Normal-pressure densification method of sodium potassium niobate-based leadless piezoelectric ceramic

Abstract

The invention discloses a normal-pressure densification method of sodium potassium niobate-based leadless piezoelectric ceramic, and belongs to the technical field of the preparation of functional ceramic materials. Sodium carbonate, potassium carbonate and niobium pentaoxide are taken as main raw materials; the leadless piezoelectric ceramic with high density is prepared by sintering the raw materials under normal pressure by the conventional solid reaction method by adding second components such as calcium titanate, lithium antimonate, lithium tantalate and the like without sintering processes such as vacuumization, hot pressing/hot isostatic pressing and the like; and the prepared ceramic which consists of a morphotropic phase boundary has high piezoelectric and ferroelectric properties. By the method, the defects of over-high equipment requirements, rigorous production processes and higher production cost of the sintering processes such as the hot pressing and the like are overcome; and the leadless piezoelectric ceramic with the high density and high piezoelectricity is prepared by a normal pressure sintering process by adding the second components and optimizing process parameters.

Description

technical field [0001] The invention belongs to the technical field of preparation of functional ceramic materials. Potassium sodium niobate (NKN)-based lead-free piezoelectric ceramics are prepared through an atmospheric pressure sintering process to achieve the purpose of simplifying the process and saving energy. By adding a second component and optimizing process parameters, Overcoming the disadvantages of easy volatilization of alkali metal ions such as Na and K in the sintering process, which leads to the deviation of stoichiometric ratio, realizes liquid phase sintering at a lower sintering temperature, and obtains NKN-based inorganic materials with high density and good electrical properties. lead piezoelectric ceramics. Background technique [0002] Piezoelectric ceramics is a new type of ceramic material in the field of functional ceramics. It is widely used in many high-tech fields such as electronics, communications, lasers, and biology. It can be used to make ul...

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Problems solved by technology

[0002] Piezoelectric ceramics is a new type of ceramic material in the field of functional ceramics. It is widely used in many high-tech fields such as electronics, communications, lasers, and biology. It can be used to make ultrasonic transducers, piezoelectric transformers, filters, and piezoelectric buzzers. However, the current research and production of piezoelectric ceramics mainly focus on lead zirconate titanate (PbZrO 3 -PbTiO 3 , PZT)-based multi-system lead-containing ceramics. The content of lead oxide in PZT-based ceramics exceeds 70% of the total raw materials. Due to the volatility of lead, it will cause great harm to the environment during production, preparation, use and disposal. Therefore, it is an urgent and scientifically important topic to develop lead-free environment-friendly (green) piezoelectric ceramic materials to replace PZT-based piezoelectric ceramics.

[0003] Since the early 1960s, people have gradually realized the importance of research and development of lead-free piezoelectric ceramics, and studied lead-free piezoelectric ceramics with perovskite structures based on niobate and titanate, among which NaNbO 3 -KNbO 3 The system is similar to the PZT system, and the antiferroelectric NaNbO 3 and ferroelectric KNbO 3 Can form a continuous solid solution, the structure is a perovskite structure, the study found that in NaNbO 3 -KNbO 3 In the system, when the molar ratio of Na / K is close to 1:1, it exhibits good piezoelectric performance, which is similar to the quasi-isomorphic phase boundary of the PZT system; compared with lead-based piezoelectric ceramics such as lead zirconate titanate, niobium Potassium sodium lead-free piezoelectric ceramics have the characteristics of small dielectric constant, large frequency constant, large electromechanical coupling coefficient, and high acoustic velocity, and are especially suitable for use in functional devices such as transducers. However, because Na and K are volatile , Na 0.5 K 0.5 NbO 3 It is difficult to sinter ceramics densely, and generally need to use hot pressing, discharge plasma, hot isostatic pressing sintering and other methods to obtain dense NKN ceramics; the stability of the ceramics prepared by the above methods is not satisfactory, and at the same time, the equipment is too demanding High, harsh production process, high production cost, limited material size, difficult to obtain industrial application, in order to optimize the preparation process of NKN-based lead-free piezoelectric ceramics, improve the piezoelectric performance of NKN-based ceramics, scholars from various countries add sintering aids , A-site and B-site doping substitution, addition of new components, etc. have been studied on NKN-based lead-free piezoelectric ceramics, which provides a new idea for the normal pressure sintering and densification of NKN-based lead-free piezoelectric ceramics

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