Improved coprecipitation PZT piezoelectric ceramic powders
PZT piezoelectric ceramic powders of various chemical methods, co-precipitation method due to its simple process, and the resulting powder good performance has been widely used. 1976 Japanese body Murata M. et al prepared by co-precipitation PZT ceramic powders, but the process in order to avoid precipitation of PbCl2 and PbOCL priority generation, the whole process needs to be controlled for temperature, and the final product was X diffraction analysis showed that the structure as a mixture of amorphous, sintering activity is not, for in a large number of experiments, the improvement of the process was to obtain a particle size distribution of PZT piezoelectric ceramic powder 0.3-0.6um compared with the similar preparation process has certain advantages.
Experimental Methods:
Select 1 materials: directly determines the nature of the production cost of the level of complexity of the process and product particles. Use TiCL4, ZrOCL2 * 8h2O and Pb (NO3) 2 was prepared from PZT powder, the priority the following reaction:
Since the volume of the dissolved and PbOCL PbCL2 are larger than Pb (OH) 2, at room temperature, is difficult to formulate Zr ^ 4 +, Ti ^ 4 +, Pb ^ 2 + coexist in a clear solution, while PbOCL and PbCL2 and difficult to convert into Pb (OH ) 2, the temperature must be strictly controlled throughout the process, resulting in complicated process. We Pb (Ac2) * 3H2O replace Pb (NO3) 2 as Pb material, in solution following complexation reactions occur first:
Complex ion [Pb (Ac) 4] ² generation, and avoid the formation PbOCL PbCL2, formulated at room temperature Zr ^ 4 +, Ti ^ 4 +, Pb ^ 2 + salt solution coexistence transparent female simplifies the process of temperature control.
Preparation of the raw material liquid 2 (the parent salt solution)
Preparation of the raw material solution is coprecipitation material during the first critical steps. The aqueous solution prepared in this experiment TiCL4 particularly important because TiCL4 easily hydrolyzed to form a white precipitate. Typically TiCL4 aqueous preparation methods: The TiCL4 slowly added dropwise to ice water or ice water was slowly added dropwise in TiCL4. A method of preparation of a solution before TiCL4 partially hydrolyzed due to the inevitable, resulting in the final solution was cloudy, should be filtered prior to use; latter method, in the initial preparation of the very thick paste is formed, the viscosity is large, not stirred difficult to achieve in the industrial production. We have made the process of solution preparation TiCL4 following improvements: the dropwise addition of a small amount of liquid and TiCL4 IICL of deionized water were placed in ice water and cooled to about 4 ℃, and then poured into a large amount of TiCL4 beaker on the magnetic a heating stirrer, separatory funnel with deionized water was slowly added dropwise, with constant stirring, until a clear liquid, to control the concentration of 200g / L, an aqueous solution of the prepared TiCL4 cold standby.
3 Process: Preparation of piezoelectric ceramic powder process shown in Figure 1.
Orthogonal experiment to get the powder particle size and particle shape as a measure to judge the merits of the process, in order to investigate the influence of various factors on the size and shape of grains, grain size and grain shape observations and measurements by SEM photographs, orthogonal experiment results shown in Table 2, from the orthogonal experiment results in Table 2 poor R-value, primary and secondary factors affecting precipitation is: precipitant - drying - aging time - mother salt - dispersing agent - stirring speed - precipitating agent Join way; Ki (i level granularity for the sum) -Ki (i horizontal average particle size) value shows that seven factors in combination A2B2C2D2E1F2G2 optimal level consistent with the theory.
4 Powder Performance Measurement
PZT powder particles are spherical, diameter of 0.3-0.6um soft aggregates. SEM determined using electron spectroscopy powder component performance measurement, found that because of the precipitation process, Zr (OH) 4 is formed of very fine particles easily through the filter, resulting in the loss of some of Zr, in order to compensate for this loss, when 1.040 mole to prepare PZT precursor than quantitative join Zr, after adjusting the ratio of powder spectrum curve shown in Figure (energy spectrum in the AL, Si, Fc derived from the scanning electron spectroscopy analysis: according to a the substrate employed), the main component in Table consistent with a predetermined formula.
5 Conclusion: Improved can be prepared by a coprecipitation method PZT piezoelectric ceramic powder body; main factor affecting sedimentation is the precipitation agent powder type, as a precipitating agent in a buffer solution than ammonia; 1: molar ratio of 1.040 quantitative adding Zr precipitation process can compensate for the loss of Zr; using Pb (Ac) 2 * 3H2O replace Pb (NO3) 2 as Pb material, you can simplify the process, reduce production costs, shorten production cycle.
