TY - JOUR
T1 - Liquid immiscibility in a CTGS (Ca3TaGa3Si2O14) melt
AU - Nozawa, Jun
AU - Zhao, Hengyu
AU - Koyama, Chihiro
AU - Maeda, Kensaku
AU - Fujiwara, Kozo
AU - Koizumi, Haruhiko
AU - Uda, Satoshi
N1 - Funding Information:
This work was supported in part by JSPS KAKENHI Grant No. 24360002 .
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/11/15
Y1 - 2016/11/15
N2 - Although many studies have indicated that Ca3TaGa3Si2O14 (CTGS) grows congruently from a stoichiometric melt when using the Czochralski (Cz) technique, the occurrence of a secondary phase during growth when using the micro-pulling down (μ-PD) technique has been reported. We have examined the detailed growth mechanism of μ-PD grown CTGS as well as its congruency. Differential thermal analysis (DTA) at an elevated temperature up to 1650 °C shows no peaks associated with the presence of a secondary phase, whereas a secondary phase related peak was detected at an elevated temperature up to 1490 °C with the same heating rate. Back-scattered electron images (BEIs) revealed the occurrence of Ca3Ta2Ga4O14 (CTG) as a secondary phase. The secondary phase appears at the very early stage of growth, which is not possible to explain by a eutectic reaction. The experimental results suggest that liquid immiscibility was present in the melt at around 1490 °C during the growth of s-CTGS. Liquid immiscibility produces Si-rich and Si-poor melts, from which different phases with different compositions are solidified. The μ-PD technique poses a more static environment in the melt than that of Cz technique due to low melt convection and the lack of stirring, which enables liquid immiscibility to emerge.
AB - Although many studies have indicated that Ca3TaGa3Si2O14 (CTGS) grows congruently from a stoichiometric melt when using the Czochralski (Cz) technique, the occurrence of a secondary phase during growth when using the micro-pulling down (μ-PD) technique has been reported. We have examined the detailed growth mechanism of μ-PD grown CTGS as well as its congruency. Differential thermal analysis (DTA) at an elevated temperature up to 1650 °C shows no peaks associated with the presence of a secondary phase, whereas a secondary phase related peak was detected at an elevated temperature up to 1490 °C with the same heating rate. Back-scattered electron images (BEIs) revealed the occurrence of Ca3Ta2Ga4O14 (CTG) as a secondary phase. The secondary phase appears at the very early stage of growth, which is not possible to explain by a eutectic reaction. The experimental results suggest that liquid immiscibility was present in the melt at around 1490 °C during the growth of s-CTGS. Liquid immiscibility produces Si-rich and Si-poor melts, from which different phases with different compositions are solidified. The μ-PD technique poses a more static environment in the melt than that of Cz technique due to low melt convection and the lack of stirring, which enables liquid immiscibility to emerge.
KW - A2. Growth from melt
KW - A2. Single crystal growth
KW - B1. Oxides
KW - B2. Piezoelectric materials
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U2 - 10.1016/j.jcrysgro.2016.09.005
DO - 10.1016/j.jcrysgro.2016.09.005
M3 - Article
AN - SCOPUS:84988941855
VL - 454
SP - 82
EP - 86
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
SN - 0022-0248
ER -