Control Of Growth Orientation Research Articles

Growth orientation control in rapid solid-state crystal growth of (K,Na)NbO3 single crystals using plate-like NaNbO3 single crystal particles

The rolling-extended orientation technique and plate-like NaNbO3 (NN) single crystal particles prepared by a single-step molten salt synthesis, both of which have been developed to fabricate (K, Na)NbO3 (KNN) textured ceramics, were utilized to control the growth orientation of KNN single crystals synthesized by a rapid solid-stated crystal growth (RSSCG) method. As the seed crystals, two kinds of NN single crystal particles were synthesized using pure NaCl and KCl-NaCl mixed molten salts. Plate-like KNN single crystals of about 1 cm squares with the upper and lower faces almost parallel to the (100) (001) planes were obtained with a probability exceeding 50% when NN single crystal particles were synthesized from mixed salts and were subsequently thermal-treated again in Na2CO3-NaCl mixed molten salts under appropriate conditions to remove the Bi element, which is known as the suppression factor of the crystal growth. The average crystal growth rate was 0.6–1.2 mm h−1. Controlling the growth orientation of KNN single crystals produced by the SSCG method using seed crystals other than KTaO3 single crystals was successfully accomplished for the first time.

Control of growth orientation in as-deposited epitaxial iron-rich nickel ferrite spinel

The authors here report epitaxial growth of the ferrimagnet NixFe3–xO4 (NFO) by atomic layer deposition at low temperatures. Films grow epitaxially at a reactor temperature of 250 °C and require no further postannealing treatment. (100)-, (110)-, and (111)-oriented thin films of NFO are attainable by using MgO (100)/LaAlO3 (100), LaAlO3 (110), and Al2O3 (001) substrates, respectively. This means that the direction of the easy axis of magnetization relative to the film surface can be selected by the choice of substrate. The authors carefully study nucleation onset and growth dynamics by varying the number of cycles used to deposit the films. This shows that the initial growth is mostly inhibited by the Fe-species, creating a small composition gradient for the first few nanometers of the film. The growth rate varies as a result of the choice of substrate, explained by the direction of the close packed layers in the film. The authors believe that the ability to deposit epitaxial ferrimagnetic films with angstrom thickness control at low temperatures will make a major impact on the possibility to grow multiferroic stacks and on low temperature monolithic device integration where a spontaneously magnetized sample is required.

Modification of magnetic properties through the control of growth orientation and epitaxial strain in SrRuO3 thin films

We studied the correlation between the magnetic properties and the structural modifications in SrRuO3 thin films. Previous results on the control of growth orientation in SrRuO3 thin film have been rather limited. For example, only orthorhombic a-axis growth could be obtained for SrRuO3 film on SrTiO3 (110) substrates. Here we were able to obtain various SrRuO3 films with (100)o, (010)o, and (111)o growth orientations, as well as with different amount of strain on SrTiO3 (110) substrates by using (Ca,Sr)SnO3 and CaHfO3 buffer layers. The magnetic properties were found to change systematically with the structural distortion of the SrRuO3 thin films.

Control of growth orientation and shape for epitaxially grown In 2O 3 nanowires on a-plane sapphire

Vertically aligned indium oxide nanowires were grown on a-plane sapphire substrate by the method of catalyst-assisted carbothermal reduction. The morphology and crystal structure of the nanowires are determined by X-ray diffraction, transmission electron microscopy and field-emission scanning electron microscopy. Two types of In 2O 3 nanowires were found by controlling the growth conditions. The nanowires with a hexagonal cross-section were shown to grow in [1 1 1] direction, whereas those with a square cross-section grow in [0 0 1] direction. In addition to the temperature effects, the concept of supersaturation in Au catalyst is proposed to explain the formation of these two types of nanowires. Besides, tapering, which is explained with the interplay between the vapor–liquid–solid and vapor–solid growth mechanisms, is observed in the nanowires.

The control of growth orientation during the production of melt-textured YBCO quasi-single crystals

Melt texturing is a well-developed, if not fully understood, technique for the production of single crystals of . Although this technique can produce single crystals of up to 2 mm diameter by 25 mm in length, problems remain. For example, it is difficult to control the orientation of the crystal relative to the rod in which it grows. It is important that the crystal is oriented so that the a - b planes lie along the bar, thus maximizing the current-carrying capability of the material. This paper reports on experiments in the use of oriented seed crystals to achieve the correct single-crystal orientation relative to the bar and highlights the problems associated with the use of seed crystals.