Novel growth technology of relaxation ferroelectric monocrystal PIMNT (Lead Magnesium/Indium Niobate-Lead Titanate)

Abstract

The invention discloses a novel growth technology of relaxation ferroelectric mono-crystal PIMNT by using a Bridgman-Stockbarger method, belonging to the technical field of mono-crystal growth. The novel growth technology of the relaxation ferroelectric mono-crystal PIMNT comprises the steps of: regarding high-purity PbO, Nb2O5, In2O3, TiO2 and 4MgCO3.Mg(OH)2.4H2O as initial raw materials to prepare a PIMNT polycrystal material through a precursor step-by-step synthesis method, wherein the chemical constitution is xPb(In1 / 2Nb1 / 2)O3-yPb(Mg1 / 2Nb2 / 3)O3-(1-x-y)PbTiO3, where x=0.24-0.26, and y=0.43-0.45; selecting high-quality seed crystal in a [110], [111] or [001] crystallographic direction; adopting a single-layer or double-layer seamless platinum crucible to contain the seed crystal and a material ingot; putting the crucible after being sealed in a mono-crystal growth furnace; controlling the temperature of the furnace at 1350-1400 DEG C; adjusting the position of the crucible to enable the material ingot to be welded with the top part of the seed crystal so as to form a steady solid-liquid interface with a temperature gradient of 20-50 DEG C; and growing the mono-crystal at a dropping speed of the crucible of less than 1 mm / h to obtain a high-quality and large-size PIMNT mono-crystal. The novel growth technology of the relaxation ferroelectric mono-crystal PIMNT, disclosed by the invention, has the advantages of overcoming a leakage phenomenon of a high-temperature lead-rich melt, avoiding volatilization of components of the melt, and particularly lead oxide steam, efficiently solving a poly-crystallized growth problem of a solid solution with composition complexity, and being suitable for growing high-quality and large-size PIMNT mono-crystals in batches.

Description

technical field [0001] The invention belongs to the technical field of single crystal growth. PIMNT single crystal is a newly discovered high-performance relaxor ferroelectric crystal material in recent years. PIMNT with quasi-isomorphic phase boundary composition has a very high piezoelectric constant. Compared with the traditional piezoelectric material PZT ceramics, its piezoelectric constant d 33 , electromechanical coupling coefficient K 33 From 500pC / N and 60% to about 2000pC / N and 90%, respectively, the strain is as high as 1%, which is an order of magnitude higher than the piezoelectric material with a strain of about 0.1%. It has extremely important application value in high-tech fields such as nanotechnology, ultrasonic motor, and non-destructive testing. High-quality and large-size PIMNT single crystals meeting practical needs can be grown by adopting the technology of the invention. Background technique [0002] Since the late 1990s, material scientists have d...

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Problems solved by technology

[0005] The PIMNT single crystal system is a solid solution single crystal grown from a multi-component lead-rich melt, and the following inherent technical difficulties exist in the single crystal growth process: (1) The lead oxide content of the PIMNT polycrystalline material is quite high, and this lead-rich melt It has a strong erosive effect on the metal platinum crucible, resulting in tiny holes or cracks in the wall of the platinum crucible, resulting in varying degrees of leakage of the melt in the crucible; The solid phase sintering process is easy to form ceramic polycrystalline materials, and its single crystal growth process is prone to polycrystalline growth and it is difficult to obtain single crystal materials; (3) There is inherent component segregation in the growth of lead-based solid solution single crystals, which leads to corresponding The properties of the single crystal precursor change continuously along the axial direction, which becomes a constraining factor that significantly affects the uniformity of material properties

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