The study of the ferroelectric properties of lithium-titanium ferrite

Loop-shaped dependences of the electric polarization on the electric field strength (the dielectric hysteresis) are registered for the first time for polycrystalline Li-Ti ferrite. Temperature evolution of the hysteresis loop parameters is investigated for ferrite samples. A thermal Barkhausen effect is detected during heating and cooling of ferrite specimens prepolarized in an electric field. The results obtained can be interpreted from the viewpoint of the Maxwell-Wagner relaxation polarization or induced ferroelectric-like state in the electric ferrite subsystem

Influence of the technique for producing lithium-titanium ferrite ceramics on its electrical properties

The patterns of electrical, dielectric, magnetic, and structural characteristics for the lithium-titanium ferrite ceramics, prepared in different technological conditions have been investigated for the first time. The determining factor of the obtained patterns is structural redistribution of iron ions over the sublattices and their diffusion from the grain boundary in the volume of the ferrite ceramics grain

Effect of Mechanical Load on Defects Level in Soft Ferrite Ceramics

The article presents the results of a study of the effect of mechanical load on the temperature dependence of the initial permeability of LiTiZn soft ferrite ceramics. Regimes of mechanical load were created by a steel non-magnetic ring with screws. In this work, four levels of mechanical load were investigated: without load, with 1, 2 and 3 screws. For obtaining temperature dependences and exclude the influence of prehistory on the initial permeability, the samples were heated to a temperature exceeding the Curie point by 50 degrees, after which they slowly cooled to room temperature. The defects level was determined by the ratio of the parameters ? / ? of the phenomenological expression, which describes the experimental temperature dependences. It is shown that as the mechanical load increases, the defects level of ferrite ceramics increases, and after load removing, it returns to its original level

Influence of mechanical milling conditions on the dispersity of lithium ferrite

The effect of mechanical milling in a planetary ball mills on dispersity of the synthesized lithium ferrite powder was investigated by laser diffraction technique. The mechanical milling of powder was carried out by two planetary ball mills: SPEX 8000М and Fritsch Pulverisette 5 with different time period. The lithium ferrite powder was milled for 30, 60 and 120 minutes in the first ball mill. The powder milled for 60 minutes in the second ball mill was performed. The results showed that an increase in the milling time slightly decreases the average particle size of the ferrite powder in case both ball mills. However, only milling in a SPEX planetary mill increases homogeneity of the ferrite powder, while the milling in Fritsch causes intensive processes of particle aggregation

Data on granulometric composition of calcium phosphate obtained by dispersion method

The kinetics of calcium phosphate crystallization from model solutions of saliva and liquid phase of dental plaque has been studied by the dispersion method. It was found that the composition of the saliva model system is favorable for the growth of larger crystals. The size of the particles in crystallization varies nonlinearly. As supersaturation grows, the amount of formed particles increases, however, the average rate of crystallite growth decreases

Impact of ZrO2 additive on the microstructure, magnetic properties, and temperature dependence of the initial permeability of LiTiZn ferrite ceramics

The effect of the diamagnetic ZrO2 addition on the microstructure and magnetic properties of LiTiZn ferrite ceramics, including the shape and parameters of the temperature dependence of the initial permeability, has been investigated. The defect structure of ferrite ceramic samples is assessed according to our earlier proposed method based on the mathematical treatment of the experimental temperature dependencies of the initial permeability. It was found that the defect structure of ferrite ceramics increased by 350% with an increase in the concentration of the ZrO2 additive in the range of (0–0.5) wt.%. In this case, for the same samples, the increase in the true physical broadening of diffraction peaks is only 20%, and the coercive force by 50%. Simultaneously, the maximum of the experimental temperature dependence of the initial permeability dropped by 45%. The microstructure of all samples is characterized with a similar average grain size according to the SEM data. However, samples with 0.5 wt.% of ZrO2 are characterized by the formation of conglomerates. A linear relationship was obtained between the defect structure and the width of the diffraction peaks, which indicates that this parameter is related to the elastic stress of ferrite ceramics. These results suggest that the high sensitive proposed method can be recommended for impurity and defect monitoring of soft ferrite products

Influence of reagents mixture density on the radiation-thermal synthesis of lithium-zinc ferrites

Influence of Li[2]CO[3]-ZnO-Fe[2]O[3] powder reagents mixture density on the synthesis efficiency of lithium-zinc ferrites in the conditions of thermal heating or pulsed electron beam heating was studied by X-Ray diffraction and magnetization analysis. The results showed that the including a compaction of powder reagents mixture in ferrite synthesis leads to an increase in concentration of the spinel phase and decrease in initial components content in lithium-substituted ferrites synthesized by thermal or radiation-thermal heating

Effect of powder compaction on radiation-thermal synthesis of lithium-titanium ferrites

Effect of powder compaction on the efficiency of thermal and radiation-thermal synthesis of lithium-substituted ferrites was investigated by X-Ray diffraction and specific magnetization analysis. It was shown that the radiation-thermal heating of compacted powder reagents mixture leads to an increase in efficiency of lithium-titanium ferrites synthesis

Relationship between magnetic properties and microstructure of ferrites during sintering in radiation and radiation-thermal conditions

The studies of correlation between magnetic properties and microstructure were conducted on samples of lithium-substituted ferrite, sintered in radiation and radiation-thermal conditions. Radiation-thermal sintering was performed for compacts irradiated with a pulsed electron beam with energy of (1.5-2.0) MeV, beam current per pulse of (0.5-0.9) A, irradiation pulse duration of 500 μs, pulse repetition rate of (5-50) Hz, and compact heating rate of 1000 °C/min. Sintering in thermal furnaces (T-sintering) was carried out in a preheated chamber electric furnace. The paper shows that magnetic induction does not depend on the ferrite grain size. In this case, the coercive force is inversely proportional to the grain size and depends on the intragranular porosity of ferrite samples. In contrast to thermal sintering, radiation-thermal sintering does not cause capturing of intergranular voids by growing grains and enhances coagulation of intragranular pores