The mechanism of tapering on KDP-type crystals

Dam, B.; Bennema, P.; Enckevort, W.J.P. van

doi:10.1016/0022-0248(86)90254-x

Cited by 52 publications

(19 citation statements)

References 19 publications

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“…We have chosen to study diagonal steps D and DЈ, cut along the axes as shown, because these generate the {101} face with the K ϩ surface layer and the H 2 PO 4 Ϫ surface layer, respectively. The explanation as to why only the K ϩ -bounded {101} face is expressed has been given as relative strength of attachment, but no computational results have been reported [6]. Nevertheless, the relationship of the diagonal steps to the two possible {101} faces suggests that perhaps only step D will be expressed on the {100} face.…”

Section: Introductionmentioning

confidence: 98%

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

Salter

Wierzbicki

Land

2004

Int J of Quantum Chemistry

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Potassium dihydrogen phosphate (KH 2 PO 4 , KDP) crystals have important uses in laser components and are grown in large scale for that purpose. The need for habit control has led to interest in the step-pinning mechanisms that cause growth inhibition of the {100} face. Model systems representing five stepped KDP {100} surfaces are prepared and studied using ab initio quantum methods. Results of Hartree-Fock and density functional theory plane-wave calculations are presented, including estimated energies of ion and column removal for the steps. Steps terminated by phosphate ions are found to be less energetically favorable than their potassiumterminated counterparts. In addition, surface layer removal energies for the {100} face and the potassium-bounded and phosphate-bounded {101} faces are reported. The potassium-bounded {101} face is found to have a greater surface removal energy than the unexpressed phosphate-bounded {101} face.

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Section: Introductionmentioning

confidence: 98%

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

Salter

Wierzbicki

Land

2004

Int J of Quantum Chemistry

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“…The relatively low figuration cannot be realized due to the high cryscontent of M" impurities on (011) could be cxtallization rate. Slowly growing crystals will tend plained by the presence of larger areas bounded to comply with the conditions of lowest surface by NH~ions, which is not favourable for Mẽ nergy and should be similar to those forms preadsorption according to Dam et al [18]. Hence it is sented in fig 3a. not possible to draw the conclusion, on the basis Dam Ct a!.…”

Section: Halving Of the Slice D011mentioning

confidence: 91%

“…Hence it is sented in fig 3a. not possible to draw the conclusion, on the basis Dam Ct a!. [18] tried to explain their observaof the attachment energy calculations, that the K tions on the tapering of KDP crystals by means of bounded slice of (Oil) is the unique growth layer. (011) slice energy calculations.…”

Section: Halving Of the Slice D011mentioning

confidence: 99%

Theoretical growth and equilibrium forms of ADP (NH4H2PO4)

Aguiló

Woensdregt

1987

Journal of Crystal Growth

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The Hartman-Perdok theory enables one to establish the F forms of ammonium dihydrogen phosphate (ADP) as (100} and 011 }. Although the 0 kl } forms are theoretically expected to be S faces, they nevertheless exhibit K face characteristics for k <1.The forms {Okl), with k >1, which are typical of the so-called tapering of the ADP crystals, are S faces. The attachment energy of a particular face, which is assumed to be directly proportional to its growth rate, can be computed in an electrostatic point charge model. As the ionic charge distribution in the crystallizing units is not known exactly, the calculations have been made in 36 models, with P-O and N-H bond varying from purely ionic to completely covalent. The theoretical growth forms comprise always the (011 and sometimes (100)~The presence of the latter is a function of the ionic charge of the oxygen, q0, and that of the hydrogen H0 belonging to the [H2P04] group, q~0.The form (100) is present, if -0.9

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“…In addition, it is also excellent electro-optic crystals with high electrooptic coefficients, widely used as electro-optical modulators, Q-switches, and Pockels Cells, etc. The ideal morphology of DKDP consists of prismatic{010} and pyramidal {011} faces(point group 42m), in reality often high index {0kl} orientations are observed in DKDP crystal [1]. Originally the occurrence of these anomalous high-index faces has been related to the adsorption of metal impurities.…”

Section: Introductionmentioning

confidence: 98%

The effect of metallic ions on tapering phenomenon of DKDP crystals and its elimination

Li¹,

et al. 2007

Cryst. Res. Technol.

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The anomalous wedge-like shape of KH 2 PO 4 -type single crystal, also called tapering, is discussed in this paper. DKDP single crystals grew on seeds from the solutions containing high concentrations of Al 3+ , Fe 3+and Cr 3+ impurities. The tapering phenomenon occurred on the prismatic {010} faces, and the tapering angle θ was nearly measured as 10°. We adjusted the pD value of the solution from 3.0 to 4.2 by adding K 2 CO 3 , the tapering angle of DKDP crystal grown from the same solution at same supercooling was reduced to 0°.

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The mechanism of tapering on KDP-type crystals

Cited by 52 publications

References 19 publications

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

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

Theoretical growth and equilibrium forms of ADP (NH4H2PO4)

The effect of metallic ions on tapering phenomenon of DKDP crystals and its elimination

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