or films. The proof of concept is demonstrated using the example of Sb2S3 single crystals that are grown in Sb–S–I glasses. In this first unambiguous demonstration of an all-solid-state glass/crystal transformation, extraneous nucleation is avoided relative to crystal growth via spatially localized laser heating and inclusion of a suitable glass former in the composition. All-solid-state single crystal growth begins with a laser-formed single crystal dot, which is then extended into a straight line by moving the laser spot at the speed of 1 µm/s on the surface of Sb2S3 glass. The ability to fabricate patterned single-crystal architecture on a glass surface is demonstrated, providing a new class of micro-structured substrate for low cost epitaxial growth, active planar devices, etc. During the presentation, we will also discuss complexities of crystal growth that result from its confinement within the solid glass matrix.

Figure 1. The single crystal nature of laser crystallized Sb2S3 within glass matrix is established by electron backscatter diffraction. The solid state nature of the transformation is demonstrated by the scratches on the surface, which persist even after the atoms in glass have formed single crystal lattice. Scale bar corresponds to 5 µm. (a) SEM image, (b) Image quality (IQ) map, and (c) and (d) colored orientation inverse pole figure (IPF) maps with reference vector along surface normal and an in-plane direction, respectively

(1) Dmytro Savytskii, Brian Knorr, Volkmar Dierolf, Himanshu Jain. Sci. Rep. 6, 23324; doi: 10.1038/srep23324 (2016).