Fabrication of transparent lead-free KNN glass ceramics by incorporation method

Abstract

The incorporation method was employed to produce potassium sodium niobate [KNN] (K0.5Na0.5NbO3) glass ceramics from the KNN-SiO2 system. This incorporation method combines a simple mixed-oxide technique for producing KNN powder and a conventional melt-quenching technique to form the resulting glass. KNN was calcined at 800°C and subsequently mixed with SiO2 in the KNN:SiO2 ratio of 75:25 (mol%). The successfully produced optically transparent glass was then subjected to a heat treatment schedule at temperatures ranging from 525°C -575°C for crystallization. All glass ceramics of more than 40% transmittance crystallized into KNN nanocrystals that were rectangular in shape and dispersed well throughout the glass matrix. The crystal size and crystallinity were found to increase with increasing heat treatment temperature, which in turn plays an important role in controlling the properties of the glass ceramics, including physical, optical, and dielectric properties. The transparency of the glass samples decreased with increasing crystal size. The maximum room temperature dielectric constant (εr) was as high as 474 at 10 kHz with an acceptable low loss (tanδ) around 0.02 at 10 kHz.

Effect of Er2O3 dopant on electrical and optical properties of potassium sodium niobate silicate glass-ceramics

“…The average crystallite size is about 100 nm in length and 10 nm in diameter, which is small enough to reduce the light scattering and giving rise to high transparency of this sample. This result is consistent with our previous works [11,12], which have found that high heat treatment temperature increased the crystalline size, leading to the increase light scattering and decreased the light transmission in glass-ceramics until opaque. The FE-SEM micrograph in Fig.…”

“…KNN powder was firstly prepared by conventional mixed oxide method according to our previous work [11,12]. For incorporation method, the prepared KNN ceramic powder was then mixed with SiO 2 , in order to form transparent based glass.…”

Optical and Microwave Dielectric Properties of Phase Pure (K0.5Na0.5)NbO3 Thin Films Deposited by RF Magnetron Sputtering

“…The packing density of the annealed films was calculated by using following equation,where, n b is the bulk KNN refractive index (2.2) of KNN and n f is the observed film refractive index (at 700 nm). The thicknesses of the films were found to be in the range of 280–300 nm and 260–290 nm for as‐deposited and annealed films, respectively.…”

Outstanding optical temperature sensitivity and dual‐mode temperature‐dependent photoluminescence in Ho3+‐doped (K,Na)NbO3–SrTiO3 transparent ceramics

“…To achieve splendid optical transparency of ceramics, particularly high density with quite low porosity, absence of impurities, small‐sized grains, high crystal symmetry as well as very smooth surface are usually indispensable to extremely eliminate light scattering . Ferroelectric transparent ceramics, such as (Pb 1− x La x )(Zr y Ti 1− y ) 1− x /4 O 3 (PLZT), were first developed to combine the multielectrical properties of ferroelectric crystals with the transparency of a material matrix, making them suitable for the potential applications of smart phones, high‐power lasers, e‐readers, optical switches, optical integrated circuit, optical resonators, and microwave devices …”