Insight into the Growth Reaction Mechanism of Ceramic Co₃TeO₆: Synchrotron Structural and Thermal Analysis

Abstract

A two‐step solid‐state reaction is proposed to synthesize monophasic cobalt tellurate Co3TeO6 (CTO), a type II multiferroic, using Co3O4 and TeO2 as the starting reagents. First step of the reaction results in the secondary monoclinic (P21/c) CoTeO4 compound, which on further calcination (second step) leads to the primary monoclinic (C2/c) Co3TeO6 phase. High‐resolution synchrotron X‐ray diffraction and the subsequent Rietveld analysis are used to probe different phases present in the synthesized CTO and to achieve its single phase. X‐ray absorption near‐edge structure studies at Co K and Te L edges reveal mixed oxidation states (Co2+/3+) of Co and hexavalent Te, respectively. Charge imbalance due to mixed valence Co ions has been attributed to cations vacancies. Enhanced multiferroic properties, such as effective magnetic moment, spin phonon coupling, etc., have been attributed to the aforementioned observations in grown ceramic CTO via proposed synthesis route.

Hydrothermal Synthesis of Ni3TeO6 and Cu3TeO6 Nanostructures for Magnetic and Photoconductivity Applications

“…However, the NTO_H diffraction patterns (Figure a) present a small broad peak at 31.08°, indicating possible impurities of another metal tellurate, NiTe 2 O 5 (PDF 00-027-1306). With the aim of deeply studying the crystalline structure of NTO, the sample was analyzed by synchrotron radiation XRD and converted to the same 2θ angle scale as lab-source X-ray (Figure a). , Under synchrotron radiation, XRD NTO_H shows mainly characteristic diffraction peaks of Ni 3 TeO 6 (PDF 04-009-2820), indicating that this is the main phase. However, a small peak at 31.62° is observed indicating the presence of a NiTe 2 O 5 impurity.…”

“…Previously, MTO such as NTO and CTO has been grown mostly using conventional synthesis approaches such as solid-state reaction and/or coprecipitation methods. ,, These processes show challenges in getting single-phase MTO materials probably because of the structural diversity of Te-based compounds and a wide range of possible Te–O bond lengths and in the size of the particles due to the high temperatures used. , Aforesaid potential applications and reported complicated synthesis demand a cost-effective and facile approach for MTO with improved performances and are the focus of the present work. Alternative synthesis of MTO materials can be found in wet chemical methodologies (sol–gel or co-precipitation) to enable the materials’ applications in photocatalysis, electrocatalysis, and sensors .…”

Unique Structure-Induced Magnetic and Electrochemical Activity in Nanostructured Transition Metal Tellurates Co1 – xNixTeO4 (x = 0, 0.5, and 1)

“…23 In addition, the signature of CoTeO 4 has been noticed as being the intermediate compound for type-II multiferroic Co 3 TeO 6 . 24 None of the reports, however, reported any functionalities. The present report, on the other hand, not only provides an optimized design route for such nanostructured MTeO 4 but also proposes a new structural model along with its implications on the observed magnetic and energy storage properties.…”

“…To the best of our knowledge, only two reports on CoTeO 4 and NiTeO 4 were published a few decades ago. , Sikač and Jenškovský reported the crystal structure of CoTeO 4 as cubic Pm 3 m , whereas Isasi reported the crystal structure of CoTeO 4 and NiTeO 4 as monoclinic P 2 1 / n structure . In addition, the signature of CoTeO 4 has been noticed as being the intermediate compound for type-II multiferroic Co 3 TeO 6 . None of the reports, however, reported any functionalities.…”

Shape-Controlled Synthesis of Cu3TeO6 Nanoparticles with Photocatalytic Features

“…13 However, one of the main challenges of the application of MTOs for sensors, solar cells, or photocatalysis, is the synthetic procedure. 7,14 A main synthetic route relies on the solid-state synthesis, but it fails to control the Te coordination, the morphology, and the particle size of the materials. 13,15 Besides, this methodology requires high temperatures.…”