Nanocrystalline Oxalate/Carbonate Precursors of Ce and Zr and Their Decompositions to CeO₂ and ZrO₂ Nanoparticles

Abstract

The oxalate and carbonate precursors of cerium and zirconium have been prepared using reverse micelles as nanoreactors. Cerium oxalate precursor on thermal decomposition leads to a mixture of nanorods and nanoparticles of cerium oxide (nanoparticles of 10 nm and nanorods with 7 nm diameter and 30 nm length). Cerium oxide with crystallite size of 10 nm was obtained from cerium carbonate precursor. Monodispersed nanoparticles of zirconia with an average size of 3-5 and 12 nm were obtained from the oxalate and carbonate precursor, respectively. Detailed dielectric properties of sintered discs of nanocrystalline ceria and zirconia have been studied with variation of frequency and temperature.

Controlled Synthesis of Nanomaterials using Reverse Micelles

“…The methodology followed was the reverse micellar (microemulsion) route with CTAB (cetyl trimethyl ammoniumbromide) as the surfactant 3 . For the synthesis of cerium oxalate precursor two different microemulsions, one containing cerium nitrate hexahydrate and the other containing ammonium oxalate, were slowly mixed and stirred for 15 h. The centrifuged product was washed with 1:1 mixture of chloroform and methanol and dried at room temperature.…”

“…Various types of materials, viz., dielectric [1][2][3] , magnetic 4,5 , and optical 6 , have been synthesised using the reverse micellar route. In addition, nanorods of a variety of transition metal oxalates 4,6,7 have been successfully obtained.…”

Hydrothermal Synthesis, Characterization and Dielectric Properties of Zirconia Nanoparticles

“…Thermodynamically most stable form of ZrO 2 is monoclinic. The cubical form of ZrO 2 is stable at high temperature (above 2370 °C), tetragonal form is stable between 1170-2370 °C whereas monoclinic ZrO 2 is stable below 1170 °C [20]. ZrO 2 is well known refractory oxide and a potential candidate as high k-gate dielectric material.…”

“…A number of binary oxides such as TiO 2 , Y 2 O 3 , ZrO 2 and some perovskites materials such as SrTiO 3 , BaZrO 3 , Ba (1-x) Sr x ZrO 3 and Ba (1-x) Sr x ZrO 3 have been studied as dielectric oxide material for complementary metal oxide semiconductor (CMOS) devices [24][25][26][27] but ZrO 2 have been investigated extensively as potential candidate for dynamic random access memory devices (DRAM) owing to its moderately high dielectric constant (k = 20) and higher thermal stability [28]. Numerous chemical methods have been reported to synthesize pure ZrO 2 , such as thermal decomposition [20], sol-gel methods [29], reverse micellar method [30,31] and hydrothermal techniques [32]. In this paper we have synthesized the single phase ZrO 2 nanoparticles to check their applications as dielectric material as a function of frequency and temperature.…”

“…To select any material as gate oxide applications, the first and very important requirement is high dielectric constant value. The material possessing too high dielectric constant value, such as for TiO 2 (~80), fringing fields from the drain through the gate dielectric are observed which may degrade the source to channel potential barrier and may lead to poor sub-threshold device functioning [13][14][15][16][17][18][19][20][21]. Pure zirconia has been known to exhibit anionic vacancies defects predominantly.…”