Unveiling the Inhomogeneity and Impurities within 6LiInSe2 Crystals Using LIBS
A Breakthrough in Advanced Detector Material Research
Recently, a research team led by Dr. Brenden Wiggins from the Department of Life and Physical Sciences at Fisk University in the United States presented a noteworthy paper at the conference of the International Society for Optics and Photonics (SPIE), titled "Investigating the Inhomogeneity and Impurities in 6LiInSe2 Crystals using Laser-Induced Breakdown Spectroscopy (LIBS)". This innovative study opens new avenues for improving the performance of novel thermal neutron detectors, showcasing the determination of researchers in utilizing advanced techniques to solve material challenges.
6LiInSe2–The Rising Star in Thermal Neutron Detection
6LiInSe2 is a compound semiconductor with a high responsiveness to ionizing radiation, attracting significant attention for its tremendous potential in thermal neutron detection. Compared to traditional gas detectors, solid-state 6LiInSe2-based thermal neutron detection devices offer advantages such as small size, low power consumption, and strong radiation resistance, making them valuable in medical imaging, industrial inspection, and national defense applications.
However, to achieve widespread deployment of 6LiInSe2-based solid-state detection devices, it is crucial to optimize and standardize the crystal growth process, producing large-sized and performance-stable single-crystal ingots. This is the key focus of the research undertaken by the Wiggins team.
LIBS Unraveling the "Secrets" within Crystals
The researchers employed advanced characterization techniques, including infrared microscopy and Laser-Induced Breakdown Spectroscopy (LIBS), to deeply investigate the inhomogeneity and impurity distribution within 6LiInSe2 single crystals.
LIBS is an in-situ, rapid, and minimally destructive elemental analysis technique that can precisely identify and quantify the elemental composition within materials. Through LIBS analysis, the Wiggins team discovered the uneven distribution of alkali metal and alkaline earth metal impurities in 6LiInSe2 crystals, with these impurities primarily concentrated in the reddish regions of the crystals. These impurities may form charge traps, significantly affecting the electrical performance of the crystals.
Furthermore, LIBS also revealed the spatial variation in the stoichiometric ratios of the Li, In, and Se ternary elements in the 6LiInSe2 crystals, reflecting the compositional non-uniformity during the crystal growth process.
Li/In ratio distribution (top left), Li/Se ratio distribution (top right), In/Se ratio distribution (middle left), Li distribution (middle right), In distribution (bottom left), Se distribution (bottom right) Blue regions indicate a value of less than the threshold value for the spatial maps.
PBN Crucible–Key to Enabling Crucial Experiments
To ensure the synthesis of high-purity 6LiInSe2 crystals, the Wiggins team chose pyrolytic boron nitride (PBN) crucibles as the growth containers in their experiments.
The researchers used high-purity indium (99.9999%, or 6N) and selenium (5N) as raw materials, and purified 95% isotopically-enriched 6Li through a multi-stage vacuum distillation process to achieve ultra-high chemical purity (5N). They then synthesized 6LiIn and 6LiInSe2 in PBN crucibles to maximize the chemical compatibility with the constituent elements.
PBN material possesses excellent chemical stability and thermal stability, preventing any reaction with the experimental materials even at high temperatures, thus ensuring the purity and quality of the 6LiInSe2 crystals. The superior thermal conductivity of PBN crucibles also helped to achieve precise temperature control in the crystal growth environment, providing a crucial guarantee for obtaining high-quality crystals.
As a leading PBN crucible supplier in the domestic market, QSAM has provided high-quality customized services to the research community, greatly promoting the development of advanced material research.
PBN crucibles made by QSAM Inc.
A Promising Future with Further Performance Improvements
Through the extensive application of LIBS technology, the Wiggins team has gained a more comprehensive understanding of the inhomogeneity and impurity issues within 6LiInSe2 crystals. This lays a solid foundation for subsequent optimization of the synthesis and growth processes, further improving the performance of this novel thermal neutron detection material.
In the future, with precise control of crystal growth conditions and optimization of the purification procedures, 6LiInSe2 is expected to play an increasingly important role in medical, industrial, and defense applications, bringing more convenience and security to human society.
During this process, QSAM will continue to provide high-quality PBN crucibles and customized services to the wider research community, contributing to the continuous innovation of frontier technologies. Let us look forward to the exciting future of 6LiInSe2 detectors!