IMR researchers over the years have grown many crystals for nuclear, optical, and electronic applications. A large amount of work has been dedicated to scintillators, mostly oxide crystals but also some halides. Additionally, the important oxide crystal yttrium aluminum garnet (YAG) is doped for scintillator applications and differently for laser gain media. Over the years, IMR researchers have grown more than 60 crystals of YAG with various doping schemes.

Additionally, some exotic oxide crystals have also been grown, including substantial studies on other garnet crystals, LiAlO₂, (1-x)[Pb(Mg_1/3Nb_2/3)O₃]-x[PbTiO₃] (PMN-PT), and Zn-Te-O. Currently, we are interested in Ga₂O₃ and related ultra wide bandgap materials for electronics.

Scintillation detectors operate through emission of light flashes that are detected by a photosensitive device, usually a photomultiplier tube (PMT) or a silicon PIN photodiode. They can be used to detect X-ray and gamma-ray photons, accelerated charged particles, or neutrons. Wide bandgap semiconductors or insulators in a single crystal form are most suitable for this purpose. A scintillation detector is one of the most versatile particle detectors and is widely used in industry, scientific research, medical diagnosis, and radiation monitoring.

For example, Ce-doped Yttrium Aluminum Garnet – Y₃Al₅O₁₂ (Ce:YAG) single crystals were reported as excellent candidates for fast scintillators as early as 1978. In spite of all the advances, these materials fall short of performing close to their theoretical limits. Defects competing with Ce³⁺ ions in the energy transfer process are responsible for decreased performance and have been subject to numerous studies in the literature. The ability to understand and modify defect behavior is a key to unlocking the full performance potential of YAG and many other scintillator materials. Some selected publications of this work are shown below.

Publications on scintillators:

• Solodovnikov, D., M. Weber, and K. Lynn, “Improvement in scintillation performance of Ce, Er codoped yttrium aluminum garnet crystals by means of a postgrowth treatment,” Applied Physics Letters, 93, 104102 (2008).
• Haven, D., D. Solodovnikov, M. Weber, and K. Lynn, “Quenched ultraviolet defect emission and excellent scintillation performance on a photodiode from heavily cerium doped yttrium aluminum garnet,” Applied Physics Letters, 101, 041101 (2012).
• Solodovnikov, D., M. Weber, D.T. Haven, and K. Lynn, “Single crystal Ce doped scintillator material with garnet structure sensitive to gamma ray and neutron radiation,” Journal of Crystal Growth, 352, 99-102 (2012).
• Haven, D., P. Dickens, M. Weber, and K. Lynn, “Yttrium antisite reduction and improved photodiode performance in Ce doped Y3Al5O12 by Czochralski growth in alumina rich melts,” Journal of Applied Physics, 114 (2013).
• Dickens, P.T., J. Marcial, J. McCloy, B.S. McDonald, and K.G. Lynn, “Spectroscopic and neutron detection properties of rare earth and titanium doped LiAlO2 single crystals,” Journal of Luminescence, 190, 242-248 (2017).
• Dickens, P.T., D.T. Haven, S. Friedrich, and K.G. Lynn, “Scintillation properties and increased vacancy formation in cerium and calcium co-doped yttrium aluminum garnet,” Journal of Crystal Growth, 507, 16-22 (2019).
• Saleh, M., K.G. Lynn, L.G. Jacobsohn, and J.S. McCloy, “Luminescence of undoped commercial ZnS crystals: A critical review and new evidence on the role of impurities using photoluminescence and electrical transient spectroscopy,” Journal of Applied Physics, 125(7), 075702 (2019).

Publications on laser crystals

• Shafer, K., D. Eakins, D. Bahr, M. Norton, and K. Lynn, “Strength enhancement of single crystal laser components,” Journal of Materials Research, 18, 2537-2539 (2003).
• Wang, C., K. Lynn, S. Tebaldi, M. Weber, K. Shafer, R. Tjossem, T. Williams, and J. Dougherty, “Enhanced Laser Performance Through Reduction of Surface Damage in Nd:YAG,” SPIE, 4968, 143-150 (2003).
• Lebret, J., M. Norton, D. Bahr, D. Field, and K. Lynn, “Characterization of low angle grain boundaries in yttrium orthovanadate,” Journal of Materials Science, 40, 3347-3353 (2005).
• Saleh, M., S. Kakkireni, J. McCloy, and K.G. Lynn, “Improved Nd distribution in Czochralski grown YAG crystals by implementation of the accelerated crucible rotation technique,” Optical Materials Express, 10(2), 632-644 (2020).

Publications on other functional crystals

• Keeble, D., B. Nielsen, A. Krishnan, K. Lynn, S. Madhukar, R. Ramesh, and C. Young, “Vacancy defects in (Pb, La)(Zr, Ti)O3 capacitors observed by positron annihilation,” Applied Physics Letters, 73, 318-320 (1998).
• Dhar, R., R. Tjossem, and K. Lynn, “High-pressure vertical Bridgman growth of lead magnesium niobate–lead titanate single crystal,” Journal of Crystal Growth, 312, 971-977 (2010).
• Nawash, J. and K. Lynn, “Czochralski crystal growth of Zn2Te3O8,” Journal of Crystal Growth, 310, 4217-4220 (2008).
• Nawash, J.M. and K.G. Lynn, “ZnTeO3 crystal growth by a modified Bridgman technique,” Materials Research Bulletin, 60, 819-823 (2014).
• Saleh, M., J.B. Varley, J. Jesenovec, A. Bhattacharyya, S. Krishnamoorthy, S. Swain, and K. Lynn, “Degenerate doping in β-Ga2O3 single crystals through Hf-doping,” Semiconductor Science and Technology, 35(4), 04LT01 (2020).