Ab initio studies of stepped {100} surfaces of KDP crystals

Salter, E. Alan; Wierzbicki, Andrzej; Land, T. A.

doi:10.1002/qua.20238

Cited by 11 publications

(9 citation statements)

References 17 publications

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“…We have studied five possible steps on the {100} face of KDP (see Figure 4) using ab initio quantum methods, and we have presented energetic data which may be useful in theoretical modeling of KDP crystal growth [18,19]. We have presented estimated surface removal energies for the {100} and {101} faces, as well, and we have confirmed that the K + -bounded {101} face has a higher surface removal energy than the H2PO4 --bounded {101} face.…”

Section: Molecular Modeling Of Aluminum Incorporation In the Kdp Latticementioning

confidence: 70%

Advanced Crystal Growth Technology

Land¹,

Hawley-Fedder²

2005

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Although the fundamental mechanism of crystal growth has received and continues to receive deserved attention as a research activity, similar research efforts addressing the need for advanced materials and processing technology required to grow future high quality crystals has been sorely lacking. The purpose of this research effort is to develop advanced rapid growth processing technologies and materials suitable for providing the quality of products needed for advanced laser and photonics applications. In particular we are interested in developing a methodology for growing high quality KDP crystals based on an understanding of the fundamental mechanisms affecting growth.

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Section: Molecular Modeling Of Aluminum Incorporation In the Kdp Latticementioning

confidence: 70%

Advanced Crystal Growth Technology

Land¹,

Hawley-Fedder²

2005

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“…The combined effect of the above two mechanisms leads to a strong transverse growth arrest of prismatic faces, yet a high-speed growth of the pyramidal face. In the following, we present density functional theoretical (DFT) analysis − to support this molecular orientation based self-shielding and self-channeling hypothesis. We first calculate surface adsorption energy of a molecule on the (100) face/surface of a KDP unit cell, revealing a strong molecular-orientation selectivity in the surface-adsorption process.…”

Section: Resultsmentioning

confidence: 87%

Strong Mesoscopic Prismatic Face Growth Suppression in High-Speed Unidirectional Growth of KDP Single Crystals

Fang

Zhu

Zhao

et al. 2020

Crystal Growth & Design

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We show strong mesoscopic prismatic face growth arrest that coexists with high-speed pyramidal face growth in single-crystalline KDP crystals with large aspect ratios. To explain this unique growth morphology, which cannot be explained by any current theories, we introduce a new set of surface concentration rate equations and demonstrate a molecular-orientation-selective surface-self-shielding and channeling mechanism. We numerically solve full diffusion equations with time-dependent surface boundary conditions for the crystal growth driving force and growth rate, demonstrating the quick arrest of both quantities as the result of molecule-orientation selectivity based self-shielding and channeling effects. The growth dynamics thus derived can satisfactorily explain all experimental observations in single-crystalline KDP crystal growth reported here.

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“…We refer to the termination where the protons of the step-edge phosphates point parallel to the surface as A (Figure b) and to the termination where the protons point normal to the surface as B (Figure c). On the {001}-facing step, one termination is the most energetically stable (Figure d) 3 Atomic structures of the KDP surface.…”

Section: Methodsmentioning

confidence: 99%

The Growth Morphology of the {100} Surface of KDP (Archerite) on the Molecular Scale

et al. 2004

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The surface morphology of the {100} face growth hillock of potassium dihydrogen phosphate (KDP) is examined through first-principles calculations and using periodic-bonded-chain (PBC) theory. KDP, or archerite ([K, NH 4 ]H 2 PO 4 ), is used extensively in industry and is an excellent model for more complicated materials that have considerable ionic and hydrogen bonding as part of their structure. Here, we have calculated the gas-phase detachment energies of KH 2 PO 4 growth units adsorbed to steps oriented normal to the [010] and [001] PBC directions. The detachment energies of growth units adsorbed to the two different terminations of the {010}-facing step are +4.2 and +4.5 eV, and detachment from the {001}-facing step is +3.8 eV. Detachment from the {010}-facing step is more unfavorable, indicating that the adsorbed species will be less labile and the step will advance more quickly than the {001}-facing step. The relative detachment energies are qualitatively consistent with experimentally observed fast and slow step velocities on the {100} growth hillock. Detachment energies of growth units adsorbed subsequently to the {010}-facing step are similar, but detachment of a second growth unit from the {001}-facing step is much more unfavorable, +5.1 eV. The increase in detachment energy indicates that the high rate of detachment of the initial KH 2 PO 4 unit from the {001}-facing step may limit the advance of the step, whereas the second growth unit detaches much more slowly. To explain this behavior, we propose that the first growth unit adsorbed to the {001}-facing step has a higher lability because of the lack of hydrogen bonds to the step edge. This study provides a qualitative picture of how crystal structure may control growth morphology of KDP and emphasizes the importance of anisotropic hydrogen bonding in the system.

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Ab initio studies of stepped {100} surfaces of KDP crystals

Cited by 11 publications

References 17 publications

Advanced Crystal Growth Technology

Advanced Crystal Growth Technology

Strong Mesoscopic Prismatic Face Growth Suppression in High-Speed Unidirectional Growth of KDP Single Crystals

The Growth Morphology of the {100} Surface of KDP (Archerite) on the Molecular Scale

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