Single crystal growth of Gd2.3Tb0.7Fe5O12 by a grain growth technique

AbstractCeramics based on (Na1/2B1/2)TiO3 are promising candidates for actuator applications because of large strains generated by an electric field-induced phase transition. For example, the (1−x)(Na1/2Bi1/2)TiO3-xSrTiO3 system exhibits a morphotropic phase boundary at x = 0.2–0.3, leading to high values of inverse piezoelectric constant d*33, which can be further improved by the use of single crystals. In our previous work, single crystals of (Na1/2B1/2)TiO3-SrTiO3 and (Na1/2B1/2)TiO3-CaTiO3 were grown by the solid state crystal growth technique. Growth in the (Na1/2B1/2)TiO3-SrTiO3 system was sluggish whereas the (Na1/2B1/2)TiO3-CaTiO3 single crystals grew well. In the present work, 0.8(Na1/2Bi1/2)TiO3-0.2(Sr1−xCax)TiO3 single crystals (with x = 0.0, 0.1, 0.2, 0.3, 0.4) were produced by the solid state crystal growth technique in an attempt to improve crystal growth rate. The dependence of mean matrix grain size, single crystal growth distance, and electrical properties on the Ca concentration was investigated in detail. These investigations indicated that at x = 0.3 the matrix grain growth was suppressed and the driving force for single crystal growth was enhanced. Replacing Sr with Ca increased the shoulder temperature Ts and temperature of maximum relative permittivity Tmax, causing a decrease in inverse piezoelectric properties and a change from normal to incipient ferroelectric behavior.

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Effect of Na2CO3 Addition on Grain Growth Behavior and Solid-state Single Crystal Growth in the Na0.5Bi0.5TiO3-BaTiO3 System

Journal of Korean Powder Metallurgy Institute ◽

10.4150/kpmi.2018.25.2.104 ◽

2018 ◽

Vol 25 (2) ◽

pp. 104-108

Author(s):

Kyoung-Seok Moon

Keyword(s):

Crystal Growth ◽

Solid State ◽

Single Crystal ◽

Grain Growth ◽

Single Crystal Growth ◽

Growth Behavior ◽

Grain Growth Behavior

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Effect of Composition on the Growth of Single Crystals of (1−x)(Na1/2Bi1/2)TiO3-xSrTiO3 by Solid State Crystal Growth

Materials ◽

10.3390/ma12152357 ◽

2019 ◽

Vol 12 (15) ◽

pp. 2357 ◽

Cited By ~ 2

Author(s):

Le ◽

Fisher ◽

Moon

Keyword(s):

Growth Rate ◽

Crystal Growth ◽

Solid State ◽

Single Crystal ◽

Single Crystals ◽

Grain Growth ◽

Ceramic Powder ◽

Single Crystal Growth ◽

Crystal Growth Rate ◽

Mixed Control

The (1−x)(Na1/2Bi1/2)TiO3-xSrTiO3 (NBT-100xST) system is a possible lead-free candidate for actuator applications because of its excellent strain vs. electric field behaviour. Use of single crystals instead of polycrystalline ceramics may lead to further improvement in piezoelectric properties but work on single crystal growth in this system is limited. In particular, the effect of composition on single crystal growth has yet to be studied. In this work, single crystals of (NBT-100xST) with x = 0.00, 0.05, 0.10 and 0.20 were grown using the method of Solid State Crystal Growth. [001]-oriented SrTiO3 single crystal seeds were embedded in (NBT-100xST) ceramic powder, which was then pressed to form pellets and sintered at 1200 °C for 5 min–50 h. Single crystal growth rate, matrix grain growth rate and sample microstructure were examined using scanning and transmission electron microscopy. The results indicate that the highest single crystal growth rate was obtained at x = 0.20. The mixed control theory of grain growth is used to explain the single crystal and matrix grain growth behaviour.

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SINGLE CRYSTAL GROWTH AND TEXTURING OF LEAD-BASED PIEZOELECTRIC CERAMICS VIA TEMPLATED GRAIN GROWTH PROCESS

Functional Materials Letters ◽

10.1142/s1793604708000204 ◽

2008 ◽

Vol 01 (02) ◽

pp. 127-132 ◽

Cited By ~ 6

Author(s):

THOMAS RICHTER ◽

CARSTEN SCHUH ◽

RALF MOOS ◽

ENDER SUVACI

Keyword(s):

Crystal Growth ◽

Single Crystal ◽

Single Crystals ◽

Grain Growth ◽

High Performance ◽

Piezoelectric Materials ◽

Secondary Recrystallization ◽

Single Crystal Growth ◽

Templated Grain Growth ◽

Textured Ceramics

In the field of high-performance piezoelectric materials, PMN-PT single crystals and textured ceramics have been attracting increased research interest for several years. On the other hand, the growth of single crystals from melt for PZT-based compositions is impossible due to its incongruent melting behavior. In order to obtain the characteristics of pure single crystal PZT as closely as possible, the PZT must be textured by secondary recrystallization of introduced seeds in a fine-grained matrix. Zirconium was therefore added to a PMN-PT-ceramic with 32 mol% PT ( Pb ( Mg 1/3 Nb 2/3)0.68 Ti 0.32 O 3) in order to obtain a PMN-PZT-ceramic with 37 mol% PT and 21 mol% PZ ( Pb ( Mg 1/3 Nb 2/3)0.42( Ti 0.638 Zr 0.362)0.58 O 3). Initially, the growth mechanism of (001)-oriented BaTiO 3 (BT) single crystals in those matrices was investigated. The piezoelectric single crystals were produced via a process that starts with the hot pressing of a BT single crystal in cold isostatically pressed ceramics, followed by an additional sintering step in order to achieve a secondary recrystallization. The measured growth lengths in PMN-PT and PMN-PZT matrices were up to 140 μm and 65 μm, respectively. Having developed this understanding, both ceramics were textured via the templated grain growth (TGG) process by using (001)-oriented BT templates. Sintering of templated grain bodies resulted in template growth into the matrix to produce textured ceramics with Lotgering factors up to 0.99 for both compositions. In textured samples unipolar strain s33 was enhanced by a factor of up to 1.8 compared to randomly oriented ceramics. By contrast, BT single crystal growth in an alternative PZT matrix with NdMn doping was not successful. Hence, in the present work, growth experiments in this NdMn -doped PZT were first performed using PZT fibers of similar composition as seeds. Growth of the fiber diameter of up to 100 μm was observed in that matrix.

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