Effect of foreign phases on the growth of NaBi(WO₄)₂ crystals

Abstract

Single crystals of NaBi(WO 4 ) 2 (NBW) have been grown by Czochralski technique, employing differently synthesized starting charge and different axial temperature gradients. The causes behind inherent problems related to compositional changes and associated lowering in crystallization temperature have been probed by analyzing XRD and DTA patterns of post growth residual charge. Presence of low melting phases viz. Na 2 WO 4 and hitherto unreported compound Na 5 Bi(WO 4 ) 4 is thought to be responsible for the observed decrease in crystallization temperature. This problem was tackled by segregating pure phase material through re-crystallization, under high axial temperature gradient. The use of re-crystallized charge enabled transformation of almost the entire charge into a single crystal of high transparency. The effect of starting charge synthesis and temperature gradient on the optical transmission characteristics of NBW crystal has also been investigated.

A Comparative Study of Li6 R(BO3 )3 ; R = Gd, Lu, & Y), Single Crystals for Thermal Neutron Detection

“…The large supercooling is an inherent property of these borate single crystals and the crystallization at multiple temperatures for LLBO has been reported by other authors as well . The supercooling value in other oxide crystals which are relatively easy to grow lies in the range of 5–10 °C and hence it is relatively easier to control the nucleation for the single crystal growth . A large supercooling allows multiple nucleations in a super‐cooled liquid and presents a challenge to grow single crystals.…”

“…[17] The supercooling value in other oxide crystals which are relatively easy to grow lies in the range of 5-10 C and hence it is relatively easier to control the nucleation for the single crystal growth. [18] A large supercooling allows multiple nucleations in a super-cooled liquid and presents a challenge to grow single crystals. To overcome these challenges due to large supercooling, axial temperature gradient has to be carefully optimized for each material by suitably positioning the platinum crucible within the RF coil and using appropriate passive after heaters.…”

Polymorphs of 2,4,6-tris(4-pyridyl)-1,3,5-triazine and their mechanical properties

“…The mechanisms behind such extraordinary behaviour were attributed to the existence of weak dispersive intermolecular interactions, which extend the structure into a three-dimensional network. In previous reports, the molecules crystallized in a long needle or fibril lamella shape along the direction of eitherstacking (Hayashi & Koizumi, 2016, 2018Hayashi et al, 2017Singh & Chopra, 2018;Liu et al, 2018;Huang et al, 2018;Liu, Di et al, 2019;Liu, Bian et al, 2019;Devarapalli et al, 2019), metalÁ Á Á interactions (Brock et al, 2018;Worthy et al, 2018), halogen bonding (Ghosh et al, 2015; or hydrogen bonding (Ghosh & Reddy, 2012;Horstman et al, 2017). The elastic bending behaviour along these directions arose when an external stress was imposed perpendicularly.…”

Growth of Nd-doped NaY(WO4)2single crystals from nonstoichiometric melts

“…Some of these crystals have been grown using the Czochralski technique for the bulk crystal production. However, the problem of stoichiometric variations of the melt during the growth of crystals has been observed in several materials including PbMoO 4 , CaWO 4 , PbWO 4 , Al 2 (WO 4 ) 3 , NaGd(WO 4 ) 2 , NaBi(WO 4 ) 2 , NaY(WO 4 ) 2 , etc [2][3][4][5][6][7][8][9][10][11][12]. These stoichiometric variations were found to be detrimental for the growth as well as different properties of the grown crystals [11,13,14].…”