Structural, magnetic and dielectric properties of Cr substituted yttrium iron garnets

Abstract

Chromium substituted polycrystalline Yttrium Iron Garnets (Y3Fe5–xCrxO12 with x = 0 to 0.5) were prepared in single‐phase form with lattice constant in the range of 12.3775 Å to 12.3560 Å. All samples exhibit ferrimagnetic transition with transition temperature (Tc) in the range of 547 K for x = 0 to 494 K for x = 0.5. The saturation magnetization value at room temperature is found to increase with Cr concentration that is, from 24.8 to 26.6 emu/g and this is attributed to the preferential occupation of Cr3+ ions at octahedral site of Fe3+ ions. The frequency dependence of impedance data shows the relaxation and thermal activation of charge carriers across grains and grain boundaries. The complex impedance spectra were modeled by considering equivalent circuits having contributions from the resistance and constant phase element due to grains and grain boundaries and capacitance across grain boundaries. The dielectric constant is found to increase from 20 to 52 as the Cr concentration is increased and it is attributed to hopping of charge carriers across Fe2+–Fe3+ centers. The Arrhenius plots of relaxation time of charge carriers and conductivity show an anomaly in the vicinity of ferrimagnetic transition temperature and it highlights the presence of magneto‐electric coupling.

Análisis de la respuesta magnética de YIG dopado con Ce3+, Nd3+ y Bi3+

“…Los materiales magnéticos son ampliamente utilizados en la fabricación de dispositivos para almacenamiento de datos, sensores, transductores, tratamientos médicos, imágenes de resonancia magnética, entre otros. En respuesta a la generación de fuentes de energía económica, que incremente la eficiencia de diversos procesos industriales, la ferrita tipo granate, con fórmula {Y3 3+ } c [Fe2 3+ ] a (Fe3 3+ ) d O 12 , es empleada en la fabricación de dispositivos de sistemas de comunicación como: telefonía celular, antenas, radares, láseres, condensadores, osciladores y dispositivos que operan en frecuencias de microondas ( > 10 GHz) [1,2,11].…”

“…El Y3Fe5O12 en presencia de un campo magnético externo y a frecuencias de microondas, presenta momento angular (spin), momento dipolar magnético con un campo magnético intrínseco, asociado al giro de los electrones, relacionado con el movimiento orbital y angular (spin) y a sus interacciones (ver figura uno). Con respecto a la permitividad dieléctrica el Y3Fe5O12 transporta ondas electromagnéticas debido a la reflexión interna de la interface airedieléctrico [4,12].…”