Electron- or Hole-Assisted Reactions of H Defects in Hydrogen-Bonded KDP

Abstract

We present an ab initio study of the stability and defect reactions of neutral and charged H interstitial (H i ) and H vacancy (H v ) in KH 2 PO 4 (KDP). We find that while there is no interaction between the neutral H i and the host, the addition of an electron leads to the ejection of a H host atom and the subsequent formation of an interstitial H 2 molecule and a H v . In sharp contrast, the addition of a hole results in the formation of a hydroxyl bond. Thus, H i in both charged states severs the H-bonded network. For the H v , the addition of a hole leads to the formation of a peroxyl bridge. The neutral H i and the positively charged H v induce states in the gap. The results elucidate the underlying atomic mechanism for the defect reactions suggested by experiment.

Performance of rapid-grown KDP crystals with continuous filtration

“…It was found that typical damage pinpoints were caused by defects, which efficiently absorbed laser energy, leading to a temperature rise and subsequent 'micro-explosion' [5][6][7] . Various types of bulk defect, such as metallic impurities [8][9][10] , electronic defects [11][12][13] , organic materials, bacteria [14,15] , dislocation [16] and insoluble impurities, have been reported. In 1999, the continuous filtration Correspondence to: Y. Zhao, No.…”

Transmittance increase after laser conditioning reveals absorption properties variation in DKDP crystals

“…So in some parts of area, the point defects stay close together and the concentration in this area is in an order of 10 −2 [24], which is quite higher than the average concentration. First principle calculation for hydrogen point defects in KDP has found that the band gap for the neutral interstitial H and positive charged H vacancy are greatly reduced to 2.6 and 2.5eV [13,14], which is smaller than photon energy of 355nm laser. Therefore, this defect cluster can be the major factor of inducing laser damage.…”

“…Recent work based on the electron paramagnetic resonance and resonance Raman scattering experiments provided direct evidence of the [HPO4]¯ hole center and the hydrogen interstitial H 0 electron center [12]. First principle calculation for hydrogen point defects in KDP have found that the band gap for the neutral interstitial H and positive charged H vacancy were greatly reduced to 2.6 and 2.5eV [13,14]. It suggested that thermal point defects played an important role on the lowering LIDT of KDP crystal.…”

Inflaton field governed universe from NKK theory of gravity: stochastic approach

“…This model represents an early inflationary expansion followed by a decelerated (radiation dominated followed by a matter dominated expansion) that finally suffers a present day quintessential accelerated expansion. Other cosmological models without inflationary expansion has been considered recently in the literature [11]. The power of expansion (68) is shown in the figure (1), being x(t) = log 10 [t/t 0 ].…”