Structures and Properties of KxCryNi1-x-yO Dielectric Materials Prepared by an Ultrasonic-Assisted Sol-Gel Method

Abstract

K x Cr y Ni 1-x-y O (x = 0.05-0.20, y = 0.02) dielectric materials were prepared using a facile simple green ultrasonic-assisted sol-gel method. All samples have a main phase consisting of a cubic NiO structure and with nanoscale crystallite sizes (28.58-37.51 nm). However, secondary phases were also observed for the samples with x values exceeding 0.10. The fractured surface microstructures of the samples with x values less than 0.15 exhibited uniformly distributed spherical grains. Other samples showed irregularly shaped grains. The grain sizes were larger when x was increased to 0.15 and exhibited increased grain growth probably due to substitution of K ions into the NiO lattice. However, a reduction of grain sizes was observed in the sample with x = 0.20, possibly due to inhibition of the grain growth by the secondary phase. At room temperature and a frequency of 1013 Hz, the highest dielectric constant of 2.25 × 10 4 was obtained for the samples with x = 0.15.

Epoxidized natural rubber composites containing K0.15Cr0.02Ni0.83O nanoparticles: Curing characteristics, dynamic mechanical, mechanical, morphological, and dielectric properties

“…0, 0.5, 1.5, and 5 phr. In our previous work, 25 the XRD patterns of KCNO powders exhibited 2θ main peaks at 37.7°, 43.9°, 63.7°, 76.2°, and 79.6°, corresponding to the (111), (002, (022) (113), and (222) planes, respectively, and are identical to the cubic NiO structure in the COD database, code 9008693. The ENR0 pattern displays a broad diffraction peak at a 2θ value of ∼18°, identifying amorphous polymer behavior.…”

“…Preparation of K 0.15 Cr 0.02 Ni 0.83 O nanoparticles KCNO powders were prepared via a previously published ultrasonic-assisted sol-gel method. 25 First, stoichiometric amounts of CH 3 COOK, (CH 3 COO) 2 NiÁ4H 2 O, and Cr(NO 3 ) 3 Á9H 2 O were dissolved in deionized water and then mixed with 1,3-propanediol to obtain a precursor solution. Afterward, 50 cm 3 of the precursor solution was poured into a flask (Schlenk Tube, 100 cm 3 , diameter (f) 5.0 cm).…”

“…The average diameter of the spherical KCNO particles, determined from SEM images, was around 492 nm. 25 Preparation of K 0.15 Cr 0.02 Ni 0.83 O/epoxidized natural rubber dielectric elastomer composites ENR-25 was dissolved in dichloromethane (CH 2 Cl 2 ) and continuously stirred at 30°C for 2 h to form an ENR-25 solution. After that, KCNO nanoparticles were added to the ENR solution at various levels of 0, 0.5, 1.5, and 5 phr at 30°C via a batch mixer with strong and continuous stirring for 30 min.…”

“…The average diameter of the spherical KCNO particles, determined from SEM images, was around 492 nm. 25…”

“…24 Recently, we successfully prepared potassium chromium nickel oxide (KCNO) with the aid of ultrasonic irradiation. 25 It was found that the K 0.15 Cr 0 . 02 Ni 0 .…”