Electron paramagnetic resonance spectroscopy and first-principles calculations of Cr³⁺ doped KDP crystals

Abstract

The characteristics of potassium dihydrogen phosphate (KDP) crystals with the Cr(NO3)3 doping at ～10 ppm level were studied by the ultraviolet-visible (UV-Vis) absorption spectrum, electron paramagnetic resonance spectroscopy (EPR), and...

Influence of Cr3+ cluster defects on crystal structure and optical properties of KDP crystals studied by DFT and UV-Vis

“…In our previous studies, it was clarified by electron paramagnetic resonance spectroscopy and DFT that Cr 3+ ions mainly replace K + ions in the KDP crystals (the defect formation energy of Cr 3+ that replaces K + is 3.31 eV). 12 In electron paramagnetic resonance spectra, there were two sets of resonance peaks for Cr 3+ , which were caused by the different relative positions of hydrogen vacancies near Cr 3+ . To further clarify the charge state of the point defects and build a reasonable cluster defect model, the defect formation energies of the point defects with different charge states were calculated.…”

“…Two spin-allowed transitions, 4 A 2g (F) → 4 T 1g (F) for 451 nm and 4 A 2g (F) → 4 T 2g (F) for 650 nm, which are researched in our previous manuscript. 12 From the calculation of the electronic structure (Fig. 4), the absorption peak at 285nm is induced by electrons jumping toward the conduction band from the energy level of the donor impurity (which may induced by Cr 3d spin-down electron states).…”

“…This is mainly due to the different relative positions of the hydrogen vacancies complexed with Cr 3+ . 12,13 By analyzing the stability of the cluster defects in the KDP crystals, the most stable defect clusters are formed by complexing with the nearest neighboring hydrogen vacancies. 17,31 Therefore, neighboring hydrogen atoms are removed to form the Cr K 2+ + 2V H À cluster defect.…”

“…11 The Cr 3+ ions are tentatively characterized by electron resonance spectroscopy to substitute K + ions in the crystals. 12,13 However, the charge state of point defects, and the compounding of point defects with intrinsic defects have not been explicitly studied. It is experimentally difficult to further develop this type of study at the atomic level.…”

Study on the defects of KDP crystal with different states by the positron spectroscopy method

“…The EPR technique could qualitatively and quantitatively detect unpaired electrons in crystals and explore the structural properties of the surrounding environment. 18,19 However, it is not sensitive to the specific type and distribution of defects. Thus, the advantage of the positron technology was apparent.…”