Optimization of PbTiO₃ Single Crystals with Flux and Laser Floating Zone Method

Abstract

PbTiO 3 is an established high temperature ferroelectric and component of multiferroic devices. Single crystal growth of clean PbTiO 3 has largely been limited to flux growth, in part due to the volatility of PbTiO 3 near the melting point. We demonstrate the ability to grow single crystals of PbTiO 3 using the laser diode floating zone technique. Crystal quality is examined using Laue, powder, and single crystal X-ray diffraction. Low temperature specific heat and annealing experiments using thermogravimetric analysis/differential thermal analysis were used to compare the disorder and vacancies generated in the laser diode floating zone with those produced by flux growth. Samples grown using the floating zone method showed minimal oxygen deficiency, while samples grown via flux had a higher density of vacancies and metal impurities (determined using glow discharge mass spectrometry), resulting in room temperature ferromagnetic behavior. The use of laser diodes as a heating source in the optical floating zone technique is essential in the stability of the zone growth and could be applied for production and zone refinement of other volatile materials.

Self-Polarization in PbTiO3 Crystals Induced by Chemical Inhomogeneity in the Surface Layer

“…Althou diffraction pattern of our crystals shows the typical lattice parameter [40] and and Raman measurements a correct sequence of the phase transitions [41,42, chemical point of view, the composition of the crystal due to the method shows a surplus of Pb. Most scientific articles dedicated to FE properties or d istry are based on such prepared crystals [44,[59][60][61][62][63], although some refineme able [64]. Using the chemical analysis ICP-OES (for determination of the con and Pb) and infrared spectroscopy (for the analysis of the amount of oxygen), that the chemical formula of our crystal can be written as follows: Pb1.02±0.02Ti This additional incorporation of a few percent of Pb in the matrix of the cr explained in two ways: either additional PbO will create a stacking fault in (PbO)0.06PbTiO3 [65][66][67][68], where an equidistant distribution of PbO planes wil RP phase [40]; or, if the valence of Pb is reduced to 4+, an anti-structural dis…”

“…Although the X-ray diffraction pattern of our crystals shows the typical lattice parameter [40] and the dielectric and Raman measurements a correct sequence of the phase transitions [41,42,58], from the chemical point of view, the composition of the crystal due to the method flux growth shows a surplus of Pb. Most scientific articles dedicated to FE properties or defect chemistry are based on such prepared crystals [44,[59][60][61][62][63], although some refinements are available [64]. Using the chemical analysis ICP-OES (for determination of the concentration Ti and Pb) and infrared spectroscopy (for the analysis of the amount of oxygen), it was found that the chemical formula of our crystal can be written as follows: Pb 1.02±0.02 Ti 0.96±0.012 O 3±0.04 .…”

Recent Progress of Floating-Zone Techniques for Bulk Single-Crystal Growth

“…Since the successful growth of silicon in the middle of the last century [27,28], the floating-zone technique has been widely applied to various categories of materials: oxides [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45], chalcogenides [46][47][48][49], silicides [50][51][52][53][54][55], borides [56][57][58][59][60][61][62][63], carbides [64][65][66][67][68][69][70], and intermetallic alloys [71][72][73][74][75][76]…”

Tunable W5+ Absorbance in Laser Floating Zone Grown Bismuth Tungstate

“…20−26 The technique thus presents a unique opportunity to improve upon the availability/properties of crystalline samples. 27 Here, we report the growth of single crystals of Bi 2 WO 6 using a laser diode floating zone technique. As grown crystals show the presence of oxygen deficiencies leading to the formation of W 5+ defect sites, providing an opportunity for post growth annealing.…”

“…Such oxygen deficiencies result in W 5+ centers surrounded by oxygen octahedra. These centers in perovskite structures have been investigated for applications ranging from quantum information to electrochromic materials. − Bulk crystal growth has been largely limited to flux methods due to the high-temperature phase transition that results in cracking upon cooling. − The utilization of laser diode heating for floating zone furnaces (LDFZ) has enabled/improved the crystal growth of various systems, including those exhibiting high-temperature structural transitions. − The technique thus presents a unique opportunity to improve upon the availability/properties of crystalline samples …”