Large Size Single Crystal Growth of Ti₄O₇ by the Floating-Zone Method

Abstract

We report the growth of large size Ti4O7 single crystals by the floating-zone method using an infrared image furnace. By employing a high rotation rate of the seed rod, we improved the temperature gradient at the solid–liquid interface, thereby suppressing the decomposition of Ti4O7 at high temperature. By systematically studying the influence of growth parameters on crystal quality, we found that pure argon atmosphere is a prerequisite for getting a pure Ti4O7 phase and that a moderate rotation rate of the seed rod is a critical element in obtaining high crystal quality. The X-ray rocking scan confirmed the quality of the grown single crystal with dimensions of 2.7 mm × 2.3 mm × 1.7 mm, which was further characterized by electrical resistivity measurements. With decreasing temperature, the electric resistances of the Ti4O7 single crystal along a, b, and c axes all have two abrupt drops at ∼154 K and ∼110 K but show significant anisotropy. Moreover, it is noteworthy that the resistivity of the Ti4O7 single crystal in the high-temperature (HT) phase (T > 154 K) exhibits different behavior along different axes, exhibiting semiconducting behavior along the b axis but unusual metallic behavior along the a and c axes, in which the resistivity is proportional to T instead of T 2. Therefore, our results apparently do not support the Fermi liquid model proposed in the literature.

Andersson‐Magnéli Phases TinO2n‐1: Recent Progress Inspired by Swedish Scientists

“…(c) Physical properties (electrical conductivity and magnetic susceptibility) : The temperature dependence of resistance R and magnetic susceptibility χ of a Ti 4 O 7 single crystal is shown in Figure 7. From Figure 7a, the material shows metallic behaviour in the high temperature region and undergoes two transitions (MIT) on decreasing temperature from room temperature to 50 K, namely a metal‐semiconductor transition at T c1 ≈154 K and a semiconductor‐semiconductor transition at T c2 ≈115 K, consistent with a previous report on Ti 4 O 7 [15] . Further cooling drives the sample to more insulator‐like behaviour with considerably higher resistance (in the MΩ regime), beyond the measuring limit of the instrument.…”

“…The Ti 4 O 7 single crystal was grown using the calcined rods by the optical floating‐zone technique in pure argon atmosphere at growth rate 8–10 mm/hr. A high‐quality Ti 4 O 7 single crystal was obtained only at a seed rod rotation rate of 35 rpm [15] …”

“…Recently one of us (Y. Sui) has succeeded in synthesizing a high‐quality single crystal of Ti 4 O 7 and has measured electrical conductivity along three principal axes in the temperature range from 50 K to 250 K, with abrupt changes observed at 154 K and 110 K [15] …”

A hetero-phase growth method to control the crystal growth of β-antimony single crystals with high quality and large sizes

“…1 Increasing the content of raw feedstock in the single crystal growth system is one of the important factors for improving the size and quality of single crystals. 2 Large size Ti 4 O 7 single crystals were produced by a floating zone method, where a high rotated seed rod was used to ensure the continuous supply of molten Ti 4 O 7 for single crystal growth. 2 However, it is even more challenging to obtain high concentrations of vapor sources for the crystal growth of the vapor-solid phase transformation ones.…”

Laser Floating Zone: General Overview Focusing on the Oxyorthosilicates Growth

“…The micro-pulling down (μPD) and the floating zone (FZ) are alternative techniques to grow crystalline fibers from a melt [10][11][12]. The μPD technique is suitable for prototyping; however, the melt is continuously in contact with crucible, being also applied low pulling rates.…”