Study details effects of laser and electron irradiation of silver-based compounds

An article reporting the study is featured on the cover of Nano Letters; the findings can help design next-generation electronic materials for the semiconductor and nanotechnology industry.

By José Tadeu Arantes  |  Agência FAPESP – The effects of laser irradiation (LI) and electron irradiation (EI) on the structural and electronic properties of different semiconductors were investigated in a computational study developed through a collaboration between Brazil and Spain. An article on the study is published in the journal Nano Letters and featured on its cover.

The study was conducted by postdoctoral researcher Luís Antônio Cabral and supervised by Professor Edison Zacarias da Silva. Both are affiliated with the State University of Campinas’s Gleb Wataghin Institute of Physics (IFGW-UNICAMP) in São Paulo state, Brazil.

“We investigated several types of silver halide [AgX] – silver chloride [AgCl], silver bromide [AgBr] and silver iodide [AgI] – using a two-temperature model to simulate the effects of irradiation by a laser beam and ab initio molecular dynamics with the addition of electrons to simulate the effects of irradiation by an electron beam. The ab initio molecular dynamics simulations provided a clear visualization of how temperature and the number of electrons affect the crystal structure and electronic properties of the materials,” Cabral said.

The results, he explained, show the processes of Ag⁺ and X^- ion diffusion and AgX lattice amorphization. Amorphization is a structural phase transformation of crystalline materials (made up of atoms, molecules or ions arranged in a repeating three-dimensional pattern) into amorphous materials (which do not have long-range order at the atomic level). Both forms of irradiation result in a gradual loss of the ordered crystalline structure of AgX, leading to amorphization. 

Another important finding is the formation of nanoclusters of silver and halides under high temperatures and electronic irradiation levels, suggesting a fundamental change in the chemical properties of the material.

Potential technological applications include next-generation electronic materials for the semiconductor and nanotechnology industries.

“In recent years, laser and electron irradiation have become powerful and innovative tools to modify semiconductor materials at the nanometric and atomic scales. This is particularly promising when it comes to synthesizing novel semiconductor materials and for advanced technological applications, but a detailed understanding of the structural evolution of off-balance processes initiated by these two kinds of irradiation is required,” Silva said. 

Research groups interested in the results obtained in computer simulations can contact Prof. Zacarias by email at: [e-mail].

Cabral conducted the study while he was on a postdoctoral internship as a member of Professor Juan Andrés Bort’s research group at Jaume I University in Spain, with a scholarship from FAPESP. 

The other co-authors of the article are Edson Roberto Leite, a professor at the Federal University of São Carlos (UFSCar) and Division Head at the Brazilian Nanotechnology Laboratory (LNNano), part of the Brazilian Center for Research in Energy and Materials (CNPEM); Elson Longo, emeritus professor at UFSCar; and Miguel Angel San Miguel Barrera, a professor at UNICAMP’s Institute of Chemistry. FAPESP also supported the study via four other projects (18/20729-9, 13/07296-2, 16/23891-6, and 17/26105-4).

The article “Disentangling the effects of laser and electron irradiation on AgX (X = Cl, Br, and I): insights from quantum chemical calculations” is at: pubs.acs.org/doi/10.1021/acs.nanolett.3c04130.