Influence of admixtures on the properties of biferroic Pb(Fe_0.5Nb_0.5)O₃ ceramic

Abstract

The ferroelectromagnetic Pb(Fe0.5Nb0.5)O3 (PFN) ceramic was synthesized by a powder calcining method. The aim of this work was to decrease the electric conduction of the biferroic PFN ceramic as a result of admixing it with metal oxides or carbonates. Investigation results concerning the influence of admixtures of manganese, chromium and lanthanum oxides and potassium and strontium carbonates on direct current electric conduction and dielectric parameters of the PFN ceramic are presented. Crystallographic and morphological studies were carried out using X‐ray diffraction and scanning microscopy techniques. The specimens obtained were subjected to dielectric, electric direct current conductivity, hysteresis loop and electromechanical tests. By adding small amounts of admixtures it was possible to decrease (admixtures of manganese or chromium) or increase (admixtures of lanthanum, strontium or potassium) the area of the phase transition of the PFN ceramic. It was found that admixtures of manganese and potassium decreased the electric conduction of the PFN ceramic. PFN admixed with elements of small ions, manganese and chromium, is characterized by a better set of dielectric parameters and lower dielectric losses compared to the PFN ceramic without admixtures.

Magnetic and ferroelectric properties of PbFe1/2Nb1/2O3 synthesized by a solution precipitation method

“…Materials showing at least two out of four possible ordered states are called multiferroics [1,2]. Biferroic PbFe 1/2 Nb 1/2 O 3 (PFN) belongs to a group of the multiferroics, in which there is simultaneous ordering of an electric subsystem (at T < T CE ≈ 114 • C) and a magnetic subsystem (at T < T N ≈ −130 • C) in the specified temperature ranges [3,4]. PFN has a structure of the perovskite type with general formula A(B B )O 3 , where ions of iron and niobium substitute for octahedral B and B positions at random, whereas lead is placed in positions A.…”

Lead-free BFN ceramics doped by chromium, lithium or manganese

“…The BaFe 1/2 Nb 1/2 O 3 ceramics (BFN) may be an alternative material to replace lead-based ceramics such as: PbFe 1−x Nb x O 3 (PFN), which, due to its excellent piezoelectric and electromechanical properties, have been widely used for various devices, especially piezoelectric actuators, transformers and transducers [1][2][3][4][5]. The BFN, just like PFN, ceramics belong to the family of multiferroic materials [6] possessing perovskite structure of the general formula ABO 3 , where barium ions enter in the A positions, while iron and niobium ions alternately occupy the B position.…”

Internal Friction In The PFN Ceramics With Chromium Dopand

“…In a case of admixing the PFN ceramics with chromium, the Cr 3+ ion will replace the Nb 5+ decreases electric conductivity of ceramics [8]. There is also a possibility here for the excess of the chromium admixture to be placed in the interstitial positions, what results in formation of donor centers generating additional electrons.…”

“…These additional electric charges will be placed in the interstitial areas causing a decrease in effective resistance of the grain boundaries. In this case conductivity of the PFN type ceramics may increase [8].…”

“…A change of the base chemical composition of the PFN ceramics by incorporating admixtures is one of those factors. A lot of admixtures both soft and hard ones can be added into the PFN ceramics [7][8].…”