The influence of thermodynamic history and external influences on the electrophysical properties of ferropiezoceramic materials based on a multicomponent system PZT-PMN-PZN+SiO_(2)

This paper presents the results of a comprehensive study of the industrially produced ferro-piezoelectric ceramic material based on the PbZrO_(3)-PbTiO_(3)-PbMn_(1/3)Nb_(2/3)O_(3)-PbZn_(1/3)Nb_(2/3)O_(3)+SiO_(2)system.Studies have confirmed that this material refers to ferrorigid materials with high coercive fields,stable dielectric properties in a wide temperature range,practically no Curie temperature hysteresis,as well as low controllability of the dielectric constant and deformation characteristics by constant bias electric fields.The revealed correlation between dielectric,deformation characteristics and dielectric hysteresis allows us to consider this material as promising for devices operating in power modes:piezotransformers,highly loaded ultrasonic devices,piezoelectric motors,etc.

Microstructure features of the BST/(Mg,Ln)-ceramic

Solid solutions of the composition Ba_(1-x-y)(Mg,Ln)_(x)SryTiO_(3)(x=0.01;0.025;0.04;y=0.20;0.50;0.80;Ln=La,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tu,Yb)were prepared by two-stage solid-phase synthesis followed by sintering using conventional ceramic technology.The influence of rare-earth elements on the microstructure of the prepared ceramic samples was investigated.It was found that regardless of the type of modifiers introduced,the grain landscape of the studied solid solutions with different amounts of SrTiO_(3)is refined(in the initial system,the average grain size,d,at x=0.20 is 6μm;at x=0.50 is 4μm;at x=0.80 is 18μm)to crystallite sizes not exceeding(2-3)μm,and compacted.The using of mechanical activation procedures leads to an even greater decrease in the size and an increase in the density of ceramics.The increasing in the concentration of modifiers in each group(within the considered range of dopant variation)against the background of such a fine-grained structure has little effect on the dynamics of changes in d.It is concluded that it is advisable to use the data obtained in the development of functional materials based on BST/(Mg,Ln)and devices with the participation of these compositions.

Obtaining,structure,microstructure and dielectric characteristics of ceramics and thin films of ferro-piezoelectric materials based on the PZT system

This paper presents the results of studies of the structure,microstructure,dependences of the piezoelectric properties on the electric field(dielectric hysteresis loops,reversible nonlinearity,deformation characteristics)and dielectric properties of the ceramic material PCR-13(based on the PZT system)in the temperature range 300-900K and frequencies of an alternating electric field(25÷2·10^(6))Hz.The character of the obtained dependences made it possible to attribute PCR-13 to ferro-hard materials.Using the HF cathodic sputtering method,PCR-13 thin films were fabricated on Si(001)substrates.It is shown that they are polycrystalline textured,while in comparison with bulk material,the film contains tensile stresses of the unit cell in the plane of the substrate and compresses in the perpendicular direction with the valueε_(33)=-0.018.The capacitance-voltage characteristics of the Al/PCR-13/Si/Al heterostructure were studied.The reasons for the revealed patterns are discussed.

Destruction phenomena in ferroactive materials

The results of a comprehensive study of the crystal structure,grain structure,and strength properties of ceramic bismuth ferrite with rare earth elements(REE)obtained by two-stage solid-phase synthesis followed by sintering using conventional ceramic technology are presented.The reasons for the formation of low mechanical strength and the development of destruction phenomena in solid solutions with small REE(
R<0:94Å)are considered:Tb,Dy,Ho,Er,Tm,Yb,Lu.The causes of the observed phenomena associated with the composite-like structure of the studied media and,as a consequence,the occurrence of local stresses of structural elements that provoke crack formation are established.A source of the latter are also the structural features of the grain landscape.The conclusion is made about the appropriateness of taking into account the information obtained when developing devices based on BiFeO_(3)/REE multiferroics.